Winter Model Discussion 18Z 19/2/13 onwards.

[bluearmy]

Thats the second ecm fi wanting to make nw europe the home of a trough (sourced from way north and crucially, attached to the vortex). The gefs control similar. given the time of year, could be a messy old solution re varied surface conditions but certainly a wintry outlook if it were to verify.

[shaky]

sundays frontal snowfall has been downgraded on the fax charts!mind you they always have things further south!!yesterday the ukmo gm had thingd 50 miles further north than what the 12z fax charts were showing!!so wouldnt surprise me at all that thats the case this morning'!!oh and the ecm is a beauty especially in its latter stages!!

[woldsowl]

UK4 indicative of circa 10cm snow parts of Kent by end of Friday but this is almost certainly overestimated: 3-6cm more likely. The backing flow into Friday means we will see 2 or 3 discrete shower bands: one through Lincs; another through Thames Estuary to S parts of London; and a third probable into E Kent. Meanwhile, the Channel shower stream focussed into Dartmoor/S Devon/SE Cornwall remains a very consistent feature through Friday.

1-2cm accumulations fairly commonplace under any such convergence areas through Friday, with scope for 3-6 as previously mentioned. However, given lateness in the season, there's likely to be a marked diurnal bias governing longevity of settling: i.e. generally only from late afternoon to mid-morning at low levels wherever amounts of snow are 3cm or less (the majority).

The Fax chart shows a band stretching form Lincs up to SE Scotland, which seems to have a kink in it as well. Could this enhance the precipitation?

What is UK4, I seem to have missed out on this one?

[bluearmy]

The Fax chart shows a band stretching form Lincs up to SE Scotland, which seems to have a kink in it as well. Could this enhance the precipitation?

What is UK4, I seem to have missed out on this one?

uk4 is an in house met office product. the convergence zones will not show on the slp charts. the troughs are a clue as to where marked bands of instability lie but there will be other areas prone to precip - more localised and not possible to show on a european map.

[Gibby]

Good morning. Here is the report of the 00z output from GFS, UKMO, GEM and ECM for today Thursday February 21st 2013.

All models continue to support a very cold spell for the next 4-5 days at least with High pressure over Scandinavia the driving force to the UK weather. A cold and fresh easterly or Northeast flow will blow over the Southern half of the UK with a lot of cloud carried West in the flow at times. There could be some light snow flurries at times with more prevalence to these for more Eastern and Central areas while the West and North stay dry with the best of the sunshine reserved for here. There will be sharp frosts nationwide over this period cloud or no cloud at night, severe in the South coupled with the breeze.

GFS then shows that the cold will loosen it's grip somewhat as warmer uppers mixes the air out though the UK lies in a very similar synoptic pattern right out to the end of the working week with still some night frosts under any clear skies as the East or NE flow eventually falls light. Through FI a small disturbance moves North into the UK coupled with a Northerly flow developing to the NW of Britain. A little rain or snow will develop over the UK for a time before a NW flow brings clearer, cold and fresher air down from the NW though with some wintry showers in the North. Late in the run High pressure lies close to the West of the UK with a slack Northerly flow over the UK delivering dry and rather cloudy conditions in temperatures still on the cold side.

The GFS Ensembles show the operational was a marked cold outlier this morning for Southern Britain. In general a cold start is shown giving way to less cold conditions next week with the traditional large spread between members as we go through the second half of the run. Precipitation toatals remain largely suppressed and confined to rather later in the run.

The Jet Flow continues to be split North and South of the UK with a link over the Atlantic joining the two early next week before a split flow resets later next week.

UKMO shows a slow moving High pressure area over the Northern North Sea with a slacker ENE flow over the Southern half of the UK. Though still largely on the cold side of normal temperatures would be less low than of late with continuing dry and settled weather for all with some sunshine at times but frost at night,

GEM shows High pressure to the NW slipping slowly SE over Britain later next week then away to the SE. Low pressure sinks South through the Atlantic setting up a SW flow over the northern half of the UK with the chance of rain in the NW while the South holds on to dry and bright weather under a tenuous ridge from the sunken High pressure.

ECM shows High pressure based over the UK towards the middle of next week losing it's identity as winds turn more NW or West late in the week as Low pressure moves down from the North. Rain would arrive up here with snow on the hills. At the end of the run this unsettled weather moves further South slowly with some eventual rain for all in Westerly winds.

In Summary there is complete agreement on the short term pattern which takes us out to the middle of next week with dry and very cold weather the general theme with light snowfall at times in the East and South giving a light covering here and there. Then, longer term there are plenty of options in what the models do with the High pressure area as it weakens after midweek. The trend for weak disturbances to move North into the UK with some rain is shown by various output which acts as a catalyst for a more concerted attack from the NW with rain at times later from GFS,GEM and ECM.

