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

[Chris.R]

What is TC?

tropical cyclones. ☺ï¸

[Paul]

Place your vote on the first HO-PI (Hope Index) for Winter 2015/16!

 

https://forum.netweather.tv/topic/84055-ho-pi-winter-index-201516/

[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 Monday (ECM)

High pressure just sits along the South of the UK as the low from the West of Iceland starts to move South East down to the UK.

 

48 Hours Tuesday (JMA)

The low pressure from Iceland now sits over the UK.

 

72 Hours Wednesday (FIM)

Low pressure remains over the UK as another low forms to the West of Iceland.

 

96 Hours Thursday (NAVGEM)

The low pressure from Iceland now begins to move over most of Scotland and Ireland.

 

120 Hours Friday (FIM)

Low pressure remains over Scotland as high pressure begins to move in from the South West of the UK. Another low pressure system begins to form this time to the South of Greenland.

 

144 Hours Saturday (CFS)

Most of the UK and Ireland see high pressure apart from Northern parts of Scotland. The low pressure system has deepened a lot and now sits to the South East of Greenland.

 

168 Hours Sunday (ECM)

High pressure continues to build up over most of the UK while the low pressure system continues to stay to the South East of Greenland.

 

192 Hours Monday (FIM)

High pressure is still expected to be over most of the UK at this point while the low pressure system to the South East of Greenland finally starts to weaken while another low to the South of it begins to form.

 

216 & 240 Hours Tuesday & Wednesday (ECM)

Still a trend of high pressure to be strong at this point over the UK as we reach the end of the month.

 

Edited September 20, 2015 by Zenarcher

[Summer Sun]

Hints from UKMO again this afternoon that it may settle down towards the end of the coming week with any rain / showers becoming confined to the far north west of Scotland

 

[Polar Maritime]

This evenings GFS shows the Atlantic push at the turn of the Month gain further West diminishing the block to our N/E as fronts cross the country with pressure lowest to the N/W. 

Edited September 20, 2015 by Polar Maritime

[Scorcher]

But the ECM shows nothing of the sort PM, fronts briefly brush the far NW corner of the UK later on in the run, but generally high pressure dominates from Saturday onwards. In fact by the end of the run the pressure is higher than ever over the UK:

 

[johnholmes]

Some suggestion of a change in emphasis this evening with NOAA, both 6-10 and, rather unsuaully, the 8-14 keeps and increases the idea.

link below

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

ECMWF-GFS was not consistent again this morning, today it is the turn of EC to suggest more ridge than trough driven weather.

[William of Walworth]

Those UKMO charts that Summer Sun posted above look like the most positive for the earliest HP build -- from Friday.

 

Plus the recent Countryfile BBC forecast (still UKMO sourced, for now!)  for the coming week was also bullish about a HP build for next weekend, starting Friday.

Edited September 20, 2015 by William of Walworth

[Polar Maritime]

But the ECM shows nothing of the sort PM.

 

Absolutely, As Johns post above verifies things are starting to firm up slowly. Maybe a fair share of fine settled weather to be had on the way, With cool nights/mornings with fog in places, But feeling warm were sky's clear with average temps and Cloud/Rain for the North at times, A typical settled Autumnal affair looks the probable outcome at the moment.   

Edited September 20, 2015 by Polar Maritime

[Singularity]

Just got back from a weekend away (got lucky with the weather!) and it's fair to say that there are some fascinating model runs to be found at the moment, the GFS 06z and ECM 12z operational runs being fine examples!

 

At a glance, it seems that tropical developments will encourage the jet stream to become more meridional in about 5-6 days time, with a trough digging down toward the Azores and high pressure being displaced east from the Azores to take refuge across the UK and/or Europe.

 

If the pattern then amplifies as the runs mentioned above show, with the ridge dominant and the trough continuing to extend toward the Azores and/or becoming elongated south to north, then there is the recipe for some exceptionally warm conditions to occur as we close the month and start October. 

 

The GFS 12z operational shows us how this may not come to pass, however; it does have the trough/ridge amplification, but without such settled/toasty results for the UK due to the Atlantic trough absorbing some kind of tropical/extratropical hybrid and becoming a monstrous system of remarkable size and intensity for the time of year.

 

 

On a side note, ECM's glancing blow to the Azores Isles with a hurricane raises eyebrows, as systems tracking there often end up delivering the UK a glancing blow too - or more than that on rare occasions. 

