UK meteorology

Cheers gents. He's not so much feeling ill; more in discomfort, but we're concerned as to what's causing it.
Back to meteorology - we've had our first snow shower of the week here, though the sun is now out. Here are Malcolm's thoughts:
The UK is now well and truly into the cold and snowy regime which will continue over the next few days becoming increasingly bitterly cold with snow accumulations in many places thanks to ever increasing showers and periods of more persistent snow, By the end of the period things tend to get a tad more complicated.

Anyway today, after a hard frost in many areas, temps will struggle to reach 2C but it will stay dry and sunny in western areas, Further east snow showers will become more frequent as the day progresses and reach further inland and later this evening the much mentioned wave feature will appear on the scene introducing more persistent snow to the north. Showers can of course turn up anywhere but some idea from the gfs-wrf model







The wave will track south west across the Midlands into Wales overnight and through Tuesday morning taking the band of more persistent snow with it snow with it Elsewhere frequent snow showers and feeling bitterly cold.





Wednesday another bitterly cold day with a significant wind chill with widespread snow showers (by now accumulations mounting up) perhaps more concentrated in the north east.



Thursday is another bitterly cold day in the strengthening easterly wind but the complications are arriving in the form of a deepening depression tracking north to the west of Cornwall through Thursday and Friday with upper and surface fronts doing likewise across southern England into the Midlands. These could bring with them substantial snowfalls and very strong winds leading to blizzard conditions in many areas. The detail of this is still along way from being a done deal so currently a watching brief,




The uncertainty regarding the end of the week is illustrated quite well given last night's fax for 1200 Thursday and this morning's update for the same time. The updated 12 Friday chart may well be the key.
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Cheers gents. He's not so much feeling ill; more in discomfort, but we're concerned as to what's causing it.
Back to meteorology - we've had our first snow shower of the week here, though the sun is now out. Here are Malcolm's thoughts:
This cold weather has given me the chance to dig out my submariners pullover out and with my Swanndri heavy bushshirt over the top I'm as snug as a bug in a rug! Bring it on! :) P.
 
Netweather's chief forecaster has contributed to the 72 hour model discussion thread, so I thought I'd quote him:
My own synoptic analysis for the next few days, won't bother with Thursday/Friday's low until nearer the time, but will concentrate on tonight, tomorrow and Wednesday.

Current synoptic overview

A large blocking anticyclone is in place over Scandinavia, with a surface high around 1051mb centred over northern Norway Monday evening and a strong upper ridge over the Norwegian Sea extending from Iceland NE toward Svalbard. A slow-moving low pressure system affects central and eastern Mediterranean. Below 500mb/MSLP and T+00 fax from Exeter for 18z this evening





The jet stream loops around the Scandinavian ridge going northeast over eastern Greenland before dropping south over Svalbard then southwest across Scandinavia and then on across the British Isles, south into Iberia before joining the southern arm of the jet extending from the Azores eastward across the Mediterranean.



Between Mediterranean low and the high over Scandinavia, a very cold easterly flow covers much of Europe, bringing snow as far south as Rome today, while the deep cold air (-13 to -14C 1500m above) crossing the relatively warmer North Sea (between 5-6C) is causing a classic ‘lake effect' snow shower machine.



Tonight

Wind convergence zones this evening and overnight will enhance snow showers activity across eastern and southeastern England – particularly areas southwest of the Wash as far as the Southeast Midlands, also from areas around the Thames Estuary/North Kent coast and southwest across Kent and East Sussex. We could see up to 10-15cm in some spots that receive frequent heavy falls through the night, but not far away may see only a few centimetres at best.



Tuesday

Scattered snow showers overnight elsewhere along eastern coasts overnight giving a dusting in places. Then as we head into Tuesday morning and already appearing on the radar this evening is a mass of heavy snowfall over the North Sea off eastern Scotland and northern England – which marks an area of enhanced ascent ahead and along a surface trough and associated back-to-front frontal system over the North Sea moving toward NE Britain. This will bring an area of heavy snow showers or more persistent heavy snow in across parts of eastern Scotland and NE England overnight, before spreading southwest across northern England and north Wales during Tuesday morning. Further scattered snow showers for eastern areas through Tuesday, some flurries getting further inland towards the west too.





