Short range model discussion - into 2018

[lottiekent]

I always enjoy your posts on this thread too Knocker, thank you for the time and trouble taken (you make much more sense than a lot of the mainstream forecasts!)

 

[knocker]

No significant changes with the medium term anomalies this evening.

Upstream Siberian vortex lobe and east Pacific ridge and still the intense vortex lobe N.Canada which stretches south east to a secondary lobe in the area of Iceland with the trough across the UK The very strong upper westerly flow south of the vortex and then across the Atlantic is maintained and with the adjustment of the alignment of the upper trough to the NW and the demise of the one to the SE/S continues across the UK. Although the northern arm of the flow does diverge in the vicinity of the UK and swings N/NW around the European ridge that is stretching over the Franz Joseph/Svalbard regions.

Consequently systems will track across the UK portending some unsettled weather, period of rain (Perhaps snow on the high ground) and wintry showers with temps a little below average. But the usual caveat that the details await sorting by the det runs.

[MattStoke]

Looks good for snow showers on Friday and Sunday, particularly for areas exposed to the NW wind. -8 uppers should be cold enough. Not sure it will stick very easily to low levels though. Temperatures will be above freezing. 

[moorlander]

@knocker really enjoy reading your daily reports

@MattStoke a nice brisk walk across the Roaches should keep you happy Sunday

[MattStoke]

Just now, moorlander said:

@knocker really enjoy reading your daily reports

@MattStoke a nice brisk walk across the Roaches should keep you happy Sunday

Indeed  Looks good for the Cheshire Gap streamer.

[knocker]

Currently most of central southern, south east and eastern England are waking up to quite a hard frost, -5C in places, but warmer air is on it's way as a weakening warm front currently lying across Wales western parts of England brings cloud and patch drizzle/rain further east.before the precipitation dies out. But there is another frontal system lurking close behind which occludes as it crosses the country. This will bring heavier rain with it as it crosses the country west-east through the afternoon and evening. Leaving frequent wintry showers in the NW in it's wake.

The front and rain continuing south east during the night finally clearing during the morning whilst in the meantime a belt of snow is affecting the NW before that too finally clears in the morning. From there after Friday will be cold with frequent squally showers in the NW and W.

But by Saturday 00 (as discussed last night) there is a deep low adjacent to southwest Iceland with the associated warm front orientated N/S just west of N. Ireland and western Scotland with a wave forming on the cold front to the south west in mid Atlantic (the fax is a tad more complicated than this but best leave that aside)

By 1200 saturday the warm front has brought rain and strong winds to the western half of the UK whilst the little wave has developed and is 999mb west of Ireland. Over the next 12 hours it deepens as it crosses southern Scotland into the North Sea where it is 987mb at Sunday 00. This could bring snow on the high ground in the north whilst the front proceeds south east across England and Wales so a pretty wet and windy saturday.

Once all of this has cleared on Sunday the UK is in a cold NW airstream with frequent wintry showers in the west and north, many of snow before on Monday the next low and fronts are lined up to the west of Ireland but this must be left here.

Keeping in mind last night's anomalies the GEFS 2-7 this morning

Edited February 8, 2018 by knocker

[knocker]

The ecm treats the wave on Saturday a little differently. At 1800 Saturday it has it over a fairly broad area around the Irish sea 994mb but then takes it east to be over the Humber 985mb by Sunday 00. Thus the rain belt, as against snow. is further south

And the ecm 3-7 anomalies Pretty unsettled with temps a little below average.

Edited February 8, 2018 by knocker

[knocker]

Apropos nothing at all really but the midnight Herstmonceux sounding is not a bad example of a radiation inversion at the surface with frost and warmer moister air sneaking in aloft from the decaying warm front presumably Although on second thoughts it could be from the old occlusion just to the south east

Edited February 8, 2018 by knocker

[knocker]

Tracking the 0C isotherm today and overnight

[knocker]

As mentioned previously the front and rain tracking east today and overnight clearing the south east by early morning with much colder air behind.

Edited February 8, 2018 by knocker

[knocker]

The 12 geostationary, courtesy Dundee Satellite Receiving Station. Showing the current fronts

[chrisbell-nottheweatherman]

5 hours ago, knocker said:

Apropos nothing at all really but the midnight Herstmonceux sounding is not a bad example of a radiation inversion at the surface with frost and warmer moister air sneaking in aloft from the decaying warm front presumably Although on second thoughts it could be from the old occlusion just to the south east

Upper-level soundings are the next thing I want to become familiar with, so I might save that output as an example of a radiation inversion - thanks.

[knocker]

Might be a little snow in the west on the decaying cold front behind the main fronts in the morning.

[knocker]

The gfs up to it's explosive cyclonenesis tricks again. Keep an eye on these two depressions over 24 hours

And a wave forms on the front and perhaps copious amounts of snow in Scotland

Edited February 8, 2018 by knocker

[knocker]

According to the ecm there could be some quite strong winds across Wales and central southern Britain in the early hours of Sunday as the low deepens and moves into the North Sea gusting 50-55kts and a fair whack of rain.

