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Model output discussion - after the beast, what next?


Paul
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GFS & ECM mean for 72 back to back

C0DC0643-50AF-4B58-A3BF-3A67E90081F7.thumb.png.9f3eaee3610feb5c4b0ac5f879a278eb.png64594F64-02AC-4683-8AD1-6265945428BF.thumb.png.c50a56a773a0e50a2e482a4177b8acba.png

GFS slightly more enthusiastic on lower heights but its much of a muchness-

Entry point of core instability still ~ Suffolk / North Kent....

No change. - Widespread snow up to about the newcastle possible dry slot in the middle -

S

Edited by Steve Murr
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Posted
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
  • Weather Preferences: Severe Storms and Snow
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
1 hour ago, Walsall Wood Snow said:

I don't like the look of that big dry spot across the central Midlands, though I think I'm actually to the west of that. Hopefully that's wrong still.

Arpege looks inaccurate to me, as it was the previous spell. No way would it be that light towards the south east.

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

One more day of double-digit temps for some tomorrow then it is all change over the weekend as beast 2 arrives

33-778UK.thumb.GIF.f90be84f69d95337fe9097939e103187.GIF57-778UK.thumb.GIF.562af7f391558cd791aedf846af5935d.GIF

81-778UK.thumb.GIF.e4448b606caf6c9a41c8d361f687d893.GIF102-778UK.thumb.GIF.7ea2b4fdb1b5598e3119c314d8d9241b.GIF

126-778UK.thumb.GIF.9bd90ee3b55e3cf851dbee8398993ba9.GIF150-778UK.thumb.GIF.ef89c5aedc520228665f2534e75174e1.GIF

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
7 minutes ago, Steve Murr said:

GFS & ECM mean for 72 back to back

C0DC0643-50AF-4B58-A3BF-3A67E90081F7.thumb.png.9f3eaee3610feb5c4b0ac5f879a278eb.png64594F64-02AC-4683-8AD1-6265945428BF.thumb.png.c50a56a773a0e50a2e482a4177b8acba.png

GFS slightly more enthusiastic on lower heights but its much of a muchness-

Entry point of core instability still ~ Suffolk / North Kent....

No change. - Widespread snow up to about the newcastle possible dry slot in the middle -

S

The dry slot will be 'sunny donny' Steve. but one never knows, we do get lucky once a blue moon, the last one was 30 Nov-1 Dec 2010

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
4 minutes ago, feb1991blizzard said:

And then another go, this time from the NE.

gfsnh-0-264_dnx5.png

 

Any thoughts of spring round the corner are rather fanciful. Here's the ECM D10 clusters - a deep trough on its way to the UK, perhaps en route to Europe in the same way as your GFS chart:

ec-ens_nat_z500scenarios_2018031500_240.

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Posted
  • Location: Hull
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Hull

GFSP07EU06_96_1.png

I mentioned yesterday about the potential for energy to our SSW keeping the high propped up longer. P7 shows my line of thinking. The high just about sinks but such a scenario aid retrogression and tap into the colder then normal arctic air for a northerly.

Anyway a brief warm up looks likely towards the end of the week but a further sharp northerly appears in quite a few of the recent ensemble runs. Either that or some form of cool zonality to see us through to the end of the month.

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Posted
  • Location: Wellseborne, Warwickshire
  • Weather Preferences: Southerly tracking low pressure in winter. Hot and thundery in the summer
  • Location: Wellseborne, Warwickshire
26 minutes ago, johnholmes said:

The dry slot will be 'sunny donny' Steve. but one never knows, we do get lucky once a blue moon, the last one was 30 Nov-1 Dec 2010

Can I ask what causes the dry slot? I just don't get why because we are all under the same airmass

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

Rain turning to snow on the latest Euro 4 as the front moves SW and the colder E,lys set in.

18031706_1506.gif

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

A few GEFS try and curve the jet back towards the UK as the high topples bringing some deeper cold air back very close to the east and se.

At the moment the GFS wants to maintain the colder air for longer than the Euros.

 

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
1 hour ago, johnholmes said:

I don't want to be seen as a kill joy but perhaps a word of caution to those relatively new to this forum.

PPN is much more difficult to get correct even 24 hours out let alone 72+ hours than pressure charts and even the position of fronts and troughs, odd as that may seem.

If you watch the predictions in summer, be it frontal or showery/storm, how often does the model (any of them) get the spatial distribution, let alone amount correct?

