Models, teleconnections and nowcasting

[knocker]

The North Atlantic 500mb and surface analysis for midnight

Much of England and Wales are breezy and being effected by rain at the moment, courtesy of the waving fronts, but the rain should clear through this morning leaving most areas cloudy with some sunny breaks. Further north Scotland is still under the influence of the low pressure so frequent squally showers tending to die out by the afternoon. But a further pulse of rain will creep into the south west of England and Wales by 1800/ And note the temp variatiom

This rain is down to the warm front(s) associated with next developing wave to the west and moves steadily north east through the evening and overnight and could well fall as snow over the higher ground of North Wales and the Midlands northwards

The amount and location of any snow is tricky depending on the precise track of the low through Monday and the change to a colder airstream behind the cold front

By Tuesday the low is well away in southern Sweden and the UK is under the auspices of the tpv lobe, thus a windy and cooler day with frequents showers and longer periods of rain, courtesy of the troughs/fronts running east within the circulation. But note another energy channel to the south west

A not dissimilar day on Wednesday

And again on Thursday but a shallow wave has sneaked up from the south west whilst the showery, and perhaps longer, precipitation in northern regions could be quite wintry with snow down to quite low levels

 

[knocker]

The unsettled and cool theme continues over the next five days. This according to the gfs

[knocker]

This morning's fax has tomorrows low a tad deeper and the triple point a little further south. The latest wrf snow forecast, but looking at the dew points this would have to be over higher ground

Edited February 23, 2020 by knocker

[knocker]

Although the detail will vary, not surprisingly the  ecm is singing from the same hymn sheet as the gfs

[knocker]

This is the movement that hopefully will be consolidated over the next few days, Namely the re-orientation of the tpv that involves the withdrawal of the Atlantic trough facilitating amplification of the subtropical high, portending a more settled and warmer period of weather

 

[knocker]

The formation of a high cell over northern Scandinavia on the 0600 gfs (merely out of interest of course)

At t144 a surface is forming along the eastern seaboard

It then tracks north east and undergoes rapid cyclogenisis which promotes amplification of the downstream subtropical high

The latter then gets disrupted and voila11

 

Edited February 23, 2020 by knocker

[knocker]

The rain associated with the warm front should arrive in the south west by early evening

And them track north east through this evening and overnight falling as snow on the higher ground of N, Wales and N. Ireland by 0100 and then over the north Midlands. the north of England and much of Scotland by 0800 Monday

And by this time the cold front is on it's way south east across Wales and England clearing the south east by 1800 with colder air following behind. Scotland remains cold with snow down to low levels near the center of the low

 

Edited February 23, 2020 by knocker

[knocker]

Heavy snow alert as frontal wave tracks east over the southern UK next Saturday. Oh my

[knocker]

Tricky detail at the end of the week according to the ecm with two energy flows effecting the UK. Certainly wintry showers in the north and possible rain with higher temps in the south

Before the lobe of the tpv takes control ob Saturday

Edited February 23, 2020 by knocker

[Dorsetbred]

7 minutes ago, knocker said:

Tricky detail at the end of the week according to the ecm with two energy flows effecting the UK. Certainly wintry showers in the north and possible rain with higher temps in the south

That'll make a change then Knocker....

[Dorsetbred]

1 hour ago, knocker said:

Heavy snow alert as frontal wave tracks east over the southern UK next Saturday. Oh my

Nowt to get excited about, it's a week away and we all know what that means, a wishin' and a hopin'...and then there's reality...

[knocker]

26 minutes ago, Dorsetbred said:

That'll make a change then Knocker....

