Model Output Discussions 12z 03/05/2016

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON FRIDAY MAY 13TH 2016

THE CURRENT GENERAL SITUATION Cooler air is moving South across Northern Britain today and all areas by tomorrow with a ridge of High pressure edging in from the West over the weekend.

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

CURRENT SNOW FORECAST AND/OR FREEZING LEVEL OVER THE UK The freezing level across the UK will fall everywhere over the next few days behind a weak cold front moving South across the UK. The level will lie at or around 3000ft over the far East over the weekend to around 6000ft over the extreme West.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE After a dry start becoming changeable with rain at times.

THE GFS JET STREAM FORECAST The strong Eastwards moving flow across the Mediterranean Sea is weakening and easing away east over the coming days with a weaker flow moving slow South across the UK. Renewed energy to the flow crosses the Atlantic towards the middle of next week approaching Southern Britain before being directed South for a time before crossing West to East across the UK for much of the second week.

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

NEW GFS OPERATIONAL The New GFS Operational Run today shows dry and quiet conditions until around Tuesday and it will be cooler across all areas than of late. Then from Tuesday the model run shows quite unsettled conditions across the UK under Low pressure drifting in from the West and becoming complex and slow moving for a time before a build of pressure from the South in the second week sees all areas becoming dry, warm and sunny towards the end of the month as High pressure extends in a belt from the Azores to Northern Europe in the last frames of the run.

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

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

GFS CONTROL RUN The Control Run follows a broadly similar path with the added ingredient of deep Low pressure over next weekend with the chance of gales and heavy rain for many as a deep Low passes over from the West before the same pressure build shown above occurs on this run too but less extensive than the Operational Run affecting the South and East of the UK while the North and West under a weak SW flow continues to throw a risk of occasional rain to the North and West.   

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA The clustering today for day 14 shows a lot of slack pressure across the UK with all members having a common denominator of High pressure to the SW and/or NE with set fair conditions likely. Some members show this High pressure as less dominant with Low pressure delivering some rain at times.

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 The UKMO model this morning shows a weak WNW flow early next week with dry and bright conditions to begin with. Then as we move through the week it will become unsettled for all with rain at times as Low pressure with Westerly winds shown to edge down from the North from Tuesday.

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

THE FAX CHARTS The Fax Charts show the weak cold front completing it's journey through the UK bringing cooler and fresher air to all parts tomorrow. Then it's all about the ridge of High pressure following it collapsing away South early next week with Westerly winds and falling pressure ahead of a gang of troughs over the Atlantic pushing towards the UK by Tuesday and beyond.

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

GEM The theme of GEM this morning is one of falling pressure next week following several days of fine and cooler weather under a weakening ridge pulling it's way South early next week. This opens the door to Low pressure drifting into the UK from the NW and setting up a belt of showery low pressure across the UK then well into the second week. 

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

NAVGEM NAVGEM has a fine and cooler weekend for many with the theme of next weeks weather showing a slow deterioration into Westerly winds with rain at times extending to all areas with the worst of the rain and breeze to the North with drier conditions with less wind likely towards the South. 

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

ECM ECM today also shows a dry and bright few days if cooler than of late lasting into the start of next week before the trend of the weather from Tuesday shows Low pressure regaining control from the North and the Atlantic with a cool and showery period of weather looking likely well before next weekend and continuing on through to the start of the second working week.

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

ECM 10 DAY MEAN (12z) Despite the Operational showing quite unsettled and relatively cool conditions likely in 10 days time the mean chart shows a relatively warm SW flow across the UK between Low pressure to the West and NW while the SE lies under a slacker SW flow with less rain and more warmth the further South and SE over the UK you live.

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

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS  As yesterday the main emphasis shown by the models continues to point towards a return to a westerly flow across the UK next week with a trend this morning leaning towards this becoming quite unsettled for all.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.5 pts with UKMO at 99.4 pts and GFS at 99.2 pts.  At 3 days ECM is leading with 97.2 pts to UKMO's 96.2 pts while GFS lags behind at 95.6 pts. At 5 days ECM leads with 88.4 pts to UKMO at 87.0pts and GFS at 83.0 pts. Then at 8 Days ECM has the leading spot from GFS with 62.8 pts to 51.0 pts. Finally at Day 10 ECM has the lead from GFS with a score of 43.7 pts to 37.8 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

