Category Archives: Mark Hunt’s Weatherblog

March 12th / 13th….

Hi All,

This time last year we were basking in mid-teen, day temperatures and mild nights to boot and the grass had already been growing strongly for 3 weeks. In 2017, we packed on 30GDD in this week, whereas in 2018 we will be lucky to get to a quarter of that.

Bizarre really when you consider we have just had a nice mild weekend for most but the reality is that the Sudden Stratospheric warming (SSW) that took place in the third week of February looks set to leave a cold and wet influence on March 2018.

Image courtesy of Metman James (

I say that because the NAO index which is still sitting in a negative situation (i.e high pressure above us and low pressure below instead of the reverse) and as you can see from some of the weather model projections it isn’t due to cross that dotted line past the end of March. Now some models have this happening sooner (7 – 10 days off) but looking at the jet stream it is still sitting way lower than normal and it isn’t showing any signs of moving northwards till the weekend after next….

So low pressure systems are orientated south of the U.K instead of coming in from The Atlantic and this results in lots of rain. With the thaw last weekend and a wet week, last week for many, the ground is saturated and the bad news is we have more to come I am afraid until that jet stream pattern changes. It’s also likely that we aren’t done with the snow just yet and those biting easterlies (heaping on the good news…not)


I had a lot of feedback last week and over the weekend about the blog so to everyone that ventured an opinion, thank you very much, it is important to me.

For the time-being I am going to carry on with the present format although this week’s version will start on Tuesday from a weather perspective simply because I have had no electricity till lunchtime so no WiFi (cracking start to the week that :))

General Weather Situation

So I’ll start this week’s blog on Tuesday because by the time I’m likely to finish it, Monday’s forecast will be irrelevant. So Tuesday looks to start dry for most of us save for some wintry showers across the north-west of Scotland. By lunchtime we should start to see some gaps in the cloud base and sunshine across eastern and western areas including the east of Ireland. It won’t last for long here though as a rain band is due to push into western Munster in the early afternoon and push eastwards across Ireland and into The South West by early evening, with more rain to follow for Ireland overnight into Wednesday. Elsewhere, a dry and nice end to the day really just with the threat of an odd shower across The Midlands and Central England. Temperature-wise, 9-10°C for most areas and winds likely to be north-westerly for most places except Scotland where you are more southerly.

Onto Wednesday and that overnight rain will be set fair over most of Ireland by the morning rush hour and if anything intensifying across South Munster and Leinster during the morning, so some heavy rain forecast here. Nipping across The Irish Sea to the U.K, Wednesday doesn’t look too bad with some showers across the north-west of England / south-west of Scotland during the morning and across The South West. Elsewhere a cloudy start with hazy sunshine allowing temperatures to lift nicely into the low double figures through the day, so not bad at all really.  Ireland looks to have that rain all day on Wednesday, with heavy rain towards the south of the country for most of the day, I would expect there to be local flooding. Just after dusk we see some of that heavier rain push into The South West and into West Wales as well. Windier on Wednesday with a strong southerly / south-easterly wind.

For Thursday we see that rain over The South West push across the western half of the U.K overnight and it’ll still be there by the morning rush hour. Ireland will be drier but with another rain band following up behind the one now affecting the west side of the U.K. So by lunchtime we have two vertical bands of rain, one moving slowly across Ireland, the other sitting across a line from North Wales to the south-east of England. The picture will also be unsettled along the north-west coast of England and south-west of Scotland. The Midlands and east of the country will probably stay dry in the morning but that rain band consolidates and moves eastwards to give a wet afternoon here with some of that rain heavy over the north Midlands and north of England I’m afraid. Still unsettled for Ireland despite the bulk of the rain moving away through the day, more in the way of sunshine here though between the showers. Temperature-wise, cooler on Thursday with a strong south-easterly wind in situ so perhaps only just scraping high single figures in the wind.

Closing out the week on Friday we see that rain band now sitting from the North Midlands up to Scotland so a wet start to the day here. This rain band will push slowly northwards into Central Scotland as we progress through the day. South of this rain, a nice day on Friday with good spells of sunshine and much lighter winds. Ireland looks to have the same though still with a threat of a shower along the far south coast. These showers look set to move north through the second half of the day for Ireland, still with some sunny spells between them. For the U.K, that rain band will be slow to clear the east and north of the country with a threat of rain late on Friday across The South East and East Anglia. Late in the day there’s also a risk of a rumble of thunder or two in amongst that rain. Temperature-wise, a little up on Thursday and nudging into double figures especially where you see the sunshine across the south of England.

Ok so how is the weekend looking ? hmmmm…

There’s some disagreement among the weather models for the weekend or more precisely the exact timing of a change to an easterly airflow and plummeting temperatures. Meteoblue has this occurring on Saturday whereas most models show the wind changing from mild southerlies on Saturday to easterlies overnight into Sunday with an overnight frost and very cold temperatures during the day on Sunday. I think the weekend outlook will be reasonably dry save for some rain across Kerry and some wintry showers across Scotland and the north-east of England. Sunday looks reasonably dry at this stage but much, much colder and with the threat of snow showers across eastern areas blown in off The North Sea. It will really feel absolutely Brass Monkey’s weather when you open the door on Sunday morning.

Weather Outlook

So we have some potential good and bad news looking ahead at next week.

The good news is that it should be a lot drier than this week, the bad news is that we will see a return to some pretty un-typical March temperatures with Sunday and Monday in particular looking well parky. I’ve already seen the t****y headlines proclaiming a return of “The beast from the east”, ho-hum and all that, but yes we will have a period of northerly and then easterly winds commencing some time between Saturday and Sunday and kicking off into next week. The easterly wind is coming from a slightly different direction to previous so I can’t see it being like before in terms of snowfall and temperature extremes, but it will be cold and we will see some snow on easterly coasts. So expect overnight frosts probably from Friday night onwards and lasting till at least next Wednesday night, perhaps longer. I think we will be dry and cold though on the whole. That said with northerlies and then easterlies, there’s always a chance of moisture pushing in from The North Sea in the way of snow showers. Towards the end of next week there’s a suggestion that the jet stream will kind of ‘reset’ and assume its traditional place across Ireland and the U.K, thus returning us to a milder, westerly airstream and more normal temperatures. If this comes to pass it will mean a cold spell of around 5 weeks since the occurrence of the SSW.

Agronomic Notes

So with some slightly milder weather last week (albeit wet weather), we have seen signs of growth out there in some areas of the U.K and Ireland. I am also very aware that some northerly locations still have standing snow due to the magnitude of the drifts the previous week.

Soil temperature taken at 10 a.m. on Friday 9th March, 2018. Last year on the same day it was 8 degrees C

So where are we versus last year growth-wise ?

We are way behind last year as the graphs below of daily and cumulative Growth Potential show….

As you see from the above year-on-year graph showing cumulative Growth Potential we will have reached the same total on the 22nd March, 2018 (calculated by using forecasted temperatures as I haven’t quite mastered time travel as of yet..) as we did on the 25th February, 2017. That puts us about 25 days behind last year from a growth perspective.

SSW’s aren’t good news for business or growth….

If I compare it with 2013, when we also had a late SSW event, you can clearly see the similarity between 2013 and 2018 in terms of low growth levels through March..

So my advice is plan for a low temperature run through March in terms of nutrition….

Stop – Start Growth Signs..

