Model Output Discussion 31/03/14 onwards.

[IDO]

GFS ensemble shows the high starting to drift over the UK by day 10 still some cool air with it but given the strong sunshine now it would be pleasant in any brighter spells

 

 

 

Nice try, SS. Thats the control run you posted. The mean at D10 is: 

 

The ensemble members are about 60% UK trough, 25% on the periphery and 15% HP at D10.

 

The push of cold uppers from the vortex breaking up is apparent from the mean 850s: 

 

The Aberdeen ens graph shows the fall back to normal of the uppers after D5: 

 

So more unsettled and feeling cooler still looking likely.

[Frosty.]

Summer Sun (Gavin) could be right, in any case, at least he's always positive about high pressure building in, winter was a bitter pill to swallow for most of us with the constant unsettled muck but now the balance is more even with high pressure from the azores having much more chance than it ever did for several months.

[Summer Sun]

Nice try, SS. Thats the control run you posted. The mean at D10 is: http:////d321955.r.worldssl.net/forum/public/style_images/master/attachicon.gifgens-21-1-240 (12).png

 

Sorry clicked on the GEFS ensemble tab and assumed it was.....

 

ECM looking unsettled the further south you are next week though the easterly winds could bring some warm air with them later next week though the best temperatures would probably the further west you are with some shelter

 

[Cloud 10]

All change over the next couple of weeks across the northern hemisphere as the polar vortex

enters self-destruct mode.

 

ecm today..  ecm day 10..

 

 

Cold air being forced to lower lattitudes,a classic sign of a developing negative AO.

 

 

 

[draztik]

Days 10-15 trending cooler, esp compared to recent days. ext ECM shows heights building to our NW, with the UK under the influence of a pronounced scandi trough into this period.

Days 10-15,temp anom.

The ecm control, however, sees it very differently. It shows high pressure centered over the UK, with above average temps nationwide into days 10-15.

Edited April 19, 2014 by draztik

[davehsug]

Models aren't improving if you ask me. If you take them at face value, you'd say something much colder in 10 days, but only 8 days ago, they pretty much agreed we'd be under a coldish showery North Westerly this weekend.

Edited April 19, 2014 by davehsug

[knocker]

Draztik it could be that its warmer than what it implies, wonder if snowking is still here as he can nail when settled and unsettled spells are going to occur?

 

I would imagine he has been beatified then and moved on to a higher place.

[knocker]

METO rainfall forecast for today

 

 

[johnholmes]

The latest cpc 8-14 day chart looks pretty unsettled in my eyes with the LP extending into Spain:http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

 

remember those charts are 500mb not surface. Like with any model individual outputs are not as reliable as watching them over several days. That said they have, the 3 I use, have all been showing the upper trough in the UK area with upper ridging to the NE mainly.

That trough on both NOAA outputs (6-10 and 8-14)  is part of the remains of the major upper vortex over NE USA/Canada, but is shown as a separate feature on the EC-GFS outputs most of the time.

I tend to agree that the pattern suggested over several days does suggest unsettled rather than settled. How much so is for the synoptic models to decide as they firm up on what the upper and surface patterns will be a week or more away.

One other comment, the anomaly charts at the season change over periods, spring and early autumn, are less reliable than the rest of the year. This seems to be due to the major pattern shift as the polar region changes from winter-summer-winter etc. It usually lasts about 7-10 days but can be longer than this. To me it seems not yet to have started this spring.

Edited April 20, 2014 by johnholmes

[IDO]

Looking at the ECM and GFS mean for the 15 day period the cooling down is apparent:

 

GFS 0z:  ECM 12z:

 

Still lots of uncertainty after D10 but reasonable agreement before then. The upper PV moves from NE Canada to Siberia and heights try to build to our NW:

 

ECM at D10:  GFS: GEM: 

 

So from there a Scandi trough is a strong possibility. However GFS in FI are uncertain whether the UK will fall within that, on the border or the AH may edge in on occasions. The op run is the latter this morning, and the mean at T300 emphasizes that:

 

 

Looking at the ensemble members at T300 suggests that even if we are located within the trough it is rather a slack affair so showery and chances of warmth when the sun shines.

