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Model Output Discussions 12z 03/05/2016

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Time for a new Model thread then as we are now into the last month of Spring and with it at last the prospect of some real warmth.

A look at 2 of the 3 day mean temperature anomalies expected from the weekend and into next week certainly underline this.

viewimage.pngviewimage (1).png

The 12z run will be on it's way now so please continue below.

 

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UKMO shows the warm air continuing next week on a south easterly flow

Rukm1441.gif

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That's a bit off dragging the cooler air in on Saturday. The next seven days look like being very warm for the whole of the UK with the possible exception of the east coast.

gfs_t2maf_slp_uk2_17.png

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h850t850eu.png h850t850eu.png

Uncertainly levels are returning to more typical values for 7+ days range, with the models struggling to resolve the balance of power between one ridge to the northwest and another to the northeast.

If the former is closer to us, it drives cooler air down from the north, which not only lowers the UK temps but also increases the upper level westerlies (jet stream) in the vicinity of the Euro trough, encouraging a motion between NE and E. At that point, either the ridge to the northwest saves us, or we end up cool and wet for a time.

Having the latter nearer by maintains a warm flow of air from the east, with the Euro trough becoming weak and 'flabby' while slowly drifting east. This is a more unusual outcome, and one that could keep the UK basking in warm conditions (low to mid 20's by day) for quite some time, depending on to what extent low pressure advances from the Atlantic. This 12z GFS run takes until 18th May to bring fresher conditions from the west, which would mean the warm spell was a full fortnight in length for some parts. Not bad going!

The ECM 00z voted strongly in favour of the ridge to the NW taking control, and the GEM 12z has just thrown out a particularly unpleasant variation on that theme. So at this stage the GFS 12z seems overly optimistic - with the 06z a more reasonable reflection of current probabilities, though still better than the ECM 00z in that it cuts off the northerly feed before it's really got going.

Best we make the most of the impending warm conditions, just in case!

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2 hours ago, Summer Sun said:

UKMO shows the warm air continuing next week on a south easterly flow

Rukm1441.gif

That's not a bad chart. That low to the SW looks stuck there for a while. Continental air for most of next week on that.

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The GEFS 7-11 is still hanging on to the cut off low Iberia so the UK still under influence of low pressure to the south and temps still good at above average. But this does appear to be the time of transition but precisely to what is not clear cut at this stage apart from the fact indications are a veering of the upper flow to the westerly quadrant with possible some temporary height rises to the south west. Not completely bad news temp wise albeit they will drop to nearer normal. A watching brief required.

The EC32 means update on this is to regress the cut off low to a trough just to the west and after that westerlies with no discernible significant signal.

gfs-ens_z500aMean_nhem_7.png

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The ecm 6-10 anomaly also still has the cut off low Iberia.thus low pressure to the south producing an easterly component regarding the streamlins and temps above average as shown.

ecm_eps_t850a_5d_natl_11.png

But as mentioned previously this is around the transition period and by day ten the cut off has weakened and moved east allowing build up of heights to south west and a fairly rapid change of airmass and the winds becoming NW with a concomitant decrease in the positive temp anomaly to around average albeit with some settled weather for a few days. This is not dissimilar to the GEFS so maybe along the right lines but the jury is still out.

ecm_eps_z500a_natl_11.png

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Saturday still looking as if it could be quite interesting on the convective front.  Saturday 12z sees the low southern Ireland and maybe a convergence zone Somerset/Dorset. I see there is a separate  thread on this so will leave it there. for the rest of next week with low pressure remaining in the southern quadrant the prevailing streamlines will be easterly with dry weather for most but there could well be showery outbreaks in the south. Temps above average but cooler on the east coast.

gfs_t2maf_slp_uk2_15.pnggfs_pwat_uk2_15.png

Edited by knocker
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The ecm has a similar take on Saturday as the GFS. Next week it also has an easterly component to the streamlines but as the week progresses the low pressure to the south moves steadily east thus a longer easterly fetch resulting in the above average temps cooling a little.

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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 WEDNESDAY MAY 4TH 2016

THE CURRENT GENERAL SITUATION Pressure is high over Southern England today as a couple of cold fronts move very slowly East across Northern areas today and tomorrow while weakening and eventually decaying in situ by Friday.  A thundery Low pressure area will then develop to the SW of the UK resulting in a warm ESE flow across the UK by the weekend.