Yes I know we talk about this every year and in fact I tweeted this image on Friday because I thought I’d drag myself into this century and use Twitter more….I had a lot of reaction so thanks for that…

The above shows some biotypes of (in this case) Poa annua displaying the typical purple colouration that we associate with a run of warm days and cold nights. During the day (and in particular on turf areas that are more out in the open) the grass plant produces sugars by photosynthesis but with rapidly falling temperatures at night, these sugars are not translocated from the leaf. They therefore accumulate and in so doing bind to a purple pigment called anthocyanin. The upper layer of the plant leaf then takes on a purple colouration, as opposed to the more usual green that we associate with the pigment chlorophyll. The biotypes that are growing better during the day display a purple pigmentation vs. other biotypes that are slower growing which remain green. If you look closely at the purple areas with a hand-glass and turn the leaf over, you’ll see it is only the upper leaf surface that is purple, the underneath is still green. This is because the upper leaf of the grass plant is exposed to the greatest temperature variation.

Now I’ve seen this pigmentation on Poa annua and Bentgrass, but not on Ryegrass so I’m interested to know if anyone has noted it on the latter ?

Normally the purple pigmentation grows out once temperatures become more stable, in particular night temperatures, so that won’t be anytime soon then eh ?

Disease activity

Last week I included this image of new activity around existing scars and sure enough we saw quite a bit of disease activity of this type through the week, courtesy of some pretty rapid increases in air temperature accompanied by high humidity. This mix as we know is very conducive to Microdochium nivale development.

Downloading my faithful little Netatmo Weather Station’s readings for last Monday highlighted the above conditions clearly…

The columns marked in red show when conditions were in favour of disease development. We can see this was from 10.42 a.m. right through till 4.42 p.m. on the 5th March, that’s 6 hours and more than enough time for this pathogen to develop mycelium. The humidity was flat-lining at 100% for pretty much the entire day with only a short period (2 hours gosh golly) when it dipped down to 96% ! In other words the plant leaf surface was pretty much saturated with moisture, another reason why fungal mycelium could develop.

Not the only pathogen problem at present…

As many Corvids (Crow species) currently have young in the nest, they are on the hunt for food and so pecking damage is very much in evidence on turf surfaces be it golf, cricket or race courses. I saw Magpies doing this damage on the approach to a golf green and expected to find Leatherjackets as the intended target but was surprised to see Bibionid sp. larvae (shown below)

These are larvae of species like Fever Fly or the most-aptly named, St Mark’s Fly (nice to have a fly named after you 🙂 ) and are found in clusters just below the turf surface in the upper layer of thatch. I say surprised because I’ve seen these larvae at the same stage of development in December so they’re obviously like grass, a bit behind the curve….Nothing really we can do right now for this species or the other types of insect larvae present at this time of year.

Behind the curve on shoots but maybe not roots…

The other interesting point that I would make before signing off this blog in the middle of a damp and dank Monday evening relates to the image above. I’ve noted lots of white roots in evidence on cores I’ve taken recently even though as our GDD / G.P information shows we are a long way behind the curve growth wise in terms of top growth. It’s a fact that when the plant isn’t putting its efforts into top growth (leaf shoot growth), more resource (biomass) is available for root development and although the temperature cut-off for leaf shoot development is around 6°C air temperature, root development in grasses appears to continue right down to 1-2°C . Part of the reason for this is that the soil provides some insulation to the effects of colder air of course, but part is due to a partitioning effect in terms of growth between leaf and root biomass production. When conditions are conducive to growth (light, temperature and moisture) and particularly when there’s surplus nitrogen around, the grass plant will divert its energies into shoot development at the cost of root development. This clearly isn’t the scenario now and so that’s why you are more likely to see some pretty positive root development at present, particularly if you’ve carried out some early season aeration (that old chestnut again you sigh…)

Ok that’s it for this week, sorry for the delay in posting this blog.

All the best for the coming week and wrap up well if out and about at the weekend 🙂

Mark Hunt




March 5th

Hi All,

Well that was a week and a half weather-wise and I know for Scotland it isn’t quite over yet in terms of recovering temperatures and a thaw. I ventured out into the countryside for a walk (climb) on Saturday and have never seen drifts like it, they were literally huge.

Amazing then that when the thaw started on Saturday night and through Sunday, such a large amount of snow disappeared so quickly. Now I’m not talking about these type of drifts, they’ll be hanging around for a while yet, but in general the snow in the fields went so fast. Part of this was because the real level in the fields was quite low as it had been pushed into drifts along the hedgerows. Part of it is because the snow had a very low moisture content so it didn’t pack down as hard, had more air spaces between the flakes and then when the air temperature increased, the melt occurred.

Snow to rain ratio

Usually you can work on 10mm of snow = 1mm of rain as a rough guide but this ratio can run as high as 50:1 with fine powder snow. In the latter, 300mm (12″) of powder snow can be equivalent to 6mm of rainfall.

The severe weather brought some unusual birds into the garden as well, not because they’re rare but because I don’t normally see them. Fieldfares took full advantage of the Apples I put out (I found putting them on skewers allowed me to slide them up above the snow as it fell saving them from being buried), Pied Wagtails and even a Treecreeper landed on my patio to feast on Mealworms, it must have been hard for them this spell of freezing weather.

One last point before I leave my anecdotal weather ramblings, yesterday it was a heady 5°C when I was fly fishing but it felt so warm compared to the earlier days freezing temperatures, I didn’t even need gloves on. Isn’t it amazing how quickly the human body adapts ? The Trout were a little picky though 🙂

So the thaw is well under way in most places south of the Scottish border but we aren’t totally out of the woods yet because the jet stream is still lying lower than normal and we are sitting in a cool temperature trough. The Unisys GIF above for today clearly demonstrates this. So a thaw yes, but a recovery to normal March conditions not. The same week last year we sat with maximum air temperatures between 10-15°C, this week we will be lucky if they just break double figures. The long-term prognosis is that we are to stay in this trough pattern until at least the middle of March and perhaps longer. In other SSW event years, we have seen the subsequent low temperature effects carry on for a number of weeks, so yes things will improve, but no we aren’t back to normal just yet.

General Weather Situation

I had some good feedback last week on my blog and its format, specifically this part (thanks Adam) where my friend and colleague said that he rarely reads this part of my blog because he can get that from a forecast, it’s the longer-term and agronomic notes part that is important for him. Now this part takes a good chunk of time so can I ask for some feedback if you agree or disagree with the above please as I’m always looking to save time 🙂

So onto this week and Monday sees a North-South divide in place with north-east Scotland still on the receiving end of wintry showers through this morning. There’s also a band of rain moving up the east Leinster / north-west England coastline through the morning. Elsewhere we look to be dull, dry and calm with a noted absence of wind. That’s the way we are set to stay through Monday save for a rain front that is due to affect The South West and south coast later this afternoon, pushing up into Central England and The Midlands through the evening. You can see the North-South divide in action today with a wintry 3°C for Scotland, 9-11°C for Central England and Wales and 6-7°C for Ireland.

Tuesday sees that overnight rain across the south of England pushing up through Wales, the north of England and The North East by morning rush hour. As it meets the cold air sitting still over Scotland it will turn to sleet and snow at elevation so winter is still knocking at the door for you guys I’m afraid. By lunchtime the rain has cleared The Midlands and will be affecting the north of England and still falling as wintry showers over Scotland. Ireland looks to have a dry day over most of the country save for some rain that’s into Kerry and will push north and east across into The Midlands through the day. By late afternoon we may just see that cloud cover break across Wales and the west to give a sunny end to the day. Temperature-wise very similar to Monday 3°C for Scotland, 9-11°C for southern England and Wales and 6-7°C for Ireland. Winds will be light to moderate south-westerly.

