After 5 frosts on the bounce, the last 4 down at -3°C and a strongly Baltic easterly wind, you could be forgiven for thinking that the Sudden Stratospheric warming event promised for late January, took a sabbatical and turned up in April !.
Cracking timing with Augusta on the telly as well, I’d love to say I joined the many millions and stayed up to watch up but with it being a MotoGP, WSB and F1 weekend, I’d had my fix of telly 🙂 Great result though and nice to age comes before beauty sometimes. So we have two limiting factors to growth at present, temperature and of course moisture. Spring is now definitely late, my local Bluebell walk (Coton Manor) advertised that their Bluebells won’t be out in time for Easter if people are visiting the gardens and it would be more like the May Bank Holiday this year. Even the Swallows, Martins and Swifts are late. Last week I did some talks in Faro, Portugal and saw many Swift, Martin and Swallow overhead to the point where I wondered why they don’t just stop there, why did they keep coming to the U.K and Ireland ?
So is there any end in sight to this run of frosts / easterly wind and if so, will moisture follow ?
General Weather Situation
Well Monday dawns dry and cold for many, except of course if you are over The Irish Sea where they have a band of heavy rain currently sitting over Leinster and more heavy showers across Munster and Connacht. You can see the low pressure system bringing that rain to Ireland in the new Meteoblue graphic above (Like that Karl 🙂 ) and during the morning it will move north and away from the U.K, but a slither will push into The South West and western coasts later today to bring some much-needed rain. (though not much). Most of this easterly progress will be tonight and into the small hours of Tuesday. So The South West, Wales and western coasts can expect to see rain overnight. Away from this rain front it is business as usual for England and Scotland with a bright and cool day, but up a bit temperature-wise on the weekend courtesy of a no-show by frost earlier on Monday. There’s another reason for the increase in temperature and that’s a change in direction of the wind, swinging round to the south-east through Monday. The source of the south-easterly wind is Southern Europe rather than Scandinavia for the easterlies, and that will mean a gradual increase in temperature as we go through the week peaking nicely over the Easter weekend. Temperature-wise, expect 11-13°C in moderate to strong south-easterly winds and an end to the run of frosts as well with milder nights the other flip side to the weather this week.
Onto Tuesday and overnight that rain front will slowly move inland, into western Scotland, the north-west of England, possibly the west Midlands and along the south coast. I note here in The Midlands we are down for 2mm but I also note a 41% probability attached to that rainfall event so I won’t hold my breath 🙁 It’ll be a slow-moving front mind so some areas may not see any of that rain till the evening and eastern areas may not see it at all. It all depends on the strengths of the two respective fronts as to how much progress it makes inland. So as you can imagine, Tuesday will be a cloudier affair for most of the U.K, due to that rain front, with the exception of the east and south-east which should see more of the sunshine during the first part of the day. Ireland looks to have a largely dry but dull day after the damp start on Monday. Despite the cloud cover and rain front, temperatures will continue their slow climb, up to 14°C I’d reckon on Tuesday, especially if you get to see the sun and again a reasonably mild night.
Mid-week beckons and Wednesday sees a really nice day as that continental high pressure exerts its influence and the rain front has fizzled out overnight. So some warm sunny intervals expected on Wednesday with a warm south-easterly wind pushing temperatures up into the mid to high teens I’d say. Lighter winds as well by mid-week, swinging round briefly to the north before settling back in the south east again. So 14-17°C temperatures and good growing weather (if you got the rain)
Thursday sees the high strengthen its grip on our Easter weather and another improving weather picture despite stronger south-easterly / easterly winds. A mild night will allow temperatures to push up into the high teens with long spells of sunshine for many areas and hazy cloud as well. That lovely weather picture will encompass all of the U.K and Ireland so a beautiful spring day beckons.
I’ll do the Easter weekend in one forecast because really there isn’t a lot to say about Good Friday to Easter Sunday (apart from it’ll be rubbish for fishing) because the forecast is long spells of unbroken sunshine from dawn to dusk with temperatures pushing up into the low twenties through the weekend. For most, an absolute cracker of an Easter weekend. Maybe some low cloud cover lingering over eastern coasts but lovely weather for our Easter break. I’ll be hanging up the fishing rods and getting out on the bike / motorbike to lose some winter lard 🙂
So will it last ?
Some of you may be hoping not because you’re so dry. Here in The Midlands we are in that camp, desperately needing rain before the EA starts to dust off its water restriction policies.
So the outlook currently is indeed for change with low pressure pushing down from Monday to start to introduce a cooler and more unsettled picture for next week. If this occurs we can expect rain moving in from the north-west to Scotland and Ireland by the 2nd half of Monday. This rain front will push down on north-west winds across the U.K through Tuesday to bring rain to many areas. The change in wind will also drop the temperatures down to the mid-teens, not bad though. By Wednesday a really deep low will be in situ over the U.K bringing strong winds and rain to many areas. This unsettled, wet and windy weather is likely to stay put for the rest of the week as the low pressure forms a trough in the jet stream. Experience has shown when this occurs, the low may be very slow-moving and therefore rainfall amounts could be significant. Blessed they will be if they occur.
Now of course there’s a caveat here because we have two competing weather systems but I’ve looked at 3 different GFS models and they all predict the low moving in after the weekend. Time will tell…..