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

CURRENT SNOW FORECAST AND/OR FREEZING LEVEL OVER THE UK The UK continues to see the freezing level across the UK rise to as high as 10000 feet across the South by the weekend while levels are slower to rise in the NW where they remain around 5000ft before rising to 7000ft  or above by the weekend.

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

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

MODELS-2 WEEK HEADLINE Becoming warmer with the risk of some thundery showers in the South at times later.

THE GFS JET STREAM FORECAST The Jet Stream currently moving NE across the NW of the UK will weaken in the coming days with the main cyclonic flow around Spain becoming the driving force over the weekend and next week before the flow becomes very light and split across the Atlantic and NW Europe with no clear definitive structure shown within the latter end of the forecast period this morning.

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

GFS OPERATIONAL The GFS Operational Run today still shows a lot of Northern blocking anticyclonic patterning over the next few weeks. Pressure will be lower across Southern Europe and later other parts of Europe too with the best weather eventually likely to be in the NW. In the meantime the weather will be much warmer than of late with sunny spells but with the likelihood of some thundery showers at times especially in the South but not everywhere will see them. Eastern Coasts continue to look like seeing a lot of fret and here it will be rather chilly for much of the time in an onshore breeze and on this run all areas become cooler at the end of the period as cold North or NE winds and Low pressure feed down the North Sea in two weeks time with some rain or showers.

GFS CONTROL RUN The theme of the Control Run is very similar to the Operational for the next 10 days with warm and later humid weather with some thundery rain in places especially in the South. Then the run diverges late in the run as a more traditional pattern of Low to the NW and South-Westerly winds reset across the UK with the best weather reverting to Southern and Eastern areas.

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

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

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 clusters today show the UK likely to be lying under an area of quite slack pressure biased towards lower pressure rather than high, so a lot of potential shower risk conditions in temperatures around or slightly above average with High pressure likely to be lying either to the NW, West or SW with the UK itself lying under shallow and showery Low pressure areas.

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 Low pressure developing down towards Spain and Portugal over the weekend with a strengthening Easterly flow across the UK. This will feed up the risk of thundery rain and showers towards the South and SW of the UK though most Northern and Eastern parts of the UK should stay dry and most areas it will become warm and humid. However, I cannot emphasize enough how much chillier it will feel near the East coast in an onshore and stiff wind with sea haar and fret persistent.

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

THE FAX CHARTS The Fax Charts mirror the theme of the raw data well today showing warm SE winds and a lot of dry weather come the weekend with just the chance of a thundery shower in the South and especially the SW between hazy but warm sunny spells.

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

GEM GEM this morning shows a similar pattern over the next week as Low pressure developing over Spain and Iberia deepens and strengthens an Easterly flow across the UK with some fine and warm weather for many but also with some occasional thundery showers across the South and West. Then towards the end of next week this Low over Spain is sucked away to the NE and backs winds off to the North or NE across the UK with much cooler and unsettled weather with cold rain and showers at times spreading to all areas at the second weekend.

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

NAVGEM NAVGEM today shows the same Low pressure area down to the SW of the UK by the weekend pumping warm East to SE winds up across the UK with warm sunshine and well scattered thundery showers especially in the SW at first but to many more areas by the middle of next week as the pattern tries to reset to a more traditional UK pattern of Low pressure to the NW and High pressure to the South though it seem unclear whether such an attempt would be successful or not from the Day 7 Chart.

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

ECM ECM today shows warm weather developing later this week as the High pressure area currently near the South moves east and then North into Europe. The developing East or SE flow in association with deepening Low pressure over Biscay and Spain sends winds into the East with warm and humid conditions extending North across the UK by the weekend with some thundery showers at times down over the South and SW. Longer term changes look very slow this morning with the Spanish Low transferring into the Med and other parts of Europe maintaining an Easterly feed and the risk of showers across the South of the UK while the NW sees the best weather at the same time as all eastern coasts remain cool and misty. 

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

ECM 10 DAY MEAN (12z) The 240hr mean Chart from last night shows no pressure system having overall control though the theme of maintaining lower pressure across Europe and higher pressure just to the West or NW of the UK remains with the likely weather being rather showery in average temperatures at worst.

