Model Output Discussion - Spring 5th March Onwards 6z--->

[stodge]

The collapse of the NAO underway on the current index:

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

 

Will get to -2 over the next few days so a major pattern change but not perhaps of long duration with general agreement on a rapid return to near neutrality by the turn of the month so where does that leave us going into May ?

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

 

The AO also going negative now so that suggests heights to the north as an ongoing feature.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015042312/gfsnh-0-252.png?12

 

The GFS 12Z Operational showing the polar heights but those heights not oriented towards the British Isles - indeed, hints of a west-based negative NAO still evident and LP able to develop and move in.

 

http://modeles.meteociel.fr/modeles/gem/runs/2015042312/gemnh-0-240.png

 

GEM at T=240 - the polar heights are in place but not too far south.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2015042312/ECH1-240.GIF?23-0

 

ECM very different at the same timeframe - this would suggest the negative NAO and AO continuing with heights to the north and east.

 

The immediate picture is very different synoptically to what we've had for many months but into May and the picture is far from clear.

[ANYWEATHER]

With such a complicated set up ,those regularly on here realize that finer details on major breakdowns are always notourious to forecast! The major breakdown will happen, forget the its and bits of day to day model output, this always happens, look at the general trend.....

[knocker]

Looking at tonight's anomalies I'm not even going to venture into a guess at the surface evolution during next week. Just looking at T168 the difference between the GEFS and ECM is apparent.

 

The GEFS is going for a relaxing of the UK trough with another trough mid Atlantic and the HP nudging into southern England. This would essentially give LP mid Atlantic and a SW flow over the UK.

 

The ECM on the other hand keeps the trough orientated down the North Sea and a ridge building to the west which would put HO either over the UK or a little to the west with a northerly flow or little flow at all.

 

One thing to be said is they agree on a LP dominated zonal flow at day ten so tentatively I'll go along with the GEFs version at T168

Charts weatherbell

Edited April 23, 2015 by knocker

[Polar Maritime]

The GFS shows -7/8 850's over a vast swath of the UK by Monday.

Edited April 24, 2015 by Polar Maritime

[knocker]

A brief look at the latest EC32 output.

 

Firstly it has the ridge at T168 (above) as a very transient affair and at T240 has troughs to the east and west of the UK bringing LP pressure into play from the west Atlantic to NW Europe with a SW airflow over the UK.

 

By the 10th of May the influence of these troughs is abating although there is still low pressure to the NW but more influence from the HP to the SW. with temps around average.

 

By May 17th there aren't many clear signals except general height rises in NW Europe and continuing influence of the Azores HP.

 

By the 24th again no clear signals of anything nasty in the woodshed with HP over the Pole down to the Azores HP so HP dominating the Atlantic and also as it happens the Pacific.

 

Summary

 

Next week looks very unsettled with temps well below average at times with LP to the NE bringing NW/N winds for a short period before SW regime sets in which should persist until around the 4th May with temps rising to around average. The south may even get a peek of better weather, From thereafter conditions become more settled with more influence from the HP to W and SW. Temps possibly nudging above average.

 

This mornings GFS not clever next week with LP buzzing across until HP settles in for the weekend until the 10th but temps next week below average including the weekend but always remembering this is just one run any detail best ignored.

Edited April 24, 2015 by knocker

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON FRIDAY APRIL 24TH 2015.

 

THE CURRENT GENERAL SITUATION A trough of Low pressure will move NE across England and Wales later today with another one moving slowly South over Scotland.

 

http://www.wetterzentrale.de/pics/Rtavn001.gif 

 

MODELS-2 WEEK HEADLINE Becoming unsettled  and changeable with bright spells and showers, heavy and wintry on hills in the North for a time. Local night frosts still possible.

 

THE GFS JET STREAM ENSEMBLE FORECAST The main flow of the Jet stream over the coming couple of weeks will  be generally to the South of the UK with varying degrees of strength and structure in association with a trough of low pressure close to the UK for a good portion of the period. 

 

http://www.netweather.tv/index.cgi?action=jetstream 

 

GFS OPERATIONAL The GFS Operational this morning shows Low pressure and cool conditions affecting the UK weather for much of the coming couple of weeks with winds generally blowing from a Northerly source with rain or showers at times for all. Later the theme os for pressure to build to the West then North of the UK with the thrust of showers by then focused most On Southern Britain with drier conditions further North.