OK, so we know have 2 limiting factors to growth at the moment, cold nights and of course soil moisture. Here in Leicestershire, our last significant rainfall (> 4mm) was on the 16th of March with a whopping total of 5mm in dribs and drabs since and it’s showing. Cracks in the ground and plants already under drought stress, particularly where we have new seedlings from last autumn or dormant seeding in the winter.
Let’s look at the effect of temperature first on growth using the Growth Potential model…
So I picked some worked examples with 3 different temperatures, typical of what we have and will receive this week weather-wise and then looked at the effect on growth potential…
So the first example is a mild day, 12°C but with a significant ground frost, this would be typical of the last 5-7 days for many of us. Bearing in mind the scale for G.P goes from 0 (no growth) to 1.0, (optimum growth), a G.P total of 0.05 means we will see very little upright growth with this temperature scenario.
The second example would relate to a day like today, milder overnight, but not really setting the world on fire during the day temperature-wise. Currently my weather station is showing 12°C so that’s about right for this example. A G.P total of 0.26 would appear as pretty slow growth, not much more than a small amount of clippings in the box and I wouldn’t rank it as good spring growth day (My cut off would be 0.4 for that)
Lastly, we have an example which hopefully will be closer to reality at the end of this week with a mild night and a warm day. A 50% increase in day and night temperature over example 2 gives a 300% increase in resulting G.P. So here a figure of 0.72 for me would represent significant growth and for areas that aren’t moisture-limited, a good growth flush.
You can see the G.P building in the Meteoturf readouts for the 4 locations below ;
So we have temperature enough for growth but of course in some areas this won’t be enough and we need rain. To further compound this problem, the coming week is showing some pretty significant E.T stress. If you look at the readouts above for Southern England and South Wales, we are looking at 20-21mm moisture loss over the next week which means more drying winds and unless you pick up something tomorrow, no rainfall.
If you have irrigation to areas then really you have no excuse not to help the grass plant out through this time. I simply don’t get the argument of not watering with the reasoning that you would be lowering the soil temperature (temporarily) and slowing growth when the lack of water is slowing growth anyway ???
We all know this kind of weather puts Poa annua on its backside and gives bentgrass a nice start to the year. We also know that the temperature spike on the way together with the accompanying E.T loss will hasten in the arrival of seedheads and so we will have seedy greens with a slow to grow Poa annua component, remembering that when it is seeding, it isn’t tillering. The bentgrass will of course be leggy, woolly, whatever your description and so critical to managing this dynamic is maintaining a sensible cutting height so that the physiology of each plant species isn’t impacting on ball roll. Anything north of 4mm is bad news to me and many greens will benefit from 0.5mm off that to give good consistent surface at this time.
Now I know cutting height is an emotive issue and they’ll be some of you saying why lower the height and put the plant under more stress ? And you’d be right especially if you have your surface organic matter nicely under control in the top 25mm because with a roll and a 3.5 – 4mm cut, most greens will present and putt nicely but chuck in excess surface organic matter and that dynamic goes out of the window. And so we chase cutting height when we do not have control of surface organic matter which further puts the plant under stress, a vicious circle isn’t it ?
With the emergence / availability of lightweight greens rollers we can mitigate this issue by rolling to give us more green speed and a more consistent surface rather than coming down too low, too fast on the cutting height but it is a balancing act that is unique to each facility. Although you can happily trade cutting heights with your colleagues, the impact of your cutting height will be a function of your organic matter dynamic. For example if you have a golf course with greens affected by shade then we can surmise that these greens will not develop high levels of surface organic matter due to lower photosynthetic efficiency and so will feel firmer to the golfer than greens in a more open location cut at the same height on the same golf course. Greens with excess surface organic matter will also have a bigger differential between bench set cutting height and actual as the mower will tend to sink in to the surface of a softer green and so cut lower. There’s loads more variables I haven’t mentioned that also dovetail into this dynamic including soil moisture levels, nutrition and PGR usage to name but a few.
Speaking of soil moisture levels, I updated the moisture deficit graphic that I’ve been running since last June and you can see the typical dry spell-wet spell dynamic for this spring in the graph…You can download it here
Now I reckon if I had data for The Midlands our moisture deficit would be closer to -200mm since last June to the current day which puts us at a similar moisture deficit as the beginning of August 2018. You can see then why there’s such a concern about water availability if we are at this point in mid-April with the summer still to come. So I for one have everything crossed that next week’s low pressure system makes a timely appearance 🙂
Always a tricky one to advise because of the variability of site and geographical location. Many private schools at this time are rapidly trying to convert their winter season pitches to cricket outfields and I’d be hoping that the growth flush at the end of the week will help this process on considerably. I’d also be hoping with heavier soil types, more moisture would be retained within the profile and so moisture limitation won’t be as extreme as a sand-based rootzone on these sites.
If your surface is good, with good coverage and plant health then I think a light foliar timed towards the end of the week on the upward G.P curve will sort things very nicely prior to the Easter break. If you are chasing growth then that’s when a granular will be more up to the job provided you have irrigation to help things along. I’d be more confident on the latter if I knew that the low pressure / arrival of rain next week was a given. Bear in mind though that it will give a flush of growth and this may or may not be desirable.
No blog next week because I am taking a few days off after Easter, so the next one will be due at the end of April.
Till then all the best and have a happy and relaxing Easter.