Spring Model Discussion 18Z 6/3/13 onwards....

[Frosty.]

Higher elevations of the southwest would surely get a blizzard out of this approaching storm

What storm?

Anyway, the 00z op runs show a short bitterly cold snap, especially for monday but the effects will still be there on tuesday, thereafter the cold moderates and as the overall pattern becomes more and more west based, the uk eventually looks like losing all the cold air with a trough becoming aligned sw/ne over the west and north with milder winds from s europe but that's a long way off, next week will be cold but slowly less so with temps recovering but still with overnight frosts, probably milder and more unsettled by next weekend. The ecm 00z op run tries to hold off the mild but synoptically it's a losing battle, the gfs 00z op is a softer version of the ecm and during FI the weather becomes more springlike again.

[SMU]

Morning-

Bit of a stalemate on the 00z's with perhaps a little movment south- What has been upgraded by the UKMO is the uppers & longivity of the cold-

Originally this was at best a 24 hour event- however the effects are certainly longer now-

The -10C line crosses into the South at T42 on the 00z ukmo

& we have the magical -14c line ( ~ 512 DAM ) across the central portion of the UK at 72

http://www.meteociel.fr/ukmo/runs/2013030900/UW72-7.GIF?09-06

The low creeps up the coast & brings more general snow to the south- however dont forget the convective potential further North.

http://www.meteociel.fr/ukmo/runs/2013030900/UW72-21.GIF?09-06

post that 120/144 the UKMO has a slight increase in uppers but with stagnent air at the surface & clearing skies I suggest some bitter overnight temps appearing-

What was originally just one cold day Monday has now turned into 2 potential ice days across England- with a third in the offerings if we can get suitable overnight freeze-

I maintain that the surface ridge will develop over Scandi in tonights models ~ 144 & hold the atlantic further west....

no reason to be downbeat today...

S

[Nick F]

Personally I think the temperatures and the severe wind chill of this cold spell will be the most notable thing rather than snowfall for many areas.

In terms of snowfall, eastern areas look most favoured throughout, rain to snow later today and overnight before clearing, then snow showers on and off towards eastern coasts. Southern counties of England looks to be in for a shout on late Sunday through to Tuesday, initially SW England, particularly over the Moors Sunday night, then further east to the south of M4 through Monday - though ECM and UKMO GM keeping snow to coastal fringes. Could be a big snow for the Channel Islands though - perhaps even blizzard like conditions for a time.

Still a window for margin of error from the NWP with regards to threat of snow on Monday towards the south, so needs close watcing for another 24 hrs at least IMO.

Edited March 9, 2013 by Nick F

[Pixel]

2 to go Steve (-:

The -14c line is boomtastic surely?

Plenty of opportunities for surprises in the next few days - radar and sat at the ready - Enjoy

[Frosty.]

Could be a big snow event for the Channel Islands though - perhaps even blizzard like conditions for a time.

Ahh so that's roger's storm, probably a near or not so near miss for the uk mainland though.

[No Balls Like Snow Balls]

After the excitement of this weekend and early next week in regards to possible snow and freezing temps it looks set to gradually turn less cold from Tuesday. GFS and ECM both currently agree on a NWerly wind by Thurdsay turning to a South/Southwesterly by Friday and heralding in temps close to or at the March average.

[Jason M]

Very good charts again this morning.

Got to be happy with what's on offer this week :-)

Snow should settle comfortably from tommorow tonight through Monday and Tuesday where it falls given the uppers on offer and a lot of cloud cover.

Hopefully we will all get our fill this week and then a nice big fat Bartlett will set up to end the month with some lovely warmth over Easter.

Jason

[snowblizzard]

Morning-

Bit of a stalemate on the 00z's with perhaps a little movment south- What has been upgraded by the UKMO is the uppers & longivity of the cold-

Originally this was at best a 24 hour event- however the effects are certainly longer now-

The -10C line crosses into the South at T42 on the 00z ukmo

& we have the magical -14c line ( ~ 512 DAM ) across the central portion of the UK at 72

http://www.meteociel...W72-7.GIF?09-06

The low creeps up the coast & brings more general snow to the south- however dont forget the convective potential further North.

http://www.meteociel...72-21.GIF?09-06

post that 120/144 the UKMO has a slight increase in uppers but with stagnent air at the surface & clearing skies I suggest some bitter overnight temps appearing-

What was originally just one cold day Monday has now turned into 2 potential ice days across England- with a third in the offerings if we can get suitable overnight freeze-

I maintain that the surface ridge will develop over Scandi in tonights models ~ 144 & hold the atlantic further west....

no reason to be downbeat today...

