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  • Writer's pictureMark Hunt

December 5th, 2022 - I Smell Winter....


Hi All,


That title is actually from an excellent track by The Housemartins and it quite succinctly tips a nod to the weather this week and next.


Back in the hot seat or more accurately, the chilly seat, this Monday morning after a week off the blog (but not a week off I hasten to add!). I see the tabloids are full of 'Beast from the East' rhetoric, blizzards and the like. Well as you can see from the GFS output above for this Thursday, we do indeed have some pretty parky weather on the way. Not surprising really when we are only a couple of weeks away from the Winter Solstice and the shortest day.


Hats off to GFS forecasting because two weeks ago when I last typed this blog, I discussed in my outlook a period of easterlies ending in a cold, northerly scenario based on their output and indeed it has come to pass (or it soon will do anyway!).

So yes, winter is on its way and after one of the mildest autumn's on record, we took a temperature step down to normality at the end of November and are shortly set to take another one later this week.


Reports of snow as well and I'd agree, some snow is likely in this next phase but predicting how much is definitely for la la land as it is even more tricky than rainfall to get right.


It seems slightly strange after the run of very wet weather to still discuss the drought this summer, but there are still areas across the south of the U.K, particularly Buckinghamshire, Cambridgeshire, Norfolk, Suffolk, extending into Oxfordshire where they are still very dry, with less than 400mm of rain so far this year and a soil moisture deficit > 200mm (8 inches of rain). My colleague, Peter Palmer from Prodata sent me some video footage digging down into the topsoil Ely way and it is still powder dry 75-100mm down.


So the legacy of this summer's heatwave is still with us in places, whereas for others this run of drier easterlies / northerlies is mightily welcome such was the magnitude of rainfall they have received this autumn. Valencia down in south west Ireland has picked up 786mm across the last 3 months, that's over 30" of rain in old money ! Areas across the south and south west of England were well over 200mm for November alone but it is that central belt of England that still has some way to go rainfall and soil moisture-wise.


OK, let's put some flesh on the bones of the coming week's weather and look further into the month of December courtesy of a bit of meteorological Mystic Megging :)


General Weather Situation - w/c 05-12-2022


If you look at the animated GIF's above, you can see how the colder air pushes in from Scandinavia from the middle of this week to provide a very chilly interlude for the U.K & Ireland going into the middle of December and an unwelcome hit to our fuel bills :(.


So this week starts off dull and damp for many and as is typical with a predominantly north east wind direction, we have a raft of showers pushing in from The Wash and The Humber. So dull and feeling colder than it actually is because of the inherent dampness in the air. 6-7°C at best I'd say, warmer across to the west but it's all relative. That cloud cover should keep us frost-free.

Tuesday sees a similar-ish day, but with a more northerly airstream so if anything feeling a little chillier. They'll be more in the way of brightness about with some fleeting winter sunshine. Still the risk of showers though along the east coast of the U.K & Ireland. 6-8°C with the mildest temperatures across Wales and Ireland. Where you have clear skies, you might pick up a ground frost on Tuesday night as the temperatures drop down into low single figures.

Onto Wednesday and that cold air begins to push down from the north and east, so felling much colder through the day with a keen wind chill, but sunny and bright. Dry on the whole but showers are never far away from the eastern coastline of the U.K. So sunny and bright on the whole with a keen wind chill and a keen overnight frost likely going into Thursday. Temperature-wise, 3-5°C, with Scotland the coldest and Ireland / Wales, the mildest, if you can call 5°C, mild !

Thursday sees that passage of cold air continuing its way south, so after a keen overnight frost we will again see a largely dry picture. I say 'largely dry' because there's always the threat of wintry showers pushing down across the north of Ireland and North Wales. Some of these showers will indeed be wintry over elevation, so I expect The Black Mountains of Wales to be anything but black on Thursday :) Some of these showers may push in off The North Sea into eastern areas and The Midlands and could well be wintry. With clearing skies on Thursday, temperatures are set to drop markedly, so I expect -3 to -4°C overnight into Friday for the U.K, but maybe -1°C for Ireland.

