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

[That ECM]

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.

.

Having looked at all the output this morning, I see little to back up your conclusion. Yes, very cold and strong easterly. The majority of the PPN is in the channel and over France. GFS is slightly further north than UKMO. It will take a shift of 60 plus miles north for southern counties to get hit and that would be a big shift with little time left.

The trend of this low has been south, if you look at the latest nae acc chart, it shows nothing across the whole of the south.

Edit ECM has the low following the same track as the UKMO upto t 48. No magic shift north there. Time running out for the south on this one.

Edited March 10, 2013 by That ECM

[Polar Maritime]

Good luck with your forecast Roger...

After this bitterly cold next 4/5 days, the GFS continues to show a cold Northerly flow into next week, with pm shot's into FI. No sign of any Spring warmth yet, in fact more akin to mid-winter. A very cold March coming up i feel.

The ECM even has another Easterly showing from the 19th, with the Atlantic well and truly blocked.

Edited March 10, 2013 by Polar Maritime

[wightwootton]

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.

December 12th 1981 rings true Roger with the same senario!

[Gibby]

Good morning. Here is the latest report of the 00z output from GFS, UKMO and ECM for today Sunday March 10th 2013.

All models show the cold spell having reached all but the far SW of England this morning with cloudy skies and still some snow over parts of East Anglia and the Midlands slipping South and dying out. Further rain from a Low pressure area down to the SW moves East over Southern Britain later today and tonight giving snow in the extreme South while all other areas see an increase to near gale NE winds, penetrating cold conditions and snow showers towards Eastern areas pushing further west at times. This setup lasts through tomorrow too with slight accumulations of snow in places in the extreme South and over Eastern areas. By midweek winds are shown to back Northerly and decrease with brighter skies and more scattered snow showers but sharp frosts at nights. All models also agree on a milder spell of weather developing later in the week as Low pressure to the NW deepens and sends cloud, rain and hill snow slowly East across the UK late in the week.

GFS then shows a wet and unsettled interlude with rain and strong winds giving way to colder winds again from the NW with wintry showers for a time. Through FI today a more conventional SW flow steadily develops with milder air with rain at times, the heaviest of which will be in the NW of the UK.

The GFS Ensembles show good support for the milder solution later in the week but are less supportive of the much milder winds that the operational shows for the South in Week 2 preferring to keep rather chilly and unsettled conditions going.

The Jet Stream continues the Southern latitude theme of late though a new arm does develop over the North Atlantic and over the UK late next week.

UKMO for the end of the week shows Low pressure sinking slowly South towards the Hebrides with SW winds over the UK bringing less cold conditions with rain and showers as we move into next weekend.

GEM shows a vigorous SSW flow by the weekend with wet and windy weather spreading to all areas in near average temperatures by then. Later in the weekend and start of the new week the weather stays very unsettled with a complex and deep structure of Low pressure near or over the UK delivering spells of heavy rain and showers at times in near to average temperatures.

ECM shows deep Low pressure governing the UK's weather throughout the latter stages of it's run as it revolves around our island giving very unsettled and rather cold weather with rain or sleet and heavy wintry showers all in the mix as we move through the weekend and start of next week.

In Summary the cold spell will weaken later in the week as the developing Low pressure close to the NW later this week deepens and extends it's influence over all areas. Rain or shower are likely for all with temperatures becoming dependent on the position of the Low complex. Whatever happens it still looks as those looking for sustained dry, milder and settled weather will be waiting some while yet from this morning's output.

[Frosty.]

The Channel islands are in for around 2 inches of snow in the next 24 hours, perhaps as much as 4 inches. Most of the uk mainland snow is likely to come from showers spreading in from the north sea, some areas having shower after shower and accumulations are likely when the sun goes down, most of the snow melting on impact until later today because the bitterly cold air is yet to arrive. Now tomorrow will be exceptional cold, feeling like minus 7 celsius, max temps tomorrow barely above freezing or staying at or below in places and a lot of snow showers coming in from the east, remaining wintry in the days ahead with more snow showers and sharp frosts, mid winter weather.