S

Wish I could be as optimistic as you Steve!

I can only see this going wrong as per usual. I have a horrible feeling that the low will end-up tracking much further South than is currently being modelled taking most of the PPN into the Channel & Northern France!

Plus, temperatures will also be moderated due to the time of year and power of the sun, although windchill on Monday & Tuesday will be an issue.

Sorry, but I don't see any ice days, but the +2c will feel like -5c

Anyone know when we last saw a proper Channel low in winter/spring?

Edited March 9, 2013 by snowblizzard

[Man With Beard]

Higher elevations of the southwest would surely get a blizzard out of this approaching storm, coastal regions more of a mix but wind and waves on south coast will be hazardous. Think it may cut off heavy snow east of IOW as it seems more likely to start moving southeast into Brittany. But parts of Devon, Somerset and Dorset could see 20-40 cm.

The main difference I see so far on the 00z is the cold air clamping down harder on the low and deflecting it faster to the south.

This may reduce snow potential in Kent, southeast and London but otherwise the North Sea very much in play and parts of east Midlands, Yorkshire and northeast could see locally heavy amounts. The southwest however may have isolated snow emergency situations developing given the combination of wind, snowfall and cold.

I'm going to stick up for Roger a little bit here. Of course we are used to last minute downgrades in the UK but if we look at what the models are actually saying right now (and this is T48, of course, not T144), 20mm precipitation plus somewhere close to the south coast does not seem out of the question (and Roger quite rightly said "could" in his post). Yes, these precipitation charts are often wrong but I recall a situation in January where 10mm was forecast for me by NAE at T12 but we ended up with far more than that and local flooding - so totals can go up as well as down. Regarding warm ground temperatures, I remember early April 1989 I think it was, there were first 3 days of 18C+ in bright sunshine, four days later and there was 3 inches of snow on the ground where I was in a far more marginal situation than this.

The only thing that's risky to do atm is to provide a localised forecast. There must be high confidence that someone will see 20mm of precipitation falling as snow on Monday, but whether that's Exeter, Jersey or Oxford, too early to say.

[fergieweather]

Personally I think the temperatures and the severe wind chill of this cold spell will be the most notable thing rather than snowfall for many areas.

You have almost exactly quoted the UKMO Chief Forecaster!!! He said same this morning!

Edited March 9, 2013 by fergieweather

[shaky]

You have almost exactly quoted the UKMO Chief Forecaster!!! He said same this morning!

Fergie you got any news on snow amounts from the showers we going to see of the north sea?

[Nick F]

This morning's HIRLAM looking the best of the bunch for southerners on Monday looking at the precip charts:

http://www.aemet.es/en/eltiempo/prediccion/modelosnumericos/hirlam?opc2=sup&opc3=pr

[sunnijim]

Maybe just got out of bed on the wrong side here, so please allow a bit of Imbyism from me on what i agree is a fantastic March set up from a cold/snow perspective.

This Channel low,am i alone in wishing it would just take a massive hike South? Why?because i would have much rather had the possibility ( as they still do further North of convective and perhaps prolonged and heavy snow showers).For the South now we have an all or nothing scenario playing out here imo,The all being a decent dumping from the channel low,or the more likely scenario now of a cloud sheet from the low killing convection in the South,some light snow at best and a bitter wind.I would of rathered a 'clean' solution of sunshine and heavy snow showers as was originally on the menu for all.

Edited March 9, 2013 by sunnijim

[johnholmes]

You have almost exactly quoted the UKMO Chief Forecaster!!! He said same this morning!

always said Nick could hold his own with 'em!

[mushymanrob]

im surprised there so much optimism this morning. i cant see anything now other then a cold snap which gradually loses its grip as the week goes on. all models now suggest average returning by later next week when once there was continued cold, re-loads, and no sign of anything milder. ok, this could change, but a warm up WILL happen at sometime, so its not unrealistic to supose that this mornings runs actually show one.

what was first seen as a possible record breaking cold spell for mid march, is now little more then a few pesky days of rawness which isnt likely to deliver settling snow for most of the country although i expect many will see snow. im not expecting it to beat the snowfall of march 79 here, and certainly not march 1970.

on the down side the outlook does look wetter as a moblie atlantic is suggested when temps rise later next week.

...oh and i dare say we arent out of the woods yet, more cold/below average will be a real pain imho this spring, abit like 83 or 79.

[winterof79]

You have almost exactly quoted the UKMO Chief Forecaster!!! He said same this morning!

Agreed but still noticable snow for some

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2013/03/09/basis06/ukuk/prty/13031000_0906.gif

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2013/03/09/basis06/ukuk/prty/13031006_0906.gif

Snow showers thereafter a distinct possibility.

