Model Output Discussion 18z 30/09/15

[damianslaw]

The generally settled autumn continues with high pressure ruling the roost, the return unsettled spell has been a bit of a damp squib for many, hardly washout territory, though the BBC seem to think its been a deluge, we've not seen much rain here.

 

The Jetstream continues to meander about and flounder at a time when it should really be kicking into higher gear. Its certainly not normal service for the time of year.

 

Looking at the charts, a mostly dry spell ahead and quite chilly under easterly/southeasterly airstream. Next week will see high pressure dominating, where it goes is uncertain, some signals we will see a trough drop down from the NW to affect scandi causing heights to back into mid atlantic and possibly ridge northwards, pulling down a cool NW flow.. very reminiscent of the default set up we saw May-August.

 

In overview a very benign outlook, temps a little below average, with no clear path to anything particularly mild or cold on the horizon, and a predominantly dry one - yes not very exciting, but good for autumnal displays with many trees able to maintain there leaves for some time yet, nothing worse when a good display is stripped away in a gale.

Edited October 7, 2015 by damianslaw

[knocker]

Last might's 18z GEFS upgrade at T240 has quite an amplified pattern over North America with troughs to the NE and eastern Pacific. In the eastern Atlantic ridging over the UK  This continues into the ext period but with the Scandinavian block weakening considerable.

 

Ergo the surface analysis is HP remaining dominant but losing the easterly component as the HP from the west becomes more influential. Eventually this could bring about an airflow from a westerly quadrant.

 

Thus a period of quiet, pleasant weather with temps about average or slightly below.

Charts courtesy weatherbell

Edited October 8, 2015 by knocker

[knocker]

An overview of the GFS run this morning is HP dominant but next week showing the transition from the NE block which slips away to HP from the west  Generally cool but becoming average.

http://www.tropicaltidbits.com/

 

[Frosty.]

Those of us hoping for a late october cold snap will find this encouraging from the Gfs 00z op with a brief Arctic incursion following a prolonged anticyclonic spell. Any cold snap in october would be a welcome bonus and it's good to see the gfs continuing to show wintry charts so early in the autumn / winter season..much more of this please  

Edited October 8, 2015 by Frosty.

[Ali1977]

No models are showing any large scale PV over Greenland or Northern Canada by mid Oct, is this normal? There is a large chunk over central Siberia, not sure how quick that can flip back towards Canada. Siberian snow cover definitely looks like increasing westwards over the next few days also.

[mountain shadow]

Those of us hoping for a late october cold snap will find this encouraging from the Gfs 00z op with a brief Arctic incursion following a prolonged anticyclonic spell. Any cold snap in october would be a welcome bonus and it's good to see the gfs continuing to show wintry charts so early in the autumn / winter season..much more of this please  

There was snow fall in late October 2009 if I recall which was also El Nino.

[knocker]

This morning's GEFS anomalies continues the HP theme for the next 15 days with the upper flow moving to the westerly quadrant with temps a tad below average becoming average. Hallelujah, praise the lord.

http://www.tropicaltidbits.com/

Edited October 8, 2015 by knocker

[MR EXTREMES]

 

arctic blast futher west this morning that's 4 or 5 runs showing this idea...

not only that pretty chilly surface heights sticking around and I would not be surprised to see this persist for 10 days or more.

 

eastern Europe cooling down nicely

other models like the ecm gem ect ect are not a million miles away from the gfs ideas few little tweaks here and there and it will be our first cold blast for sometime.

 

regardless still a very different set up from last season.

 

so cool cold nights and blocked even hints in fi of heights building to our west up into southern Greenland with low pressure to our east we see a lot of this in 09/10

[MR EXTREMES]

yep there most certainly was i wonder if models use winter 09/10 in there data when producing outputs.

[johnholmes]

yep there most certainly was i wonder if models use winter 09/10 in there data when producing outputs.

 

nope

simply run with current actual weather as they always have done

[MR EXTREMES]

ok thanks john was always something i wondered.

[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 THURSDAY OCT 8TH 2015

 

THE CURRENT GENERAL SITUATION  A ridge of High pressure will lie across the UK over today and tomorrow.

 

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

 

CURRENT SNOW LYING UK AND NORTHERN HEMISPHERE There is currently no snow lying in the UK with the freezing level at just under 5200ft in the far West and NW and close to 8200ft in Eastern England.

 

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 mostly fine and settled with frost and fog patches at night. Perhaps more unsettled and colder later.