[ANYWEATHER]

Good Evening everyone. ! An unsettled spell this week  for all and yet again the pressure build from gfs and ecm  is for the weekend. Great news! From there on though, signals for weather computer output gets very confused from there on....No shaking hands tonight from gfs and ecm. at the lowly model output at T+240......Ex tropical storms are the big stirrer in the North Atlantic at this time of year...

[knocker]

Last night's GEFS anomaly did flirt with moving the Atlantic trough a little further east than the ecm so a quick look at the 18z GEFS (P). It does move it close enough for depressions to maybe impact slightly on the NW next weekend as they track NE but thereafter it retrogresses with HP becoming established in the eastern Atlantic, albeit with no pronounced ridging, and to remain so in the ext period with the trough poised around Iceland. Last nights ext ecm still looking okay.

Charts courtesy weatherbell

Edited September 21, 2015 by knocker

[knocker]

The ecm this morning has the upper trough mid Atlantic by the end of the week so the deep depression consigned to a favourable route with HP over the UK. Slight chance of the NW copping some rain Sunday.

http://www.tropicaltidbits.com/

 

[Frosty.]

The Ecm 00z looks rather unsettled this week with showery rain spreading southeast at times but with some fine and sunny weather too, especially midweek and then again from friday onwards as high pressure gradually builds in across the south and then the rest of the uk becomes anticyclonic and warmer with a superb spell during late sept / early oct with unseasonable warmth and plenty of sunshine across the whole of the uk, really fantastic looking charts later on this run.

Edited September 21, 2015 by Frosty.

[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 MONDAY SEP 21ST 2015

 

THE CURRENT GENERAL SITUATION A trough of Low pressure will move East across the UK today followed by a Westerly flow veering NW tomorrow behind a showery trough moving SE tonight.

 

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 troughing back down over the UK over the next day or so where it continues to lie through the first few days of this week. the trend is then for the flow to move to a position NW of the UK with the worst of the Low pressure based weather likely to be. The flow becomes very variable and unclear in location late in the period.

 

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

 

GFS OPERATIONAL The GFS Operational Run today shows Low pressure in control over the working days of this week as one centre drifts SE down the North Sea over the first few days of the week and then another crosses East to the North of Scotland soon after midweek with rain and showers for all of the UK at times. By next weekend High pressure is shown to build across the UK from the SW and then maintains a strong ridge across the UK for much of the time thereafter with fine  weather but with some mist and fog patches night and morning. The weather is then shown to turn more changeable again later as the High recedes away to the East and Atlantic fronts make inroads across the UK.

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 very similar to the operational through much of the period though the methodology of returning unsettled weather across the UK in Week 2 is somewhat different in detail but not on theme as rather more changeable weather develops later but still with plenty of dry and bright weather around too.

 

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

 

THE GFS CLUSTERS(14 Days) The GFS Clusters this morning still show a lot of variation between members on the conditions likely to lie across the UK in 14 days time with the confusion remaining on how and what influence High pressure from the Azores affects the UK at that time with a slight bias towards drier conditions towards the South and East while more unsettled conditions are more likely towards 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 building across the UK next weekend with a centre moving NE out into the North Sea by next Sunday with a continental airflow over the South and light winds elsewhere. There should be plenty of dry and fine weather with overnight mist and fog once the working week's unsettled weather dissolves away by the weekend.

 

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

 

THE FAX CHARTS The Fax Charts this morning show a changeable week with rain at times as Low pressure and troughs continue to move East across the UK from the West right up to next weekend. The improvements forecast for then are just coming into view on the 120hr chart as pressure is shown to be building from the SW.

 

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

 

GEM GEM this morning is somewhat less favourable as the rise in pressure at the weekend is restricted more towards the South and East of Britain where a dry spell is likely whereas the North and NW stay breezy under SW winds and rain at times as troughs brush by. This more unsettled and eventually windy cyclonic weather is then shown to advance to all of the UK through the course of next week.

 

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

 

NAVGEM NAVGEM too is also reluctant to bring anything more than a ridge across the UK next weekend with a dry and bright period for a time before Atlantic Low pressure and troughs return East across all areas again soon after the start of next week.

 

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 (with the exception of GEM and NAVGEM show a lengthy period of fine and settled weather across the UK from next weekend.

