Monthly Archives: November 2019

11th November

Hi All,

Last Thursday was yet another pivotal day in our ever-changing climate picture with excessive daily rainfall falling over a localised area of the U.K.

How many times recently have you heard the forecasters say “A month worth of rain fell in a day” ?

Downloading the stats from a Doncaster-based weather station paints a depressing picture ;

On its way to recording 92.46 mm for the day, the rain rate hit a maximum of 12.7 mm per hour at 6.34 pm (that’s 1/2″ an hour in old money) and didn’t rescind for another 3 hours or so.

That’s the straw that finally broke the camel’s back and the banks of the river Don.

Next week I’m doing a couple of talks at the Sportsturf Ireland Conference (should have them finished some time this week Damian 🙂 ) and in one of them I’ve looked back at daily rainfall and temperature data over the last 55 years and analysed that data statistically for signs of patterns/trends in the Irish weather. Surprisingly temperature trends weren’t consistent but rainfall trends were.

Last week’s excessive rainfall event (I won’t call it biblical) was forecast a good week before by the GFS (Global Forecasting System). I’ll qualify that statement in that GFS forecast a trough pattern to form and for a low pressure system to sit in it. When this happens the low pressure moves very slowly west to east and often pivots round on its own axis. This has the result of dumping rain and more rain over a localised area. You can see in the bottom trace for pressure on the graphic above that the low pressure was moving very slowly over Doncaster.

What we can’t forecast at the moment is exactly where that excessive rainfall event is going to take place. Over recent years, The South West and North West has been hit and now the north Midlands and the north of England.  Here we got 14.8mm last Thursday, another very wet day but nothing like the above.

I can’t help thinking that there’s also other factors at play here. More houses and roads are being built in questionable flood plain areas as local government ticks the U.K governments housing target box regardless of the consequences. More garden lawns are being turned into patio and plastic thereby increasing the run off rate and of course due our friends in London and austerity cuts, there’s been little or no investment into flood prevention measures (until after it happens of course then there’s money available).

A perfect storm indeed…

General Weather Situation

So as predicted we start this week with another low pressure system sitting over the U.K & Ireland and that’s bringing general rain in a belt from the west of Scotland down to The South East. Ireland is seeing rain across Connacht and north Leinster work its way south and east as well. During Monday morning that rain is projected to push away from the south and east of England but at the same time more rain pushes into western Ireland and the west coast of England. In other words a dull, wet and cool day for some with a moderate to strong north-westerly / westerly wind. Away from the rain showers they’ll be some brief sunny intervals. Temperature-wise nothing to write home about at 5-7°C.

Onto Tuesday and overnight the centre of the low has pushed out into The North Sea off the north east coast. So this means most of the rain will be more north and east focused initially on Tuesday. Ireland looks to start and stay dry most of the day but they’ll be rain and wintry showers across Scotland particularly for central and north-eastern regions from the off. As we progress through the morning rain pushes into North Wales and this will then drop south and east into The Midlands and eastern / south-eastern counties. As we approach the early evening most of the rain across the U.K will move out into The North Sea leaving a drier and cooler picture. Again a strong to gale force north-westerly / westerly wind will trim back the temperatures and take the last of the leaves off the trees at the same time. Similar temperatures to Monday with a high of 7°C.

Mid-week beckons and a dry start to the day for the U.K and most of Ireland but of course this won’t be the case for long as a new rain front pushes in from The Atlantic. So the west of Ireland will see rain some of it heavy push in through the course of Wednesday morning moving across Ireland quickly. By mid-afternoon that rain will push into The South West and Wales as the low tracks south and east. Again another feature of a trough pattern in the jet stream is that low pressure systems often track further south. So by late afternoon we see heavy rain into Wales and The South West but further east and north including Scotland, Wednesday will be a drier day. Ireland will see that rain clear from the west through Wednesday afternoon to leave a dry end to the day for all areas except eastern Leinster possibly. Lighter winds for Wednesday and that means slightly milder but maybe only nudging 8°C maximum across the south of England.