A unusually deep pool of cold air or upper low, coming out of NW Russia tonight, moves southwest on Tuesday and over the British Isles Tuesday night into Wednesday morning. This deep upper cold pool is forecast to have 500mb temperatures of below -40C and will create steep lapse rates allowing vigorous convection, with increase of thunder and lightning, over the north North Sea and into eastern Scotland and NE England. It may also enhance snow shower activity further south along North Sea coasts of England Tuesday night.



Wednesday

Into Wednesday, and it looks like the wind will veer more easterly or southeasterly while strengthening – which will mean snow shower activity will ease across SE England, with shorter sea track to near continent and concentrate showers along eastern coastal areas from East Anglia northwards with longer sea track but showers also getting well inland across central and northern Britain. The strong easterly wind, which may touch gale force towards eastern coasts, may cause drifting of snow, given its powdery nature.

 
Just drove down to Huddersfield through a blizzard, drove back five minutes later with only a few flakes swirling about and some powder on the pavements. Going to be an interesting couple of days.

Fairly typical of conditions today - the cloud wasn't that dense so precipitation was light and patchy. Had it been warmer it would have been one of those days with light fleeting showers.
 
Good to hear that others have snow (and nice to have contributions from those who don't normally comment in this thread)! I think we in lowland Norfolk have more than the Count does in the Pennines (3 inches) thanks to being just far enough inland from the North Sea to allow the showers to deepen as they come onshore but not so far inland that they weakened before getting here.
Anyway, here's Malcolm's usual 72 hour model post with my annptations in bold:
After the excellent summation by Nick above (obviously this was in the Netweather thread not here) it's really a question of attempting to dot the eyes and crossing the Ts a bit.

Out little wave feature has been busy tracking south west overnight bringing more consolidated snow showers to many areas and by 00 it is SW of Ireland.There have been some hefty snowfalls in many areas in the east, north the Midlands and north Kent. Behind a rather perturbed low level flow with some hefty convection going on as the UK comes under the influence of even colder air.





And talking about colder air the UK is now entering what is likely to be the coldest two or three days of this cold spell so worth a quick glance at the forecast wind chill over the next 36 hours according to the GFS-WRF



As the depth and intensity of cold increases it serves to boost convection and perhaps it's no coincidence that tomorrow there are likely to be some steep 850mb-500mb lapse rates (these are the difference between the temperature at the 850mB/hPa pressure level and the 500mB/hPa pressure level, which I've mentioned previously; the greater the difference, the higher the lapse rate, and the more unstable the air mass is) in the north and much showery activity in the same area, according to the GFS-WRF anyway The showers will continue through the day with strong winds along the north east coast, and later in the south, perhaps reaching gale force, thus feeling bitterly cold.



Thursday starts with a severe frost in many areas and feeling bitterly cold in the strengthening E/ESE wind touching gale force but changes are afoot to the south.



So the key question remains how will the breakdown in the south materialize and will it produce copious amounts of snow in southern and western areas? It remains unanswered but as to the latter looking leas likely but the best way to illustrate the problem is to post a few charts from this morning's gfs.following on from the one above.



And then on Friday the warm front does push north but there does not appear to that much snow on it and freezing rain is still being bandied about (keep an eye out for the warm nose this is the northernmost extension of the warm sector between the warm and cold fronts just south of the triple point associated with a low pressure area - if you go back to my lesson posts you'll notice it) so as mentioned previously the detail of this is still not sorted and it is certainly questionable as to how far north the 'warmer air will reach without 'mixing out' as for most areas, apart from God's Little Acre (Malcolm's from Cornwall), Friday remains a bitterly cold day.



 
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