With snow, other than the rare times when surface and upper air temperatures are more like central Europe than for an island, there are up to another 8 variables to get right. So just be aware of how much value to put on the PPN outputs even down to T+12, seriously.

The radar is usually your best short term guide and a bit beyond that the Fax charts, (they are human produced using all the available model data)

 

I know this isn't exactly what you are saying - but might be interpreted as such - it would also be wrong to suggest predicting precipitation can't be attempted at very least, based upon educated guesses on what could happen through a combination of models and experience?

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
54 minutes ago, Severe Siberian icy blast said:

Can I ask what causes the dry slot? I just don't get why because we are all under the same airmass

Got to say I am not at all sure. Winds from a westerly point and this area is in a rain shadow from the Peak District at times, depending on the actual direction of the isobars, why from the east unless it is the Lincs Wolds or the York Moors, again depending on the actual isobar direction..

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Posted
  • Location: uxbridge middlesex(- also Bampton oxfordshire
  • Weather Preferences: blizzard conditions. ice days
  • Location: uxbridge middlesex(- also Bampton oxfordshire
19 minutes ago, Quicksilver1989 said:

image.thumb.png.a395063d9c5481925bd493ce81508171.png

All ensemble members going for a direct hit now. Its a full house. Milder air makes its way through at the end of the week on all ensemble members but the shifting of the cold is put back a little bit on some ens as Nick mentions.

Don't be surprised if its prolonged further especially if little pockets of energy keep slipping under the high or it ends up further west.

A few members have us under a NE'ly as opposed to an anticyclone on Tuesday (uppers by the are less cold obviously but what if it kept going? :D)

Also ICON shows a load of showers in the NE on Monday afternoon which are associated with the movement of less cold uppers from the North Sea I presume. Been shown to fall as rain in recent runs but its getting very close to falling as snow....

 

Yeah- and its clear to note; the potential for the cold never really wanting to shift.

Via london ens...

Good to view where this one goes??! 

MT8_London_ens (2).png

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
28 minutes ago, Man With Beard said:

I know this isn't exactly what you are saying - but might be interpreted as such - it would also be wrong to suggest predicting precipitation can't be attempted at very least, based upon educated guesses on what could happen through a combination of models and experience?

My experience of the models over the past 5-10 years plus what I dealt with before I retired leads me to make my comment.

Hopefully the later and shorter range models will show increasing accuracy with this problem.

 

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Posted
  • Location: East Ham, London
  • Location: East Ham, London

Morning all :)

Excitement continues as individuals see if they will get a late snowfall over this weekend. For fans of cold it looks like a short spell of very low temperatures before a recovery during next week.

From there, as I reported earlier, the road was far from certain so let's see if any semblance of clarity has become established as I look forward to Sunday March 25th with the morning output.

Starting as always with ECM 00Z at T+240:

ECM1-240.GIF?15-12

After the cold snap of the weekend, the HP sinks SW and is absorbed into the Azores HP but that leaves a few days of settled and quiet weather until that too declines as the Atlantic re-asserts. The two-centre trough started with the northern centre as the main one but by T+240 the southern centre has deepened into a prominent feature to the west of Biscay. This throws a light SSW'ly flow up over the British Isles so average to mild conditions but an increasing risk of rain or showers from the south and south west spreading north and east. Hard to know the path from here - will the LP swing up towards us or head further south ? Note the ridge behind the trough to the west.

GEM 00Z at the same time:

gem-0-240.png?00

A different evolution from ECM but more akin to yesterday's GFS. After the brief spell of HP weather at the beginning of next week the trough sinks south over western Europe with a negative alignment taking it quite far south through France toward the Mediterranean. Weak heights to the north and north west persist. A slack NNW'ly airflow covers the British Isles with a shallow LP over the east coast. Rain or showers for many with snow to altitude would be my take from this chart.

GFS 00Z at T+240:

gfs-0-240.png

Oddly enough, this chart reminds me of yesterday's ECM 00Z. The trough is negatively aligned and while there is technically a SSE'ly flow over the British Isles at this time it's not a warm flow as it's essentially PM air taking the long way round. Rain or showers spreading from the west with snow on hills looks the call and temperatures struggling in the cooler sir mass. Further into FI and the unsettled theme continues with rain or showers never far away and a new LP slowing far to the SW hinting at a renewed build of pressure from the NW.

GFS 06Z OP at T+234:

gfs-0-234.png?6

A different shape to the trough but still an unsettled prospect with rain or showers for many. Further into FI, the trough sinks south and a brief NE'ly flows before the inevitable GFS reset to a more zonal outlook with light W'ly winds and the Azores HP ridging into Europe with the jet pushing back north.