It is also going in for some 'bombing'. A small wave depression is WNW of N. Ireland at T96 that tracks NE and NW as it rapidly deepens to be over Iceland 960mb at T120. the associated cold front with rain  impacts Scotland, west Wales and Cornwall 0600 Tuesday having cleared N. Ireland with more strong winds, possible gale force

[booferking]

5 minutes ago, knocker said:

According to the ecm there could be some quite strong winds across Wales and central southern Britain in the early hours of Sunday as the low deepens and moves into the North Sea gusting 50-55kts and a fair whack of rain.

It is also going in for some 'bombing'. A small wave depression is WNW of N. Ireland at T96 that tracks NE and NW as it rapidly deepens to be over Iceland 960mb at T120. the associated cold front with rain  impacts Scotland, west Wales and Cornwall 0600 Tuesday having cleared N. Ireland with more strong winds, possible gale force

Some snow to.

[knocker]

27 minutes ago, booferking said:

Some snow to.

Certainly likely in some areas, not that I personally take any notice of these snow charts. It will be interesting to see whether a wave develops on the front.

Edited February 8, 2018 by knocker

[booferking]

Just now, knocker said:

Certainly likely in some areas, not that I personally take any notice of these snow charts.

Me either

[knocker]

Keeping a close on the anomalies as the witching hour approaches.

I'll skip the upstream spiel as essentially that's much the same as the previous couple of days but downstream some reasonable significant changes. The axis of the  Canadian vortex/Iceland trough is now orientated a tad further south as the east European ridge extends further into the Arctic and pushes into northern Greenland.

This may well strengthen the westerly jet in the western Atlantic but it will diverge and weaken in the eastern sector as the norther half swings north and then north west courtesy of the aforementioned ridging which is part and parcel with the block to the east. This may well create an environment in the Atlantic with some pretty intense thermal gradients for some pretty active depressions to form but they will a have tendency to swing NE/ N rather than across the UK although a far bit of energy will track east so the associated fronts might. So continuing unsettled with temps below average and tricky detail for the det. runs to sort.

Edited February 8, 2018 by knocker

[knocker]

Today is pretty much of a mixed bag that will be covered in detail in other threads but essentially the main front and moderate rain is currently affecting south eastern regions but will clear during the morning to clearer colder conditions. But there is another band of patchy rain, sleet and possibly snow on the higher ground following on behind that will affect the SW, Wales, the Midlands and the north. Behind all of this squally wintry showers in N. Ireland, NW England and Scotland will be more widespread for a while and quite windy in places but later the showers will die out leaving a quiet night. Quite a cold day with a widespread frost overnight.

But as can be seen on the last fax the next set of fronts with cloud and rain are just about infringing on western Ireland by 00 and by 06 this has reached N. Ireland, NW England and Scotland where there may well be snow on the higher ground. But as can be seen a wave is forming on the front west of Ireland.

The fronts track south east across the country during saturday bringing rain to most parts accompanied by strong winds, possibly gale force in western areas whilst the wave deepens and tracks north east to be over N. Ireland 986mb by 1800.and then into the North Sea by 00 Sunday. If this turns out to be the precise track then perhaps blizzard conditions for a while in N. Scotland.

By 1200 Sunday the low is over south west Norway, having brought with it some very nasty conditions in the northern North Sea on it's travels, leaving the UK in a cold north westerly airstream with frequent wintry showers of just about everything in western and northern areas, This continues over the next 24 hours to 1200 Monday although the wind will gradually back westerly

As can be seen on the last chart there is a deep low 975mb south of Iceland with associated fronts trailing south west. The low deepens rapidly to be 955mb east of Iceland by 00 Tuesday with the front already impacting Scotland (where the precipitation could fall as snow) and N. Ireland and again bringing strong winds, possible gale force. But it's quite a complicated scenario with the colder air sweeping east behind the front which actually trails a long way south west along the interface between the colder air ( upper trough) and the high pressure to the south. And along this intyerface, as can be seen, lows are forming.

What happens next as the front tracks south east across the UK is not without interest but there we must leave it.

[knocker]

And the ecm charts for T24,48 7 72

Certainly not looking great tomorrow,

Edited February 9, 2018 by knocker

[knocker]

Just to update and clarify where to day is going. As can be seen the fronts should clear the south east this morning leaving everyone in the cold, showery, NW airstream

 

[Man With Beard]

Snow for some today:

        

Some disagreement over a snowy period for E Anglia this evening (though I would always back a combination of EURO4 and ARGEPE)

      

[chrisbell-nottheweatherman]

1 hour ago, knocker said:

Just to update and clarify where to day is going. As can be seen the fronts should clear the south east this morning leaving everyone in the cold, showery, NW airstream

 

From checking to 24 hour FAX that you included in your earlier post, Malcolm, I think my area may see precipitation again later as per Man With Beard's post due to the occluded section of the cold front which curves north, west and then south over northern England at present.

 

Edited February 9, 2018 by chrisbell-nottheweatherman

[knocker]

1 hour ago, chrisbell-nottheweatherman said:

From checking to 24 hour FAX that you included in your earlier post, Malcolm, I think my area may see precipitation again later as per Man With Beard's post due to the occluded section of the cold front which curves north, west and then south over northern England at present.

 

Yes that looks likely Chris  looking at the radar and the high res. Modis for 1130 although the temps are a tad high for snow with 41F at Norwich at 12.