[nick sussex]

Close but not close enough yet is my view of the ECM, you can see how just a se 'wards correction could really bring a spring shock to many.

The problem is by 264hrs you'd have phasing of that energy to the sw with that over the UK and this then will see a mixing out of any cold. It's essential then to get the pattern further se.

Still a chance the models could do that given the timeframes involved, the GFS is a better trend synoptically because that takes more energy into the Med and not ne towards the UK although its a bit flabby to the west which effects the cold advection.

Edited February 21, 2013 by nick sussex

[BLAST FROM THE PAST]

Well as per discussions earlier, I think we are seeing the signal of prolonged cold getting picked up on. ECM T216 to T240 doesn't look right, AZH HP regaining some strength? Not for me, LP bomb to continue to drop from E Greenland.

BFTP

Well 00z ECM shows lower heights over Azores with the northerly cold digging down and winter reload and compared to the 12z it shows the correction trend needed that Nick Sussex refers to. UKMO out to t144 but look at the heights way out west, the HP over us backing west, generally heading towards same as ECM nad GFS. No sign of any SW flow returning on the runs at present and certainly not by early next week!

So cold is in, snow chances and amounts being upgraded as anticipated, cold looks like elongating and reloading...brrrrr...no early Spring....but when it comes I suspect a sudden marked flip....and possibly more issues for the UK but after a notable cold spell for late winter.

BFTP

Edited February 21, 2013 by BLAST FROM THE PAST

[TEITS]

I bet some members in Scotland and N England are delighted with the output this morning. Further S and I continue to believe we're going to need to see a shift E. If this was Dec or Jan I wouldn't be saying this but due to the time of year you need a direct hit with the coldest upper temps. If the output remains the same then I can see some crazy weather coming up.

Back to the E,ly and Ian Fergusson covers the E,ly this weekend excellently. The predicted amounts he suggests seem spot on and the only thing I will add is some locations may see more than 3cm. I have found in these situations that if some locations are under a constant stream of light snow showers then snow accumulations can mount up. I remember Dec 2005 where a majority in my region missed the snow and yet I witnessed 10cm because of a steady stream of light snow showers. However due to the time of year accumulations are less likely during daylight hrs.

Im expecting the snow showers to arrive late this evening by the way across Lincs, E Anglia,SE.

[mushymanrob]

Here we go again winters over blah blah blah, any charts to back up this claim?? the models cant even agree on whats happening over the weekend and first part of next week, yet here come the spring is in the air posts......

if the models cant agree on whats happening over the next weekend, why is it not ok for someone to suggest that winters over (which it MIGHT be, although theres no real evidence for this), but ok for snowlovers to ramp up the meagre potential that something might happen regards snow in fi?... just the other day there was some great early springlike charts, i dare say that the pendulum could swing back in favour of milder.

theres no agreement from the anomoly charts, the gfs anomoly contradicts the op run in fi, by holding on to a large northern block stretching from canada to scandinavia. no northerly there. the ecm anomoly does suggest a polar maritime airflow in over a weeks time, but thats certainly subject to change..... EITHER WAY.

[Purga]

After remarkable agreement of the runs up to the beginning of march, the Op was on the minority cold side of the ENS 0z but then so is the control run which is a favourable indicator.

Now looking less likely for a warm 'flip' as may have seemed ealier this week.

[Tom Montalbano]

Close but not close enough yet is my view of the ECM, you can see how just a se 'wards correction could really bring a spring shock to many.

The problem is by 264hrs you'd have phasing of that energy to the sw with that over the UK and this then will see a mixing out of any cold. It's essential then to get the pattern further se.

Still a chance the models could do that given the timeframes involved, the GFS is a better trend synoptically because that takes more energy into the Med and not ne towards the UK although its a bit flabby to the west which effects the cold advection.

Yes, as I think you're suggesting Nick, the ECM in FI, looks to be developing a west based -NAO but certainly too far out to be worried about just yet, core of heights just too far west.

Regards,

Tom

[No Balls Like Snow Balls]

GFS has daytime temps no higher than 5c for most parts right upto the end of the high res part of the run. ECM shows a slight warm up over the next 2 weeks but never getting above average.

It would kind of feel like no mans land with temps not cold enough for snow but not warm enough for it to fell like spring either

[Mair Snaw]

if the models cant agree on whats happening over the next weekend, why is it not ok for someone to suggest that winters over (which it MIGHT be, although theres no real evidence for this), but ok for snowlovers to ramp up the meagre potential that something might happen regards snow in fi?... just the other day there was some great early springlike charts, i dare say that the pendulum could swing back in favour of milder.

theres no agreement from the anomoly charts, the gfs anomoly contradicts the op run in fi, by holding on to a large northern block stretching from canada to scandinavia. no northerly there. the ecm anomoly does suggest a polar maritime airflow in over a weeks time, but thats certainly subject to change..... EITHER WAY.

my last post at 23:09 last night if had seen it said similar. i just dont see the point in one liners without charts to back them up. if a chart shows poss spring then by all means but a one liner that spring is coming when no charts show it is not what this thread is for.

