Model Output discussion 1st September 00z------->

[Frosty.]

Looking for a prolonged spell of warm anticyclonic weather? The Ecm 00z ensemble mean would deliver it

[phil nw.]

After a few more showery days it is indeed looking much better come the weekend.

Good agreement from the 3 main models at day 5 for high pressure building across NW Europe/UK by Saturday.

 

Looking at the ens this morning they are quite decent and this block could well last a few days at least,maybe giving a mainly dry and fine week to follow.

Usual caveats though for fog maybe taking it's time to clear on occasion.Afternoons should be quite warm where the sun does shine though,so quite a pleasant outlook to end September is in prospect.

[Zenarcher]

Daily comparison using the GFS, ECM, UKMO, JMA, ICON, GEM, NAVGEM, NASA, CMA, FIM and the CFS all up to 240 hours along with the ECM and GFS ensembles. For each day whatever model has the most support will be shown for that time.

 

24 Hours Tuesday (ECM)

Low pressure sits over the UK.

 

48 Hours Wednesday (GFS)

Low pressure moves over to the East of the UK as high pressure attempts to come in from the South West. A low pressure system forms to the West of Iceland.

 

72 Hours Thursday (FIM)

The low pressure from the West of Iceland moves down to the North West of Scotland.

 

96 Hours Friday (ECM)

Low pressure sits over the Northern half of the UK while the South starts to see high pressure moving in while another low pressure system out in the Atlantic begins to form.

 

120 Hours Saturday (FIM)

High pressure continues to build over most of the UK apart from Scotland. A large low pressure system now places itself to the South East of Greenland.

 

144 Hours Sunday (FIM)

High pressure remains over most of the UK apart from Western parts. The large low pressure system still remains in the same place and weakens in strength very slowly.

 

168 Hours Monday (NASA)

As the large low pressure system continues to weaken there are signs of high pressure gaining more strength and covering all of the UK and Ireland.

 

192 Hours Tuesday (NASA)

High pressure is expected to still stay over the UK and Ireland.

 

216 - 240 Hours Wednesday & Thursday (FIM & ECM)

The trend remains for the end of the month to see high pressure over the UK while low pressure systems will pass over Greenland and Iceland.

 

[knocker]

Seeing as it's quiet in here the little the GFS is playing this evening.

 

At day ten a little low that had it's origins around the Great Lakes is in mid Atlantic with TS IDA away to the south west. Moving on 36hrs and things have progressed and then to T312....voila.

http://www.tropicaltidbits.com/

 

 

[Man With Beard]

So Indian Summer looking on the cards for the end of September. Inevitably, any such spell will be compared to that incredible heatwave of September/October 2011. And here it is the comparison, see the links below! Not a replica because 2011 had a long draw southerly like 1st July did, but the 2015 version could be good for low to mid 20s with a bit of luck. So dependant on a southerly fetch at this time of year, even south-easterly is dodgy by early Oct.

http://meteociel.fr/modeles/archives/archives.php?day=31&month=9&hour=0&year=2011&map=0&mode=2

http://meteociel.fr/modeles/ecmwf.php?ech=192&mode=1&map=0&type=0&archive=0

[Singularity]

Interesting to see low pressure poking a finger at tropical storm Ida in 7 days time before leaving it alone. GFS has a similar feat of behaviour taking place. For both models to come up with that at the same time at a week's range is a bit uncanny.

 

Once again ECM (left two images below, for 7 and 9 days time respectively) has the jet stream aligning more favourably than GFS for pumping our high full of warm tropical maritime air.

 

The build up of that airmass type across the North Atlantic by the late stages of the run is something to behold. It happens as a result of two things; high pressure over Greenland proving strong enough to drag all the polar maritime air on the western flank of the lows right over to Canada and the Eastern U.S., and low pressure never hanging around long enough to drag much down across the North Atlantic.

 

GFS (right-hand image) is a world apart in that respect, as a large Atlantic low becomes slow moving to the west of the UK, with cool polar maritime air reaching as far south as the Azores Isles by +192 hours.The UK ridge is weaker as well so it all serves as a reminder that we could be left with much more ordinary conditions, albeit still with the potential to remain dry for an unusually long time in places.  

 

Edited September 21, 2015 by Singularity

[Milhouse]

 even south-easterly is dodgy by early Oct.

 

 

As highlighted well on the GFS 12z. A battle going on between warm air from Spain and a large pool of cooler air over central and northern Europe. The result is mid teens for the UK. The ECM is looking far more summerlike.