Wednesday sees a drier day on the whole but still unsettled with a risk of wintry showers over Donegal and the north of Ireland and the north-west of England / North Wales. Dull again with maybe a chance of seeing the sun down in Kerry but perhaps not for long as some wintry showers are due there during the morning. For the south, central areas and The Midlands, a dry, dull day, a little cooler than Monday or Tuesday but fine really when you consider where we came from. Through the afternoon we will see those wintry showers push up into Central Scotland and also some new rain fronts push into The South West and across South Munster / Leinster. A little cooler on Wednesday dropping a couple of degrees off the temperature for the day so 3°C for Scotland, 7 – 8°C for England and Wales and 6-7°C for Ireland.

Thursday starts dry for most areas except the north of England where we will see a re-occurrence of wintry showers and rain dependent on elevation and a consolidated rain front across The South West. The latter will quickly gather up its heels and sally forth into Central England, Wales and The Midlands through the morning with some rain also crossing Ireland from The South West. Still some wintry showers affecting the north-east of England but Scotland for once looks drier and sunny. At this stage that band of rain over England is due to only progress up to Nottingham sort of way so a wet day down south and forThe Midlands on Thursday. Ireland will see those showers cross through the day but you’ll also get a glimpse of the sun across the south-east of Munster. Similar temperatures to Wednesday but with a changing wind dynamic switching to more northerly for a brief time as we end the day.

We close out the week on Friday with a settled, dry picture across the U.K and Ireland save for some wintry showers crossing Scotland from The South West and also some snow showers across Donegal. Dull again as is the theme for this week but by the afternoon we should see that cloud break over Ireland, the north of England and The Midlands. Staying dry for pretty much the whole day with similar temperatures to the rest of the week but enjoy it because we have a deep low on the way 🙁

So you’ve probably guessed it already but the outlook for the weekend is most definitely unsettled with a deep low pressure pushing up from south west of the U.K. (Because the jet stream is low) Now of course timing is everything and it might not reach us till Sunday so if I wanted to try and get a dry day out there then Saturday would be my pick but it’s by no means guaranteed !  A clear sign that it’s heading your way will be the wind direction changing from south-westerly to south-easterly though temperatures will be up around high single figures so not bad. With the low coming up from the south it won’t likely reach Scotland till later on Sunday but I expect it to be pretty entrenched over Ireland and the southern half of England by Saturday tea time. Much windier at the weekend as well with winds easterly for the U.K and a chiller northerly for Ireland.

Weather Outlook

Ok so is the jet stream likely to take a hike north back to its usual place or will we stay in our cool trough ? So first off I consult my oracle – Metman James 🙂

Image courtesy of Metman James, you can find him on Twitter here…

As you can see from the above, the highly negative North Atlantic Oscillation (NAO) that followed the SSW (it’s all acronyms you know), we are slowly pulling back towards normal but as intimated in last week’s blog it won’t be until the middle of the month that we start to pick up a westerly airflow and a return to more typical March temperatures. Even then I can’t see us losing the cooler trough pattern in the jet stream. So my feeling is that we will continue cool and unsettled with a high chance of a re-occurring low pressure systems with a southerly orientation i.e they come in from the English Channel as opposed to The Atlantic.

So next week I think will start unsettled following that deep low pressure system that arrives at the weekend with frequent rain showers across the U.K and Ireland and a strong north-westerly wind.  Now the North-South Divide is likely to continue so I expect Scotland to have more in the way of northerlies and wintry showers I’m afraid. Once that low has rattled through I expect a quieter time on Tuesday and Wednesday as we are between low pressure systems before the arrival of a new low pressure system into the south of the U.K on Thursday. This means a change back to strong easterly winds (likely to stay on the cool side then) and more rain for the end of next week. Now there’s not a lot of agreement in the models as we speak although on Jame’s GIF above you can see a dip in the NAO on Thursday 15th which will be that low pressure system I’m on about above.

If I really mystic meg it, I think we will be into a westerly airstream around about the 17th March and that’s when we will see a true return to March’s normal temperatures and critically better night temperatures, always the hand brake to growth.

Agronomic Notes

Ok so since it’s the first blog of March I’ll take this opportunity to play ‘Spot the GDD in February’ 🙂

February GDD – U.K Location – Thame

So we can see that pretty much nothing went on at this location during February 2018 with nearly the joint coldest February we have recorded in line with 2010, but not as low as 2013.

I looked back at the SSW event in 2009/ 2010 and although it occurred earlier in the winter, we also experienced an SSW around February 9th, 2010 which is about 10 days earlier than the date of the SSW we experienced in 2018.  You can see a great animation of the 2010 SSW here

So where am I going with this SSW analogy ?

Well looking back at the weather data from this location in 2010, it took 5 weeks from when the SSW occurred for the wind direction to swing back to westerly and temperatures to rise to their March normal. Interestingly this occurred on March 15th, 2010.

This suggests that it took the jet stream 5 weeks to swing back to normal after a negative NAO back in 2010.

Our SSW event occurred on Feb 17th so if we apply the same logic then 2nd-3rd week of March is a similar outcome. We also experienced SSW events in 2013 which saw extended cold weather right through till the end of March with heavy snowfall on the 25th March, 2013.

During late winter 2016, we also experienced an SSW and looking back at my data, that took 4 weeks to right itself, so we can tentatively conclude that on average it takes 4-5 weeks after an SSW event for things (NAO, Jet Stream, etc) to right themselves but as 2013 showed us, this isn’t always a cert.

What we need to see for certain to know we are on our way back to spring is for the NAO to return to positive and cold air to re-assume its place over the North Pole. Last week The North Pole wasn’t even freezing and was some +35°C warmer than normal due to warm air being pushed over the top of the blocking high pressure system.

Cumulatively speaking 2018 already represents a cold start to the year at this location when we compare it with 2017.

In 2017, we reached a cumulative GDD of 36 on the 3rd of February, this year we reached it on the 28th February so that’s a good 3 1/2 weeks behind last year already and I expect this gap to grow because in March 2017 we piled on the GDD.

In this week last year we recorded 26.5 total GDD at this location, this week I think we will be lucky enough to record 5-6 maybe, see what I mean about not being back to normal ?

What to expect in the coming week ?

Well depending on your location you may already have gone through a phase of rapid thawing yesterday when the air temperature increased and we had mild air temperature rainfall. This is always a difficult time on a golf course or sports pitch because the upper region of the rootzone thaws first and deeper down it is still frozen solid. Initially when only the extreme upper layer (10mm) thaws you can get a very unstable surface with the upper layer shearing off from the frozen lower layer.

Once the thaw has extended deeper into the profile then you gain stability and I believe less risk of surface shearing. The problem is the surface looks thawed and so Joe Public will want to get out there and play but if you have slopes / mounds etc there is a pronounced health & safety risk until the thaw sets in deeper into the profile.

Looking at the temperature profiles across the U.K and Ireland I would have expected most of England, Wales and Ireland to have gone through this thawing cycle yesterday but areas like The Lakes and the entirety of Scotland will still be frozen and receiving more snow turning to rain through this week so possibly your pain is yet to come I’m afraid 🙁

Microdochium activity – How low can you go ?