Thursday sees that low pressure drop south into The Channel but its northern arm will pull in cool north-easterly / easterly winds as it does so and rain from the off for The Midlands, East Anglia, The South East and for Wales. The latter may fall as snow across The Black Mountains. Ireland and Scotland look to stay reasonably dry with just some rain moving down the eastern coastline of Ireland through Thursday morning. As we move into the afternoon we will see a continuation of showers, some of them heavy across the southern half of the U.K, really anywhere from The Lakes south.  Ireland and Scotland look to stay dry most of the day  with maybe some wintry showers across the north-east of Scotland a possibility.

Closing out the week on Friday and that low has finally moved off to leave a pretty dry picture across all of the U.K and Ireland. There may be a few showers down the north-east coast but winds will be light and they’ll be some sunshine as well so not a bad end to the week after a crap start it has to be said. No change in the temperature though with my lucky number seven being the order of the day across most of the U.K.

The weekend of course won’t be so straight-forward with another low edging in off The Atlantic and bringing rain for west of Ireland from the off on Saturday. This rain will slowly edge eastwards through Saturday and we will also see further rain and wintry showers over elevation as we move into Saturday evening for the western coastline of the U.K. By Sunday this low is projected to bring rain some of it very heavy for the east coast of Ireland, particularly around Dublin and Wicklow I’d say 🙁

They’ll also be further rain for the south coast and a line up to The Midlands and across to North Wales as that low swings up southerly winds as it passes through. Further north we will also see showers on Sunday throughout the day as that low pushes through but from The Lakes northward up to and including most of Scotland should be reasonably dry. Staying on the cool side for everyone with yes you guessed it, 7°C the most you can hope for.

Weather Outlook

So I guess this is the part most people focus on when I write about the weather, the outlook for the next week. i know the question I get asked the most currently is not surprisingly when is it going to stop raining ?.

Well to me next week does look a bit drier, not completely dry but drier and colder I think with a potential for a trough pattern to extend across from Russia and Scandinavia. So that means more frosts and perhaps snow towards the end of the month. Now I know I’m sitting here on the 11th of November and projecting forward but it does look pretty cold with a pronounced northerly / easterly bias to the weather. In the winter north and east in my book mean cold winds and an increasing risk of snowfall. (and Waxwings…yeah :))

Here’s the GFS output for November 27th…

Image courtesy of TropicalTidbits.com

Now it is just a hunch at the moment but this type of pattern doesn’t appear that often and it would tally with nature.

So next week looks to start off pretty much as a repeat of the end of this week. That is to say with a southerly biased low pressure moving through and bringing rain for the southern half of the U.K and Ireland on Tuesday after a reasonably quiet Monday. So unsettled through Tuesday and Wednesday but then we start to see a drier picture, still with showers around coming in off The North Sea on a north / east airflow. So a cooler, drier end to the week still with some showers across Scotland and north-eastern coasts but less in the way of heavy rain events after the one early in the week. After that we will see…..

Agronomic Notes

Disease Pressure

Now I know your minds are most likely preoccupied with water-logged courses / pitches, washed out bunkers for the ‘nth time’ and the inability to start / continue winter projects but I thought it timely to update the autumn so far from some of the locations we are forecasting disease pressure.

As you can see we had a spike prior to the weekend from the forecasting perspective but there’s another factor coming into play here that probably would negate this spike from a practical perspective, more on this below…

So the good news and let’s face it we need some good news is that we have decreasing disease pressure as an outlook on all sites monitored. Now in sheltered locations there was a recent smaller spike prior to the weekend but of course we must take into account ground conditions in the growth of Microdochium nivale. What I mean by this is that a wet, cold surface isn’t actually the ideal environment for Microdochium nivale and for this reason we can expect low disease pressure when we have saturated ground conditions from a spore germination and mycelium growth perspective.

There’s further good news in terms of spray longevity with the now normal 14-day or so longevity for a spray applied in early October. As with last year, the 2nd half of October was cooler and actually as reported last week one of our coolest. So a spray applied mid-October is still likely to be working well in the grass plant and with a low disease pressure forecast there’s no need to scramble looking for a spray day this week (even if you are able to get a tractor out on your golf course!)

The graphic below shows estimated fungicide longevity for a Northampton location (Ta Rob)

Grass growth dip equals problems for areas under wear pressure…

That tail off of growth over the last 14 days or so has meant that surfaces that are receiving wear are not able to regenerate sufficiently with virtually no growth at the end of October and over the last 5 days (and little on the horizon either).