 

[Summer Sun]

We shouldn't be surprised by these charts ECM is producing becoming all too common these days where we get a pleasantly warm settled spell at some point in September

 

 

Misty starts are possible but pleasantly warm by the afternoons

 

Hopefully this will happen before the days really start and draw in

Edited September 21, 2015 by Summer Sun

[bluearmy]

The gefsp 12z throws up a promising mean/spread for the settled conditions to persist for our part of nw Europe (although the bump in the spread does look a tad odd.at that timeframe)

[Scorcher]

So Indian Summer looking on the cards for the end of September. Inevitably, any such spell will be compared to that incredible heatwave of September/October 2011. And here it is the comparison, see the links below! Not a replica because 2011 had a long draw southerly like 1st July did, but the 2015 version could be good for low to mid 20s with a bit of luck. So dependant on a southerly fetch at this time of year, even south-easterly is dodgy by early Oct.

http://meteociel.fr/modeles/archives/archives.php?day=31&month=9&hour=0&year=2011&map=0&mode=2

http://meteociel.fr/modeles/ecmwf.php?ech=192&mode=1&map=0&type=0&archive=0

 

I'd say at least the low 20s going by the ECM- comparing the charts to the warm spell of late September/early October 2002 in which the low 20s were reached quite widely, I'd say the charts being shown are far superior. There appears to have been more of a SW element during that spell.

 

[William of Walworth]

All I can say is that the synoptic agreement between almost all recent/current models from about Friday onwards is very September-like.

 

We rarely get such reliably settled spells so easily forecastable in July and August, but that's life!

 

Don't let's forget either, that UKMO was most confident earliest, about a quick (Friday onwards), start to HP influence.

 

Our juat this morning serviced campervan is happy, and so will we be in Gloucestershire, Friday to Monday coming up!

Edited September 21, 2015 by William of Walworth

[knocker]

The GEFS anomaly has broken ranks this evening with the mid Atlantic trough running a fair way south which tends to fit the ops scenario. The ecm is having none of it and is rock solid until the end of the ext period.

http://www.tropicaltidbits.com/

Edited September 21, 2015 by knocker

[knocker]

IDA

Chart weatherbell

 

[knocker]

The 18z GEFS (P) also has the upper trough quite close to the west. Providing it doesn't nudge further east a few days of warm weather still beckons.

Chart courtesy weatherbell

 

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

i  know  its  fantasy world but early oct is looking a bit intresting  if you like rain !!!

[Troubleatmill]

just for fun, but someone has to

[Mair Snaw]

just for fun, but someone has to

Would cause xmas uproar would that.....

[ANYWEATHER]

Big difference between ecm and gfs at day 10  

[I remember Atlantic 252]

384 chart the worst! would 'ate that now

[Polar Maritime]

Yes the GFS & ECMWF evolutions are miles apart as we head into the new Month, The position/strength of the block is still all to play for. With the GFS bringing the Atlantic into play much sooner, An interesting day or two coming up re detail.. 

[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 TUESDAY SEP 22ND 2015

 

 

THE CURRENT GENERAL SITUATION A showery trough of Low pressure will clear SE England this morning followed by a cool NW then West flow with a weak ridge crossing East over the UK followed by another front tomorrow.

 

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

 

MODELS-2 WEEK HEADLINE Becoming more settled after this week with sunny spells and mist and fog by night.

 

THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast shows the flow currently cyclonic across the UK before it migrates to the NW later this week and over the weekend. At the same time it dips well South over the Atlantic and returns North to the west of the UK early next week before reverting to a more cyclonic, light and broken pattern late in the period around the UK.

 

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

 

GFS OPERATIONAL The GFS Operational Run today continues to run with the theme of High pressure developing across the UK from the weekend although on this run it all too quickly gets to the east and NE of the UK allowing pressure to fall over the Atlantic which in turn pushes troughs close to Western Britain before midweek next week which then moves slowly East across the UK. Pressure then builds strongly to the North of the UK in the second week sending Low pressure over and then to the South of the UK in Week 2 and setting up a strong Easterly flow across the South to end the period still with some rain in the South.

 

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

 

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

 

THE GFS CONTROL The theme of the GFS Control Run this morning is similar but holds the influence of High pressure a little longer before on this run trouble arrives from the SE with a strengthening East wind and showers for a time in the South. High pressure is then shown to reassert it's authority across many areas, again just for a time before more unsettled and cool weather returns this time from the NW at the end of the period.

 

http://www.meteociel.fr/modeles/gefs_cartes.php

 

THE GFS CLUSTERS(14 Days) The GFS Clusters this morning have shifted today to a much more unsettled outlook likely across the UK once we get to the 14 day time point. Most members show Low pressure in an assortment of locations, all with influence over the UK with only 30% indicating some influence from a ridge close to the South.

 

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 today shows High pressure building across Southern Britain and drifting out into the Southern North Sea early next week. With warm uppers aloft and High pressure at this time of year comes the recipe for some cool, misty nights and warm and sunny afternoon's once the mist and low cloud clears.

 

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

 

THE FAX CHARTS The Fax Charts this morning show High pressure building nicely from the SW at the weekend warding off all Atlantic troughs well to the West and NW late in the period.

 

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

 

GEM GEM this morning is quite similar to UKMO up to day 6 with High pressure in the Southern North sea at that time point with the UK under fine and settled weather. Fronts do make slow inroads into Western Britain later next week but make little significant progress over the rest of the UK before High pressure reasserts itself to the North of the UK at the end of the run with Easterly winds developing across the South.