 

http://www.wetterzentrale.de/pics/Rtavn1441.gif

 

http://www.wetterzentrale.de/pics/Rtavn3841.gif 

 

THE GFS CONTROL The theme of the GFS Control run is broadly similar to the operational in many respects though after the thrust of cold early next week and the following changeable period pressure eventually rises quite strongly near the UK with a lot of dry weather for many. High pressure then settles over Northern latitudes later and like the operational it then shows the risk of showers across the South as pressure falls to the South of the UK in an easterly flow.

 

THE GFS CLUSTERS The GFS clusters today show the usual mix of options at 2 weeks with the most likely scenario being an Atlantic driven changeable pattern of weather with rain at times especially towards the North and West.

 

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

 

UKMO UKMO now looks much more unsettled next week as Low pressure North of Scotland drives our weather with Westerly winds and showers after a cold Northerly to start the week and then at the end of the 6 day period a small but significant Low pressure crosses East over the South of the UK with longer spells of rain in tow.

 

http://www.wetterzentrale.de/pics/Rukm1441.gif 

 

THE FAX CHARTS The theme of the Fax charts this morning is to gradually push trough South and East across the UK at the weekend and replace them with a slack and chilly North or NW flow with further showers at times to start next week in much cooler air.

 

http://www.weathercharts.org/ukmomslp.htm#t120.

 

GEM GEM this morning shows a very unsettled period to come with a brief cold and showery period early next week displaced by wet and windy conditions at times in more average temperatures as we move towards the end of the run as deep Low pressure areas settle close to Northern Britain.

 

http://www.wetterzentrale.de/pics/Rgem2401.gif 

 

NAVGEM NAVGEM also shows unsettled conditions next week though soon becoming less cold next week as winds switch from the North or NW to more of a SW flow with the heaviest rainfall across Northern and Western Britain later next week.

 

http://www.wetterzentrale.de/pics/Rnvg1681.gif.

 

ECM ECM this morning shows a very complex pattern as we move through next week all hinging on lower pressure than has been the case of late with outbreaks of rain or showers at times for all areas in temperatures far from inspiring for much of the time as the flow of air  is for much of the time from a cold source to the North of the UK.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

ECM 10 DAY MEAN(12z) The ECM 10 Day Mean Chart  from last night shows many options between individual members indicating Low pressure over or around the UK with outbreaks of rain or showers at times.

 

http://www.wetterzentrale.de/pics/Reem2401.gif 

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trends this morning show a common theme of Low pressure driven weather with centres close to or over the UK.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.3 pts followed by UKM at 96.8 pts and GFS at 96.1. At 5 days ECM  continues to lead the field at 88.4 pts over UKMO at 88.3 pts and GFS at 85.9. At 8 days ECM remains the leader with 62.6 pts over GFS's 58.0 pts. Then at Day 10 ECM retains superiority at 46.5 pts over GFS at 41.8. 

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png 

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig

 

 

MY THOUGHTS Today sees the commencement of a spell of much more unsettled weather across the UK as fronts move up from the SW and from the North through the next 24 hours. The South will stay quite warm for another ay or so as the SW wind following today's trough is sourced well South in the Atlantic but the front coming down over Scotland has some very chilly air behind it and this will make progress down over all areas late in the weekend perhaps accompanied by a wet day in the South on Sunday. Then after a couple of cold and potentially showery days changeable conditions persist as we move through next week but the very coolest conditions should ease as winds back West or SW at times. However, in comparison to recent times all this will be a shock to the system and a stark reminder that it is still very much Spring, UKMO has now shifted away from it's rise of pressure being significant close to the South next week and instead shows a pattern replicated by other output too that further Low pressure late next week will feed further rainfall across from the West at times. GFS in Week 2 shows pressure rising to the North of the UK with some dry and fine weather by then most likely in the North while the model continues to threaten the South with rain or showers at times in an East flow due to Low pressure to the South. All this of course a long way off but certainly telling the message than fine and warm weather will now be on hold for a week or two with some much needed rain likely for all at times though unfortunately temperatures look generally uninspiring at times over the forecast period but having said that and being that we will be into May any sunshine will feel quite warm in shelter. 

 

Next update from 08:00 Saturday April 25th 2015

[seaside 60]

What the models show for this part of the world, is today tomorrow the warmest days.

Sunday onwards  will still be warmer than the last week.

I realise this is not true for most central south west and northern uk.

However I must speak up for the east and south east dwellers.

It will be warmer than last week.

Apart from the northern part of the UK, I think its another case of over the top models like all winter.