Friday looks to be a sunny but absolutely Baltic day with temperatures not really pushing much above freezing for many, despite the sunshine. Maybe +2°C for Ireland, but below freezing for England and Scotland certainly. There's a risk of wintry showers across the north east of Scotland pushing down across The Highlands and into central parts of Scotland later on Friday.

The outlook for the coming weekend looks very similar, with cold, dry and sunny conditions for most after a penetrating overnight frost. This run of weather is probably going to give us our longest run of consecutive ground frosts that we have had for a long time (2013 maybe?). Maybe a little milder across the west due to the likelihood of more cloud, but cold nonetheless. As we go through Sunday, it looks like showers are massing along the eastern coastline of the U.K and Ireland and I think there's a growing risk of these pushing inland to bring a dusting of snow maybe. Those night time temperatures will drop to -3 to -4°C over the weekend.



Weather Outlook - w/c 12-12-2022


So we start next week with cold air firmly entrenched across the U.K & Ireland. In addition, we have a low pressure system sitting off the north west tip of Scotland, so I think we will see more snow next week across Scotland from the start of the week. This low pressure will also increase the risk of wintry showers pushing inland early next week along the eastern coastline of the U.K. Some of these showers could reach further inland on Monday and Tuesday and we will continue our run of overnight frosts and very cold, low single figure, daytime temperatures. On a side note, I see my Motherland, Denmark looks likely to get a snowy clattering early next week.

As we approach mid-week, next week, the low pressure pulls in more colder air and a more northerly airstream for the second part of next week. So feeling colder, with a risk of snow showers across Scotland and further south, with continuing ground frosts. As we get to the weekend after next, the wind turns more easterly. Now it's too early to say whether we will have a White Christmas, but many places may have a white December prior to that.


So dig out your winter clothes because you are going to need them over the next two weeks and please remember to feed your birds because they're really going to need our help. I thought all my visiting Hedgepigs had gone into hibernation last week because they always seem to know when cold weather is on the way but this poor chap was out and about last night. I don't fancy his / her chances much knowing what is coming temperature-wise :(


Agronomic Notes


As this is the first blog of November and because I was too busy in early November to do it, I am going to look back at October and November and see how we panned out from a GDD, G.P and rainfall perspective.


So we start off with our default location of The Oxfordshire, primarily because Sean has been great at allowing me to use his weather station data from way back in 2005 till now. That makes me feel a tad old :)


2022 - GDD Data - The Oxfordshire, Thame


The great thing about having a dataset that goes back that far is you can look back at recent years from a comparison perspective.


Looking at October 2022's GDD figure of 212, we can see it is towards the high end of our GDD tally going back to 2005, but we have had warmer months (from a GDD perspective measuring minimum and maximum temperature) in 2005, 2006 and more recently, 2017. So although the collective media likes to get hooked up on 'maximum temperature this' and 'warmest that' type of statements, we can say from a GDD perspective, October 2022 was high, but not the highest, for this location. November '22 was a slightly different ballgame though, coming in at 105 total GDD for the month. That is the 3rd joint highest GDD since 2005 and marks it out as one of the warmest (from a GDD perspective) November months.


Feeding these figures into a cumulative chart, we can see how 2022 as a year compares up until the end of November.

Well 2022 ranks as the 2nd highest GDD years measured and only misses out on being the highest by a paltry 2GDD vs. 2017. Now actually I can't see us adding much to the overall GDD tally in December because I think it'll go out as one of the lower GDD months, so 2022 will continue the trend for being a +2,000 total GDD year.


Since 2005, the years that have exceeded a total GDD figure of 2,000 are ;


2006, 2017, 2018, 2020 and 2022


In other words, 4 out of the last 6 years have been the highest GDD figures, so that does suggest a trend (albeit a short one) towards warming day and night temperatures over the last 5-6 years, but not definitive by any means as we have also had cooler years within that same timeframe.


Let's look at October and November's stats across the U.K & Ireland and talk through the agronomic consequences....


