Model Output Discussion 12z 10/05/13

[phil nw.]

New thread then ready for 12z runs.

 

An unsettled and cool spell is now established and looks like continuing through next week.

No quick evolution out of this upper trough is currently modeled although recent ens. means are just hinting at some improvement as we go into the last third of the month.

 

Please try to post around what the models actually say and confine your wider discussions including thoughts on Summer prospects to the relevant threads.

Summer thread here

http://forum.netweather.tv/topic/76293-summer-2013/

 

OK thanks all- continue below.

[BornFromTheVoid]

Looking at the 500hPa GPH charts at one week intervals since early April, we can see several pulses of heights building to our south, with the last one covering the most of the British Isles. You can see this by clicking on the animation below.

 

 

The 8-10 day mean heights anomaly comparison indicate another pulse of heights building, but with a focus towards Scandinavia, and a less strong signal for heights to our west also.

 

 

This may introduce some higher SLP and increased upper air values over Scandinavia.

 

The current MJO forecast isn't looking too strong, but does indicate a drift into phase 6 in around 10 days time, which supports the building of heights to our east and west.

 

The MJO then hints at moving into phase 7 after that, which shows a linking of the heights to our west and east, with the opportunity for a spell of more settled weather over the British Isles.

 

 

So perhaps a better chance of some settled, warm weather as we move into the last 10 days or week of May.

[Alex]

Looking at the 500hPa GPH charts at one week intervals since early April, we can see several pulses of heights building to our south, with the last one covering the most of the British Isles. You can see this by clicking on the animation below.

Apr4May8GIF.gif

The 8-10 day mean heights anomaly comparison indicate another pulse of heights building, but with a focus towards Scandinavia, and a less strong signal for heights to our west also.

8-10day.gif

This may introduce some higher SLP and increased upper air values over Scandinavia.

Hels850.png HelsSLP.png

The current MJO forecast isn't looking too strong, but does indicate a drift into phase 6 in around 10 days time, which supports the building of heights to our east and west.

The MJO then hints at moving into phase 7 after that, which shows a linking of the heights to our west and east, with the opportunity for a spell of more settled weather over the British Isles.

So perhaps a better chance of some settled, warm weather as we move into the last 10 days or week of May.

I have been tracking the MJO very carefully this year and the eastward movement has been faster than predicted so I expect this is going to continue to fool the models somewhat within the 10-15 day timespan. Interestingly according to the GFS we are 1-2 days away from phase 4, only a few days ago we was in phase 1!

You can see more of my weather views on my twitter account - @alexbweather

[SP1986]

The models couldn't be making the outlook any easier to be honest.. whilst the Greenland High sticks around, it will be cool, wet and unsavoury. It does not look like the Greenland will be going anywhere, any time soon, so these carrots on sticks in FI are dream chasers.. ie they will never occur while the Greenland High is setup as strong as it is. 

 

It's clear to me, and of course people will dsagree, but were fast heading away from the settled warm spell, I cannot see any potential in the models other than the odd flit with a outlying scenario which doesn't 'fit the bill'.

 

I have no reservation in saying I'm sure, in my opinion entering this summer will be extremely frustrating if you are looking for any type of warmth and dry weather, or even perhaps, average conditions.

[Frosty.]

A very unsettled, cool and cyclonic Gfs 12z but with some drier, sunnier and warmer intervals, the first being this sunday which looks drier and sunnier in central, southern and eastern england with average temperatures, then later next week the main shower activity becomes more concentrated across northwest britain with the south & east having a drier and sunnier spell with temperatures rising higher to around 18-19c 65f. It also trends drier, brighter in the far northeast of the uk due to the influence of a building scandi high but apart from that, the weather on this 12z run is dominated by trough(s) either directly over or very close to the uk throughout with widespread showers on most days with torrential downpours containing hail and thunder but with sunny spells inbetween, cold nights with a risk of ground frosts where skies clear.

[ANYWEATHER]

The models couldn't be making the outlook any easier to be honest.. whilst the Greenland High sticks around, it will be cool, wet and unsavoury. It does not look like the Greenland will be going anywhere, any time soon, so these carrots on sticks in FI are dream chasers.. ie they will never occur while the Greenland High is setup as strong as it is. 