 

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 86.5 pts over UKMO at 86.3 pts then GFS at 84.1 pts. Then at 8 Days ECM still leads at 58.2 pts over GFS's 51.7 pts. Finally at Day 10 ECM leads GFS at 36.8 pts to 33.5 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 The models continue to point towards a better period of weather which may last longer than a few days starting towards this coming weekend. In the meantime we have another 3-4 days when Low pressure to the North and NE affects the UK with showers or rain at times and cool West or NW winds. By Friday pressure then rises steadily and strongly from the SW and by the end of the weekend perhaps with the exception of the far North and NW all places should have become dry and fine. The High then settled across the UK as well as much of NW Europe next week which indicates that this spell could last a fair while characterized by some quite warm and sunny days or afternoons once the inevitable Autumn mist and fog patches have cleared which could become quite problematic for travel at times. It should be noted that all this is not quite set in stone yet as GEM and NAVGEM are less supportive at this stage but all the main players both sides of the Atlantic do give us a week of decent weather before there are any signs of a push from the Atlantic. So in a nutshell the weather will improve from the weekend for all with plenty of dry and quiet weather and while it should become warm by day this will be all dependant on how quickly morning mist and fogs evaporate each day on what will probably be chilly nights.

 

WORST CHART OF THE DAY 00z RUN

 

http://www.wetterzentrale.de/pics/Rgem2281.gif

 

The accolade for the worst chart of the day goes to GEM at 228hrs this morning as it forgets about High pressure almost as soon as it arrives with a deep Low running close to Southern England and delivering wet and windy weather to these areas as a result.

 

BEST CHART OF THE DAY 00z RUN

 

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

 

For the best chart I have gone for the Day 10 chart from ECM which shows a large belt of High pressure across the UK at that time with centres to the East and West ensuring the door is closed on Atlantic fronts and depressions to affect the UK anytime soon from that time.

 

Next update from 09:00 Tuesday Sep 22nd 2015

[Summer Sun]

Hopefully UKMO is onto something bar some chilly nights and misty mornings we'd have some pleasant days as the high slowly moves in during Friday

 

[knocker]

This morning's anomalies still maintaining high pressure from around next weekend, albeit with no pronounced ridging over the UK. Ergo the orientation of the HP is still up for grabs with a NE/SW alignment being the preferred option at the moment but it remains to be seen whether this continues to be so. At the moment it would appear some pleasant warm weather may be on the cards next week. What with the forthcoming mild and quite wet Oct/Nov I can see the daffs being out early this year.

http://www.tropicaltidbits.com/

Edited September 21, 2015 by knocker

[Frosty.]

The Gfs 00z shows a strong blocking scandi high through most of low res controlling our weather with pleasantly warm and fine conditions becoming firmly established across the whole of the uk but with chilly nights where skies clear and winds fall light which is the perfect recipe at this time of year onwards for mist and fog patches to form, however, this run shows a freshening easterly breeze across the south by the end of sept and early oct with the risk of fog restricted to the north. Coming back to the reliable timeframe, this week looks rather unsettled with showers and longer spells of rain, some heavy and thundery but with fine periods too, wednesday looks decent away from the far northwest and then high pressure starts to build in from the southwest during friday and increasingly through next weekend with a lot of fine and pleasantly warm weather across the south and east in particular but before the anticyclone takes complete control, a narrow and weakening band of rain pushes east across the northern half of the uk early next week but then it looks fine for all.

Edited September 21, 2015 by Frosty.

[Frosty.]

The Gfs 6z has more of a uk based anticyclone dominating from the end of this week onwards with pleasantly warm and sunny days but with chilly nights and an increasing risk of overnight mist and fog patches which could be slow to clear in places but scotland and n.ireland has another brush with the atlantic with some rain and stronger winds for a time later next weekend and into the early part of next week but then we see the anticyclone taking complete control and becoming centred over or just to  the east of the uk and intensifying, we would be looking at a very pleasant late sept / early oct if this or something similar verifies...the message from this run is once this week is over, low pressure is the weakest link..goodbye.   

[Singularity]

Some furious looking windstorms are starting to appear in the North Atlantic on the model runs now.

 

GFS had the most impressive of the morning on its 00z operational; just look at the wind field as it reaches its peak:

 

Huge areas at strong tropical storm strength. The gusts would be ferocious - high 90's perhaps?

 

It spawns as a result of an exceptionally strong jet stream, driven by a clash of subtropical air with some Arctic air over Canada in 6 days time:

 

 

One to watch for shipping interests, especially now that ECM has started to show something similar, albeit not quite so immense.

 

 

Later in some runs, another interesting feature is a tropical cyclone which has been reaching as far north as Southern England with only slight weakening and signs of tropical characteristics remaining intact:

 

Notice the warmer 850's in the core. ECM had it in a similar location on yesterday's 12z operational, also at 10 days from now.