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.png

MY THOUGHTS  Instead of a lot of dry and fine warmer shown as hoped this morning it appears to me if that there is a growing desire within the models to bring back more unsettled conditions across all parts of the UK next week with an open ended answer to how long this continues or not in the period thereafter. As things stand at the moment today shows the last day of warm weather in the South as the weak cold front moving South currently clears the South Coast tomorrow with fresh but dry and bright weather affecting most through the weekend. then next week starts in the same vein but from Tuesday Low pressure looks like drifting down from the NW or North with some rain for all and following this further Low pressure seems destined to move in across the UK from the Atlantic maintaining the unsettled and relatively cool feel. GEM goes for a major storm system next weekend and for personal reasons I hope this does not occur as it could give heavy rain and gales for all if it moves in as shown. Outside of that model the main theme though is for unsettled weather more likely than fine weather lasting into the second week and although GFS does offer an olive branch of a reversion to warm and sunny weather under extensive High pressure towards the end of the month it really is to far out to call at the moment with some alternative less favourable conditions also shown within it's ensemble members. So the output today can best be summed up as offering changeable conditions with rain at times and near average temperatures with any repeat of this weeks warmth held at arms length on this morning's output. So lets hope the models offer something rather better over the upcoming days and I have something more positive to report in my next report on Sunday morning. 

Next Update Sunday May 15th 2016 from 09:00

[Summer Sun]

10 days away but at least the ECM ens (right) shows more promise than its Op (left)

[Ben Lewis]

Only yesterday Gibbys update : The next few weeks present few if any troublesome features to talk about with a lot of quite benign conditions likely across the British Isles as the pattern resets to normal UK synoptics over the next 4 to 5 days.

24 hours later:

Instead of a lot of dry and fine warmer shown as hoped this morning it appears to me if that there is a growing desire within the models to bring back more unsettled conditions across all parts of the UK next week with an open ended answer to how long this continues or not in the period thereafter. I hope this does not occur as it could give heavy rain and gales for all if it moves in as shown

Makes you realise that the models are infact just rainbow chasers and anything could happen/change/turnaround very quickly.

I wouldn't be surprised if Gibbys update this time next week is talking of Heatwave conditions.

 

[MP-R]

3 minutes ago, Ben Lewis said:

Only yesterday Gibbys update : The next few weeks present few if any troublesome features to talk about with a lot of quite benign conditions likely across the British Isles as the pattern resets to normal UK synoptics over the next 4 to 5 days.

24 hours later:

Instead of a lot of dry and fine warmer shown as hoped this morning it appears to me if that there is a growing desire within the models to bring back more unsettled conditions across all parts of the UK next week with an open ended answer to how long this continues or not in the period thereafter. I hope this does not occur as it could give heavy rain and gales for all if it moves in as shown

Makes you realise that the models are infact just rainbow chasers and anything could happen/change/turnaround very quickly.

I wouldn't be surprised if Gibbys update this time next week is talking of Heatwave conditions.

 

The models have been showing a return to westerly conditions as the broader pattern for a while now, it's the details that will chop and change - and in a westerly, as we know, that can mean the difference between a warm flow close to the periphery of a high, a cloudy windy one sandwiched between a high and a low, or a much wetter picture under the influence of a low. This will probably continue to change over the coming days but it's certainly looking like next week will become more unsettled, especially further north.

However, I'm interested in the ongoing signs of a much better end to May / start of June. The GFS 00Z being an example. An end of May like 2003 or 2012 could be in the offing if such charts come off. Lots of water under the bridge before then though of course.

[knocker]

The GEFS and ecm mean anomalies are broadly speaking in agreement with low pressure over the Pole/western Atlantic and trough Scandinavia/Easter Europe.Streamlines in the westerly quadrant driving systems east so an unsettled wet period although the south could well fayre better.

The ext period is still up for grabs. There is agreement on the rapid decline of the trough to the east and shunting it SE to the eastern Med. For example the EC32 does this whilst at the same time retrogressing the Atlantic trough and building heights in the eastern Atlantic, Ergo more settled and warmer weather. This GEfs and EPS are not adverse to this scenario so at the moment it's the percentage play but there is plenty of time to firm this up..............or not.

Edited May 13, 2016 by knocker

[mb018538]

Looks like they made a bit of a hash of it, it's changed markedly in the last 24-48 hours to something pretty unsettled. I guess they didn't handle the low off the eastern seaboard and its interaction with the jet too well at longer range. Now it's come closer in, it appears we're going to have to put up with at least 7-10 days of zonal weather before the next opportunity for some warmth.

[knocker]

I'm not sure it's fair to say that they made a complete hash of it. This is the10-14 GEFS anomaly from four days ago with a mid Atlantic trough and indications of an unsettled zonal period.

