Spring Model Discussion 18Z 9/3/13 onwards....

[J10]

Evening all.

A new thread just prior to the coldest 850's of the last couple of years are about to take hold. The main question is still unanswered - will these be accompanied by low lying settling snow?

Whether we see significant snow or not, it is certainly likely to be a significant deep cold spell for early spring. How exactly will it play out and what is to follow - discuss here.

Please remember to be civil and courteous. Not everyone is looking for a continuation of cold and snowy conditions and those hoping for a return of warm settled conditions are just as welcome to hope for that - as those looking for cold.

Personally I would be happy with one final cold shot followed by a warm, sunny and particularly dry spell. Here's hoping.

Post away.

With those upper temps in the middle of winter, what daytime maxes would be looking at I would imagine a few degrees below freezing.

[No Balls Like Snow Balls]

I'm sorry but I have certainly never held the ECM at 'God like status'. What has been posted RE the ensembles is common sense in relation to the ensemble mean maps

I see the the ECM london and Birmingham ensembles trending less cold through the whole output.

[nick sussex]

It's a good job I'm not still living in Sussex otherwise my laptop would have met with a grisly end! Very frustrating to see these continuous southwards corrections in the low.

At this point the low should just get lost completely, given the strength in the wind at least convection could drive showers well inland.

Who needs to watch the fish getting pummelled in the Channel, unless theres a major turnaround tomorrow morning I would just expect not much from this.

Perhaps some rich member will charter a plane to the Channel Islands before the airport shuts and use it as a tax write off under Net Weather mercy mission!

[Cheshire Freeze]

I see the the ECM london and Birmingham ensembles trending less cold through the whole output.

Yes but that was always likely as we go from a frigid airmass to a cold (but less cold) upper air regime. -6 850s at this time of year will result in temperatures of 7-8C

[Paul]

I'm sure virtually everyone on here is a pretty reasonable type of person in their daily lives (the majority of people are), so please have a step back before posting and ask yourself whether you would speak to someone face to face in the way your post may be worded and the tone you're using too. We're talking about weather, it's a shared hobby/interest for all of us so there's no need to be aggressive or disrespectful when you're putting your opinions on here

[Purga]

those are 12z charts purga. only the precip accums are out thus far for the 18z run.

JH, i think it was worth pointing out that the less cold trend, whilst 100% certain, may not be as marked for the uk as for holland, given the locale of the mean trough.

The 18z NAE is not quite as bad but it still isn't good!

[london-snow]

NAE is BAD as BA says

Interested to hear METO's take on it from Ian F?

Sorry but why is that chart bad?

Snowfall into the south east and into eastern areas.

I don't know you're location however but for MARCH you cannot ask for much more can you?

Precip amounts and snowfall will vary the only thing worth keeping a eye on at the moment is the channel low and even that track will change.

[chionomaniac]

I'm sure virtually everyone on here is a pretty reasonable type of person in their daily lives (the majority of people are), so please have a step back before posting and ask yourself whether you would speak to someone face to face in the way your post may be worded and the tone you're using too. We're talking about weather, it's a shared hobby/interest for all of us so there's no need to be aggressive or disrespectful when you're putting your opinions on here

Just to add to this that if you post something and then realise that it may not come across the way you intended, then you can edit or even delete your own post! I know that I have self deleted my own posts a number of times so don't be afraid to do that yourselves!

[Hurricane Buckley]

The NAVGEM keeps the snow over the SW, S and later the SE, this has just updated, i know this isnt in line with other charts but this has stuck when others have chopped and changed, maybe its on to something which others might pick up on at the 11th hour.

[chionomaniac]

On the latest GFS run the WAA on the west side of Greenband is increased and substantial. I wouldn't be surprised to see a fairly strong GH set up from this - and further east than the previous run.