 

Just a reminder that it's not impossible, with the right conditions, for a tropical cyclone to make it to the UK, though usually only just (i.e. weak tropical storm at best - though I seem to recall hearing of one hurricane in the written records from centuries ago).

 

The storm shown above has been kept west of the UK by a strong area of high pressure on pretty much all runs over the past few days, so appears to be of little concern to us directly. It may serve to 'supercharge' the Azores trough/Europe Ridge setup, though. 

[Scorcher]

Another excellent set of runs this morning for those looking for something warmer and more settled- the ECM 00Z is a fantastic run after 120 hrs, with the high centering itself just to our east and giving us a very warm continental feed. The GFS is not quite as good but has come closer to the ECM this morning.

 

The ECM op has been remarkably consistent for next weekend onwards for a couple of days now, when I looked at this morning's charts it was a case of spot the difference from yesterday evening's.

[stodge]

Just a reminder that it's not impossible, with the right conditions, for a tropical cyclone to make it to the UK, though usually only just (i.e. weak tropical storm at best - though I seem to recall hearing of one hurricane in the written records from centuries ago).

 

The storm shown above has been kept west of the UK by a strong area of high pressure on pretty much all runs over the past few days, so appears to be of little concern to us directly. It may serve to 'supercharge' the Azores trough/Europe Ridge setup, though. 

 

Indeed, some extra-tropical features have affected the UK - one, I recall. passed north up through Ireland from near the Azores.

 

As for the models, the 06Z GFS Operational keeps the very strong anticyclonic flavour we've seen in recent days for the end of the month and the start of October.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015092106/gfs-0-240.png?6

 

The HP doesn't linger around Scandinavia as there is strong LP to the north of the Norwegian Sea but migrates around and over the British Isles so several days of quiet autumnal weather for most with the attendant issue of morning fog for many areas.

 

The impact of ex-hurricanes is so dependent on their path - those which form further east and head through the Azores often disrupt the normal HP and send part over the British Isles while those recurving from the Eastern US normally amplify the jet stream and keep us in a more unsettled regiment though the exact path of the jet stream is the key to their development and progress as extra-tropical systems.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015092106/gfsnh-0-336.png?6

 

Just an observation of the PV getting its act together in the usual place so with the jet stream at the same time:

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015092106/gfsnh-5-336.png?6

[johnholmes]

Some furious looking windstorms are starting to appear in the North Atlantic on the model runs now.

 

GFS had the most impressive of the morning on its 00z operational; just look at the wind field as it reaches its peak:

 

Huge areas at strong tropical storm strength. The gusts would be ferocious - high 90's perhaps?

 

It spawns as a result of an exceptionally strong jet stream, driven by a clash of subtropical air with some Arctic air over Canada in 6 days time:

 

 

One to watch for shipping interests, especially now that ECM has started to show something similar, albeit not quite so immense.

 

 

Later in some runs, another interesting feature is a tropical cyclone which has been reaching as far north as Southern England with only slight weakening and signs of tropical characteristics remaining intact:

 

Notice the warmer 850's in the core. ECM had it in a similar location on yesterday's 12z operational, also at 10 days from now.

 

Just a reminder that it's not impossible, with the right conditions, for a tropical cyclone to make it to the UK, though usually only just (i.e. weak tropical storm at best - though I seem to recall hearing of one hurricane in the written records from centuries ago).

 

The storm shown above has been kept west of the UK by a strong area of high pressure on pretty much all runs over the past few days, so appears to be of little concern to us directly. It may serve to 'supercharge' the Azores trough/Europe Ridge setup, though. 

There are several examples of modified ones making it right across the UK.

[johnholmes]

All 3 anomaly charts (that I use) now show that ridging looks the most liely outcome at 500mb from day 6 out to day 15.

links below

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

this is the first time both have shown the same or very similar pattern and also agree with the idea from NOAA in both 6-10 and its 8-15 day time scale

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

To be objective the above link shows as the first time of a real solid looking +ve anomaly and ridge, prior to this it was a bit 'sit on the fence' for a couple of days.

However, unless it does an about face this evening (unlikely in my view) then the pattern does look more ridge than trough especially the further SE one lives.

[Frosty.]

The GEFS 6z mean shows rock solid support for an anticyclonic outlook for most of the uk from the weekend onwards into early october, especially across the southern half of the uk where pressure stays high for longest whereas it becomes more unsettled across more northwestern / northern parts of the uk through early october with lowering heights to the northwest but the medium range looks set fair with plenty of pleasantly warm sunshine but chilly nights / early mornings with mist and fog patches.