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

[Frosty.]

It does look like we could be heading towards a pattern change to quiet weather with high pressure becoming dominant during late september and early october, most of the models show high pressure taking control with pleasantly warm sunshine but chilly nights under clear skies with an increasing risk of mist and fog forming, the standout is the Gefs 00z control run which brings a lovely spell across the southern half of the uk for a while and the exception is the Ecm 00z which looks more unsettled and the Gfs 00z later in low res shows high pressure retrogression to the northwest with a colder plunge sweeping south through scandinavia.

Edited September 18, 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

FRIDAY SEP 18TH 2015

THE CURRENT GENERAL SITUATION.  A slack and showery North-westerly airflow will be replaced by a ridge of High pressure moving East across the UK tomorrow.

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

MODELS-2 WEEK HEADLINE  Becoming less unsettled next week with longer drier spells with most rainfall likely in the form of scattered showers.

THE GFS JET STREAM FORECAST  The GFS Jet Stream Forecast shows the flow ridging across the UK ahead of the flow turning South across Western Britain early next week. While the flow then becomes disorientated and variable thereafter and often to the North of the UK the undulating nature of the flow allows cut off Low pressure to the South of the UK on occasion with their own secondary flow.

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

GFS OPERATIONAL The GFS Operational Run today shows a ridge of High pressure becoming replaced by Low pressure early next week as it trundles SE across the UK. Things then gradually improve from the NW later next week and High pressure takes control from thereon eventually settling to the North of the UK and setting up a strong Easterly flow across the UK with fine weather in the North but possibly more unsettled across 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 very similar to the operational through Week 1 but couldn't be different through week 2 with High pressure much further South across Southern Britain to begin with and then Low pressure moving in across the UK from the NW later with rain and showers in cool conditions for all at the end of the period.

THE GFS CLUSTERS(14 Days) The GFS Clusters this morning still show no set pattern having supremacy in two weeks time although High pressure in one shape or another holds the most likely evolution. 35% of members opt for something much more changeable and Autumnal.

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 Low pressure slipping SE across the UK at the start of the new week with showers or outbreaks of rain for many, reluctant to clear from the East and South even by Thursday. 

 

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

THE FAX CHARTS  The Fax Charts this morning show a ridge of High pressure crossing over the UK over the weekend with Low pressure following SE behind it to affect all of the UK early next week with rain and showers at times under cyclonic conditions.

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

GEM  GEM too shows the ridge at the weekend being replaced by a return to Low pressure moving SE across the UK next week. This hangs about for some time so maintaining rain and showers for all before a slow recovery in conditions moves slowly north across the UK as pressure builds, ending the run mostly dry and settled with a rather warm ESE flow developing across the South at the end of the period.

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

NAVGEM NAVGEM shows a similar theme with Low pressure across the UK next week slowly giving way later to a SW flow for all with unsettled weather becoming more pronounced towards the NW whereas the South and East should become somewhat drier by next weekend.

 

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

ECM ECM this morning is quite poor showing the same Low pressure based conditions next week as it moves SE across the UK with rain and showers for all. the later stages of the run sets up a mobile pattern with another deep Low crossing the UK late next weekend with gales in places. 

 

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

ECM 10 DAY MEAN  The ECM 10 Day Mean Chart  from last night shows a ridge extending SW from High pressure over Scandinavia with probably fine conditions for much of the UK but with SW winds and more unsettled weather probable towards the NW.

 

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

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models are still undecided on whether next week's slip back under Low pressure is just a short blip before fine and settled weather returns to most of the UK thereafter or not.

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 leads at 96.6 pts with UKMO  at 96.5 pts while GFS lags behind at 95.6 pts. At 5 days ECM ties with UKMO at 86.4 pts  each then GFS at 84.1 pts. Then at 8 Days ECM still leads at 59.2 pts over GFS's 51.2 pts. Finally at Day 10 ECM leads GFS at 36.9 pts to 33.4 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.prig
 

 MY THOUGHTS   There  remains much doubt on the eventual course of weather over the UK behind the almost inevitable shift back under Low pressure across the UK early next week which all models now support. So after a fine weekend with some warm sunshine but chilly nights rain followed by a very showery period looks like becoming established next week with England and Wales likely to see these conditions last longest before High pressure possibly ridges back in across the North later. Things then become much more unclear as we have a variety of options on the table ranging from a NW/SE split in the weather with rain more confined to NW Britain than elsewhere to High pressure building strongly to the North of the UK and setting up a strong Easterly flow across England and Wales in the second week. While this wind may still be relatively warm at this time of year any cloud cover and the influence of Low pressure possibly easing up from the South could make for cool feeling conditions with rain in the far South possible. My own feeling are that more of a NW/SE split is likely with unsettled conditions more likely to affect the NW most and while that doesn't discount some rain elsewhere too the main focus of weather towards the SE should be more dry than wet conditions. While the pressure patterns across the UK are far from ideal there are no immediate concerns from severe gales and excessively heavy rain and what is more notable to me is the desire to build pressure to very high levels at Northern latitudes by some output which could have big implications if this theme and trend continues to be shown and later evolve across the UK during the Winter months.

BEST CHART OF THE DAY 00z RUN

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=240&mode=0&carte=0

The accolade for the best chart of the day today goes to the GFS Control Run chart at 240hrs which shows the Azores High ridging NE towards and over the UK with the prospect of fine and settled weather for all of Southern Britain and much of the North too for a time.