GFS 06Z Control at T+240:

gens-0-1-240.png

Not too different to the OP though with a different shape to the trough. Further into FI and after a couple of failed efforts the Azores HP migrates SE to set up over southern Britain promising something rather drier and more settled for Easter.

The 06Z GEFS at T+240:

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

Broad agreement on the main pattern - HP to the SW trying to ridge in but the trough basically in charge across the British Isles. The odd cold option but nothing terribly exciting at this time. Further into FI and I don't see a clear option for Easter at this time with plenty of evolutions on the table though the possibility of colder conditions has, I think, receded since earlier in the week.

In conclusion, the path for the next week or so looks set as the cold Scandinavian HP drops through the British Isles bringing in several days of settled weather but the trough follows as the HP declines and all the models seems to want the trough to drop south either over to the just of the west of Europe and that will have an impact on conditions in the British Isles with either a warmer S'ly flow or something colder on offer. Either way, the drier spell earlier next week looks set to give way to an increasingly unsettled spell later in the week. Moving further ahead toward Easter and no clear trend at all as yet. Colder options have diminished and the 06Z Control offers quite a decent evolution but it's not got huge support from the Ensembles at this stage.

 

 

 

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Posted
  • Location: Thornaby-on-Tees
  • Location: Thornaby-on-Tees

If this is just a cold snap, cold enough for low level snow mid March, doesn't it put to bed the myth that once the cold and snow are here, it will be harder to shift? Something that was being said on the last cold spell too. 

Edited by shawty1984
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Posted
  • Location: Warminster
  • Weather Preferences: Snow, stormy
  • Location: Warminster
2 minutes ago, shawty1984 said:

If this is just a cold snap, cold enough for low level snow mid March, doesn't it put to bed the myth that once the cold and snow are here, it will be harder to shift? Something that was been said on the last cold spell too. 

I think this is more applicable in blocked situations, with the prevailing westerly regime trying to push across the UK from west to east and displacing continental cold air. In the past there have been repeated occasions of expected returns to westerlies and warmth that have not occurred (or sometimes only partially).

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Posted
  • Location: Ramsey, Minnesota (USA)
  • Weather Preferences: Thunderstorms/Snow/Hail & Strong Winds
  • Location: Ramsey, Minnesota (USA)
7 minutes ago, shawty1984 said:

If this is just a cold snap, cold enough for low level snow mid March, doesn't it put to bed the myth that once the cold and snow are here, it will be harder to shift? Something that was been said on the last cold spell too. 

That notion must be put in context through a number of aspects. The first being the synoptics itself, this spell hasn't been modeled as extending for a great period. The background signals have seemingly suggested the likelihood of a limited window. The first cold spell was in fact extended by a day or two as a result of models generally being a little bullish with Storm Emma. The cleanness of the synoptics has also made keeping the cold conditions difficult. Secondly the time of year has to considered, the upcoming spell would likely be extended to the end of next week with very low maxima if in January, though mid march inhibits this. 

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Posted
  • Location: Swansea
  • Weather Preferences: snow, snow and more snow
  • Location: Swansea
32 minutes ago, shawty1984 said:

If this is just a cold snap, cold enough for low level snow mid March, doesn't it put to bed the myth that once the cold and snow are here, it will be harder to shift? Something that was being said on the last cold spell too. 

yes I tend to agree with you on this.  those who say, get the cold in first and the snow will follow and the cold will be harder to shift doesn't necessarily ring true.  the last 'potent' cold blast from the east was supposed to be a corker but the cold really only lasted a few days and was booted out relatively quicker by milder air again.

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Posted
  • Location: Swansea
  • Weather Preferences: snow, snow and more snow
  • Location: Swansea
20 minutes ago, Frosty. said:

It's really an amazing situation from the latest models, especially for the s / se where temps tomorrow are expected to reach 10 / 11c around 51f but then plunge to around freezing give or take a degree or so on sat / sun ..(like flipping a switch)..mon also looks cold, especially in the SE..and as for snow..❄❄❄❄❄❄❄❄..I would expect disruption across parts of scotland tomorrow and then the southern half of the uk throughout the weekend with frequent snow showers and accumulations in bitter Ely winds..is this winter?..nope it's definitely spring!:crazy::cold::D

our weather patterns this winter, particularly with regards to the large fluctuations in temperatures on an almost daily basis seems very similar to those experienced in places like New York which frequently sees temperatures of 15c one day and then below freezing one or two days later. 

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