U.K Locations - Monthly Growth Potential & Rainfall Stats

So here we are looking at the monthly Growth Potential (G.P) for a number of different locations across the U.K. The maximum monthly Growth Potential is a function of the number of days in a month x 1.0 (Optimum Daily G.P = 1.0). For example, in April we have 30 days, so the maximum monthly G.P figure is 30. If we take Northampton, the actual monthly G.P for April 2022 was 10.6. This equates to 35.3% of optimum and underlines why April is such a rubbish month to grow grass in the U.K. (In fact November's total monthly G.P was pretty similar to April's !)


If we look at October's G.P Stats, we can see that the average monthly G.P figure was around 20, out of a theoretical maximum of 31, in other words, around 66% of optimum. That is why we were so busy grass cutting in October !


In many locations, the total G.P for October was practically the same as for May and that in my view is quite an eye opener. November was as we know a cooler month but we had a very mild interlude (more on that later) from the 8th - 16th, when day and night time temperatures were in double figures. This mild spell meant November '22 as a month ended up being 75% higher G.P-wise than 2021 ! So that's why cutting extended into November and we experienced some very aggressive disease as well.


The graph above shows rainfall from a number of U.K locations and within the U.K we can see some really wide variability. Not just between our Scottish location and our English ones, but within England itself. This is the rub. Some areas have had more than sufficient to restore water levels after this summer's drought, while others haven't. I put 1976's rainfall for the south east of England as a reference and you can see 4 of our locations are below this figure. If I had time to download data from areas of Cambridgeshire and Suffolk, I could show you that there are some locations that have had less than 350mm of rain y.t.d ! When you compare that with a typical y.t.d. E.T figure of 550 mm, you can see how far behind these places still are and why the soil is still dry.


We can also see how wet November has been across the south / south west of England with some locations showing > 200 mm.


Irish Locations - Monthly Growth Potential & Rainfall Stats

Looking at the Irish stats, we can see a pretty similar picture for monthly G.P for October in terms of equalling or in some cases exceeding the amount of growth in May !

November also came in with higher growth than April in just about all of the Irish locations. The east side of Ireland tends to show higher monthly G.P levels (in general) vs. the west and north west. There is an exception of course and that is Valentia, stuck down in the pretty south west of Kerry, which exceeds (from a total G.P perspective) all of the Irish and U.K locations, courtesy of the mild winter conditions it 'enjoys'. There is a very wet flipside to that coin though as you will see below, just before you get onto Ryanair flight booker 😃

In terms of rainfall, the eastern locations come in drier (see Bray and Dublin vs. Cork for example) and pretty similar to what would be an average rainfall total in the U.K. As we head south and west, the rainfall totals start growing because we are heading into the area where most Atlantic storms make landfall, culminating in Valentia's sky-high rainfall total (> 2x of Dublin). As with the U.K, October and November have been wet ones across many locations in Ireland, with 250 - 430 mm of rain falling.


So mild and wet would sum up Ireland's autumn from these stats.


Disease Pressure Update


I mentioned earlier in the blog that this autumn we have seen significant grass growth due to the higher than average air and night temperatures. Higher temperatures don't only cause an increase in grass growth, they also promote fungal growth. Dovetail this with some really high humidity peaks and extended periods of leaf wetness and we have a perfect recipe for Microdochium. Last week I saw some really active Microdochium on what were nearly pure Fescue tees. I note also that in Syngenta's monthly turf blog they have seen active Dollar Spot in November. You can read about it


Continuing an exercise from earlier in the autumn, below is a graph showing the Smith Kerns Dollar Spot Probability Model from September to the end of November at 3 locations. You can clearly see the first initial peak in early September followed by smaller peaks at the end of the same month. Come the end of October, we can see another significant peak of disease activity and although this drops back in early November, it peaks again from the 8th-16th Nov. This explains why we saw active Dollar Spot during November.

The plus point now is that with colder weather in situ we should a marked decline in activity. That's a bonus because we won't be seeing much growth in terms of providing recovery !


So a very interesting autumn to put it mildly, whichever side of The Irish Sea you live and a real taste of winter to come. By next Monday I should have the first inkling of whether we are heading towards a 'White Christmas'. I hope so as I've laid odds on it with William Hill (Paddy Power have withdrawn their White Christmas betting...can't think why !!!!)


All the best and wrap up well !


Mark Hunt

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