 

In the short term we have the battle between the high to our NE/E and the finger of lower pressure to our west:

 

 

that will probably last till next weekend and the LP system will become less active time it crosses the UK. The next 8 day rainfall totals highlight that the SW/west will be more unsettled:

 

 

Looks like most of the rain in the SE in that timeframe will fall in the next 24 hours.

 

 

[Summer Sun]

With the exception of some south western parts the UK's run of above average 2m temperatures continues to at least the 28th

 

 

Normal 2m temps

 

 

Expected 2m temps

 

[knocker]

Forthcoming Temps according to Roger. http://www.met.rdg.ac.uk/~brugge/

Edited April 20, 2014 by knocker

[knocker]

The ECM has a familiar upper air set up next weekend with the cold air in the Atlantic with strong heights to the north. Both the GFS and ECM are, at the moment placing a low to the west of Ireland by Friday that doesn't portent well for the UK especially in the west. But then a week is a long time in politics and meteorology.

Edited April 20, 2014 by knocker

[Summer Sun]

GFS 00z ensembles showing a pressure rise for a time towards the end of the coming week for a few days

 

The London ensemble shows today and the 26th into 27th to be the wettest days with no rain from the 22nd to 25th, 20c should be reached tomorrow in London making it significantly warmer than Easter Monday 2013

 

 

Manchester ensemble also showing pressure rising for a few days but slightly more rain here

 

 

The Aberdeen ensemble follows the rest with a rise in pressure later in the week however it also looks the wettest of the 3 for next Thursday and Friday

 

 

All 3 agree on a fall in pressure from the 26th

Edited April 20, 2014 by Summer Sun

[Polar Maritime]

A quick glance at the Models, And they certainly have a cool and unsettled look about them.

 

Even towards the end of the runs. As JH states the Vortex is heading for Spring/Summer mode, So with such a disrupted Vortex over the next week or two at least, And with Heights pushing North squeezing Lows South over the UK I would't expect anything to settled or Warm ! 

Edited April 20, 2014 by Polar Maritime

[IDO]

Forthcoming Temps according to Roger. http://www.met.rdg.ac.uk/~brugge/

 

 

I notice the forecast max at Heathrow today from the above is 15c. However the UKMO has only 13c:

 

 

source: UKMO

 

Also, contrary to most of the last few weeks the "feels like" temp will be 1-2 degrees below the actual highs (see above), due to the cooler wind, colder uppers and more cloud cover. So definitely feeling cooler than of late in the coming ten days plus.

[Milhouse]

A quick glance at the Models, And they certainly have a cool and unsettled look about them.

 

 

Longer term trending cooler but this coming week will see fairly warm winds from off the continent bringing above average temperatures. Next weekend sees low pressure introducing more of an easterly, then a northerly for the following week. A quick look at the already well above average April CET will show no fall predicted this coming week so it must be mild/warm for the next 7 days.

[snowking]

I would imagine he has been beatified then and moved on to a higher place.

 

They tried...

 

MJO forecasts fairly coherent in terms of the overall phasing (heading towards 7/8) but still some uncertainty on amplitude - ECM least keen on taking us into something Amp >1 territory, where as UKMO and GFS forecasts more bullish on this. Phase 8 tends to offer the direction in which I think we are headed, particularly with falling AAM projected too:

 

 

That leaves the UK still under the force of a persistent trough (yawn) but it's which side of this trough we end up which could prove crucial. Current ensembles would tend to suggest our humble little island is left on the cooler side of the trough, with rising pressure and falling heights to our North-West:

 

 

I still remain cautious over this given recent tendencies to over-egg any height rises around the Greenland locale in recent months, but we can only work with the tools we have available and to derive a 10 day ensemble mean such as those above there must be fairly good consistency within each suite for the above signal.

