Short range model discussion - into 2018

[knocker]

The ecm takes the upper low across central southern England, Wales and into the Irish Sea. Thus the main snow belt East Anglia west to Wales 00 Saturday to 1200 Sunday. Open to revision.

Max temps 3-4C Monday, 7-8C Tuesday.

Edited March 15, 2018 by knocker

[chrisbell-nottheweatherman]

3 hours ago, knocker said:

The updated fax charts for 122, Friday, 00 Saturday and 12 Saturday. Showing the fronts stalling and reversing tomorrow joined by the cold front and then all tracking south west clearing the there by 1200 Saturday.when there is also a convergence line into the Wash

Wash Streamer possible?

[knocker]

Just now, chrisbell-nottheweatherman said:

Wash Streamer possible?

And one or two others I imagine

[knocker]

Today and overnight sees the start of transition to the very cold and snowy regime set for the weekend as this slowly sets in from the north east with only the far south west remaining,  for the time, in the milder air

The band of rain and snow over the higher ground will continue in the north east as the front grinds to a halt with the wind increasing from the south east later in the day Showery rain further south will tend to die out leaving sunny intervals. But later this evening the front will start returning south west, with the rain turning to snow, under pressure from the high cell in the NE and will be joined by the cold front behind which lies the much colder air which is making progress by 00 Saturday.

The front will continue it's journey SW overnight and through Saturday morning but tending to weaken as it goes so perhaps sleet and rain entering the mix but behind the colder air is established with with frequent heavy snow showers streaming off the North sea in the increasingly strong wind, perhaps reaching gale force in exposed areas. Feeling very cold with a nasty wind chill.

But during Saturday evening the ubiquitous upper low has tracked west from around Lincolnshire across Wales to be NW of Cornwall by 00 Sunday accompanied by the cold pool which could well beef up the showers somewhat in the corridor of travel and further south. And by now it's feeling very cold.

So Sunday bitterly cold with possible disruptive snow in the east and south with possible less streamers further north but this is just according to the GFS and not definitive by any means.

Monday, although still cold with temps below average sees a respite from the bitter cold as further regime change gets underway with the Azores surging to the west linking to the high cell to our north and cutting off the easterly. Thus a much quieter period of weather with snow showers easing considerable.

 

Edited March 16, 2018 by knocker

[knocker]

This morning's updated fax charts for 00 Sat., 12 Sat, and 00 Sun, which tie in okay with the above.

[southbank]

Thanks Knocker for making this thread a truely enjoyable read with a smidge of dry rye and none of the emotions 

 

just a quick question , the convergence zones ( both wash and thames) that were on the fax charts for Sunday aren’t there today , is that because the forecaster doing them thinks it’s less likely to happen ?

[knocker]

1 minute ago, southbank said:

Thanks Knocker for making this thread a truely enjoyable read with a smidge of dry rye and none of the emotions 

 

just a quick question , the convergence zones ( both wash and thames) that were on the fax charts for Sunday aren’t there today , is that because the forecaster doing them thinks it’s less likely to happen ?

I would imagine so but you have to remember that just slight variations in the low level winds can make all the difference so nothing is set in stone even with 24-48 hours to go go.

[knocker]

The ecm takes the upper low and cold pool slightly further north than the GFS and doesm't have the same concentration of snow in the south but possibly some significant falls in the south west courtesy of a shallow surface low.

Edited March 16, 2018 by knocker

[knocker]

Just got in after popping down to see Sidney and I see the GFS has pushed the cold pool a bit further north. Not that it's particularly cold with the 850mb temp -13C and 500 -34C. Still good convective environment but the more concentrated snowfall may still be to the south.

 

 

Edited March 16, 2018 by knocker

[knocker]

The 1200 geostationary (courtesy DSRS) showing the low near Iceland, the front and cloud across the north of the UK and the quasi-stationary front to the NE in the North Sea with the clear cold air behind.

