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Model Output Discussions 12z 08/03/17


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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

Our problems mostly come from quite early on as the Atlantic system which moves in this weekend disrupts and sinks south east through the UK creating a cut off area of low pressure somewhere across central Europe, this prevents the Azores ridge from building strongly through most of Europe and instead we end up with heights further west and not as warm.

ECM1-96.GIF?26-0   ECM1-120.GIF?26-0   ECM1-144.GIF?26-0

So that south easterly predicted quite strongly a couple of days back with warm air and high heights have been replaced by cooler easterlies, possibly north easterly which will bring cloud into Eastern areas. That said the position of this Euro low and depth will have an impact on the high that develop. a weaker cut off low will certainly result in warmer conditions which is something the GFS this afternoon tries and results in a couple of days approaching the 20C mark.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

The Ecm 12z eventually goes for full blown retrogression with significant height rises around Greenland and lowering heights to the NE..this would be an exciting prospect in winter but in May I would rather see something much warmer from southern europe but at least next week becomes more settled and hopefully we will see some strong sunshine to help offset the cool Easterly flow.

216_mslp500.png

240_mslp500.png

Edited by Frosty.
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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

What a shame from a couple of nights ago! It was looking so warm and settled, now it looks like a nagging easterly will peg back temperatures. I remember early June last year was horrific here with persistent easterly winds and temps in the low teens. Anything but that again!!

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

http://www.theweatheroutlook.com/twodata/chart.aspx?chart=/charts/ecm/240_mslp500_arc.png?cb=695

This is some truly exceptional blocking yet again from ECM and GFS is similar a day or so later.

Some hope may actually be drawn from this; such an extensive block that reverses most of the N Hem circulation very rarely manages to become reality.

Then again, it is May, not January :p

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Posted
  • Location: Port Glasgow, Inverclyde, Scotland. 200m ASL.
  • Weather Preferences: Thundery summers, very snowy winters! Huge Atlantic Storms!
  • Location: Port Glasgow, Inverclyde, Scotland. 200m ASL.
10 hours ago, Singularity said:

Slight differences in jet stream orientation in the N. Atlantic having big impacts on the location and movement with time of the big ridge next week.

This is an occasion where we could do with a little of the northern jet steam arm remaining in place to keep lower heights between Greenland and Iceland and so allow the ridge across the UK to remain largely independent of the blocking highs across the Arctic.

This year is displaying a propensity for extensive high-latitude blocking which would be if some concern for the summer season except that it's still only April and a big shake-up is fairly common by late May to set the stage for June and much or all of July.

The other day I mentioned some similarities in the overall global picture to 2007 - this was not the same as saying that the summer will be extremely wet as some inferred; rather that there is an increased chance of an unusually wet outcome. Research since that summer has identified unusual Indonesian rainfall patterns as a key contributing factor to what could otherwise have been a reasonable summer with plenty of warmth on offer. Hopefully we'll avoid that this year. Another big question is whether Arctic blocking continues or not, and in what configuration. I have yet to find convincing evidence either way with respect to whether low Arctic sea ice extent or area encourages such blocking; the low-ice summer of 2012 was very blocked for example, but 2016 was not. There is a tricky-to-resolve interplay between altered jet stream patterns and increased heat and moisture availability to low pressure systems.

Given the Arctic blocking being modelled for May 2017, it sure does appear likely that low sea ice extent and/or area will be a present factor for the summer, and quite likely record low. Fascinating times ahead - if a bit worrying from a broader climate perspective.