The other month I was fortunate enough to share the floor with Kate Entwistle at the BIGGA Turf Managers Conference when we gave a presentation on Microdochium nivale. Kate’s task was to  briefly and I mean briefly  (because I didn’t give her much time:) ) to give a microbial perspective on this disease (and Anthracnose as well). True to form, Kate did this with time to spare (Cheers me dears) and in her part of the talk she covered the temperature range in which Microdochium is active. Although its favoured growth temperature is around 20°C, it’s main temperature range for infection is 0 – 15°C, but it is capable of completing its life cyle down to -5C.

So I took some soil temperature readings under the snow canopy last week and the average was 1.6°C, in other words not frozen even though we went into the snow cover rock hard.

So it is no surprise to see images like this of an old disease scar plug with new activity present emerging from the snow cover. This clearly suggests that disease development continued under the insulating effects of snow cover. Whilst we can expect to see cases like this with new activity around an existing disease scar, I’d be interested to know if anyone sees new infection during the same period, so please send me your feedback.

Things to do….

Now obviously if you’re reading this still staring out the window at snow drifts or a flooded surface, you can disregard the next paragraph. It’s a fact though that some regions of the country will dry quickly after this thaw and therefore some of you will be able to get out.

First off we have a pretty wetted-up moss plant so now is the time to hit it with an approved High Fe Mosskiller if you were thinking of applying it in the spring. It’s probably too early still for the chemical Mosskiller’s (Mogeton and the like) until we can clearly see the other side of this post-SSW weather event and so are guaranteed good grass growth. Species like Silver Thread Moss have to be fully wetted-up prior to application to gain any kind of benefit so the next couple of weeks could be an ideal time for treatment if a growth window presents itself.

Secondly, if you are planning aeration or carried it out just before the SSW event then you’ll be looking for some growth and recovery. Now obviously it’s staying cool with only a small amount of growth but for me this week would be ideal to apply either a liquid tonic when the air is warming or a granular feed if you need to promote more in the way of growth for longer because we have good levels of soil moisture and some rain throughout the week to enable granule breakdown and then recovery.

It goes without saying that your N sources in your chosen products should be immediately-available if you are looking for a plant response, so that’s ammonium sulphate, nitrate and / or potassium nitrate at this time of year rather than something like urea which isn’t immediately-available to the grass plant.

Urea requires the presence of an enzyme to catalyse the conversion from unavailable nitrogen to available nitrogen and since that enzyme will be in short supply in a cold soil, don’t expect anything to happen quickly with urea applied to the soil in the spring. With low soil and air temperatures giving low Growth Potential / GDD, there’s no point in applying lots of N in either form because it won’t be utilised so small N inputs are key, 4 – 6kg / N / Ha as a foliar / liquid or 12- 15kg / N / ha as a granular.

I like to split my N forms at this time of year between the immediately-available and the slowly-available, be that urea or organic N, so you get a quick response and then some longevity as well as the more longer-term N is released. Horses for courses though.

Ok that’s it for this week, remember to let me know what you think are the key parts of this blog for you and if you’ve seen any disease activity after the thaw, new or old.

All the best.

Mark Hunt

February 26th

Hi All,

As we tip-toe out of February later this week we will at the same time endure one of our coldest weeks of the year. February 2018 will also go down as one of the lowest GDD months we have recorded since we started this process back in 2010. Looking at the stats from my faithful little Netatmo weather station on Weather Underground it shows that for the 26 days of February so far, we have had frosts on 20 of them and given that the last days of February are dead cert frost days, that’ll be 22 out of 28 days frosty, nearly 80% of the month, hardly a surprise then that we didn’t see much GDD or grass growth this month.

As forecasted last week, the Sudden Stratospheric Warming Event (SSW) has indeed reversed the direction of the sub-polar jet stream by pushing the main jet south of us down into The Azores and leaving us with a blocking high sat right over us. The cold easterlies that were predicted when we have an SSW have also come to pass so there we have it, we called it a week before.

It is a major meteorological event, this blocking high pressure is forcing mild, wet air right up into The Arctic causing temperatures to jump there by 35°C and no doubt leading to more concerns about the fragility of the winter ice pack, (already the thinnest it has ever been) meanwhile the politicians sit on their collective fat behinds. (Day after Tomorrow comes to mind)

My our NAO looks negative 🙁

Image courtesy of Metman James –

We also have an extremely negative NAO at the moment don’t you know, NAO stands for North Atlantic Oscillation and is the relationship between what is normally high pressure in The Azores and low pressure across the Atlantic (that’s known as a positive NAO). Well our one is negative because the high is above us, the low’s are below and the oscillation is severe. Why is NAO important ? Well until it swings back positive then you can forget about much in the way of mild weather and growth. It is therefore a good yardstick to watch over the coming days for indications of a change away from this cold spell. You can see from the above that most projections are indicating that this cold weather will be with us (though not as severe perhaps) till possibly Mid-March.

I started a lot of my GDD work back in 2013 when we had a brutally cold spring and people were asking me “How far behind last year are we ?”, I couldn’t tell them definitively so I got to work on using GDD. This spring I think I am going to get that question a lot.

So as we look to the coming week and the threat is of snow, particularly on eastern coasts and The South East / South pushing across to The Midlands and the like at the end of the week. Already I can see the odd large, dry snowflake whisking by my window and this is just the start.

Last week I happened upon a smart weather chap, known as Metman James on Twitter, who is a Meteorology PhD student at Exeter University and we got chatting. He has some great GIF’s and output on his Twitter feed that highlight the weather situation and a prognosis for when it is likely to change. You can find him here.

General Weather Situation

Before I start this forecast I’d like to point it that it’s probably one of the hardest ones to call, first, when and where the snow showers will affect during the early part of the week and second the extent of the heavier snowfall event likely Thur p.m. / Friday. (and when and where it may turn to rain) So don’t whine at forecasts and the fact that it keeps changing, because it will. Just get hooked up to some proper rain (and therefore snow) radar and look not only at where that moisture is occurring but also from which direction it is coming from. That way you’re properly prepared.

Ok so we start Monday after another cracking frost (-2.9°C) and begin a cold and largely dry, bright day with some hazy cloud and sunshine. There is however a risk of snow showers spilling in off The North Sea and this risk will heighten as the day goes on. Already on the radar we can see a raft of snow showers affecting the east coast from Hull south and another band spilling in across Suffolk and Essex across London and into the south of England.  Really anywhere south of The Borders is fair game today for snow showers and whilst these will affect eastern coastal areas initially, they will increasingly push inland so keep an eye out. Wales, the west coast and Ireland will have the majority of the sunshine and in it expect temperatures to leap up to a positively tropical 4-5°C. Elsewhere closer to that moderate, easterly wind, expect this to be more likely 2-3°C with a negative windchill.