[fergieweather]

So, little to add currently from UKMO chief. The most rainfall equivalent generated in latest NAE for Monday is 4mm in S Devon; 2mm or less elsewhere in S England; much higher totals N France. Latest EC has v similar amounts. So on face value a non-event BUT chief cautions how "....we must be mIndful how all ingredients remain... of a severe event with blizzards (etc)..."; this more serious outcome currently given a 10-20% PROB based on all available output as of now. (He also then details possible more serious ramifications in SE from this, plus mechanisms that could create heavier falls here, e.g. Kent).

Edited March 9, 2013 by fergieweather

[chionomaniac]

On the latest GFS run the WAA on the west side of Greenband is increased and substantial. I wouldn't be surprised to see a fairly strong GH set up from this - and further east than the previous run.

Well, in fact, it only pushes the trough a slight bit further east - but that is still enough to stop any mild 850's gaining hold over the UK.

[lorenzo]

Sorry, been off grid recently and seen a lot of NAVGEM posted, what are this models res stats is it an equiv or NAE / NMM / HIRLAM mesoscale ?

[Tim Bland]

After reading comments on ECM I was expecting it to show it turning mild.. In fact at day 10 it shows -8c uppers over half the uk and -6c uppers for the rest. -6c uppers still ok for snow in march although granted it will melt if the sun gets a look at it. A bit disappointed by tonight's event, currently in Manchester and its drizzly. Seems to be a non event away from Norfolk as its dieing out now

[chionomaniac]

So, little to add currently from UKMO chief. The most rainfall equivalent generated in latest NAE for Monday is 4mm in S Devon; 2mm or less elsewhere in S England; much higher totals N France. Latest EC has v similar amounts. So on face value a non-event BUT chief cautions how "....we must be mIndful how all ingredients remain... of a severe event with blizzards (etc)..."; this more serious outcome currently given a 10-20% PROB based on all available output as of now. (He also then details possible more serious ramifications in SE from this, plus mechanisms that could create heavier falls here, e.g. Kent).

It is interesting that you mention Kent, Ian, because as the system trends south over consecutive runs there is also a trend to stall and tilt the low pressure, leading to increased precipitation over Kent and south East Sussex. One certainly to watch, and I wouldn't be surprised to see if this trend increases over future runs. Hence, I guess the watch out for Tues morning.

http://www.metoffice...se&tab=warnings

Edited March 9, 2013 by chionomaniac

[Captain Shortwave]

The NASA model is interesting, it wants to bring the -12 isotherm back over the South East of England. Would likely bring some slow moving heavy snow showers off the north sea in a light North Easterly wind.

Unfortunately I have watched most runs of this model and well it's not doing too good at the moment and seems to be behind the main models and this run doesn't include a Scandinavian surface high which I think will turn up.

[bluearmy]

Plenty of 18z gefs members want to prolong the cold.

[Cheshire Freeze]

Plenty of 18z gefs members want to prolong the cold.

Yes PTB 2 is one such beauty

Ensembles have certainly trended colder as a whole since the 12z suite

Edited March 9, 2013 by CreweCold

[Purga]

Sorry but why is that chart bad?

Snowfall into the south east and into eastern areas.

I don't know you're location however but for MARCH you cannot ask for much more can you?

Precip amounts and snowfall will vary the only thing worth keeping a eye on at the moment is the channel low and even that track will change.

Bad as in downgrade from a decent snow event to a light dusting when there is a once in a blue moon opportunity to get a memorable blizzard like snow event for the south. I am on the south coast of Sussex and boy, can I assure you that such a chance is as rare as hen's teeth! It's just a crying shame to see it all descending into mediocrity again with the snow shifting ever further south with each run and being wasted in the Channel. The UK is surely one of the most frustrating countries in the world at times - weatherwise. Edited March 9, 2013 by Purga

[london-snow]

Bad as in downgrade from a decent snow event to a light dusting when there is a once in a blue moon opportunity to get a memorable blizzard like snow event for the south. I am on the south coast of Sussex and boy, can I assure you that such a chance is as rare as hen's teeth! It's just a crying shame to see it all descending into mediocrity again with the snow shifting ever further south with each run and being wasted in the Channel. The UK is surely one of the most frustrating countries in the world at times - weatherwise.