You mention this being "worrying from a broader climate perspective". Could you elaborate on that? Not asking for a giant paragraph btw :D

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Posted
  • Location: Camborne
  • Location: Camborne

All this talk of an easterly but exactly how long is this likely to persist? The easterly regime is entirely dependent on the position of the high cell in this pattern change and as the indicators this evening are for the cell to originally be N/NE of the UK and then retrogressing to the Greenland area the easterly will be quite short  lived.and the flow will back northerly then NW before eventually leaving the UK more or less in a col. The EPS this evening has this process underway by T264 and complete by T312

 

Edited by knocker
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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
11 minutes ago, Ross Andrew Hemphill said:

You mention this being "worrying from a broader climate perspective". Could you elaborate on that? Not asking for a giant paragraph btw :D

In short - Arctic blocking patterns are very unfriendly to Arctic sea ice when they occur at any time between May and Sep. Further loss may lead to further climate impacts and so on. 

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Posted
  • Location: Port Glasgow, Inverclyde, Scotland. 200m ASL.
  • Weather Preferences: Thundery summers, very snowy winters! Huge Atlantic Storms!
  • Location: Port Glasgow, Inverclyde, Scotland. 200m ASL.
5 minutes ago, Singularity said:

In short - Arctic blocking patterns are very unfriendly to Arctic sea ice when they occur at any time between May and Sep. Further loss may lead to further climate impacts and so on. 

Ahh yes, I was thinking it was gonna be something like that. Thank you!

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Posted
  • Location: Camborne
  • Location: Camborne
7 minutes ago, Singularity said:

In short - Arctic blocking patterns are very unfriendly to Arctic sea ice when they occur at any time between May and Sep. Further loss may lead to further climate impacts and so on. 

As a matter of interest which model is indicating a blocking pattern for May because the EC46 isn't strong on this?

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Posted
  • Location: Port Glasgow, Inverclyde, Scotland. 200m ASL.
  • Weather Preferences: Thundery summers, very snowy winters! Huge Atlantic Storms!
  • Location: Port Glasgow, Inverclyde, Scotland. 200m ASL.

The Beeb definitely less "confident" if you will on a very warm spell next week. Their latest long range forecast only showed temperatures reaching 16/17C in the midlands, and Jay Wynne mentioned maybe around 20C in the south. This still is an improvement from this week's cool spell, but it really isn't as beefy as it was say 24 hours ago.

 

Still lots of time for change, we'll see how the models handle it.

Edited by Ross Andrew Hemphill
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Goodbye atlantic..Tonight's Ecm 12z ensemble mean shows high pressure taking control next week with strong early May sunshine to help offset a cool Easterly flow although inland it should feel pleasantly warm, especially where sheltered to the west of high ground..it could be a lot worse. 

ECMAVGEU12_144_1.png

ECMAVGEU12_168_1.png

ECMAVGEU12_192_1.png

ECMAVGEU12_216_1.png

ECMAVGEU12_240_1.png

Edited by Frosty.
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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

I can't recall a May with N blocking as strong as what is shown on the ECM and GFS this evening. Even 1996 isn't as spectacular. It really is eye catching. 

On the plus side, the S of the country may eventually get some useful rain as pressure lowers to the SW and slow moving fronts are propelled N across the southern half of the UK. The N would tend to be drier in such a scenario.

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Posted
  • Location: Camborne
  • Location: Camborne

The gfs this morning. At 12z Saturday the shallow depression and associated front lie west of Ireland with  the UK in a southerly drift. In the next 24 hours they get slightly more organized but a squeeze gets under way between the high pressure away to the NE and the trough edging in from the south west which tilts the trough negatively and results in this analysis with sporadic rain encroaching from the south west.

gfs_ptype_slp_eur3_15.thumb.png.95d03106de0af15d69fdde28a20a2a2b.png

This rain edges it's way north east over the next 24 hours but all the time the system is declining and eventually just peters out as a transient ridge nudges in from the south west

gfs_ptype_slp_eur3_19.thumb.png.d23cbe97a82757f2777115ccd9718323.png

Which brings us to the pattern change with the quick amplification and the high pressure surging north and with the centre of this to the north east the UK is quickly into an easterly regime with the stronger winds the further south you go.This portends little rain with temps around normal but cloud amounts will vary one suspects under an east/west split.