Edited May 13, 2016 by knocker

[Singularity]

Still recovering from that shocking GFS 06z run. Not a good first couple of days for the newly upgraded version of the model!

It seems like overnight, something in the near-term evolution, that's important with respect to the jet stream configuration later on, went totally berserk. As this has happened across all of the models, I'm inclined to wonder whether the extreme rise of temperatures now unfolding in the Arctic is having ramifications that the models have failed to resolve effectively. Perhaps they will continue to struggle over the next few days.

Indeed, this summer may be a fascinating case study into what happens when the Arctic has a lot more heat and moisture than at any time in (at least modern) recorded history. Does the jet meander around like crazy, making the standard 'Azores High ridging northeast' scenario a rare sight, with inflated, 'tall' highs (extending to higher latitudes than usual) - generally varying between positions in the North Atlantic and across eastern Europe - being instead the dominant mode?

I guess that's something for me to post in the relevant thread! Which is also where any responses on this matter should go 

[johnholmes]

3 hours ago, mb018538 said:

Looks like they made a bit of a hash of it, it's changed markedly in the last 24-48 hours to something pretty unsettled. I guess they didn't handle the low off the eastern seaboard and its interaction with the jet too well at longer range. Now it's come closer in, it appears we're going to have to put up with at least 7-10 days of zonal weather before the next opportunity for some warmth.

much as the anomaly charts suggested a day or two ago, we wait to see how good or not their prediction turns out!

[Summer Sun]

UKMO shows low pressure taking over on Wednesday give a mixture of showers or longer spells of rain and strengthening winds

[mb018538]

12z isn't much better....wet and windy out to day 10. Looking like longer spells of rain, along with sunshine and heavy showers between fronts.

[Singularity]

  

After a series of depressions run through the UK, we eventually get the classic digging low -> strong ridge from the SW/W sequence.

The continued highly meridional jet to the west of the high  keeps me wondering if we might see a dramatic escalation in temperatures by around 24th. It would be in keeping with this month's behavioural tendencies. Not that it looks particularly cool next week - just a bit below average overall, mostly by day. The first 'normal' spell of weather in quite a long time!

[stodge]

Evening all

A real mixed bag of output this evening but those claiming we are on course for a more settled and warmer spell have had to revise their forecasts somewhat. GFS 12Z OP doesn't look that settled to me and GEM follows along. ECM offers some hope but the concern for this observer is the return of northern blocking keeping the jet to the south.

Yes, GFS offers the meridonal possibility of a slowing LP to the SW and a draw of very warm air from the SE albeit with a storm or two as well but the other possibility of LP getting stuck near or over the British Isles can't be ignored.

I do think looking at the GEFS Ensembles there's no strong trend for the last third of the month as yet so as ever more output is needed...

[knocker]

The 6-10 anomalies are still indicating a pattern change towards the end of the 6-10 period which is still looking very unsettled up to then. The change is signified by a removal of the trough to the east, replaced with some build up of positive heights,and a retrogression of the Atlantic trough, It's all looking a bit fragile but certainly if the HP is fairly adjacent to the east a drier and warmer outlook more especially in the south. I think the jury is still out. Can't post the EPS.

 

Edited May 13, 2016 by knocker

[damianslaw]

Perhaps we shouldn't be too surprised to see the models taking a back track today away from a mostly settled outlook to well a continuation of the overall pattern we have been in since late Feb, i.e. a meridional flow with the UK prone to variable cooler wetter periods and warmer drier periods depending on which side of the trough we sit on. What we have now is a return to wetter cooler conditions as the trough anchors its way across the UK next week with heights in an unfavourable position, importantly more robust to our NW - mmm an ominous sign perhaps more so I suspect as we enter deeper into summer. 

Certainly won't be surprised to see a flip to much warmer settled conditions once again as we end the month and enter June which could stick for an appreciable amount of time, but a further flip back to the cooler wetter scenario again mid month.. as we move through the summer further, the warmer drier spells becoming shorter in duration but very potent affairs, strong heights to the NW becoming the major player again - the very warm arctic could be the major player.