 

THE GFS JET STREAM FORECAST  The GFS Jet Stream Forecast shows the southern arm of the currently split flow dissolving over the coming days as the Northern arm strengthens somewhat up to the NW and blows NE to the NW of Scotland. then later in the flow part of the flow dives South across the UK at times as Low pressure to the NE diverts it at times.

 

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

 

GFS OPERATIONAL The GFS Operational Run today shows the weather being influenced by High pressure to the East across the UK over the next week as a ridge extends West from it across northern areas with a chilly east flow across the South. Very little if any rain is likely and Week 2 looks pretty good too as High pressure influence transfers to coming from the West of the UK maintaining a ridge across us. Winds then settle to come from the North late in the period with a cold Northerly blast bringing some wintry showers towards the North and East at the end of the period.

 

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

 

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

 

THE GFS CONTROL The theme of the GFS Control Run shows much High pressure dominance across the UK throughout the run. This comes in the shape of a ridge lying across the UK for the next week with the Easterly flow across the South just unstable enough for a time to give the risk of a few showers towards the SE. Then in Week 2 High pressure develops right across the UK with much fine and settled weather for all though with the twin hazards of fog and frost almost anywhere likely through Week 2, slow to clear in places

 

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

 

THE GFS CLUSTERS(14 Days) The GFS Clusters in 14 days has maintained a majority bias towards High pressure lying close to or to the West and SW of the UK with fine weather for many though there are more options this morning with more of an Atlantic based period by that time with some rain at times on a Westerly wind especially over the North.

 

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 stretching West from an European High pressure, lying across the UK from the East into next week and giving rise to fine and dry weather for many with frost and fog at night in the North but with a chilly Easterly flow maintained across the South making daytime weather feel cool but allowing an avoidance of much in the way of frost and fog here by night.

 

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

 

THE FAX CHARTS The Fax Charts this morning illustrate domination of a High pressure block to the East and NE maintaining a ridge West across the UK keeping any cloud and rain bearing weather systems well away from most of the UK, well to the West, NW and South.

 

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

 

GEM GEM has High pressure ridged over the UK from the East over the next week with fine and settled weather for all areas. On this run there is less strength to the Easterly flow in the South as the axis of the ridge is more to the South than some other output. This means the far North could see a little rain especially late in the run when an attack from the North brings cloud and rain and cold weather South to most areas towards Day 10.

 

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

 

NAVGEM NAVGEM follows the theme of the rest with dry and fine weather developing from today with High pressure slow moving across the North of the UK either in the shape of a ridge or under a cell of High pressure itself with fine and dry weather for all with a keen East breeze in the South and frost and fog night and morning over the North.

 

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

 

ECM ECM this morning is broadly similar to the rest of the output until later in the period when a hiatus in the fine weather could develop later next week as a trough bisects High pressure East and West of the UK with some rain for a time with an attack from the North introducing a change in weather type at or soon after the termination of the run for most of the UK.

 

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

 

ECM 10 DAY MEAN The ECM 10 Day Mean Chart from last night indicates the UK lying in slack pressure between High pressure both to the SW and NE and Low pressure to the NW and to a lesser extent to the SE with the weather likely to be mostly quite benign across the British Isles but with some rain at times towards the North and West and perhaps a shower or two elsewhere.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS There is very good agreement on fine and settled weather for the UK under a ridge for most of not all of next week with any distant changes looking most likely to come from the North somewhen in Week 2.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM tying with UKMO at 99.5 pts with GFS closely behind at 99.4 pts.  At 3 days ECM is leading with 97.1 pts to UKMO's 96.9 pts while GFS lags behind at 95.9 pts. At 5 days ECM leads with 87.8 pts to UKMO at 87.0 pts then GFS at 83.8 pts. Then at 8 Days ECM still leads at 57.6 pts over GFS's 50.0 pts. Finally at Day 10 ECM leads GFS at 35.4 pts to 32.0 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 weather looks like becoming set fair across the UK over the next week or so at least and maybe longer. Any remaining showers left over as a legacy to the recent unsettled period will finally decay by tomorrow with High pressure building across the Uk from the East and delivering bundles of fine and bright weather for all areas. As usual this means sunny spells by day but those same clearer spells by night will likely give rise to plenty of frost and fog patches by night in the North. There looks likely to be slightly different conditions in the South as an Easterly flow looks likely to develop restricting any frost and fog patches to places with good shelter but also making it feel chilly by day in exposure. This general weather pattern looks likely to persists for most if not all of next week before some output, namely GEM, GFS and ECM all point towards the North for what may be a pattern shift away from High pressure to something more unsettled and possibly cold as winds look like they could turn Northerly later. In the meantime we should all be able to enjoy a protracted spell of fine and settled weather with very little in the way of rain, some sunny spells with some frost and fog patches at night, a chilly east wind in the South and perhaps a shift towards something more unsettled and chilly much later in the second week.