 

It's clear to me, and of course people will dsagree, but were fast heading away from the settled warm spell, I cannot see any potential in the models other than the odd flit with a outlying scenario which doesn't 'fit the bill'.

 

I have no reservation in saying I'm sure, in my opinion entering this summer will be extremely frustrating if you are looking for any type of warmth and dry weather, or even perhaps, average conditions.

Yes, very true, with this scenario, as time has told, the synoptics take a long time to change to anything different, once we have got this set-up !

[mountain shadow]

The MJO then hints at moving into phase 7 after that, which shows a linking of the heights to our west and east, with the opportunity for a spell of more settled weather over the British Isles.

 

So perhaps a better chance of some settled, warm weather as we move into the last 10 days or week of May.

I'm not convinced BFTV.

The danger is that the heights over Greenland and Scandanavia link up leaving the British Isles sitting in the trough underneath with thundery downpours resulting.

Desperately need the heights to be more mid latitude to give us some warmth.

[Frosty.]

Not much to choose between the Ukmo and Gfs 12z this evening, the ukmo 12z also indicates a very showery spell next week with storm potential but at least there will be some sunshine, temps in the 13-15c range for the southern half of the uk but nearer 10-13c for scotland & n.ireland. At least the Gefs 06z mean is still trending in the right direction with a scandi high in place and the persistent trough   drifting away to the northwest slowly.

[phil nw.]

Some posts are talking about Greenland high`s which i find hard to understand.

 

The only sign of Greenland heights in the HR part of the GFS and indeed the UKMO as far as that goes is around T96hrs when there is some brief ridging from the Atlantic/Azores high.

On the contrary if we look at the Northern Hemisphere views at various points we see very much that Greenland is the one area where there are ongoing low 500hPa heights

 

-some images

 

 

In fact this unsettled regime is very much because of an upper trough extending towards the UK being spawned from a PV segment around the Greenland area.

 

 

 

[Tamara]

 

 

In fact this unsettled regime is very much because of an upper trough extending towards the UK being spawned from a PV segment around the Greenland area.

Hi Phil  The polar vortex segment is seasonally breaking up and disrupting SE towards us and Europe from Canada and Greenland as pressure rises to the north as part of this process. I think it is a case of how quickly the troughing close to us and Europe 'warms out' thereafter as the vortex then goes awol till autumn and whether we then see a signal for the jet stream to return north if/as/when heights fade to the north with hope that perhaps the Azores high comes more into play instead

[Frosty.]

IMO the Gefs 12z mean is another step in the right direction and is a slight improvement on the 6z but we are still dominated by a large cool showery trough next week which only slowly eases away but longer range there remains a strong signal for drier, warmer and sunnier weather during late may with a scandi high, i'm sure the azores high will become more influential as we head towards late may into june.

[BornFromTheVoid]

I'm not convinced BFTV.

The danger is that the heights over Greenland and Scandanavia link up leaving the British Isles sitting in the trough underneath with thundery downpours resulting.

Desperately need the heights to be more mid latitude to give us some warmth.

 

Agreed. Nothing can be definite that far out. But I think there is at least some better potential around that time rather than in the next 10 days.

 

EDIT: Many of the 12z ensemble following the progression I suggested earlier, with a linking of the Atlantic high and Scandi high.

P3 and P18 being good examples

Here's p18

........... .............t240 ....................... ............ ........... t288 .......... ............. ............. .......... t336

[Evening thunder]

The models couldn't be making the outlook any easier to be honest.. whilst the Greenland High sticks around, it will be cool, wet and unsavoury. It does not look like the Greenland will be going anywhere, any time soon, so these carrots on sticks in FI are dream chasers.. ie they will never occur while the Greenland High is setup as strong as it is. 

 

It's clear to me, and of course people will dsagree, but were fast heading away from the settled warm spell, I cannot see any potential in the models other than the odd flit with a outlying scenario which doesn't 'fit the bill'.

 

I have no reservation in saying I'm sure, in my opinion entering this summer will be extremely frustrating if you are looking for any type of warmth and dry weather, or even perhaps, average conditions.