Well let's turn a negative into a positive here ~

A dusting as you put it is rare down south in march especially then we take that dusting and dependant on timing following on heavy snow showers cannot be ruled out which can build.

The lp and its track is far from nailed tomorrows 12z should be our focus & we are not talking a major shift north we are talking a hundred miles which in weather forecasting terms is not a great deal at any range. I guess that's why Ian F's chief forecaster has cautioned uncertainty.

Let's hope for a northward shift tomorrow. We should see some snow at least out of this spell.

[Blake]

Link did not have malware FYI.

For those who didn't see the link, it is http://www.weatherweb.net but you will just have to find the snow depth chart yourself.

As I mentioned in that deleted post, the snow depths from 15-17th fall in line with suggestions of return tocold after milder air later this week. Depths up to 8 inches near cotswolds and south and west mids.

Edited March 10, 2013 by GUWeather

[Blake]

This was the chart from the link I posted that I wished to share. Less cold blip after Tues looks to make way for more cold to filter in from north/west with snow over western areas (some central) next weekend which backs up some if what has been discussed the last couple of days regarding the 6-15 day forecasts, moreso 168-240hrs.

[Panayiotis]

This was the chart from the link I posted that I wished to share. Less cold blip after Tues looks to make way for more cold to filter in from north/west with snow over western areas (some central) next weekend which backs up some if what has been discussed the last couple of days regarding the 6-15 day forecasts, moreso 168-240hrs.

You shouldnt be using the GFS accumulation charts they are very unreliable! You would find that by today's runs that it would change quite dramatically!

[Roger J Smith]

I'm going to continue to beat the drum for potential blizzard conditions in south coast counties on Sunday night into Monday, the low is taking what seems to be the ideal track to interact with bitterly cold winds forced to a cyclonic path across the Channel, and the similarity to the Jan 1881 historic blizzard set-up is noteworthy.

I have the feeling that some are underestimating the potential of this dynamic situation. You have extremely cold uppers racing south and meeting this Atlantic moisture head-on. Temperatures are still 8-10 C all across the Channel region and can't be suppressed all that much before the storm sets in. My prediction is that a severe snowstorm will develop rapidly across most of southern England on Sunday night and some amounts will be large with this, not just on the bleakest part of Dartmoor either. Yes, a sharp northern cutoff somewhere around or south of the M-4 with other unrelated areas of heavy snow from the North Sea inland.

Not much time to wait now. This is coming, you won't get these very cold uppers in play without a big snowstorm. Channel Islands will be included eventually, may start as rain or sleet with thunderstorms then change over to snow. IOW may actually jackpot in this set-up although inland Dorset to east Devon looks favoured also. And I think at present the chances are greater than 50-50 that this would spread into at least the southern half of greater London and most of Kent-Surrey-Sussex, however, there will be a sharp northerly cut-off and north London may see much less.

[stevofunnelcl]

Roger. Storm?

Not bad at all. Met O forecast for south west. Right through to Monday PM

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Today:

Rain, heavy in places, will spread east across western parts through the day. By the afternoon, sleet or snow is likely across higher ground, particularly towards the east. Turning colder, accentuated by the strong wind. Maximum Temperature 7 °C.

Tonight:

Rain will readily turn to snow and will fall across many southern areas overnight, giving some accumulations. Drier elsewhere but with isolated snow showers. Bitterly cold with frost and ice. Minimum Temperature -3 °C.

Monday:

Snow will continue to fall across southern parts giving further accumulations before easing by the afternoon. Drier and brighter elsewhere but bitterly cold with a strong to gale force wind. Maximum Temperature 3 °C.

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