 

WORST CHART OF THE DAY 00z RUN

 

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

 

I have chosen to show another GEM 10 Day chart as the worst chart of the day as it highlights my above text summary in bringing Low pressure down from the North in 10 days or so bringing an end to the fine weather as cloud, wind, rain and potentially cold weather moves down across all areas at that time, but will it happen?

 

BEST CHART OF THE DAY 00z RUN

 

http://www.wetterzentrale.de/pics/Recm1441.gif

 

The best chart today goes to GFS in it's operational run at Day 6 which shows High pressure stretched across the UK and nearby NW Europe with fine and settled Autumn weather continuing for some time from this point for the UK.

 

Next update from 09:00 Friday Oct 8th 2015

[phil nw.]

I notice both naefs and ecm height anomaly forecasts want to maintain some form of mid-latitude blocking into week 2- and beyond,in naef's case.This along with lower hts over Europe to our south would suggest still a weak and split jet .

If the block does re- position west into the Atlantic, as some recent gfs runs have suggested, then there is scope for that cold shot coming over the top from the north or north west.That would be beyond 10 days based on the current mean runs and depends on the orientation of the block whether any cold flow would directly impact the UK or go further east.

There's certainly little sign yet of any really cyclonic weather for the UK in the meantime though.It looks fairly quiet and dry with a cooler feel where that easterly blows across the south.Some local frosts and fog likely in the coming week too.

[knocker]

the ecm in the ext period keeps the HP to the W/SW pretty much in charge but tending for it slip slowly SW giving a more westerly zonal flow but still pretty hunky dory.

[carinthian]

I notice both naefs and ecm height anomaly forecasts want to maintain some form of mid-latitude blocking into week 2- and beyond,in naef's case.This along with lower hts over Europe to our south would suggest still a weak and split jet .

If the block does re- position west into the Atlantic, as some recent gfs runs have suggested, then there is scope for that cold shot coming over the top from the north or north west.That would be beyond 10 days based on the current mean runs and depends on the orientation of the block whether any cold flow would directly impact the UK or go further east.

There's certainly little sign yet of any really cyclonic weather for the UK in the meantime though.It looks fairly quiet and dry with a cooler feel where that easterly blows across the south.Some local frosts and fog likely in the coming week too.

Hello Phil,

 Reading our own Central European model would suggest a fall in heights over Europe. As in the usual case of no dominate strong wind fields over Central Europe some form of trough developments in the relative cold /cool  flow from the NE is likely to happen next week. Of course the SE of England would be in the eventual disturbance line for some precipitation ( prob showery nature ). We have lowered our snowline to below 1000m by Sunday into Northern Austria/ Czech Rep/Slovakia area.

 C

[Frosty.]

The Gfs 6z op run shows high pressure bringing a prolonged generally fine spell to most of the uk, I say most because there is the occasional unsettled blip brushing across the far north on this run but for many it's looking settled with variable amounts of cloud and good sunny spells, some days could be almost unbroken sunshine. Nights look chilly where skies clear and winds fall light with slight frosts and also mist and fog patches and speaking of chilly, this weekend and early next week, although fine with sunny spells will be feeling chilly due to freshening Easterly winds but thereafter, winds become lighter and more variable in direction so it should feel pleasant in the sunshine. As for the remnants of Ex Hurricane Joaquin, they are heading for the Bay of Biscay in the next few days.

Edited October 8, 2015 by Frosty.

[nick sussex]

Cold second half of October?

 

Certainly looking that way at the moment, the ECM moves the PV to the Siberian side and weakens those low heights in ne Canada by day ten, that normally correlates with some interest as high pressure sets up further to the west/sw.

 

The mean although washing out some of the detail does again lift those low heights out from Canada. Still too early for anything of note but interesting to see what happens if the ECM has made the right call in terms of trend.

 

We should note however the performance of both the GFS and ECM when it comes to upstream bias in later outputs. The former likely to be too flat for too long and slow to pick up amplification and the ECM tending to over do this.