 

 

What Greenland high? see charts posted by phil nw which I was going to post, but he has already posted similar charts. Less of a Greenland high than in the archive charts for the 12th May 2006 that's for sure:

http://www.wetterzentrale.de/archive/ra/2006/Rrea00120060512.gif

 

Also I must say I will take far more notice of well structured posts with charts and evidence to back them up like post two by BFTV, than posts saying X won't happen because I say so, and apparently being able to say what will happen 3 months down the line based on I'm not sure what really, perhaps GFS charts that don't only go 15 days ahead and are likely to be pretty wrong, or previous years which usually don't mean much.

Unsettled for the next week or two it looks like, after that, who really knows?

[phil nw.]

Hi Phil  The polar vortex segment is seasonally breaking up and disrupting SE towards us and Europe from Canada and Greenland as pressure rises to the north as part of this process. I think it is a case of how quickly the troughing close to us and Europe 'warms out' thereafter as the vortex then goes awol till autumn and whether we then see a signal for the jet stream to return north if/as/when heights fade to the north with hope that perhaps the Azores high comes more into play instead

Yes some of the medium term outputs incl the NWP means have been showing our trough becoming cutoff as the the breakup of the vortex gathers pace- as you suggest Tamara.

 

It looks like we may have to be patient wrt to a real settled spell at least in the next 10days or so.Modeling still shows a stubborn upper cold pool lurking near the UK but gradually shrinking.

http://modeles.meteociel.fr/modeles/gens/run/gensnh-21-1-240.png?12

 

Hopefully current indicators will prove correct with an improvement beyond this spell where again the GFS means show the PFJ moving north as those thickness levels rise from the south in the later frames.

[Frosty.]

A very unsettled Ecm 12z with low pressure in control throughout but after a cooler spell it looks like slowly becoming a little warmer and trending drier for northern britain with a scandi high and high pressure generally to the north of the BI with the trough sinking down to the south and southwest so the cool showery spell slowly morphing into a slightly warmer and showery outlook for the southern half of the uk with pleasant sunshine between the showers but for scotland it could begin to evolve into a drier sunnier outlook with some milder temperatures for a change. This run has trended the same way as the 00z and indicates a change from cool to something eventually rather milder/warmer.

[Gibby]

Good evening. Here is the report from the 12 midday outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Friday May 10th 2013.

All models show the weekend as a cool and unsettled one with a window of fine weather through Saturday Night and Sunday moving West to East across the UK. There will be showers or spells of rain outside of this window with a brisk Westerly breeze. Through next week all models show Low pressure sinking down over the UK with further spells of rain or heavy showers at times with just the briefest of drier and brighter spells when it will feel pleasant enough but the general theme will be towards cool weather still.

GFS then shows the pressure gradients over the UK slackening late next week though still under relatively Low pressure with heavy showers and sunny intervals the order of events. Through FI tonight the pattern remains locked with Low pressure slipping down over the Uk from the NW and then becoming slow moving maintaining big showers and sunny intervals, in which it will continue to feel OK. Some of the rain will be very heavy though due to the fact that the showers will often be slow moving.

The GFS Ensembles are very uninspiring tonight with the South seeing the more of the precipitation than the North at times, indicative of Lower pressure close to the South on occasion. There are strong signals that temperatures will remain suppressed for the duration of the output.

The Jet Stream remains split with the Northern arm currently moving East towards the UK before sinking sharply South then North to the West and East of the UK respectively setting the UK up under a deep trough next week.

UKMO tonight shows the UK engulfed in a upper atmosphere pool of cold air with Low pressure close to the SE. There would be widespread heavy showers and possible thunderstorms in a slack Northerly drift with sunshine quite limited.

GEM shows a very disturbed pattern tonight with Low pressure repeatedly moving down from the NW and settling over the UK with wind, rain and showers all too frequent features of weather over the UK through the next 10 days as well as temperatures staying near or somewhat below what we would like to expect at this time of year.

NAVGEM is a little more optimistic building a ridge NE from the Azores High later next week damping the rain and showers down with longer drier spells with temperatures more respectable in any lengthier sunshine.

ECM tonight shows a very disturbed picture yet again with next weeks Low pressure slipping South over the UK filling as it goes before it engages with an opposing air mass over Europe and deepens rapidly again in the Western English Channel late next week. Rain and showers through the week will be heavy and prolonged with just brief drier and brighter spells in places. Through next weekend Low pressure remains the driving force in a slacker form with further rain or heavy showers scattered about for all.