Onto Tuesday and a heightened risk of wintry showers, this time more likely to give significant accumulations where they occur. Area-wise I would expect a similar pattern across southern England, East Anglia, the east coast all the way up to Aberdeen this time. We can also expect more significant snowfall further inland over northern England and into Wales I think as well. Similar temperatures to Monday perhaps colder across The Irish Sea as those easterlies extend their hold. Snow is even harder to forecast than rainfall so your best bet is to get onto a website that shows active radar and this will give you the heads up as to where the moisture is occurring and heading. I use Netweather for my output because it’s more national but you can get it specific for your area down to 500m2 which is pretty handy. There are lots available though, Netweather radar can be found here

Wednesday looks a re-run of Tuesday with a harsh penetrating frost and a bright, sunny, cold winters day. Again plenty of snow showers around and as the cold intensifies, the westerly reach of those snow showers extends into Wales and across the Irish Sea into Leinster. Again the majority of snow showers is along the eastern coastline of the U.K but plenty of chances of them moving inland. The wind strength will begin to ramp up on Wednesday and with a colder start to the day and stronger winds I’m not sure the temperature will get above freezing and it will be accompanied by a windchill down the wrong side of -10°C I think ! In other words, bloody freezing.

Thursday, the first day of March, will I think be the coldest day of the week with the hardest frost anticipated down to -7°C I think and possibly colder !  Overnight we have seen plenty of snow showers with accumulations right across the U.K and eastern coastline of Ireland. The suggestion is that the worst snow will be Midlands and north but I think there is plenty of time for this to change yet.

Thursday is very much the change day because we come under the influence of the southern low pressure system that is potentially due to bring heavy snow to many parts of the south of England later in the week. The first thing you’ll notice on Thursday morning is the wind strength as the isobars are packed tight together so the windchill accompanying the severe frost will be down in the -15°C region, seriously parky and not for the faint-hearted. That low pressure system south of England will begin to bring in snow showers and heavier accumulations to the south coast and up towards the M25 / M4 (Oh joy of joys) Expect more in the way of snow across Scotland and The Midlands pushing across Wales and Ireland as well, whipped along by that fierce easterly wind. High winds, bitter windchill and snow showers will continue through Thursday night.

Friday sees I think the highest threat of heavy snow however we are also seeing a temperature lift across the south of England so there’s a great deal of uncertainty of whether we will see snow or snow then rain. I’m thinking more likely the latter across the south of England, Wales and Ireland turning to snow as it moves further north. Temperatures will rise through the day with 2-3°C likely across the south and below freezing across The Midlands north but through Friday evening that milder air will push further north so snow turning to rain with a thaw is likely I think. For many Friday night may be frost-free as that thaw continues into the weekend with Sunday likely to be much milder. Bizarre, bizarre. That strong to gale force easterly wind will continue to blow hard through Friday but will moderate through the latter part of the day. At this stage I think the worst weather will be across The South West, South of England, Ireland, Wales extending into The Midlands. As I mention earlier the likelihood is that this moisture falls as snow initially giving way to rain the further west you go I think.

So the outlook for the weekend….

So we are in the grip of that English Channel low pressure system over the weekend and actually extending through Monday so that means very unsettled through Saturday with high winds, rain, sleet and snow showers principally affecting the south west corner of the U.K, along the south coast and across Ireland and Wales as well. Scotland you are the right end of the country for once but I still expect snow showers for you as well. Again the uncertainty is in what form this moisture will fall, but fall it will so a very unsettled day for Saturday, but feeling slightly milder with southerly / south easterly winds initially swinging more northwards. Across the south of England we may see temperatures up to 7-8°C, but knock that down to 2-4°C for Wales, Ireland and The Midlands north. Again uncertainty about where that moisture will fall but likely to be more rain than sleet across the south of England turning more wintry as it pushes north on Saturday evening. Sunday sees that rain band more across the north of England and perhaps southern Scotland now, falling as rain, sleet or snow depending on elevation. Milder air pushes up behind this moisture band to give a drier day across the south of England, Midlands, Wales and Ireland with temperatures on the up, touching double figures possibly across the south on Sunday. The wind will still be easterly but possibly dropping down through Saturday to a more moderate status.

Weather Outlook

So next week looks like being another complicated one to forecast but at present I expect us to remain unsettled with that low pressure lying in a trough created by a southerly positioned jet stream. That means the low will stay south and then gradually move north and east through the early part of next week so I expect heavy rain, sleet or even snow for the first part of next week down south, drier for Ireland, the west and north though. As we go through the week those easterlies will become northerlies so no quick return to mild weather but perhaps not as cold as this week with less in the way of frost. So a drier end to the week possibly as that low pressure system moves away but staying cold.

Agronomic Notes

As you can see from these wilting Hellebores in my frozen flower bed we have frost desiccation at work this week in some parts of the country. Out walking yesterday it was amazing to walk across 2 ploughed fields that last week left most of the field on my boot such was the stickiness of the soil, to this week when it was powder dry on the surface. This is the result of frost desiccation where water is frozen in the soil and therefore unavailable to the plant, it may also be due to water within the plant itself freezing. As temperatures increase the plant re-establishes its internal osmotic balance and the wilt corrects itself.

Cold temperature desiccation can lead to discolouration of shallow rooted grasses for the same reason as we see in the hellebore above. I took this picture many moons ago and in it you can see bleached patches of I think Poa annua var. annua which were subject to cold temperature desiccation. I expect to see the same occur this week, such is the severity of the frost and in some parts of the U.K, dryness of the soil as well.

For all of you guys that have aerated and topdressed recently then I expect you’ll also see some frost heave where the sand is pushed back up to the surface by the result of ice expansion in the soil down the core holes.

On the subject of soil dryness, I was asked last week to do a rainfall comparison that highlighted what a wet winter it has been across the north-west of England. Frost desiccation won’t be an issue here unfortunately. As you can see from the rainfall comparison above of 3 areas of England, The North West has experienced nearly 150% more rainfall than Oxford or Birmingham. This recent run of cold and frost is just the thing those guys need.

When are we likely to see growth again ?

With many areas of the U.K only experiencing 2 days of growth in February but still experiencing winter wear, it is likely that the pressure for growth will ramp up as we get into March as tees, walkways and winter season pitch areas begin to show the signs of a long winter with very little recovery growth. As discussed at the beginning of this blog, the critical point to watch for is when the NAO switches back away from its current negative value. What this weather jargon means to you and me is that in order for the weather to right itself,  the high pressure needs to move away and be replaced by a milder, westerly airstream and that effectively would translate to a positive NAO.

So what are the weather models saying ?

If we look at the projection for the NAO, it isn’t expected to hit neutral and swing to positive until the middle of March, the models predicting the jet stream position also agree. So I don’t expect us to see much in the way of mild weather until w/c 12th March, that’ll be 3 weeks by then of cold weather with easterly and northerly winds dominating. Now of course all this is a long way off and things can change one way as quickly as they change another but we have had an SSW and the associated easterlies, so a cold 1st part of March is looking increasingly likely.

Thaw on frozen ground risk…

For the areas in line for the main snowfall (south of England, Midlands, Ireland, The South West, etc) on Thursday night / Friday there is a risk of flooding on Friday / Saturday I think. This is because the hard frosts of earlier in the week will have frozen the ground solid to a significant depth and so snow thaw / and / or sleet / rain (depending on what we get) on top of this will have nowhere to drain causing water to perch on the surface. Another potential issue is instability in the surface as it begins to thaw over a frozen rootzone, this can be extremely tricky on sloped areas and certainly presents a Health & Safety hazard until the thaw is deeper and the surface regains stability. One to watch in areas that receive the penetrating frost and then heavy snow / sleet rain and temperature rise shortly afterwards.

Ok that’s me this week, bit of a short agronomic blog but the focus point is more weather than agronomic at the moment. Wrap up well this week, especially on Wednesday and Thursday and keep an eye peeled on the weather radar.