gfs_z500a_nh_25.thumb.png.df45e238dc26d66eacc41f169bd602b6.pnggfs_ptype_slp_eur3_25.thumb.png.e8711340c6563f6be4ae70e32befb510.png

Although the easterly regime persists the retrogression of the high gets underway immediately and it is soon over Greenland while the Atlantic trough proceeds in the reverse direction so by the weekend we have this intriguing situation with surface fronts approaching from the south west.

gfs_ptype_slp_eur3_39.thumb.png.2d37031c0977fe7433fb46bbe14715f9.png

Edited by knocker
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Posted
  • Location: Camborne
  • Location: Camborne

The major difference between the gfs and ecm by day ten would appear to be the orientation of the high pressure. Both have it centred in the southern Greenland/Iceland area but one gives it a negative tilt and the other a positive. This is important because it influences the other major players the troughs to the SW and E. This in turn influences the surface weather over the UK and is something that will need to be resolved.

Edited by knocker
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Posted
  • Location: Solihull, West Midlands. - 131 m asl
  • Weather Preferences: Sun, Snow and Storms
  • Location: Solihull, West Midlands. - 131 m asl
1 hour ago, knocker said:

:cold::cold::yahoo:

This on the 27th of January??

gfs_ptype_slp_eur3_39.thumb.png.2d37031c0977fe7433fb46bbe14715f9.png:angry::wallbash:

Knocker....

Are you just trying to wind me up!!!

Well you have done.:nea:

Why can we not get this in January?

:cc_confused:

Oh well I'm certain it is going to happen in December2017!

Edited by Midlands Ice Age
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

The key to temperature and cloud cover etc is going to be shown nearer the time but high pressure, in the 6-14 day time frame, looks to be the most likely. Currently the 500 mb pattern is as shown in the links below. All 3 are pretty similar but for the surface flow, especially with such light 500 mb flow, is not easy to decide this far out. Coolish off the N Sea or warmish if the flow is anywhere between SSE and SSW off the near continent.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

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Posted
  • Location: East Ham, London
  • Location: East Ham, London
4 hours ago, knocker said:

The major difference between the gfs and ecm by day ten would appear to be the orientation of the high pressure. Both have it centred in the southern Greenland/Iceland area but one gives it a negative tilt and the other a positive. This is important because it influences the other major players the troughs to the SW and E. This in turn influences the surface weather over the UK and is something that will need to be resolved.

I think the orientation and position of the Atlantic trough is of equal significance.

GFS 06Z has continued the theme of lowering heights in far FI but it's by no means certain and it may be we will have a prolonged if weak NE'ly flow with rain or showers for the south and drier conditions further north.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

More excitement for coldies..in May:shok:

The strong retrogression theme continues.

Say what you like about the Ecm but it's rarely dull.:cold:

 

240_mslp500.png

240_mslp850.png

240_thick.png

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Posted
  • Location: Evesham/ Tewkesbury
  • Weather Preferences: Enjoy the weather, you can't take it with you 😎
  • Location: Evesham/ Tewkesbury

Hello All!:) Apart from a little blip this weekend of some changeable conditions with a little rain here and there, the extended outlook looks dry and chilly.

uw.png

uwx.png

mindblown6.gif

freezing.gif

i2OHZE9.gif

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

ECM and GFS showing strong northern blocking this evening, exceptionally so, with a long drawn sustained northeasterly eventually taking hold as we move through the first week of May. In the reliable its quite an interesting set up, Jetstream profile highly elongated and stretched through the eastern atlantic, digging southwards, with low pressure caught in its circulation throwing frontal activity erratically northeast wards , but never managing to break the atlantic through as they come up against building heights to the NE.

The ensembles all point to heights retrogressing to the NW, sunniest and warmest conditions would thus be reserved for the NW and sheltered west, with the east disappointingly dull and cool.

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