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

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The theme remains for a warm and humid period of weather across the UK which could last for quite a while as High pressure is themed towards Northern latitudes and Low pressure likely to lie across Southern and Eastern mainland Europe.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.4 pts and GFS at 99.3 pts.  At 3 days ECM is leading with 97.3 pts to UKMO's 96.5 pts while GFS lags behind at 95.6 pts. At 5 days ECM leads with 89.1 pts to UKMO at 87.1 pts and GFS at 83.4 pts. Then at 8 Days ECM has the leading spot from GFS with 62.5 pts to 53.0 pts. Finally at Day 10 ECM has the lead from GFS with a score of 46.1 pts to 39.2 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 The theme of the models remain largely unchanged this morning with the main theme being Low pressure to the South of the UK and the continuation of once established High level blocking to the North of the UK with an East or SE flow developing across all parts of the UK by the weekend. We are not there yet though and the North and NW will continue to see a few more days of Atlantic SW winds and rain at times as weakening fronts approach from the West. These then dissolve and decay come the weekend as the High pressure over the South currently drifts East and Southerly or SE winds push the warmer air NW to all parts. As already mentioned pressure will become low or even very low over Spain with some unseasonably wet and windy weather expected down there from the weekend and some out-feed of this will move North towards the South and West at times in the form of thundery showers from the weekend. Elsewhere there will be a lot of warm, and in places very warm and humid conditions with plenty of hazy sunshine that is of course if you live away from the East Coast as in these places any chance of warm weather will be thwarted by a developing haar which does look as though it could give days of cold, breezy and dull conditions especially the further North up the North Sea coast you travel. This pattern then looks fairly set for a week or so before looking longer term it does still appear that there could be a desire to shift the Spanish Low more towards mainland Europe and the Med with winds backing to the NE or even North and it could be that colder conditions will end up being fed South through the UK with some showers in the East later. Another option shown is the chance that pressure may rebuild to the South of the UK on the exit East of the Low pressure over Spain with winds trying to counteract the Northern High pressure blocking with a slow change towards SW winds and rain returning more towards the North and West later. All these long term options look very tentative this morning and should be used as a guide rather than a forecast but for now the next week or so looks pretty well set between the output which should ensure all areas away from the East coast becomes warm, occasionally sunny and bright if breezy with time with the chance of a few thundery showers in places-especially in the South. Enjoy.

Next Update Thursday May 5th 2016 from 09:00

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The 700mb chart for 12z Saturday

rel_vort_60.gif

 

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That ECM has raised my eyebrows - it's completely changed its tune longer-term, favouring the ridge to the NE over that to the NW. A much warmer outcome as we keep a feed from a warm source even as the fetch to the east lengthens - though as Knocker eludes to, down to high teens to low 20's maximums generally after Monday, as opposed to nearing the mid-20's in places.

The mid-range has altered a little as well; the low is a bit further west, with a better alignment to bring the warmest air up from the south.

120_mslp850.png?cb=447 144_mslp850.png?cb=447

GFS has not made such adjustment, and remains cooler by Tuesday, with a band of quite persistent heavy rain advancing up from the south to produce conditions typical of a soggy summers day - mid-teens temperatures with the rain drops tending to be of the bloated variety. ECM does bring spells of rain, but they are more showery (convective) in nature, with sunny spells in between still lifting temps into the 20's quite widely.

So still some details to iron out at that range - as you'd expect. What we do have sorted out is a weekend that's very warm, with temps hitting the mid-20's in places, but also brings widespread heavy showers and thunderstorms, though the far south(east) may tend to escape, as - due to the brisk broad-scale upper level flow from the southeast - the showers may (based on model assumptions...) require a good land track to really get going in response to surface heating.

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42 minutes ago, knocker said:

The ecm has a similar take on Saturday as the GFS. Next week it also has an easterly component to the streamlines but as the week progresses the low pressure to the south moves steadily east thus a longer easterly fetch resulting in the above average temps cooling a little.

Yes Knocker, Some very nice Spring weather on the cards into week 2 with High Pressure sat over the UK. Feeling cooler on the East coast as you say with a long drawn Easterly by next weekend as shown by the ECMWF/GFS below, But very pleasant on the whole with much more seasonal temps for the time of year than of late. Will be nice not to have to turn the heating on now!

a.pnga.png

Edited by Polar Maritime
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26 minutes ago, Singularity said:

So still some details to iron out at that range - as you'd expect. What we do have sorted out is a weekend that's very warm, with temps hitting the mid-20's in places, but also brings widespread heavy showers and thunderstorms, though the far south(east) may tend to escape, as - due to the brisk broad-scale upper level flow from the southeast - the showers may (based on model assumptions...) require a good land track to really get going in response to surface heating.

