I’m going to discuss the model output for the final half of January and also any wintry potential. There’s enough of both to get my teeth into, and although there’s no real end to this tedious winter in sight, bar the warmth coming in a few months, there are some interesting things developing…
Just wanted to remind you what snow looks like 😉
Tentative signs of something colder for the final half of January still remain very much alive in the model output. A cold front will sweep south on Wednesday, timing a little uncertain however it looks like this weather front, which could be fairly active, will sweep south fairly early on Wednesday to introduce colder conditions into the afternoon. This colder polar maritime / Arctic air will be producing some showers in the north on a fairly unstable north westerly flow. These showers could fall as snow to some fairly “modest” elevations in the north so don’t be surprised, if you live in say Scotland, the far north of England and perhaps Northern Ireland to wake up to a touch of snow to start Thursday. Further south, for the bulk of England and Wales temperatures will be higher so snowflakes will be limited to higher grounds, by the most part.
The following chart shows the precipitation type forecast for midnight Wednesday night into Thursday, the pink indicates where the model is forecasting snow to fall, green sleet and blue rain. As you can see there is the indication for wintry showers for much of Scotland, and some of those pushing into the far north of England probably associated with troughs and disturbances in the flow. It’s possible we could see one of these “troughs” move south on Wednesday night which could bring a little snow to parts of Northern England, detail with regards to this will be available nearer the time though. Most areas, especially in land across England and Wales look rather dry on Wednesday night.
A cold one into Thursday with a widespread ground frost, air frost in the north. Another cold one on Thursday however most places should get a decent amount of dry weather, perhaps turning milder and wetter from the west later, possibility of snow to northern hills.
The uncertainty really peps up from around Friday on wards (18th Jan). The ICON (German computer model) and GFS are keen on introducing less cold Atlantic air from the west on Friday (in some instances starting as early as Thursday), however contrastingly the UKMO and ECMWF are more keen on weakening the Atlantic lows and building a weak ridge of high pressure to our north and west during next weekend, thus keeping it rather cold. So there are question marks with regards to this period. As the Atlantic tries to reassert itself next Friday / associated weekend there’s a risk of some transitional “snow”, however it is really a long way off to be discussing snow risk.
It’s tough to decide which solution is more likely to verify at this stage, both GFS (more progressive) and ECM (more blocked = colder) solutions are probably equally possible. What’s also interesting is that the GFS and ICON are keen on a north westerly air flow into the following week and back end of the weekend, Sunday 20th/21st, so although this slight mild “blip” is possible as the warm sector arrives next Friday, the chance of a return to colder conditions really is alive into the weekend and following week. Zonality (west to east flow – generally mild) looks weakened in the next 10 or so and although “severe cold” is by no means in the forecast and very limited in options, this idea of a “wavy” jet stream leaves the British Isles open to opportunities from next weekend on wards. And yes, with those opportunities may come the risk of snow.
Quite technical for the average person walking down the street, but this blog is intended for the weather enthusiast.
I’ve cherry picked a few perturbations from the GFS that caught my eye and also look quite feesable. (Just click on them to load them up).
This one has a very southerly tracking yet stream and attempts to produce northern blocking. The result is cold weather and snow events at the surface as early as next weekend. The warm sector is quickly shunted out of the way by “cold zonality” (cold westerlies) and later on cold air is dragged into an unstable cold pool. Quite an interesting one and entirely feesable.
This one is more interesting. We eventually set up an easterly flow next Sunday. This indicates why there is vast uncertainty in the forecast from Thursday on wards. This solution is also possible but has little support.
Credit: Meteociel.
This morning’s ECMWF run is indeed very cold and quite snowy in fantasy island, on the “extreme end” of the options available but also entirely feesable giving the background signals (the recent SSW). The idea I have personally is that we’ll probably see an attempt at Atlantic westerlies next Thursday / Friday and for a time it may turn milder, however I expect colder conditions could begin to “build back” into the weekend. There’s also wintry potential during this time frame. As this is a long range prediction, it is “uncertain” as always. Hope you enjoyed the quick read.