December 19th, 2022

Hi All,

Well the thaw has well and truly started with a 15°C temperature swing over a 12-hour period. I graphed out 4 Davis weather station locations and you can see how the change started gradually on the west coast of Ireland back on the 16th, but really gathered pace there at 22:30pm on 17-12. 4 1/2 hours later, that warmer front reached the south of England at the Bracknell location. It took a further 13 hours to reach Scarborough because it is both more northerly but also easterly and at the stage of writing my blog (06:30am this morning), it hasn't reached Glasgow.

I have seen some good communications on FB and Twitter regarding the situation we now find ourselves in, with a wet, thawed surface sitting over a frozen, deeper layer, so I only hope your facilities management and membership are both cognisant of the problem and understanding. The rain that fell yesterday and again today is falling through warm air so that will speed up the thaw and I'd hope the majority of locations will be in the clear over the next 24-48 hours, but as you can see from the graph above, we didn't all start thawing at the same time.

So how is the weather looking for the important Christmas week ?

General Weather Situation - w/c 19th December, 2022

Well as we know, we have a very mild airstream in situ since yesterday pm and overnight. So quick has been the transition that I can imagine the water companies are dealing with lots of mains bursts, judging by the trickle emanating from my tap this morning !

As you can see from the animated GIF above courtesy of www.tropicaltidbits.com, the isobars are tightly-packed so that means it is also extremely windy. This mild wind will pull showers and heavier bursts of rain across the southern half of the U.K from the south west onto western coasts and then inland. So for all areas of the U.K & Ireland today, expect a windy, mild and occasionally wet day with temperatures topping out down south around 13°C and across Ireland maybe up to 15°C.

Tuesday looks a drier day on the whole after overnight rain has cleared the south and south east of England. The winds will be lighter as well but it'll feel a little cooler, down into high single figures again but still feeling tropical after recent weeks ! Maybe too early to provide a spray window though as some areas will still be thawing and for sure, pretty wet as well making moving machinery out on the course tricky. So we are looking at 7-11°C and reasonably dry for Tuesday, with the cooler temperature across Scotland.

Wednesday is the the Winter Solstice and consequently the shortest day of the year. We will see more heavy rain and wintry showers move into Scotland and the north west of England and during the day these showers will move more inland into northern England. Ireland will see some rain across the north and Sligo, moving then easterly but this will clear by lunchtime hopefully to leave a drier picture. Dry for the southern half of England and for Wales on Wednesday and later those showers over the north and Scotland will fizzle out and become confined to western coasts. Still continuing breezy from the south west.

Thursday sees more rain on the horizon, running along the southern coast of Ireland before moving into the south west of England and Wales on Thursday morning. This front will then push across the southern half of England but may not reach eastern parts till evening. Wet also for northern England and southern Scotland after overnight rain will continue through Thursday morning. Remaining mild with temperatures sitting between 8°C (Scotland) and 12°C (Ireland, Wales and England). The wind will remain south westerly and breezy along western coasts, swinging round to the south and losing a little bit of mph through the afternoon. Thursday may present a spray day for central and eastern areas but it's highly dependent on how quickly that front moves across the country. I'd be adding a sticker for sure !!!

Closing out the week on Friday and we have another band of rain pushing in to the south west of Ireland and England and then moving diagonally (\) across the U.K, clearing those areas first affected as it does so. They'll also be rain and wintry showers across the north east of England. Bit of a temperature transition on Friday as colder air comes in from the north and west. This means that by the time that rain front reaches Scotland during the early evening, it could turn to snow over elevation. Further south and across Ireland, we hang onto that milder air for the day, so 10-12°C is to be expected.

That band of moisture is still positioned across the north of Ireland and England as we approach Christmas Eve. This band of rain, sleet and wintry showers will affect Ireland, the north of England and Scotland through the day with more of the same across The South West, south coast of England and possibly South Wales. Tricky to say at this point but we may see snowfall further north especially over elevation. Feeling much colder across the north but remaining mild in that south westerly airstream further south.

The forecast for Christmas Day is delicately balanced, especially for those like me who have a White Christmas bet on !!! The colder airmass over Scotland and the north of England will push a little further south as the wind changes to more north westerly and then northerly through the course of Christmas Day, so feeling cooler with possibly a return to frost in places. I think it will be mainly dry with just a band of rain across the north of England blotting the copybook, so the potential for a White Christmas looks limited as I sit here and type. Bah Humbug ! Winds will be lighter and turning more northerly through the day.