PLease note I am not saying it wont be feeling cool up north, however I think we need to really back down from literally reading every run as taken and look more overall.

I feel that I need to get the duvets out for my plants and stick the heating on at 30c reading here for the last few days.

Sorry not meant as a swipe, however I do think more overall model reading is needed.

Thank you.

[Smiler1709]

Top comment sea side, people are really over playing this up and coming cool spell. I reckon are still be in shorts next week. With high pressure close to the south it won't take many tweeks for high pressure to have more of a influence.

[seaside 60]

Thanks.

I am not saying it wont feel cold up north, but I also dont think many realise how cold it has been down here in the south east and east.

 

One question I would like to ask the experts.

It seems to me that this winter, there has been a larger than normal tendency for models to produce outcomes that always get watered down nearer the time, not the famous easterly here today gone tomorrow.

More especially the cold blasts from the northern latitudes which just never really make it, is there a particular reason for this and will it continue.

[Nick F]

My latest blog (below) looks at the transition to cooler and more unsettled conditions over the next few days, the warmer air taking a while to be kicked out in the south (not until later on Sunday). Turning much colder in the north, with maxes into single figures from Sunday and a risk of wintry showers falling as snow over northern hills. By Monday, we are all in a cool and showery NWly flow with temperatures below average (single digit maxes in the north and low to mid teens in the south). These conditions to last right into the first few days May, before we may see temperatures recover to more average temps into the 1st new week of May, some uncertainty between the ENS and operationals over whether it will settle down or not.

 

http://www.netweather.tv/index.cgi?action=news;storyid=6598;sess=

[Gibby]

What the models show for this part of the world, is today tomorrow the warmest days.

Sunday onwards  will still be warmer than the last week.

I realise this is not true for most central south west and northern uk.

However I must speak up for the east and south east dwellers.

It will be warmer than last week.

Apart from the northern part of the UK, I think its another case of over the top models like all winter.

PLease note I am not saying it wont be feeling cool up north, however I think we need to really back down from literally reading every run as taken and look more overall.

I feel that I need to get the duvets out for my plants and stick the heating on at 30c reading here for the last few days.

Sorry not meant as a swipe, however I do think more overall model reading is needed.

Thank you.

I do appreciate that some Eastern coastal counties have seen a lot of grey murk and cold winds off the North Sea from this recent anticyclone and elsewhere including here there has been a lot of night frosts but overall for large swathes of the UK conditions have been very pleasant in the afternoons with temperatures well up above average. If you live near North sea coasts and have a wind from the East or NE you cannot expect anything less than cool weather with the North sea jolly chilly at this time of year. The reverse of course happens like today with winds now having switched SW bringing low cloud and cool conditions to our coastal counties in the SW whereas no doubt the East coast is experiencing some of it's warmest weather of recently. For my part and within my reports I tend to keep things as a broadbrush pattern taking the UK as a whole and while I might of failed to mention low cloud and mist on the East coast at times recently it was not a denial that it wasn't there it was just acknoledgement and precedence on what the vast majority of the UK was experiencing rather than conditions in a minority part.

 

In general though it's all about complexion and while the difference in weather in the overall scheme of things nationwide has been small of late the difference of feel between 9C and haar and 19C in sunny skies is stark but very common under Spring and early Summer anticyclones across the British Isles.

 

On the other issue re the models watering down of events nearer the time there is some truth in that and is due to more small scale factors imposssible to predict at range that come into play modifying things nearer the present. This is why that in my extended reports in FI I can often be accused of overstating rather pessimistically about conditions but I only state on the likely events and conditions if the synoptics verified as shown when in reality nearer the time as new data and features come into play moderations and occasionally amplifications can and sometimes do result in changes to the overall detailed pattern I focused on earlier..

 

The main message here is we live on an island surrounded by water and a 4000 mile ocean track to the West and there will always be variations and differences in weather on most days place to place and mile to mile, something that landlocked continental land masses don't have to contend with. For forecasters this is why the absolute detail is always hard to pin down on these islands but I think the UKMO are pretty darn good considering our geographical position and local topography.

[Frosty.]

This looks great, becoming very warm through early may on the Gfs 6z, I'm looking forward to hot summer plumes and Azores high's.

[summer blizzard]

Outlook to day 10 is pretty shocking...

 

[Skullzrulerz]

Outlook to day 10 is pretty shocking...

 

Care to explain how it's shocking please especially for ten newbies that don't understand models as well.