[IDO]

Another downgrade from the GFS for snow from the Channel Low. Snow depth:

Each run sends it further south and there is still 24 hours till its effect, so there is every chance of a non-event (again) for most away from the SW and Sussex. I suppose that is why the UKMO leaves it really late to put up warnings.

Not much change from the GEFS. The op is not a mild run compared to the mean from D6-D10 anymore, as it has been in the last few days:

This ties in with the ECM op more closely. However after around D10 the GFS op again joins the milder runs whilst the mean keeps thing cool. Looks clueless from around then. Though to be fair, last night's ECM ensembles also show a split:

The trend is to keep it cool/below average from both models. It may be late in the month before we see some Spring warmth.

ECM at T240:

Edited March 10, 2013 by i'm dreaming of...

[fergieweather]

I think great caution still required re developments tomorrow. Firstly, the northern bounds of the dynamic snowfall in south remain rather flux in latest EPS, with variation between MOGREPS-R & MOGREPS-G; equally with EC. Whilst consensus is stronger to take worst conditions further south across France (and Channel Islands), there remains a 10-20% PROB of a severe event in parts of SW & S England, but for now we cater for 5-10cm Dartmoor & other SW Peninsula uplands; 5cm some other uplands of S coastal districts of England.

Perhaps of even greater concern - given better continuity in story - is situation in E areas and SE, where winter CB's, generated across SST of 4C and with tops to -30C, have real potential to deliver locally troublesome accumulations. This will be heavily reliant on focussing such as topographically through Thames Estuary.

In short, any downplay of current prognosis should be viewed with due caution until we see detail unfolding. Hopefully this will be a non-event and disruption avoided, but it's a real weather roulette with high stakes despite low probability.

[Frosty.]

The latest operational runs, just as yesterday, continue to show a less cold and unsettled spell later in the week due to low pressure to the northwest of the uk sinking south to the west of the uk or across the uk with trough disruption but the track of the low is still uncertain, it probably means we will lose the cold uppers, at least for a time but looking at the ecm 00z, cold air bites back with a vengeance with more snow on the way if the ecm verified, but until midweek it looks very cold with snow showers, more especially for northern and eastern counties and more so towards coastal areas and widespread moderate to sharp frosts, then less cold with rain, preceded by snow and winds going swly for a time but not mild.

[SLEETY]

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.

Couldn't agree more Rodger.I know the met and the bbc forecasters aren't keen on the low pushing further North currently,but these Channel Low blizzards are extremely rare,last one i remember dec81,and that forecast was wrong even as the blizzard was raging outside.

They are also notoriously difficult to forecast the exact path of the low so I would expect this to be a continuously developing situation over the

next 24 hours or so.

Edited March 10, 2013 by SLEETY

[nick sussex]

Interesting to see the ECM trying to develop colder conditions later after a milder interlude.

That does however look more marginal than the conditions expected over the next few days with the troughing for the moment stuck over the UK rather than being edged se'wards.

In terms of the Channel Low it still looks a very close call especially for the southern coastal areas, convection looks interesting further north and possibly for the the se later,there could be some fireworks with that very strong easterly flow and very cold uppers.

In terms of the rest of the week still cold upto Thursday, possibly some more snow showers Tuesday earlier in the day and Kent looks a bit more prone with a possible convergence zone, a weakening cold front heading south later in the north could bring some more snow.

Monday and Tuesday nights look very cold for the time of year with some sharp frost.

So alot going on, not bad for March!

[fergieweather]

I expected nothing less from a met office employee, to say you wanted disruption would probably mean dismissal from your job.

BBC, not UKMO. What sane person would WANT disruption on the start of a working week across some of the most populous areas of England??!!