All the best.

Mark Hunt


February 19th

Hi All,

With temperatures into double figures at the weekend in some locations and probably into them today in most, you could be forgiven for thinking that spring is on the way and we have turned the corner from winter. Last weekend I was walking in horizontal sleet and snow with all my layers on, this weekend gone I could have walked in a T-Shirt. Next weekend hmmm more about that below….

Image courtesy of Netweather…

Unfortunately the arrival of an early spring is unlikely to be the case in 2018 because of an event taking place way above our heads in the upper atmosphere known as Sudden Stratospheric Warming (SSW). I am indebted to Mick over the Irish Sea for bringing this to my attention at the back end of last week. A Sudden Stratospheric Warming event is not uncommon at this time of year but its effects on our weather can be profound and prolonged, you can read a full explanation of what constitutes an SSW here.

In a nutshell the occurrence of an SSW can fundamentally disrupt the flow of the jet stream to a point where it stops and even flows back in the opposite direction to its normal west – east flow. This then allows cold air to flow in from the Arctic east / Siberia and we have a prolonged period of cold until it kick starts again. Now the other point that should be said is that there’s no real way of predicting what’s going to happen beyond the 5-day mark forecasting-wise because an SSW doesn’t always result in prolonged cold weather but all the indications are in my view that it will do. The last time this occurred was in March 2016 and before that, January 2013, and you’ll remember how cold those springs were with snow still in the hedgerows at Easter in 2013.

Another feature of an SSW event is that we also see a shift in the position of the jet stream far to the south of the U.K and looking at the output from Netweather for this coming weekend we can see the main body of the jetstream is flowing over North Africa instead of mainland Europe. I for one have never seen it this far south.

You’ll note the deep meandering split from the jet stream over the U.K which will allow a blocking high pressure to establish over us and set in place an easterly airstream that has its origins across northern Scandinavia and Russia. Now eventually the speed and position of the jet stream re-establishes and we come back into a milder westerly airstream and currently the prediction is for this to occur in early March so we are likely to pick up 10-14 days of cold weather as a result of this SSW. I say ‘likely’ but there is great disagreement and uncertainty when an SSW occurs in forecasting beyond 5 days so I must add the caveat of watch this space and your forecasts from the weekend onwards, if you see temperatures diving and the wind direction in the east then the SSW is having its predicted effect.

One last point and it is a positive one for our industry I believe, SSW’s in my experience tend to bring in cold weather from the east but seldom wet weather so if you’re looking for a dry spell to finish off winter projects or just to dry your golf course out then you may well get it.

If you take a look at the Unisys graphic at the top of this blog you’ll see the unusual phenomenon of weather systems moving east to west towards the end of the run, that’s the SSW effect they’re projecting.

General Weather Situation

So Monday starts off mild but overcast for most of us with a band of dissipating rain sitting across central and eastern regions of the U.K in a vertical line all the way from the south coast up to Scotland. Through the morning this will drift eastwards and depart into The North Sea to leave a dull but very mild day for all of us. Ireland the same, dull, cloudy but mild with I think South Wales picking up the mildest temperatures just shy of 15°C, treasure them because you won’t be seeing the thermometer anywhere close again for awhile me thinks. Come the back end of the afternoon we see a new rain front push into west Munster / Connacht and move eastwards across Ireland and also the west coast of Scotland later on Monday evening. Winds will be light and more north westerly I think.

Tuesday sees another mild night / start to the day with temperatures unlikely to dip below 6 – 8°C in most places overnight and almost a re-run of Monday with some light rain sitting across the north east of the country and moving off into The North Sea through Tuesday morning and leaving us with another pretty dull day with the exception of Scotland which will see some brighter weather over central parts through the 2nd half of the day. We may also see the sun across the west of Ireland and along The Bristol Channel. A slightly cooler feel to the day as an arriving high pressure (cue the first piece in the SSW puzzle moving into place) brings a more northerly airstream into play, so 7-10°C is likely in a moderate to strong northerly wind with again Wales likely to be warmest.

Wednesday sees that wind swing round to the north east and so we see temperatures take another dip down from the previous day, this time towards the 5-6°C region and that’ll begin to set the stall out for what may well transpire if the SSW plays out as predicted by some weather models. With any easterly airflow it’s usually the west of the country and Ireland that sees more of the sun because of the propensity for ‘Haar’ and low cloud to push in from The North Sea and that is likely to be the case on Wednesday with brighter spells across Ireland and the west and here we will see the highest temperatures and cloud cover for the east. Dry though.

Thursday sees the wind turn full on easterly and perhaps in the direction we shall be accustomed to for a little while and so a mix of cloud and sunny intervals on Thursday, a light to moderate easterly wind and dry. Not really the end of the world though is it ? We will probably get our first night frost on Thursday night and this will then kick in a succession of night frosts I think dependent on cloud cover. It has to be said that because we have easterlies in situ, then the west will have the best of the temperatures with Ireland perhaps sitting in the 6-8°C range vs. 2-4°C for the east of the U.K.

We close out the week with a much colder day on Friday with again easterly winds in situ. A mix of cloud and sunshine though and dry so really a repeat of Thursday except we are starting each day from a progressively colder base as the degree of overnight frosts ramps up. This will especially be the case for the coming weekend where I think we will pick up some pretty keen night frosts. So dry again and with sunshine and patchy cloud, not a bad day but a pretty cold easterly wind. Temperature-wise I think Ireland will be warmest at 5-8°C and the east coast of the U.K, the coldest, at 2-4°C.

The outlook for the weekend is pretty similar to the end of the week I think but for the fact that we will have some pretty severe night frosts across the U.K, I’d say -3 / -4°C territory with Ireland just staying the positive side of a frost. The other feature of the weekend will be a strengthening easterly wind which will push in more cloud cover and ramp up the windchill so lower day time temperatures and less in the way of sunshine for central and eastern areas with the best chance of seeing the sun across the west. Truly bitter weather for sure so wrap up well with a negative windchill likely.

Weather Outlook

As mentioned right at the start of this blog there is a great deal of uncertainty surrounding where the weather is likely to go after the weekend with broad disagreement between models but I’ll pin my flag on Unisys’s interpretation and we will see how we get on. So I’d say next week looks to be a bitterly cold one with biting easterly and north easterly winds pushing cloud cover in off The North Sea, ‘Baltic’ would sum it up. There may be a risk of wintry showers from eastern and central areas as a nearby low pressure feeds moisture into the airstream but currently this doesn’t amount to much (but we will see). There’s a sneaky low pressure passing very close to the south coast later on next week and this will be one to watch if it nudges northwards but at this stage it is set to miss us. Later in the week the wind edges round to the north east to rachet down the temperatures even more. The only saving grace is that it’ll be mainly dry but I think we will have a run of successive night frosts starting at the end of this week and continuing for at least 10 days. Now that’s one interpretation, there are others but time will tell who has the correct handle on predicting our weather under the influence of an SSW. If they are right it won’t be till around the 5th of March before the job rights itself again.

Agronomic Notes

Following on from last weeks blog on spring aeration and whether March and April are the best months for us to do this I just to wanted to clarify my viewpoint.