This means golf greens, tees and winter season pitches will be on the back foot especially when you dovetail that in with the information I posted last week showing reduced solar radiation for October and now November. It’s been estimated that roughly 45% of Solar Radiation reaching the earth is in the correct wavelength for photosynthetic plants to utilise as light energy. So with declining heat energy from the sun comes much lower available light levels for the grass plant, reducing photosynthesis and therefore growth potential. So it isn’t just temperature that is growth-regulating currently, light is also an issue.

Now some grass species (famously Poa annua) are able to grow well at low light levels but others like Bentgrass and Ryegrass are less able to and so we see these species being out-competed by Poa annua currently.

Ryegrass, I think is especially sensitive to low light levels and tends to show senescence on older leaves as a result. These break down on the surface and encourage algae growth and sward thinning as a result. So don’t be surprised to see thinner ryegrass areas at the moment because of lower temperatures and light levels….I’d also expect to see more in the way of algae and moss around because of the above and prolonged surface wetness. Bad news when we no longer have very effective methods for treatment 🙁

Global warming ?

October 2019 in the U.K & Ireland actually went against the global trend for warmest October’s by being one of our coolest since we started monitoring GDD back in 2010.  OK, that isn’t a long time, but it’s enough time to show that we aren’t seeing the same trend in globally rising temperatures as the rest of the world in some months of the year

What we measured as a cooler October agreed with The Copernicus Program which monitors global and European temperature trends. (see below)

Image courtesy of The Copernicus Program https://climate.copernicus.eu/surface-air-temperature-october-2019

This doesn’t mean global warming isn’t happening here but its effects (I think) are likely to be different for the U.K and Ireland because of our location in terms of longitude and latitude on the planet and the fact that we lie slap bang in the path of the sub-polar jet stream. 

Let us remember, eighteen of the 19 warmest years on record have occurred since 2001, with 2016 the hottest since monitoring began 169 years ago. The current decade is set to be the planet’s warmest on record, according to the UK’s Met Office, who expect 2019 to “amongst the warmest of years”. Well let’s see but I’m reckoning on different.

The above graphic also highlights that some of the biggest temperature anomalies are taking place at the poles and again I think in the case of The Arctic this is because of the phenomenon of Rossby Wave formation in the jet stream. These undulating waves form peak and trough patterns in the jet stream and can pull cooler air further south and push warmer air further north. Currently Russia is experiencing a mild and wet autumn compared to usual and that is directly as a result of the sub-polar jet stream pushing warmer air than normal further north….

Image courtesy of TropicalTidbits.com

OK that’s me done  for another week, most likely they’ll be no blog next week as I’m away in Germany and Ireland doing talks unless I can grab some airport time courtesy of Ryanair 🙁

All the best.

Mark Hunt

November 4th

Hi All,

When you start the week looking at a Weathercheck forecast like the one below you won’t need me to tell you that we are still in the same pattern that started towards the end of September.

We are now into our 7th week of unsettled weather and heavy rain and to be honest there is still no break in this pattern for the foreseeable.

No re-alignment of the jet stream and no blocking high popping up to give us some respite. As you can see from the graphic above, the jet stream is sitting south of the U.K & Ireland and that’s pretty much where it has been for 6 weeks now. This allows low pressure systems forming over The Atlantic to continually swing in from the south and west, drop into the trough and dump heavy rain on us. It’s mild as well but we will get progressively cooler.

‘Beast from the East’ I heard mentioned at the weekend in the tabloids…yeah right, pretty difficult when its currently 6°C and raining north of Moscow 🙂 You can see the tail end of the jet stream is pushing that mild weather further north into Scandinavia and Russia so the cold isn’t going to come from there at the moment. More tabloid hype to sit alongside that which we are getting from the politicians currently. I mean really ?