Wont it just. I'm hoping that the change that ext anomalies have been indicating towards the end of the first week in March continues and firms up

[knocker]

The North Atlantic 300mb wind Profile and surface analysis for midnight

The developing wave is currently west of Ireland en route to the North Sea just east of Scotland by 1800. Heavy rain from the associated fronts is currently effecting north Wales and England which will turn to snow to quite low levels through this morning and then later Scotland where there could be quite significant accumulations. Further south further heavy will effect Wales and the southern half of England as the cold front tracks south east to clear Kent by 1800

The rain and snow will clear Scotland by midnight so everywhere will be a lot drier albeit with icy patches by morning, but frequent squally wintry showers will effect western regions, particularly the north west

Tuesday a much cooler day with frequent wintry showers, particularly in western regions, and these could well include thunder and hail in the mix

No great change on Wednesday but two energy flows are in play and another frontal wave is approaching from the south west

So by Thursday the country generally is in the colder air of a transient ridge with some wintry showers in the north whilst the aforementioned developing wave scoots up the Channel bringing rain to the south with possibly some snow on the higher ground

By Friday a lobe of the tpv is dominating the eastern Atlantic so a day of sunshine and showers with some longer periods of rain, courtesy of a stray cold front

 

Edited February 24, 2020 by knocker

[knocker]

I am not confident on going much further ahead vis detail, so suffice it to say remaining unsettled, but just to cover the weekend

The Upper trough moves east resulting in a very cold windy day on Saturday, particularly over Scotland. with frequent wintry showers, These will ease on Sunday as the wind veers and a ridge builds to the west

Edited February 24, 2020 by knocker

[knocker]

The 0600 surface chart. Moderate snow over northern England

[knocker]

Having seen the ecm we need to keep an eye on next weekend, particularly Saturday,and the developments at the base of the upper trough. Could be gales in some areas with heavy rain and snow to low levels in the north

 

[knocker]

A lot of moderate rain around on the 0900 chart. The quicker this cold front gets moving the better, Gusting 45mph down here as well as warm sector clag

 

[knocker]

The fronts currently effecting the country trailing all the way bck to yje next system

[knocker]

The gfs track for the wave on Thursday with rain for the far south

And moving on to the weekend and saturday finds a lobe of the tpv right over us portending very wind, heavy showers and feeling very cold. but the detail of this yet to finalized

Edited February 24, 2020 by knocker

[knocker]

And as a little bonus the GEM for Thursday and more rain for southern regions

 

[knocker]

And the ecm is completely different to the gfs for Saturday with a different orientation of the upper trough and it rapidly develops a frontal wave with the associated fronts crossing the country bringing strong winds and potentially a fair bit of rain

[knocker]

The North Atlantic 500mb and surface analysis for midnight

As can be seen the UK is now in the grip of the upper trough and on the surface that means a  much colder and unstable north westerly airstream which will get a tad colder over today and tomorrow. Thus a couple of days of frequent heavy wintry showers in the strong wind which will turn increasingly wintry. with hail and snow in the mix with the latter down to quite low levels even as far south as Cornwall.And these may coalesce at times as troughs/fronts run around in the circulation.  Feeling cold in the wind chill

But by midnight Thursday a frontal wave that has formed to the south west is curving east and is near the scilly's en route to NW France.and this will bring rain to southern parts with probably some snow on the higher ground. A very borderline scenario

But further trouble is brewing in the western Atlantic as another upper trough tracks from northern Canada to merge with the in situ one resulting in more frontal systems developing and tracking north east on Friday bringing heavy rain during the afternoon and evening

And by Saturday this has developed into a deep and complex low NW of the UK resulting in a very windy day with frequent heavy showers once the frontal rain has moved away to the east.

 

[knocker]

This morning's fax update and the ecm. Earlier comments still apply probably some snow on the higher ground along the northern edge

But at the moment it is the end of the week that is the main concern vis the wind and rain

[knocker]

Today's EC weeklies update is still looking at a change of pattern around the 9th of March with the re-orientation of the tpv and the retreat of the Atlantic trough. So a glance at the period 10-24

10-17

With the main tpv lobe now near northern Russia with the associated trough aligned down the western Atlantic the subtropical high is free to amplify to some extent in the east This would portend a drier and warmer period but systems still tending to track NW so less so for the north west

17-24

No significant changes, perhaps a tad more unsettled

 

[knocker]

Ideal; environment for hefty wintry showers. Not surprisingly supported by forecast soundings with the potential for cloud tops reaching around 20,000ft

Edited February 25, 2020 by knocker