The gist of what I was trying to say was that we have to cut our cloth to suit and so if the weather outlook / GDD looks grim for the next 7-10 days in March / April, then I don’t see the point in double hollow coring, Gradening and the like if your expectation is for poor recovery. Fine to do that in January if ground conditions and O.M levels dictate that this is feasible / necessary but not for early March if we are stuck in an easterly airstream as indeed we may well be. So I’d rachet off my spring aeration if conditions aren’t conducive to recovery but on the understanding with your club that it still needs to be done at another point in the season.

This point is typically August because with summer holidays and the like, it is often quieter from a play perspective, we have optimum growing conditions normally and provided you have the resources and an irrigation system that works, I see no reason why you can’t gain recovery in 7-10 days from aggressive aeration. The greens are then set fair for the autumn and what is now one of the most popular revenue months of the year, September.

There’s a flipside to this coin and that’s if the weather outlook / GDD looks optimum for recovery and here you could up your game in terms of organic matter removal because you know the conditions for recovery are likely to be good.

Let’s look at the last 7 years from a GDD prespective and see how an early and late spring pan out in relation to an SSW event.

We can see from the above that over the last 8 Springs we have had 3 SSW-related cold snaps and this has really affected the amount of growth as determined by GDD.

So in essence what I was saying last week is summed up in the graph below, i.e if we are looking likely to have a cold spring think about if you are going to aerate and perhaps as importantly, how you are going to aerate….

So the graph below shows a comparison of two springs, one in 2016 when we had an SSW event and subsequent cool March and April, the other 2017 when we didn’t. It assumes we aerated on March 1st in both years and that soil moisture and nutrition were in place to gain recovery. It also assumes a total Growth Potential of 4.0 is the magic figure to gain recovery from 12mm hollow coring at 2″ spacing (mixture of units there, sorry it’s just habit)

So there you have it, 15 days in a good spring and 35 days in a poor one…

Plenty of pecking out there…

Well it’s clear the Corvid species (Rooks, Crows, etc) haven’t been watching the long-term forecast because these guys were laying eggs in January and now have some hungry mouths to feed. That has resulted in alot of reports of pecking activity around greens, tees and the like. One club I visited last week had put up some rotating Crow scarers which were having some effect (if you kept moving them) and also a model of a dead crow which looked very life-like. (or dead-like I guess ?). The culprit in the above case was immature Chafer Grubs, clearly recognisable with their defined head vs. Leatherjackets. And of course we have nothing to treat either so it’s a case of trying alternative methods as described above or grinning and bearing it for the time-being I’m afraid.

Ok that’s it for this week, let’s hope all the projections are wrong and the SSW doesn’t have its predicted effect on the weather and spring arrives on time 🙂

All the best.

Mark Hunt





February 12th

Hi All,

So we’ve reached the mid-way point in February but you know this winter is really starting to drag on a bit. (sorry Adi bit it is) Out walking yesterday I endured lovely sunshine, horizontal hail, sleet and lovely big snowflakes, it really was a lottery. Lovely to be out though and I happened upon this intriguing carving on a public footpath waypoint….It did appeal to my Danish heritage 🙂

So are we set for a continuation of winter or do we see the first signs of an early spring, remembering that last year the end of this week signified the arrival of mid-teen temperatures and the start of growth ?

General Weather Situation

So we start the week with a cold, bright day after a hard frost and some overnight snow for Scotland, the north west and south west of England and Ireland. During the morning the winds will swing round to the west and that will herald in slightly milder air pushing temperatures up to 6-7°C at best. Now they’ll be some wintry showers around, chiefly in the west of the U.K with more than a smattering across Scotland, the north west of England and Ireland and the odd one moving across South Wales and The South West. For most though it’ll be a lovely, cold, bright and settled winters day with nice afternoon temperatures. Late on Monday night we see a rain band push into the west of Ireland and this will fall as a mix of rain and wintry showers as it crosses Ireland overnight.

Overnight into Tuesday and that band of rain and wintry showers has largely cleared Ireland and makes landfall along the west coastline of the U.K butting up against colder air and falling more as wintry showers than anything else. Further south across South Wales and The South West this may manifest itself as heavy rain unfortunately. This vertical band will move eastwards across the U.K so if you start dry it won’t be for long with more wintry showers than anything over Scotland and the north of England, really anywhere where there’s some elevation. Ireland should start clear, dry and sunny after the rain moves through but still with a risk of wintry showers across the west and north. By lunchtime that band of rain is across to the east coast of the U.K clearing westerly and central areas as we approach sunset. Clear skies at this time of year mean frost and that’s what I think we will see on Tuesday night. A really miserable day, dull, wet and cold with temperatures lucky to hit mid-single figures.

Mid-week beckons and with it another front of rain and wintry showers crossing Ireland in the early hours of Wednesday morning and moving into western Scotland and the west coast of England and Wales close to the morning rush hour. With cold air sitting over us it is likely this moisture will again fall as snow at elevation turning to rain as the temperature rises through the morning. Most of this moisture front will stay firmly rooted to the western coastline but I think we will see some rain move inland later in the day. A wet day for Ireland then with wintry showers turning to rain as it moves across country clearing the west during the morning and the east of Ireland by tea time. Wednesday afternoon sees that band of moisture turn increasingly wintry again as it moves eastwards inland across the U.K, so another wet day beckons I am afraid for many of us. It may take till dusk to reach the east coast of England and here it’ll be falling as rain I think. So another dull, cool and to be quite honest, crap day with plenty in the way of wintry showers and rain around. 🙁 The only plus point I can make about Wednesday is that the wind swings round to the south and this will usher in some milder night time temperatures I think, so no risk of forst on Wednesday night.

Thursday sees another band of rain, sleet and snow past eastwards across Ireland and the U.K overnight so by the time the sun comes up on Thursday morning most of it should have cleared through with the exception of the east coast of England and western Scotland. Thursday looks a much better day for most of us with dry, bright conditions, a brisk westerly wind and better temperatures pushing up close to double figures in the south of England though cooler across the west. They’ll still be some wintry showers around across Donegal and more intensely, the south west / north west of Scotland but on the whole, a much better day.

Friday sees another dry start, although colder at night with a risk of ground frost. They’ll be a band of moisture pushing into Connacht and south west Scotland from early doors and this will move diagonally (/) across Ireland and the west of Scotland during the morning and afternoon clearing behind it. For the areas not affected by this band of moisture, it’ll be a sunny day with some hazy sunshine and light to moderate south westerly winds and crucially, dry again. Temperature wise I think we will be 6-9°C, with the lower temperatures under that cloud and rain in the north and west and the highest down south.

So how does the weekend look ?

Well some good news possibly…

I think we will see an Atlantic high pressure edge in during Saturday and that will bring dry and slightly milder air across the U.K and Ireland. Owing to the fact that it’s coming in from the west I think we will see Ireland warm up first with double figure temperatures likely to be on the cards. There is a risk that Friday’s band of moisture will sink south on Saturday morning across The Midlands and East Anglia but it may just fizzle out by the same token, one to watch closer to the weekend. It would be warmer but we will have northerly winds in situ and they peg back temperatures to the high single figures on Saturday and Sunday, but crucially I think it’ll be a pretty dry picture for nearly all of us with perhaps the north west of Scotland still hanging onto some wintry showers.