Edited October 8, 2015 by nick sussex

[Nouska]

No models are showing any large scale PV over Greenland or Northern Canada by mid Oct, is this normal? There is a large chunk over central Siberia, not sure how quick that can flip back towards Canada. Siberian snow cover definitely looks like increasing westwards over the next few days also.

 

It's all looking quite normal for mid October - still early as far as seeing any development.

 

Meteociel has a useful function where you can compare the last sixty plus years - I've set it for mid October.

 

http://www.meteociel.fr/modeles/archives/archives.php?day=16&month=10&hour=0&map=4&mode=1

 

ECM 360 hour mean for local area.

 

[Mucka]

nope

simply run with current actual weather as they always have done

 

That is true, but being somewhat pedantic, could we say they do take past weather into account when the algorithms are tweaked?

Most upgrades are adding new data or bringing in higher resolution in some way but likely inbuilt bias in algorithms is also noted when compared to actual weather patterns and adjusted accordingly?

 

Still no signal for any typical zonal weather with high pressure in charge until at least day 9/10 where the possibilities of a change begin to increase.

The most prominent signal thus far for any change is still for an Atlantic block and trough dropping into NW Europe/Scandinavia which could bring a Northerly flow across the UK last third of October.

Hints of height rises getting into Greenland for a more sustained spell of colder autumnal weather but we often see this modeled in FI with a displaced Azores high/Atlantic block but ultimately as it comes into better resolution we see the Atlantic squeeze enough energy through (SW tip of Greenland) to prevent a Greenland high forming.

 

No way to tell whether this amplified pattern will continue into November and early Winter but sods law states that the first above average CET we get in many months will be in the Winter. 

[Mucka]

It's all looking quite normal for mid October - still early as far as seeing any development.

 

Meteociel has a useful function where you can compare the last sixty plus years - I've set it for mid October.

 

http://www.meteociel.fr/modeles/archives/archives.php?day=16&month=10&hour=0&map=4&mode=1

 

ECM 360 hour mean for local area.

 

 

 

Nice post. That is surprising to me.

I didn't realise it was actually unusual for mid Oct NOT to have high pressure in charge and an amplified pattern - thought the PV started to get in gear a little earlier than that.

It is also interesting to note that pattern generally flattens out with little HLB by toward months end with charts much more zonal looking overall.

Edited October 8, 2015 by Mucka

[johnholmes]

That is true, but being somewhat pedantic, could we say they do take past weather into account when the algorithms are tweaked?

 

again no to the best of my knowledge but perhaps an e mail to UK Met might reveal, if their web site does not, exactly what goes into their model?

[knocker]

Although there is always a possibility that at some time in the near future depressions will nip around the north of the Atlantic block and drop south east this seems the least likely scenario given the available evidence. The most likely would appear to be the Scandinavian HP becoming a non player, the Atlantic HP slipping a tad SW with weak troughing to the NW setting up a cool zonal pattern. The detail could of course include some cyclonic variations affecting mainly the northern half of the UK

[Daniel*]

GFS 12z is rolling out a big cold pool evident quite significant for first third of October. One thing we lacked last year was such depth of cold on mainland these synoptics are nice on the eye. No real sign of the purple beast which often settles over Greenland all good in keeping +ve pressure where we want it no Indian summer this year.

Chilly southeasterly flow suppressing the temperature in UK.

[phil nw.]

Hello Phil,

 Reading our own Central European model would suggest a fall in heights over Europe. As in the usual case of no dominate strong wind fields over Central Europe some form of trough developments in the relative cold /cool  flow from the NE is likely to happen next week. Of course the SE of England would be in the eventual disturbance line for some precipitation ( prob showery nature ). We have lowered our snowline to below 1000m by Sunday into Northern Austria/ Czech Rep/Slovakia area.

 C

Hi C,

Sorry for the delay in responding,i have been out all day and just got back in.

Yes the position of the high looks like maintaining a cool feed for C.Europe for quite a while with the flow from the east down there.

I guess any disturbances will start to build some snowcover on the higher levels over the Alps gradually coming lower with time as the continent continues to cool.

Nothing too exciting for us yet just maybe some patchy frost and fog as the nights are getting cooler now.

Edited October 8, 2015 by phil nw.

[MR EXTREMES]

looks like chilly high pressure will stick around for some time

 

gfs has more of a cold spell towards the end of the run with a few day northerly then return of azores heights which is not a bad thing !

 

settled and a cold lid to hold the chilly weather in place!

 

 

will the azores scandi combination be a trend further into autumn....

 

well not no zonal onslaught being seen.