[TEITS]

Couldn't agree more Rodger.I know the met and the bbc forecasters aren't keen on the low pushing further North currently,but these Channel Low blizzards are extremely rare,last one i remember dec81,and that forecast was wrong even as the blizzard was raging outside.

They are also notoriously difficult to forecast the exact path of the low so I would expect this to be a continuously developing situation over the

next 24 hours or so.

Problem is though this LP isn't tracking along the Channel and is actually predicted to be across N France.

http://expert-images...031115_1000.gif

This is why most of the precip associated with the LP remains in the Channel and across N France. We could see a shift N but this is a very slim chance because if ahything a shift S has been occurring which is often the case in these situations.

I would love to be wrong though but at this stage most of the snowfall that is going to occur over the next 48hrs will be of a convective nature.

BBC, not UKMO. What sane person would WANT disruption on the start of a working week across some of the most populous areas of England??!!

I would love to see a blizzard that grinds the country to a halt but I am insane.

Edited March 10, 2013 by THE EYE IN THE SKY

[LJS22]

BBC, not UKMO. What sane person would WANT disruption on the start of a working week across some of the most populous areas of England??!!

Sadly Ian the vast majority of members of this website who clearly never go out when they get the cold & snow they crave.

[chris x]

will probably snow hard as need to get to sevenoaks weld hope your Wright and nothing much er down South bring back spring

[LJS22]

I've got 80 deliveries to do in Worthing tomorrow. A further shift south by another 100 miles of that low please

[DEYS(Kent)]

Re the channel low, it's not it's fronts that is causing the headache, it's how far south the front currently lying from EA NW'ds goes and if the approaching CL and it's fronts intensify it. Is this a correct assumption? Nowcast tomorrow.

[TEITS]

Here is something I wasn't expecting to see a slight shift N of the LP according to the 06Z NAE.

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2013/03/10/basis06/ukuk/pslv/13031109_1006.gif

[No Balls Like Snow Balls]

Still the trend on the GFS 00z and ECM 00z for things to turn less cold next week. How ever It's not going to be particularly mild or cold.

come the end of the week / start of next weekend both the ECM and GFS 00z show a LP centred over or near to the UK that has originated from the NW and subsequently it brings with it much more unsettled weather.

[Cloud 10]

The best "model" to use at the moment.

Meteociel - Observations satellite - images satellite infrarouge et visible

[Average Joe]

BBC, not UKMO. What sane person would WANT disruption on the start of a working week across some of the most populous areas of England??!!

Agree totally.Some of us have a hard enough time earning a living and running a business at the moment as it is, to have to put up with the kind of disruption that could be brought by this event is very much something I'd like to avoid.

[Frosty.]

BBC, not UKMO. What sane person would WANT disruption on the start of a working week across some of the most populous areas of England??!!

Sorry ian, my ignorance there, I thought you were met office/bbc.

Enjoy this rare event cold fans, it's not often it will feel like minus 7 in march, but it will tomorrow.

[stratty]

Couldn't agree more Rodger.I know the met and the bbc forecasters aren't keen on the low pushing further North currently,but these Channel Low blizzards are extremely rare,last one i remember dec81,and that forecast was wrong even as the blizzard was raging outside.

They are also notoriously difficult to forecast the exact path of the low so I would expect this to be a continuously developing situation over the

next 24 hours or so.

..........the storm that made me fall in love with extreme weather! the 12th or thereabouts, living in Gloucester then. Was but a mere child and had a nightmare in the middle of the night. My mum (Happy Mother Day!) got up with me to get a drink from the kitchen and the first signs of snow were blowing around. Waking up the next morning to see my dad trying to clear the drive with the neighbours, blizzard absolutely chucking it down and snow drifts of already a metre around. The schools were closed right up to Christmas because of temperatures freezing up the pipes....around the minus teens? Father Christmas bought me a weather station (not quite like todays technology! lol) that year and from that day on i took the temperature every day. Happy days. Sorry but the current charts do not show any such thing unfortunately for us! I'm not sure i'll ever see such an event in this country again..............i live in hope!!!!!!!