 

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

 

NAVGEM NAVGEM this morning also shows the strong High pressure area developing near SE Britain at the weekend and maintaining it's position well into next week with virtually all of the UK fine and dry with cool misty nights and bright afternoons. Any Atlantic fronts are restricted to the extreme NW corner of the UK.

 

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

 

ECM ECM this morning is rock solid in delivering better weather across the UK from next weekend as it continues to show rising pressure from Friday culminating in a belt of High pressure stretching across the UK next week with fine and pleasantly warm weather by day once the mist and overnight fog which could be quite extensive at times slowly clears each day.

 

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

 

ECM 10 DAY MEAN The ECM 10 Day Mean Chart from last night too shows High pressure stretched across the UK with almost universal support for fine and dry early Autumn weather with fine warm days and cool misty nights.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models remain little changed from yesterday with the majority showing sustained High pressure based weather across all areas with any breakdown held well at arms length and unclear.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The Verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ties with UKMO at 99.4 pts each with GFS coming in third at 99.2 pts.  At 3 days ECM again ties with UKMO at 96.5 pts while GFS lags behind at 95.7 pts. At 5 days ECM leads at 86.6 pts over UKMO at 86.4 pts then GFS at 84.2 pts. Then at 8 Days ECM still leads at 58.2 pts over GFS's 51.3 pts. Finally at Day 10 ECM leads GFS at 35.3 pts to 33.6 pts from GFS.

 

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 Another day and another day nearer to rather better conditions likely across the UK come the weekend moving forward. We have another two or three days of more changeable weather when Westerly winds continue to bring short spells of rain and more showery conditions across the UK. By Friday pressure rises strongly across all areas from the SW with dry and fine conditions commencing just in time for the weekend. Winds will be light and with increasingly warm uppers aloft had it been July we would be in for some very hot weather. As it is we are still likely to get well above average temperatures in the afternoons but by night cool temperatures under longer nights now will allow the formation of our Autumn peril of fog and if this become extensive enough it may become a devil to shift through some days, lifting into low cloud and suppressing temperatures as a result. However, that is the only negative I can find in an otherwise very pleasant spell coming up which could last quite a while. Of course I am always looking for long term change within the models and while there is some suggestion that a breakdown could develop late in the two week period it is certainly not a given that it will happen and certainly not necessarily in the way that some output shows today. GFS is a little worrying in that field though as all it's output show a return of wind and rain scenarios returning by day 14 backed up with it's clusters but that is the exception and should not be dwelt upon at this range. So lets look forwards to a period of fine and settled weather and fog aside lets hope the Autumn sunshine can bring some impressive early Autumn temperatures to set off the colours of the trees and bring some atmospheric scenes ideal for photographers.

 

WORST CHART OF THE DAY 00z RUN

 

http://www.wetterzentrale.de/pics/Rtavn3481.gif

 

The worse chart of the day today is GFS at T+348hrs as it shows a large and deep low to the SW of the UK and High to the North. The resultant weather over most of the UK would not necessarily be that bad but strong and cool winds with rain would likely affect the South and things could be very different if this chart verified in 4 months time with snow a real possibility for the South.

 

BEST CHART OF THE DAY 00z RUN

 

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

 

Charts don't get much better than the ECM T+240hrs chart today as it shows High pressure rock solid over the top of the UK with dry and settled weather for all with mist and fog likely to be an issue at night though. With all the backing of other output it does have a larger than usual chance of verifying than most 10 day range charts.

 

Next update from 09:00 Wednesday Sep 23rd 2015

 

[Yarmy]

The GFS has backtracked over the last few runs, but the ECM has been consistent in its desire to build heights over us:

 

Sunday 0z at T216

 

 

Monday 0z at T192

 

 

Tuesday 0z at T168

 

[Summer Sun]

High pressure dominates ECM again this morning some misty starts but very pleasant by early afternoon if you have some sunshine

 

[knocker]

This morning's anomalies highlight the vast difference between the ecm and GEFS at the moment. The latter is plugging the mid Atlantic trough digging quite away south which the ecm is having none of. One suspects the answer may be somewhere in between.

http://www.tropicaltidbits.com/

 

[Geordiesnow]

Does seem quite a strong trend for a SE'ly flow, with both the GFS and ECM at times forecasting this, timing of when it will happen has been quite varied so not guranteed to come off. 

 

For those wanting one last warm spell may have to be patient regarding any real warmth out of this, its going to be quite a slow start in terms of temperatures although what cooler upper air temps tend to do is bring a lot more sunshine than cloud so at least the high should be a fairly 'clean' high to start off with. Fog could be an issue also which will most certainly give an Autumnal feel in that respect. 

 

Questions for me will be, how long will this settle spell last for and whether we can tap into any proper warm upper air temperatures from the continent.