 

This is backed up by some consistent 100mb forecasts from both suites too:

 

 

With the suggestion, as reflected in closer to the surface NWP projections, of the main thrust of the vortex being displaced towards the Siberian half of the Northern Hemisphere with an upper ridge heading towards Canada/W Greenland - of course this is something else we have seen projected a few times in the last 18 months or so, but with the warming that has already taken place:

 

 

I would suggest this signal may actually bear fruit this time around.

 

So where does that leave the UK? Well unfortunately the signals at present would suggest cool and damp - the chance of something wintry over hills in the North, but it would take something really exceptional (such as the trough over Siberia dropping through in to Europe just to our East) to inject anything significantly cold at this late stage. Instead it looks likely to have a whiff of a West-based negative NAO...a little further East based than perhaps we have seen in previous years but the general theme of rather dull and cool would be my punt in around 10-15 days time.

 

SK

[Polar Maritime]

Meto update certainly ties in with the Models we can see, With an unsettled end to the week with heavy rain and the risk of Gales it will feel much more chilly than of late especially in the wind, With this pattern continuing through to the turn of the month, We could see a more settled spell from the East during the start of May where it could feel warm depending on cloud cover, but night-time temps would be much cooler with Frosts and chilly on the Coast's, especially in the East.

Edited April 20, 2014 by Polar Maritime

[damianslaw]

Its taken its time this spring, but finally the northern hemisphere appears to be moving away from its lengthy winter state and moving into spring-summer mode. All models are forecasting the weakening and removal of the PV from its Canadian home towards Siberia with remnants being displaced south into the atlantic, hence the longer term outlook is projected to be a cool fairly unsettled one as we see the longwave atlantic trough deepen over the country with heights developing strongly to our NW - a pattern we haven't seen for a long long time...

 

Before then a few more days of relatively quiet weather with a warmish southerly drift, but always the threat of showery conditions especially in the SW as we move through the early part of next week. Next weekend could be a cool wet one especially for the SW, will wait and see, with the driest conditions reserved for the NW. Very normal situation for the time of year, this on average is the driest part of the year for Scotland, N Ireland and NW England, thanks to easterly and northerly airstreams being at there yearly peak.

 

We've been fortunate with the timing of easter this year, the last 2 weekends have been very disappointing around here with rain and cold winds, and next weekend looks much less pleasant than this one.

[Summer Sun]

Continued signals the NAO will head to its lowest point in a number of months how long it stays negative though remains to be seen

 

[Summer Sun]

The differences between GFS and GEM says it all about the uncertainties going forward

 

 

 

 

In the more reliable time frame after a week of April showers the weekend could see a more organized band of rain

 

 

The run of above average 2m temperatures shows no signs of ending away from some south western parts

 

Edited April 20, 2014 by Summer Sun

[Summer Sun]

Quite a change from ECM this evening compared to the 00z run from t192

 

12z

 

 

00z

 

 

t216 12z

 

 

00z

 

 

t240 12z

 

 

00z

 

 

The uncertainties for the end of the coming week continue

Edited April 20, 2014 by Summer Sun

[IDO]

Yes the uncertainty continues. The GFS ensembles are much like what you posted from the ECM 0z and 12z, they are unsure where the Scandi trough will sit and it shows we can possibly get more influence from the Azores High ridging NE.

 

The LP system that comes in at the end of next week appears to be the trigger, as where it parks itself will form the base of the Scandi Trough.

 

ECM has it moving through the UK into continental Europe: 

 

Whilst GFS puts it in situ over the UK: 

 

GEM has it sink towards Italy, and accordingly the trough even further east. So by T240:

 

ECM:   GFS:  GEM: 

 

Variations on a theme, one extreme to another, maybe the middle ground ECM will be the call?

Edited April 20, 2014 by i'm dreaming of...

[Geordiesnow]

Seems a rather complicated outlook although with the likely blocking that may develop then it would not surprise me if we do see quite a chilly spell of weather coming up but for the time being, quite a warm spell of weather, especially the further West you are whilst Northern and Eastern areas could turn out to be quite cool and chilly for the foreseeable future. 

 

If this blocking does come off then the potential for some grotty washout days is certainly most probable, nothing unusual about this at this time of year though.