[nick sussex]

Just looking at the ECM postage stamps at 168hrs, a few more solutions bring something colder than the operational, certainly it looks like a small shift this morning, will that grow?

http://www.ecmwf.int...t!2013031000!!/

Edited March 10, 2013 by nick sussex

[SMU]

Morning All

My 10000th Post from being here ~ 8 Years-

Only usually posting in the winter threads thats 12 posts a day where has all the time gone!

Its been a fantastic 8 years posting on net weather- thanks to everyone for making it a great forum ( even with the rollercoaster ups & downs)

A few flakes here in the wind in Greenhithe- however expecting things to deteriorate overnight.

The ltrack of the low is now firming up & it seems that the track isnt favourable for widespread frontal snow, however the south coast & SW are well in the firing line, also the channel Is. - Guernsey & Jersey could be the place to be for continuous blowing snow-

Other than that there is one significant development thats been in the wings for the last few days which is the potential for big streamers to develop- ( Ian I call them dynamic as I noticed you posted on that- but slightly at odds with the official met definition- I mean deep convective showers )

Whats been the variable in the models is the wind allignment, initially a NE flow would have brought pockets & lines of streamers just to places like North Kent ( a bit like the small area of the last poor easterly ) & thats what was modelled up to 36 hours hours ago, also the energy over scandi was being modelled to fast-

Now though, because the low is tracking close to the channel - whilst the frontal zone stays off shore it funnels strong convergence all along the thames estuary & further North towards suffolk & Norfolk-

Looking at the 500s & 850s the parameters are I would score 9/10- with the heights ideally 4 dam lower but hey we cant be picky-

The measures are-

partial thicknesses are ~ 1265 DAM ( VERY LOW)

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2013/03/10/basis00/ukuk/th85/13031115_1000.gif

Heights

http://www.meteociel.fr/ukmo/runs/2013031000/UW30-21.GIF?10-06 Sub 530 DAM ( ideal is sub 524)

850s -13/-14c !!

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2013/03/10/basis00/ukuk/t850/13031115_1000.gif

Generating a gradient of ~ 18/19c

The flow allignment- around 85 Degrees-

http://www.meteociel.fr/ukmo/run/U42-21.GIF?10-06

So, with a slight IMBY post for the E & SE- Watch for convection to fire from dusk tonight- maybe slightly later- with then the prospect of towering shower clouds & clear shower trains moving due west.-

Note of this grain snow either- proper high cloud tops with stella dendrites-

Of note today is the first shower train that developed overnight for scotland in identical parameters delivered 2-3 inches for parts of Aberdeen-

The only difference here is the low sliding along the channel supports the perfect onshore wind allignment from 00z Monday & lasts for 36 hours before the winds move back to the NE...

All in all an exciting period of weather- the roulette wheel could land on Green 0 for some over the next 24 hours-

With prospects for significant shower trains also over the E & NE pushing inland later today & overnight-The usual suspects will get a pasting as well as places like E & NE ireland could do very well overnight tonight in the mix of the strong easterly flow!!

best regards

Steve

[bluearmy]

the ecm ens mean in fi continues to promise winter nirvana charts with a cold trough sunk across the uk rather than eastern europe. apart from upland areas n half of the uk and many parts of scotland, thats unlikely to deliver too much white stuff that will settle. a few weeks too late. no guarantee that the mean will verify, especially as its unlikely to have naefs support for being quite as amplified (judging be the gefs mean). however, the ultimate in 'sods law' to see this output when its too late for coldies to benefit. no one want to see cold and damp/wet. lets hope history repeats this year when over the past decade, cold march's were followed by decent summers.

EDIT: naefs update isnt too far away - not quite as amplified/deep but pretty good as a wintry set up (if it were winter)

Edited March 10, 2013 by bluearmy