[Average Joe]

GFS has daytime temps no higher than 5c for most parts right upto the end of the high res part of the run. ECM shows a slight warm up over the next 2 weeks but never getting above average.

It would kind of feel like no mans land with temps not cold enough for snow but not warm enough for it to fell like spring either

Cold can still be enjoyed without snow though surely?

[No Balls Like Snow Balls]

Cold can still be enjoyed without snow though surely?

I think you would find that the majority would want snow with it to, you only need to read the posts prior to see that

Personally I am happy with cold and frosty, but wouldn't say no to some warm feeling days either

Edited February 21, 2013 by No balls like Snow Balls

[SomeLikeItHot]

After remarkable agreement of the runs up to the beginning of march, the Op was on the minority cold side of the ENS 0z but then so is the control run which is a favourable indicator.

Now looking less likely for a warm 'flip' as may have seemed ealier this week.

The thing to note that is that that chart is for London, the equivalent for say Aberdeen, sees many more cold members near the the Op run, (while still being on the cold side of them itself). So basically what we are seeing is a moderate confidence of scotland getting a cold northerly, with decreasing chances as we go south.

Edited February 21, 2013 by SomeLikeItHot

[Methuselah]

Cold can still be enjoyed without snow though surely?

Not sure that 'enjoyed' is quite the word I'd use, DK. That said, we're all going to experience/tolerate it, whether it snows or not...

[Severe Siberian icy blast]

Cold can still be enjoyed without snow though surely?

It depends ones definition of cold. Cold , sunny , with frost , then yes it's great , and releases those endorphins from the sun that makes us feel happy, dull 6c , breezy , with spots of rain in the air , then no , makes me deppressed , everyone enjoys the sun , no matter what the temp, but give me dull and cold . . . . Makes me wanto drive off a bridge !!!

[Average Joe]

Not sure that 'enjoyed' is quite the word I'd use, DK. That said, we're all going to experience/tolerate it, whether it snows or not...

Haha, I was meaning more bright, clear but frosty really, suggesting that it doesn't always have to snow for cold weather to be enjoyed....by some....!! But now I'm off topic, so I'll quit before the 'police' take me away......

[Average Joe]

It depends ones definition of cold. Cold , sunny , with frost , then yes it's great , and releases those endorphins from the sun that makes us feel happy, dull 6c , breezy , with spots of rain in the air , then no , makes me deppressed , everyone enjoys the sun , no matter what the temp, but give me dull and cold . . . . Makes me wanto drive off a bridge !!!

Me too...thanks SSIB, and good to see you back posting, even if from my point of view it means that winter's not leaving any time soon....but I don't bear grudges!

[mike Meehan]

Haha, I was meaning more bright, clear but frosty really, suggesting that it doesn't always have to snow for cold weather to be enjoyed....by some....!! But now I'm off topic, so I'll quit before the 'police' take me away......

But it's not so pretty

[mountain shadow]

I bet some members in Scotland and N England are delighted with the output this morning.

Irish and Northern Irish members are even more delighted. A west based -NAO can deliver not surprisingly the further North and West you live.

[chris55]

It looks as though we are going to be having a few "invisible frosts" much like this morning over the next few days.

Dew points lower than air temps means a cold but very dry air hence no visible frost.

Air temps -2/-6C

Dew points -5/-7C

[Timmytour]

if the models cant agree on whats happening over the next weekend, why is it not ok for someone to suggest that winters over (which it MIGHT be, although theres no real evidence for this), but ok for snowlovers to ramp up the meagre potential that something might happen regards snow in fi?... just the other day there was some great early springlike charts, i dare say that the pendulum could swing back in favour of milder.

theres no agreement from the anomoly charts, the gfs anomoly contradicts the op run in fi, by holding on to a large northern block stretching from canada to scandinavia. no northerly there. the ecm anomoly does suggest a polar maritime airflow in over a weeks time, but thats certainly subject to change..... EITHER WAY.

You are asking about the the difference between the statement "winter's over" and talk of the potential of further cold.

There is an obvious difference to me..... you can see from the models there is potential for another cold snap, and even if some may exaggerate it's influence on the UK, it's hard to deny it's there

But unless you have access to a model with 100% verification over a two month period, I'd say making the statement "winter's over" is a world away from discussing model output

[No Balls Like Snow Balls]

GEM, GFS and ECM all show HP near to Greenland @ T168. It's gonna be close very close as to whether we reap any benefits.

One thing is for sure in that it probably isn't gonna be mild for the foreseeable.

Edited February 21, 2013 by No balls like Snow Balls