Weather Outlook

So next week looks like that Atlantic high pressure will be sitting over us, albeit perilously with a strong low pressure system sitting north of Scotland. So there’s a risk there of moisture pushing in between the two weather systems next week but I don’t think it’ll amount to too much in the way of rain (famous last words). It is quite a complicated weather picture because although high pressure is projected to sit over us, it will be squashed between other weather systems, so it’s not a dominant high. When this happens it is my experience that sneaky low pressure systems can slink in and affect things so although I’m forecasting a pretty settled and dry week, next week, we will know more closer to the event. I don’t think it’ll be particularly warm either because I don’t yet see signs of warm air pushing up from the south as it did this time last year.

Agronomic Notes

I’ll start this week with a picture that dropped into my intray last Tuesday morning from a certain Mark Todd. The title of the email was “Extreme Coring” and I just couldn’t stop laughing. Mark, I take my hat off to you and your guys 🙂

So this brings me onto the perennial debate about spring aeration and whether we are missing a trick in some instances. I think I’ve talked enough about trying to aerate early in the season and use the weather windows if and when they present themselves (Although Mr Todd’s interpretation of a ‘weather window’ probably leaves something to the imagination :)).

I do wonder though whether the whole subject of spring aeration needs a re-think.

Traditionally we aerate in March and April and then again during the autumn with many clubs pushing the latter back past the last significant fixture. Sometimes that might be October or November and to be honest I’d question the wisdom behind this.

First off why are we aerating ?

Joining the dots….

Now I know we have lots of different approaches to aeration but essentially we are interested in controlling organic matter in the surface, facilitating water movement through the profile, decompaction and maximising oxygen availability to the grass plant. Nowadays we have a myriad of machines and techniques to help us achieve this in a fraction of the time it would have taken to do the job 20 years ago and that can only be a good thing.

There are though two sides to every coin…And it’s a hard call in this day and age of increasing competition between clubs, increasing expectation on behalf of the golfer and a more nomadic end-user who is more than happy to ditch the booking if aeration (or look for a discount) has been been carried out recently or is planned.

By the same token I also think it’s a hard call in terms of communication on behalf of greenkeepers and groundsman alike, the surface is good but we have to aerate to keep it that way and of course alot of our work is aimed deeper down the profile where the results aren’t readily apparent. Putting that over from a communication perspective isn’t always straight-forward.

So lets look at March and April in 2016 and 2017 and see what the potential was for aeration and most importantly, recovery.

Spring Statistics 

So I thought I’d haul up some stats and look at a ‘typical spring’ if such a mythical creature does indeed exist. I have collated and recorded the number of wet and dry days, the number of frost days (defined as a minimum air temp < 1°C) and the number of good growth days (defined as a daily G.P ≥ 0.4)


In spring 2016 we can see that at the Bristol location they had a very hard spring with no days of good growth in March, yes that’s no days at all and a whole 7 days in April. That doesn’t tell the whole story though because April 2016 was very dry with no recorded rainfall on 22 days, so it is a possibility that even when it was warm enough for growth, moisture may have been a limiting factor.

Indeed if we graph out rainfall and Growth Potential (above) we can see that on the days when day and night temperatures were high enough for growth, there was little or no rain, so certainly moisture availability was a potential issue. We then have the other perennial debate, when to get the irrigation system fired up !

This is a common feature of the month of April, dry conditions and also cold, because we recorded 4 frosts in April with the majority in the last week of the month.

Moving across to The South East of England and we can see a different picture at the Guildford location with more growth in March and April as we would expect. More growth yes, but only 27% of the days in March and April were conducive to good growth and again the same pattern of dry days in April albeit with less frosts at this location.

It would be wrong to ignore the north of the country and here we can see how truly hard it was to generate consistent grass growth in the north of England (York) in spring 2016. So on only 3 days out of a maximum 61 during March and April was it warm enough for good growth and again we see the pattern of frosts continuing into April with 18 frost days recorded for March and April combined. Less dry days as well because most frontal systems in the spring tend to affect the north and north west rather than further south and east when we look at the U.K.


I think alot of people would rate spring 2017 as a good spring in terms of grass growth, so let’s see how it shaped up across The Irish Sea in Cork.

So again we see the same pattern  with only 25% of the days in March and April conducive to good growth (from a temperature perspective). We also see the same pattern of a high number of dry days in April and frost though admittedly only on a single day :).

From a revenue perspective though you’d probably look at it completely differently with less risk of closure, a majority of dry days and more chance of getting golfers round.

Closer to my neck of the woods is this Northampton location where we see a pretty good picture for March in terms of growth, but still only 30% of the days available mind. April 2017 again shows more dry days and more frost with coincidentally most of the frost days in the last week of the month, the same as 2016.

How much growth do we need for recovery ?

Off the top of my head I think you need 10 days of G.P ≥ 0.4  (so a total accumulated G.P figure of 4.0) to get recovery from a hollow coring using 10-12mm tines at close spacings. Now of course there are plenty of variables circulating around this comment, not least adequate moisture, good nutrition and a grass species that grows well at low temperatures.

So if I hypothetically cored on say March 1st, this is how long it would have taken to get recovery at the locations above assuming the Growth Potential figure is accurate and moisture / nutrient levels were sufficient to promote growth.

Bristol 2016 – 34 days

Guildford 2016 – 28 days

York 2016 – 34 days

Cork 2017 – 18 days

Northampton 2017 – 15 days

So in a poor spring we can bank on a month before we gain sufficient recovery if we aerate in March or indeed April I think and in a good spring this figure drops to 15-18 days odd in the locations I have analysed. Obviously as we go head north into Scotland this will extend even further.

Lots of questions really generated from this, not least why are we aerating at a time of year when recovery is a minimum of 2-3 weeks and in some years you can 2X that ?

Well, it’s traditionally been the time we aerate, but of course now it’s the time when golfers are coming out from winter hibernation and expect good surfaces because after all Augusta or some other tournament course is on the telly and their surfaces are excellent….More often than not it is the only aeration slot provided in the calender where significant organic matter removal is planned for.

Is this a good state of affairs for our industry  going forward ?

I think not.

I think going forward golf clubs, sports clubs, greenkeepers and groundsman alike have to sit round a table and work through the aeration that they know they need to do (obviously backed up by organic matter figures and the like) and look at when is the best time to achieve it rather than the only time available between fixtures. We also have to look for those windows and exploit them and that requires flexibility (and machinery) because if aeration goes out the window, it’s going to be harder and harder to provide good surfaces, particularly from a disease perspective. We also know you can have the best rootzone in the world, but if you have a 10mm layer of compact organic matter above it, your surfaces will sit as wet as puddings regardless….

I’ll leave with the same picture I started with and joking aside at the end of last week this club had a big tick in the box of organic matter removal on greens and approaches, as daft as the picture looks…I know this isn’t workable for everyone in terms of ground conditions, machinery, resources and the like and I’m not daft enough to think it is. I am just making the point that we have to re-think when we do the work (rather than if we do it) and play to our strengths rather than in some years, our weaknesses.

The above rhetoric is also based on the benefit of hindsight and I’m sure there are plenty of people reading this with an aeration date already in the calendar for March or April. All I’d say here is closer to this date look at the 7-10 day forecast and work out your total G.P figure, if it looks very low then maybe a change from hollow coring to solid tining should be in order with a committment to hollow core later in the year or perhaps a change to smaller tines at closer spacings ? (Although I readily accept this has a finite limit when filling the holes with sand becomes impossible to achieve)

All the best for the coming week and fingers crossed that high pressure comes our way and gives us some nice respite from the frequent rain and wintry showers 🙂

Mark Hunt