In Summary it's the same unsettled picture tonight with only NAVGEM showing any sort of improvement that would be felt at the surface. Rain or showers are the order of the dominating events of the next 10-14 days as the UK remains the settling and breeding ground for Low pressure for the immediate future with temperatures remaining generally suppressed.

[ANYWEATHER]

Plenty of Northern blocking in the model output tonight! Ecm and gfs show the south getting wetter. and more unsettled the north fairing best! Lots of changes but the output at the moment is no different to what its been for a good many late springs!!

[johnholmes]

this is the link to how the 500mb pattern looks and you can see there is no sign of any Greenland high with the main feature relevant to the UK is the marked trough from the Greenland area into the UK, hence our unsettled spell of the last couple of days very probably?

http://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=1cc5a62001ec4f8b0956196eaf73ad2e

[phil nw.]

this is the link to how the 500mb pattern looks and you can see there is no sign of any Greenland high with the main feature relevant to the UK is the marked trough from the Greenland area into the UK, hence our unsettled spell of the last couple of days very probably?

http://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=1cc5a62001ec4f8b0956196eaf73ad2e

Yes John very much what the daily runs are showing.

Some posts still insist on talking up Northern blocking/Greenland Highs where there is none.

[Milhouse]

The JMA is looking nice tonight with a swift return to drier and warmer weather by the end of next week.

 

However the ECM is looking more unsettled but with an emphasis on warmer conditions later on as some notable warm air lurks just over to our east.

[Frosty.]

this is the link to how the 500mb pattern looks and you can see there is no sign of any Greenland high with the main feature relevant to the UK is the marked trough from the Greenland area into the UK, hence our unsettled spell of the last couple of days very probably?

http://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=1cc5a62001ec4f8b0956196eaf73ad2e

Yes and all being well, that trough will go back where it came from by the last week or so of the month and give the uk a taste of summer instead, there are positive signs from the ensemble mean later in may.

[Frosty.]

 

 

However the ECM is looking more unsettled but with an emphasis on warmer conditions later on as some notable warm air lurks just over to our east.

Yes Milhouse, warmer weather on the way according to the Ecm 12z, and with high pressure developing to the north and northeast of the uk, more northern parts of the uk (northern half of scotland) should eventually see a marked decrease in the showers risk with some  warm sunny spells and mostly dry weather by the end of next week but central and southern britain looks wet and windy at times (NEly winds) with low pressure to the east and with sunshine and heavy showers but slowly trending a little warmer and more humid as the cool north atlantic airmass is mixed out by much warmer T850 hPa, it would take time for surface conditions to significantly improve though.

[snowking]

Not too much support for tonights 12z ECM det. from the ensemble means out to day 10 i'm afraid to say:

 

 

 

Fairly strong signal (and almost universal support) for low pressure to be anchored just to the North-West of the UK - always the chance in such a setup of transient ridges from the south, but its a largely unsettled picture up to day 10 at present.

 

I would be looking towards the day 12-15 period at the moment for signs of something more settled, and whilst we can possibly conclude that the 11-15 day mean height anomalies are merely portraying a weakening overall signal, there is a notable reduction in the projection of the mean trough that dominates proceedings for the UK through the earlier period. Below is days 6-10 vs days 11-15 from the GFS 12z:

 

 

My summer research had always suggested that the best chance of an extended settled period was around the final days of May and into early June. Still a lot of time to run on this one at present but for now the predominant signal is unsettled and cool for most. Perhaps just the very first few signs of change on the horizon though for later this month.

 

SK

[Milhouse]

ECM mean has low pressure over the UK, gradually transferring over to the north of the UK to end the run. However depending on its exact positioning we could still import some warm and humid conditions from off the near continent as much of central and eastern Europe is set to bake over the coming week. Some thundery rain for southern Britain may occur as a result with low pressure nearby.

[johnholmes]

this is the 8-14 NOAA version this evening

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

and there is as yet little sign of the upper trough moving away or warming out along with the upper ridge to the ENE edging west. So for the time being those hoping for a summer return from the BH are going to be disappointed.

The chart takes us out to 24 May.

The consistency shown on all 3 main anomaly charts does give support to the idea that the upper air pattern shown above is going to be with us until at least the end of the third week in May and perhaps beyond.

However it does NOT mean that June is not going to give any warmth or settled weather.

For those going along this line I suggest you look at the charts for late May and early June 1975!