[karlos1983]

Maybe just got out of bed on the wrong side here, so please allow a bit of Imbyism from me on what i agree is a fantastic March set up from a cold/snow perspective.

This Channel low,am i alone in wishing it would just take a massive hike South? Why?because i would have much rather had the possibility ( as they still do further North of convective and perhaps prolonged and heavy snow showers).For the South now we have an all or nothing scenario playing out here imo,The all being a decent dumping from the channel low,or the more likely scenario now of a cloud sheet from the low killing convection n the South,some light snow at best and a bitter wind.I would of rathered a 'clean' solution of sunshine and heavy snow showers as was originally on the menu for all.

From my perspective the modelled channel low is the only chance of decent snow down here. Convective snow showers never really quite cut it, as they've usually run out if "oomph" or don't reach this far south and west at all. Would be a more widespread event as well, potentially giving good covering from Cornwall to Sussex/Kent south of the M4. Channel lows are rare, so I'll take them all the time over convective showers off the North Sea. That said I can understand frustrations for East facing coastal counties, as this was initially thought to be a shower machine if my memory serves me correctly?

Karl

Edited March 9, 2013 by karlos1983

[Captain Shortwave]

Wish I could be as optimistic as you Steve!

I can only see this going wrong as per usual. I have a horrible feeling that the low will end-up tracking much further South than is currently being modelled taking most of the PPN into the Channel & Northern France!

Plus, temperatures will also be moderated due to the time of year and power of the sun, although windchill on Monday & Tuesday will be an issue.

Sorry, but I don't see any ice days, but the +2c will feel like -5c

Anyone know when we last saw a proper Channel low in winter/spring?

Lets see about the channel low though history does tell us it will probably be corrected south.

Ice days still look pretty reasonable. I looked widely for temperature predictions around the South of the UK and generally got max temps for Monday of between -1 and 1 degrees. So looking proper bitter.

Snow is forecast for parts of Lincolnshire/East Anglia this afternoon still with 2-5cm in places so good luck to anyone in the region who is a fair way away from the coast

[bluearmy]

still hoping for that ice day monday. The hirlam output is interesting as it matches gem precip for monday morning. Gem did quite well at the business end of precip forecasting during feb. we'll see if that happens again.

Looking for evidence of steves surface scandi high on the ecm postage stamps. Not as much support as i expected to see.

The trend on the mean ecm is to sink the cold trough across the uk but not from the best direction with a westerly influence across a fair chunk of the country,

[AWD]

Latest NAE similiar to the UKMO, with the heavier PPN kept in the channel on Monday;

The far SW look favoured for something decent however.

[fergieweather]

Fergie you got any news on snow amounts from the showers we going to see of the north sea?

The degree of model disparity from the midnight runs is proving a headache now for Exeter, not least with GFS moving to the UKMO-GM solution re Sun-Mon developments to south. However, re the N Sea showers, there is at least some better continuity. These could well prove to be a significant event. Note how the upper trough digs-in across the North Sea before then disrupting... the net result, as evidenced by profiles at 12Z Monday for E coastal areas, is that when synthesized across SST's of 4C, tops go up to below -20C. Clearly, this could generate wintertime low-topped CB's and consequently some locally heavy snow showers. Thereafter, by 12Z Tuesday, a repeat exercise with profiles across SST's of 4C could generate CUSC with tops below -10C. These would be high-based, but local convergence - such as in the Dover Straits - could generate some snow showers in places. Anyway, Exeter re-visiting the warnings in discussions this morning, so anticipate some changes in various respects are likely.

[manutdmatt1986]

Things look snowy in the South West by 6am Monday according to the NAE - http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=48&ZOOM=1&ARCHIV=0&RES=0&PANEL=0&LOOP=0&INFO=0&WMO=

[BARRY]

Latest NAE similiar to the UKMO, with the heavier PPN kept in the channel on Monday;

The far SW look favoured for something decent however.

That is the best set up i have seen this winter for us. we are now getting in to the right time frame

[Man With Beard]

Latest NAE similiar to the UKMO, with the heavier PPN kept in the channel on Monday;

The far SW look favoured for something decent however.

If you study the charts for T36 and T42, though, the heavier snow is clearly heading north; you would expect snow over much of the south at T54

[fergieweather]

PS: based on high-res (UK4 / UKV) output UKMO are especially looking at Wash/Lincolnshire/Norfolk/N Cambs area for warning re snow later today/tonight. 2-5cm, locally 10cm. Intensity-dependent re settling given higher depth temperatures and RST's.