General Weather Situation

As predicted last week, we start this week on Monday with a low sitting over the U.K and Ireland. During the course of this morning this will pull in heavy rain across Scotland from the east and also down the east coast of Ireland with Leinster set for some heavy stuff. Further south and west the low is pushing showers on a light to moderate wind up from The South West / South Wales / South Coast and moving them inland. Already there’s some significant showers pushing up across northern England. Now not everywhere will have rain, The Midlands and further east should miss a chunk of the showers though the risk increases through the day. Through the afternoon we will see more consolidation of that rain along the south of the U.K, north of England, Scotland and east / Midlands of Ireland. A cool day particularly on the west / north side of that low where the wind will be north / easterly respectively and keep temperatures into the high single figures. Further south on that slightly milder wind we will be 10-12°C

Overnight into Tuesday and that low pressure is sinking south and eastwards onto the continent so a drier day is on the cards but not everywhere. It’s likely that a band of rain associated with that low will lie across The Midlands and North Wales and this will track south and east through the course of the day bringing rain to those areas as it does so. So the threat of rain on Tuesday is more along the eastern coastline of the U.K from The North East down through Lincolnshire, East Anglia and The South East. Feeling cooler on Tuesday as that low sinks south and pulls in a keen north wind behind it so 9-11°C likely.

Onto mid-week and Wednesday sees the next rain fronts pushing in from The Atlantic into the west of Ireland and tracking eastwards through the course of the morning. By lunchtime that rain will be across most of Ireland into the western coastline of the U.K. From here it’ll slowly move inland but fizzle out as it does so leaving a drier day for central and eastern parts of the U.K. The same for Scotland with showers across the north-west failing to make progress inland. Away from the western rain it’ll feel a good bit cooler on Wednesday with temperatures 2-3°C down on the start of the week. This is because of the colder air mass associated with the new low pressure pushing in rather than the wind direction. Talking about the wind, it will be light for the first half of the day, freshening from the south later. So a cool dull day with only a little in the way of sunshine pushing through and temperatures down at 7-9°C.

Thursday sees the low pressure move eastwards overnight pulling that cold rain across Wales, The South West and into most areas of the U.K. Now this rain is cold so over higher grounds it will fall as sleet overnight. By the morning rush hour the centre of the low will be across The Isle of Wight leaving a dry region across central England. Further north this low will be pushing rain and wintry showers across Scotland, The Midlands, The Peak District and Pennines and down the east coast of Ireland again with some white stuff for The Wicklow mountains I reckon. As we progress through the morning the centre of the low tracks barely 50 miles along the south coast and so that means a continuation of the rain / sleet for most areas pushed long on a cold easterly wind turning from the north for the west wide of the country and Ireland. Not a nice day it has to be said for some but like the beginning of the week there will be gaps in the rain fronts so some areas may not receive much rain at all. Remaining on the cool side though with those easterly / northerly winds so 7-9°C looks to be about right. It is November after all.

Closing out the week on Friday we see that low still just across the Kent coast and that’s a feature of a trough pattern in the jet stream as we know, slow-moving weather systems. Well this one will nearly be east of the U.K & Ireland by dawn and so that means it’ll be taking the majority of its rain elsewhere. As with earlier in the week, the threat of rain / wintry showers will now be more for the north-east, Lake District and south-east of England as that low drifts slowly away into The Channel. So a largely dry day away from that eastern rain for Ireland, Scotland, England and Wales with the sun even popping through across Ireland and the west. Further east will see more in the way of clouds and with the low to the east of us, a cool northerly wind for The Midlands and central areas. Scotland also looks to have a largely dry day on Friday with the low sitting at the other end of the country (the benefit of a low-lying jet stream). Remaining cool though with 7-9°C the new norm.

With no change in the weather patterns at the time of writing this blog, it is no surprise that the outlook for the weekend is unsettled as a band of rain crosses Ireland overnight and pushes eastwards across the U.K during the course of Saturday. Stretching from Scotland down to the south coast it’s a case of if you are dry, you won’t be for long on Saturday as that rain moves eastwards. Ireland will see more in the way of showers behind that rain front through the course of Saturday. I’d love to say it’ll be feeling milder but it’s unlikely with temperatures remaining down in the mid-single figures despite a westerly wind direction. Sunday sees a new deep low pressure push into Ireland bringing heavy rain and strong winds with it. Later this will move into The South West and South Wales / Wales edging slowly eastwards through the course of Sunday. It looks like the rain associated with this front will be heavy. That said central and eastern areas may avoid the worst until later on Sunday evening / night. Similar temperatures to Saturday, 7-9°C with a freshening south / south-westerly wind for most.