[Frank Trough]

Care to explain how it's shocking please especially for ten newbies that don't understand models as well.

 

again it's down to personal preference to some small degree, but basically it looks cold and wet....and you wouldn't want to bet on the longevity of those type of conditions if that chart were to verify....but it's at day 10 and it will change. For better or worse, who knows?! 

 

Given recent form (last year partially excluded) the start of May certainly looks like living up to my low expectations. We've had some ghastly Mays in recent years (the last week of 2012 doesn't forgive it i'm afraid). 

 

I don't like the look of it to be honest and i won't be drawn toward any warmer charts in FI yet. At least it's not the start of June we're looking at.....

[The PIT]

Interesting thing about this cold snap is that it was modeled a long time ago in deep fi and seems to managed to get close without being massively downgraded as well. A good bit of modelling by the GFS which is probably pure fluke. The next question is how long this cool spell will last. There were some hints of being a short period with the GFS twitching away while the ECM holding onto the cool weather. It seems the GFS has swung back ECM's way somewhat. All eyes on the ECM later.

[Summer Sun]

Interesting thing about this cold snap is that it was modeled a long time ago in deep fi and seems to managed to get close without being massively downgraded as well. A good bit of modelling by the GFS which is probably pure fluke. The next question is how long this cool spell will last. There were some hints of being a short period with the GFS twitching away while the ECM holding onto the cool weather. It seems the GFS has swung back ECM's way somewhat. All eyes on the ECM later.

 

JMA also picked up on an unsettled end to this month 4 weeks ago 

[I remember Atlantic 252]

This looks great, becoming very warm through early may on the Gfs 6z, I'm looking forward to hot summer plumes and Azores high's.

 

That's the spirit frosty!, hate the vile northerly wind charts here at low level south, if I lived 300m+ north, I would be excited, so for me, bring on the warmth

[summer blizzard]

Care to explain how it's shocking please especially for ten newbies that don't understand models as well.

 

Pressure is sub 1010mb, thickness values are low and the wind direction is easterly. If there was a day 11 chart we might see the low in the Channel with a front orientated W-E. As spring/summer charts go, that's a potentially wet and cool setup. 

[summer blizzard]

12z not much better to day 10..

 

[Weather Boy]

Pressure is sub 1010mb, thickness values are low and the wind direction is easterly. If there was a day 11 chart we might see the low in the Channel with a front orientated W-E. As spring/summer charts go, that's a potentially wet and cool setup.

Just having viewed your post, the graphic must have changed as there is no easterly in what I can see. The low is not in the channel but off in the North Sea off the NE coast of England. This shows, at the risk of stating the obvious except for newbies:

1. At that kind of range, the charts do change rather quickly,

2. The outlook is still grim on that model (albeit maybe not quite so awful)for now!

Some relatively experienced posters making very sweeping statements about what is to happen way way ahead - not including you in that SB!

[Man With Beard]

Bit of a clear theme here, even at D10 - southerly tracking lows, high pressure near Southern Greenland - recipe for below-average temperatures and regular rainy periods. Always seems the way on a May Bank Holiday!!

I remember countless May heatwaves back in the 80s/90s - going to have to change a bit from these charts to get that! Trouble is, whenever charts get to this place, I've found they (generally) tend to stick around. 

[ANYWEATHER]

Evening folks. If this was January this place would explode! The models are firming up on a very unseasonable weather pattern ,with injections of unusually cold air from the north, It looks like the cold weather could well extend well into May. Some very interesting weather to be had .....

[knocker]

The anomalies are in reasonable agreement at least at day ten but no real firming up on the evolution.

 

They both have a trough NE Canada and another orientated SE into Scandinavia but the zonal flow is interrupted by developing HP south of Greenland.

This is more noticeable on the GEFS. It will be interesting to keep an eye on this because the GEFS develops this idea in the ext. period with a linkage to the Azores HP which sets up ridging just to the west of the UK. The ECM is not so keen on this idea as yet or if ever.

Charts weatherbell

 

[DR(S)NO]

Been watching the latest video from gavin partridge and if jma and cfs are to be trusted middle of may onwards looks very respectable indeed with the jet stream migrating northwards inviting high pressure and much warmer conditions ahead. I checked the cfs myself and it looks like a dead cert to move further north albeit maybe a more efficient change to a northerly tracking jet pattern.

Read that myself PJ and it certainly sounds promising ..

However not so sure the words " dead cert" and Cfs should ever be used in the same sentence