[wishingforsnow]

Some very mixed model output compared to the past few days. However we are still talking about weather for roughly a week's time, again, like the 'northerly' which was supposed to make temperatures drop 15 degrees today and into this weekend, I suspect the supposedly extreme unsettled weather for next week may not be as bad as the models are suggesting i.e constant heavy rain, disruptive storms and strong winds every day. A slightly more unsettled period was always on the cards but the silver lining we can take from this is, as things stand, the heat/warmth/settled weather still looks likely to return end of May and beginning of June. As for the Met Office long range - the final part of the forecast suggesting a return to unsettled after settled weather again is in deep, deep FI weatherwise so subject to change. Hopefully the return of the heat and warmth at the end of this month and for early June still upholds. A trend for Easterlies over the UK could also mean that unsettled cooler spells of weather this Summer are shorter with longer settled spells, especially in the South, despite heights to the NW. 

Just touching upon something Tamara has mentioned before about a 'reload' of weather patterns being more likely this year as we enter the summer - in particular with the heights to the NW and melting ice in the Arctic. Also referring to @damianslaw's comment above, I do agree that we may see long hot settled spells interpresed with cooler Atlantic dominated weather rather than a lengthy settled and very warm/hot spell during the summer 1976/2003 style. On the other hand more like 2 week warm/hot spells broken up with occasional Atlantic low pressure periods inbetween but not one weather type necessarily dominating the weather like hot and dry in 2003 or cool and wet in 2007/2012: which were both caused by extremely fortunate or unfortunate weather synoptics, respectively. More like 2013/2014 as a recent example. I'd take a mixed bag but good summer over a warm Spring with a pattern breakdown ushering in cool, wet weather for the Summer any day. 

Edited May 13, 2016 by wishingforsnow

[knocker]

The GFS this morning is quite quickly summed up.

The high pressure will stick around until Tuesday when a brief Atlantic train is set in motion. Systems track east bringing some wet and windy weather to all until Monday the 23rd when HP develops in mid Atlantic.No point in looking further at this stage

The GEFS anomaly 8-13 illustrates this transition.

Edited May 14, 2016 by knocker

[knocker]

The ecm is similarly unsettled from Tuesday but it does develop a depression, it showed on yesterdays run but wasn't developed, that wings into the south west over next weekend. I suspect there will be some changes before then.

[bluearmy]

I posted on  tues/wed in quite a positive vein re the 10/15 day period.  Subsequently, things have deteriorated. I wouldn't bank on anything now. glad the ECM graphs are back and running again on meteo 24, a slightly better insight into the clustering in that 10/15 day range. 

[Summer Sun]

Looking at UKMO later Wednesday and into Thursday could be the period of the week with strong winds from the north to north west and some rain around

By Friday that low pulls away and high pressure edges in to the south

[knocker]

If I'm honest I'm a bit surprised Matt Hugo is plugging this without some support because the EPS doesn't go along with it.

 

[phil nw.]

3 hours ago, knocker said:

If I'm honest I'm a bit surprised Matt Hugo is plugging this without some support because the EPS doesn't go along with it.

 

Certainly there's no indication of a late May warm up-at least of any significance as yet Knocker.

all rather average to rather cool going by the latest ens.graph.Not bad in the sun over the next 2/3 days in fact lovely out there at this time of year.

We then see a more changeable westerly regime kicking in by Tuesday as shown by the T84hrs fax

pressure falling over the UK as frontal systems approach from the west.

 

[wishingforsnow]

Ensembles for London are showing ground level temperatures rising after the 23rd May to high 20s by the end of the month. Also the main precipitation spike is between the 17th - 21st May tying in with the forecasted period of Atlantic low pressure:

http://www.theweatheroutlook.com/twoforecasts/ensemble-forecast.aspx

As @knocker said, two weeks away is FI so this warm up is by no means set in stone especially when there is so much uncertainty on it. Not even the weather for next week can be clear cut with model divergence how much the low pressure will have on the UK. High pressure is shown to begin to edge in again around the 23rd but anything after is deep FI right now. However I would hope Matt Hugo is perhaps referring to signals from high res model output. 

Edited May 14, 2016 by wishingforsnow

[Tim Bland]

I think high 20s may be a  bit of an exaggeration !? Low 20s at a push! Average is around 18c

 

[Nouska]

21 minutes ago, wishingforsnow said:

However I would hope Matt Hugo is perhaps referring to signals from high res model output. 

I'm not aware of any hi-res output for that far ahead but he'll probably have access to more of the ECM suite than we do.

The EC32 was showing warmth for the last week of the month but as that run was initiated prior to the big swing in model output, it has to be viewed as suspect till the run next Tuesday.

This was central Europe on week two from the Thursday run - anticipating the pattern would include a warm UK in part.

This mornings EPS mean (day 15) has average 850 temps for the bulk of the UK and the Z500 is also looking to be the average north south divide - not seeing any indication of strong, warm ridging.

  MSLP spread day 15