Weather Outlook

So no surprises then that we will start the week with an intense low pressure sat over the U.K, so that means windy and very wet, perhaps the wettest period of next week will be at the start. So Monday and into the first part of Tuesday looks very wet, especially for the south and west of the U.K and possibly the south-east corner of Ireland. The northern part of this low pressure will be across Scotland and the Borders. Tuesday could be a little drier for eastern and central areas but it’s only a brief respite before more rain pushes through from the east on Wednesday and particularly Thursday looks wet for the southern half of the U.K. The end of the week and weekend look a little drier as the low slides away but already a new low is pushing into the Bay of Biscay. With predominantly easterly and northerly winds associated with the jet stream and position of the low pressure systems, it’ll remain on the cool side.

Agronomic Notes

As it is the first blog of November, here’s a look back at October from a GDD / Rainfall perspective.

GDD October 2019 – Thame Location

That’s the benefit of doing this kind of thing you know. I was wondering to myself whilst fishing yesterday whether this autumn / winter is following the same pattern as 2015 when the jet stream dropped southwards and we just got wet and windy weather for practically most of the winter ?

Well if you compare you can see that the GDD for October 2015 was 147 and for 2019, it was 130. It may come as a shock but that’s nearly the lowest October GDD we have recorded going back to 2010, so 2019 broke the mold in terms of warm October months.

Good news though from a disease perspective 🙂

Cumulatively as well, 2019 isn’t going to be breaking any records I think and courtesy of the cooler, wetter June / October we experienced, it’s falling well behind 2018 and 2017. That’s what makes our climate such a hard one to call in terms of highlighting consistent weather trends.

We are an island, we sit in the path of the jet stream and therefore variability in our climate is the norm.

GDD / Rainfall Comparison – U.K Locations

Not many contributors this month, probably my fault for being a bit hit & miss lately with my blog publishing but thanks to those that managed to send some data through. The story of October 2019 is definitely rainfall and the fact that in both the U.K and Irish locations, the south and south-west were in the firing line with roughly a 2x rainfall volume vs. their eastern counterparts. For some reason, my GDD in Market Harborough was way lower than the average, maybe it is a reflection of the shaded location of my weather station and the fact that I’m a tight arse with my central heating 🙂 100+mm in any month though is a wet one but with declining E.T to dry us down it isn’t surprising that we are soaking.

GDD / Rainfall Comparison – Irish Locations

As mentioned above, you can see the rainfall bias for the south west and southerly locations in Ireland. This is because the low position of the jet stream has meant more of the low pressure systems are swinging down into The Bay of Biscay and so the rainfall effect is more south and south-west rather than north and west as we have traditionally seen. I’m not saying of course that the north-west of either Ireland or the U.K is dry, just that the south and south-west are also getting a pasting. With that variability in rainfall comes variability in GDD because the wettest locations are also the mildest ones posting high GDD numbers for the month. Big variability in the effect of altitude as well when you look at Killiney vs. Dublin (Casement)

So why are we so wet ?

Despite the type of stats I have documented there are plenty of people who still ask why we are so wet. It’s almost as though they live in a hermetically sealed container !

One of the sheets on my GDD spreadsheet is labelled charts and if you scroll down you’ll find some data like this ;

This is for a location in North Devon and looking at the rainfall total is one thing but when you look at the number of wet days vs. dry, that to me is the eye opener.

29 days of October have recorded rainfall with just 2 dry days !

Here’s another way to look at it….

I think this is a smart graph, but then I am biased 🙂

The above shows the last 3 months at The Oxfordshire and tells a convincing story….

Despite the fact that it is in a reasonably dry part of the country, you can see how the rainfall totals are increasing each month and how the E.T and the amount of solar energy the grass plant / ground is receiving is heading in the opposite direction.

So we are receiving less warmth as defined by solar energy with approximately 34% of the solar radiation in October as September. Less heat tends to means less E.T and indeed for October we are only 43.5% of September’s E.T figure.  If you look at the rainfall and E.T in September, they were pretty equal but in October, the rainfall exceeded the E.T by nearly 48 mm.

So surfaces tend to be water-logged and with low E.T levels are slow to dry down.

What we need is a cold, stable high pressure to give us some respite but currently it isn’t anywhere to be seen. Maybe better news next week ?

All the best for the coming week.

Mark Hunt

 

 

 

 

 

 

 

So Mr Punter that’s why we are wet…..For my location it’s slightly better, 21 days out of 31 were wet in October.