Weather Outlook - w/c 26th December, 2022

The outlook for next week starts off I think with some wintry showers across Scotland and the north of England with some of these moving further south along easterly coasts. Further south I think we will see more settled weather, on the cool and dull side, possibly with overnight frost and fog. Through next week I think the wind will drop and swing round to the north east and then east later in the week. Predominantly dry as we go through the week, some showers may push in from The Wash as is the way with this wind direction, but cold, frosty and possibly foggy. Any showers are more likely along eastern and north eastern coasts. As we move closer to the start of The New Year, it looks a tad colder with a finger of cold air pushing across towards the south of England, but I think mainly dry although this last feature is one to keep an eye on.

Agronomic Notes

There are probably two main considerations as I sit here.

Spray Windows

The first is spray days and that for sure will be tricky this week because of the prevailing wind strength and the frequent rain events. It is also going to depend on how soon your location started thawing out and how quickly it continues to do so. I spoke to a golf course manager earlier who has observed 25mm of thawing depth over a 3 hour duration (from 25mm @ 7am to 50mm @ 10am) so things are moving quickly (Thanks Rob for that and Happy Christmas to you :) )

With the heavy rain some locations have experienced, the ground may well thaw but be too wet for machinery.

With the variability in rainfall (intensity and location) and wind strength, it is pretty impossible for me to say when it may or may not work for your location and I'd also say the rainfall forecast is changing rapidly. My best advice is to keep an eye on your specific location and wind strength and try to pick your moment.

On the subject of wind strength and direction, I use a website / app called windy.com and it is excellent, both for its forecasts and ease of use. There's a snippet of their output below and you just put in your location and scroll through the days. I tend to use the GFS interpretation (bottom right) because I favour their forecasting model / accuracy but it's entirely up to you. I also use their app on my smartphone because it's great for fishing in particular !!!!!

The output above is from www.windy.com

One caveat, it can't help you with respect to Sprout-induced wind and 'forecastability' 😊

Potential Disease Pressure - Christmas Period 2022

I think the second part of the spray window question is perhaps more important and that is how are we looking with respect to disease development between Christmas and New Year. Again that's a tricky one because I've known times when we have seen some accelerated Microdochium development after periods of sustained, heavy frosts so I am a bit reticent to comment on this one but here goes. I no longer have access sadly to my Microdochium forecasting model but obviously I know the pertinent triggers and so this is my SWAG (Scientific-Wild-Assed-Guess - copyright - Dr. James Beard)

Obviously this week is set to be really mild but it'll also be very windy and wet on occasion and I think that's enough to discourage Microdochium development. It doesn't tend to figure during spells of wet and windy weather as a rule. As we go through into next week and we begin to lose that wind strength and temperature, there is perhaps a small window for disease development but I think it's limited. Once we get through to the easterly winds kicking in around mid-week then this threat decreases.

In the past, the period between Christmas and New Year has served us up some really aggressive Microdochium development but usually this has been because of a Omega blocking event in the jet stream when high pressure has funnelled up warm and humid air from the south / south east. (see image above showing warm air pushing in on the run up to Christmas 2021)

As I sit at this desk now I can't see this happening. Yes, we will have some weather from the east during the Christmas period but it doesn't look mild, warm and muggy to me, it looks cold, dry and settled and probably with reasonably low humidity as well.

So, if everything goes against you this week, ground conditions are sub-optimum, the wind is too strong and when it isn't raining, it is blowing a houlie, then don't worry too much because I don't think disease pressure will be high over this period. This mild weather on the run up will probably just get the plant back to a happy place and you may even see a bit of clip coming off if you manage to get a pre-Christmas cut in (though that may be more to do with the mower sinking into the surface a little to give you a lower-then-usual cutting height !) and then we will ready for The New Year and whatever that brings with it.

Those of you who know me, will know I'm a bit of a humbug when it comes to Christmas and not a fan at all, but I'd like to wish you all a safe, peaceful and relaxing one. A big thanks for following me on my re-invented blog and sticking with me, it is appreciated. Your feedback and this industry keeps my brain ticking, so thanks. A big thanks for all of you who have sent me in data as well. It's essential and again, appreciated.

All the best for Christmas and 2023...

Mark Hunt