Edited March 16, 2018 by knocker

[knocker]

The cold front on it's way. The 1500 geostationary and 1200 analysis

[knocker]

The front and snow belt will track south overnight and in it's wake a very strong and cold easterly wind becomes established which will lead to frequent heavy snow showers in many areas covering the east and north and some way inland and perhaps becoming longer periods of snow in places as the showers merge

The cold core can be seen at 700mb and although the 700-500mb lapse doesn't appear exceptional (certainly in comparison with the last cold outbreak) more than enough for some nifty convection.

Edited March 16, 2018 by knocker

[johnholmes]

As always thanks k, saves me wading through piles of bumf on the other thread. I may even get snow on the ground here, twice in March-wow. Will see what actually happens but after a quick look at the outputs for this area it may well happen. Shame all the coal tips have gone, they would have made decent short ski runs!

[chrisbell-nottheweatherman]

5 hours ago, knocker said:

Just got in after popping down to see Sidney and I see the GFS has pushed the cold pool a bit further north. Not that it's particularly cold with the 850mb temp -13C and 500 -34C. Still good convective environment but the more concentrated snowfall may still be to the south.

 

 

I'd say -13C 850hPa temperatures are fairly low, Malcolm, given that, most winters, cold-loving Netweather members are pleased when -9 or -10 850s are shown in the outputs.

[knocker]

51 minutes ago, chrisbell-nottheweatherman said:

I'd say -13C 850hPa temperatures are fairly low, Malcolm, given that, most winters, cold-loving Netweather members are pleased when -9 or -10 850s are shown in the outputs.

Well when you put it like that. I think I had the Albermarle sounding where the 500mb temp was -38C in the back of my mind. The latter can be just as significant when looking at deep convection This wasn't the sounding I was thinking of

This is the sounding 850mb -15C and 500mb -46C now that's deep cold for the UK

 

Edited March 16, 2018 by knocker

[knocker]

The updated fax charts 12 Sat-!2 Sun. Must warn Sidney

[knocker]

The ecm has the Azores ridging nicely Monday/Tuesday with temps slowly climbing. Max 3-4C on Monday 7-8C

[knocker]

That should of course read 7-8C on Tuesday

I told Sidney the coldies weren't impressed

 

[shotski]

1 hour ago, knocker said:

The ecm has the Azores ridging nicely Monday/Tuesday with temps slowly climbing. Max 3-4C on Monday 7-8C

Simply sub tropical ? 

[knocker]

Satellite at 2100

[knocker]

Well the witching hour, or I should say the 48 hours, is finally upon us as the weather turns very cold for all in a bitter easterly wind with accumulations of snow in many areas from heavy showers. I will not attempt detail as this will be covered in the regional s and in any case it is really a matter of radar watching and keeping abreast of METO updates.So merely an overview,

The band of snow on the cold front that is tracking south will clear during the day giving way to a copious number of showers with a couple of convergence zones around the Wash and the Thames valley. Later in the day and overnight more persistent snow will affect the south east and south courtesy of a waving front just the south and a beady eye needs to kept on this.

During Sunday the aforementioned wave develops as it travel west along the Channel giving further snow in the south west before clearing whilst elsewhere a continuation of snow showers but but becoming less frequent as the day moves on. Bitterly cold in the easterly wind with temps struggling to get above freezing.

Monday sees the Azores high pressure ridging NNE to connect with the high cell to the north which starts to relegate the cold upper trough south and thus by Monday evening the temps are on the up in the 5-6C range.

This good work continues on Tuesday, albeit the max temps in the 6-7C range are still below average

And on to Wednesday for the last shove but now a new regime beckons which doesn't exactly herald Spring warmth but this for another day.

 

 

[knocker]

The updated fax's for midnight tonight and after  showing the developing wave over the south east tracking west

Edited March 17, 2018 by knocker

[knocker]

Satellite at 0500 and surface chart for 0600. Obviously the precipitation belt in the south and Midlands is very marginal vis rain/snow

Edited March 17, 2018 by knocker

[knocker]

Classy depiction of showers sweeping across the North sea around the anticyclone on the 0900 geostationary. (courtesy of the DSRS)

 

[lottiekent]

Is it the long wiggly line of fronts extending east that is expected to bring this afternoon and evening's snow over the south?