Hmm, think there's a bit of "ooo, slight risk for me so I'll emphasise it" going on here. ;) 

If you have a look at Nick F's post in the latest convective thread, he states that most thundery showers/thunderstorms will be mainly focussed around south western areas due to the stronger theta plume, more instability and being closer to the low. I think the heat in the east will be more of a drier variety with thunderstorms being either non-existent or very isolated. Still, things could change. However, this statement is backed up by especially the latest GFS run but also the latest NMM and ECMWF runs.

Edited by William Grimsley
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15 minutes ago, William Grimsley said:

Hmm, think there's a bit of "ooo, slight risk for me so I'll emphasise it" going on here. ;) 

If you have a look at Nick F's post in the latest convective thread, he states that most thundery showers/thunderstorms will be mainly focussed around south western areas due to the stronger theta plume, more instability and being closer to the low. I think the heat in the east will be more of a drier variety with thunderstorms being either non-existent or very isolated. Still, things could change. However, this statement is backed up by especially the latest GFS run but also the latest NMM and ECMWF runs.

Come on Will. Singularity's made a very fair assessment there - you don't have to boast about the SW's chances; we all know things can change last minute. as you've even said yourself. Let's just enjoy the next week or so of charts unfolding and the associated ups and downs. :)

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MP-R, I never said his statement wasn't fair... In fact, his statement is fair. All I'm saying, is I was advising that people don't get too excited in the east (as well as in the west) because of the possibility of more elevated thunderstorms here.

Edited by William Grimsley

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8 minutes ago, William Grimsley said:

MP-R, I never said his statement wasn't fair... In fact, his statement is fair. All I'm saying, is I was advising that people don't get too excited in the east (as well as in the west) because of the possibility of more elevated thunderstorms here.

Good. Tbh, I think it's wise that nobody in particular gets too excited, simply so as to avoid too much disappointment. Far too often in these setups lower level cloud hinders anything exciting kicking off, leaving us in the hope of something elevated. In such setups, further east is actually favoured as there is less cloud overall. Like I said, let's just let things unfold and see what happens. 

N-W's ten day forecast for my location indicates some very large rainfall totals into next week, especially Monday and Tuesday, which would possibly bring more rain than the whole of April in one day with good storm chances on all days after Saturday. Flooding could be an issue whether from intense thunderstorms or prolonged heavy rain. May 2008 springs to mind.

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Afternoon all :)

Some very reasonable weather upcoming though signs of a return to something cooler as the winds turn more E'ly or even NE'ly later next week.

The GFS 06Z OP keeps the theme of Northern Blocking and low European heights far into FI so it looks as though there will be periods of warmth if we get a SE'ly feed and cooler periods if we end up more NE'ly.

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2 minutes ago, William Grimsley said:

stodge, I think as the winds NE'ly, western areas will still be quite warm.

Agreed.  Especially locations like mine. :-) 

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Some great weather options on offer from the models at the moment :) - could be a wonderful end to Spring and start to Summer on the cards :D Hope this is a start of frequent periods of warm/hot settled and thundery weather as we enter the Summer season soon. 

Edited by wishingforsnow
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Correct, Chris.R.

I've just had a look at both the GFS and the NMM charts, both show widespread heavy thundery showers/thunderstorms across my area through this weekend, not sure why some (very knowledgeable) aren't seeing this?

Edited by William Grimsley
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10 minutes ago, William Grimsley said:

stodge, I think as the winds NE'ly, western areas will still be quite warm.

Yes, your part of the world will do fine from a NE'ly. My part of the world (lowland East London) not so good and I fear for parts of the east coast of England and Scotland, it won't matter if it's a NE'ly or a SE'ly in terms of mist and low cloud.

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1 hour ago, William Grimsley said:

Correct, Chris.R.

I've just had a look at both the GFS and the NMM charts, both show widespread heavy thundery showers/thunderstorms across my area through this weekend, not sure why some (very knowledgeable) aren't seeing this?

Why this preoccupation with thunderstorms? Surely we need some prolonged sunshine first...the fields are still very soggy in a lot of areas. The thunderstorms can wait until after June as far as I'm concerned!

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