WORSE CHART OF THE DAY  00z RUN

http://www.wetterzentrale.de/pics/Recm2161.gif

For the worst chart I have gone for the Day 9 chart from ECM who delivers an awful chart at day 9 with a deep low moving east across the UK with wind and rain for all. Of note is an example of how diverse the models are at a latter range today with the best and worst charts just 24 hours apart.

Next update from 09:00 Sunday Sep 20th 2015 

Edited September 18, 2015 by Polar Maritime
Coped & Pasted over in warp speed time..

[Polar Maritime]

The GFS this morning continues to show quite a disrupted PV as High Pressure pushes North around Southern Greenland/Iceland drawing a cool cloudy Easterly type flow around the turn of the Month.

Edited September 18, 2015 by Polar Maritime

[Nouska]

A very brief overview of the latest EC32 run

 

It too is looking at the transition from trough domination to the benign influence of HP around next Friday. It signals the start of a period of pleasant weather with temps average or above. This could well last until around the 8th October. Even after that (until the 19th) there doesn't appear to be anything deadly lurking in the woodshed with a return to a familiar scenario of LP to the NW and the HP to the SW giving a westerly airflow and the not unfamiliar N/S split. Keep in mind this is pretty broad brush towards the end of the run, I obviously don't have access to the full ecm suite, but even so I feel a quick play of a well known Dave Clark five song is called for. I might even order an Indian as well.

 

Shhh.... there's a 'beast from the east' stirring in the woodpile 

 

Most will have no idea who/what DC5 were but will be shaking themselves down and singing a modern version.

 

Are we seeing a turbulant pattern of blocking emerge as a response to the very low ice and/or diminishing solar output?. It is certainly not the 'normal' early autumn fayre to see such a cold pool whizzing in from the far NE.

[snowy weather]

if the vortex is aligned like that this winter,chaos will decend.

Why? what does it mean?

[joggs]

Please connect your charger...

.....October... gensnh-5-1-384.png

snowy weather,we know the vortex will grow stronger from here on in but if you look at it aligned more from the pole to our direction(blues)and with hp to our West,we would benefit more with north type weather(not all the time).This as been how the ne states has benefited over the last few year.And for us on our side of the Nh,it's been aligned more West to East with no hlb.A hard phase to escape.Hope that helps in my own amateur way.From a cold perspective just to add. Edited September 18, 2015 by joggs

[snowy weather]

snowy weather,we know the vortex will grow stronger from here on in but if you look at it aligned more from the pole to our direction(blues)and with hp to our West,we would benefit more with north type weather(not all the time).This as been how the ne states has benefited over the last few year.And for us on our side of the Nh,it's been aligned more West to East with no hlb.A hard phase to escape.Hope that helps in my own amateur way.From a cold perspective just to add.

thats helps, thank you for the explanation

[Singularity]

...and just as I though the theme of LP out to mid-week followed by HP from the SW becoming dominant by the weekend was starting to look odds-on, along comes this mornings ECM 00z and GFS 06z operational runs!

 

It's a shame because I was starting to think 'shades of 2011' for late September/early October this year - one of my favourite weather events of all time - the balmy warmth yet relatively low sun angle and intensity (Example chart from 30 Sep: http://www.wetterzentrale.de/archive/ra/2011/Rrea00120110930.gif).

 

 

So... ECM appears to be within the range of yesterday's GFS ensembles up to the end of Friday, albeit at the changeable/unsettled end for late in the working week as the Atlantic LP is very close to Scotland for a time. But then things go awry as a low imported into the Atlantic from down near Florida engages with the jet stream, bombs out and slams straight into the UK (shown below for dramatic effect).

 

 

Now this, I can view as an anomalous solution driven my low-probability events (the behaviour of that low is very vigorous!), but the way the GFS 06z operational run goes is another matter.

 

You see, it involves a deviation in the behaviour of the sliding low in just four days time, which places it a little further west as it becomes cut-off from the main Atlantic jet stream. This adjustment is relatively small, yet has big impacts later in the run, as now the ridge from the Azores is first held back west of the UK and then left with little choice but to build over the top of the cut-off low. So it's the north that ends up most settled, with the south seeing a continuation of more unsettled weather with showers and some longer spells of rain (example chart below).

 

 

The run does go on to suggest that a 2011 type event may still be possible, but I reckon it would be harder to achieve when starting out with LP closer to the S of the UK - the Atlantic has an easier time pushing far west enough to bring spells of rain instead.

 

Here's hoping the GFS operational's deviation with respect to the sliding low is not the start of a consensus shift.

Edited September 18, 2015 by Singularity

[Polar Maritime]

A real mix against the background signals towards the end of the lunchtime run, With the Atlantic battling against the High to our N/E. Sending Lows well South of the UK on a strong meridional Jet.

Edited September 18, 2015 by Polar Maritime

[phil nw.]

ECM Op not so keen on a developing block in the medium term compared to the GFS output.

See here at day 8

 

ECM picking up a deep mid-Atlantic low with the jet eventually pushing across the north and into Scandinavia later on.

Quite a noticable disagreement on what happens towards the end of the month with Naef's  and the ECM ht.anomalies here at day 10.

 

By no means a really unsettled outlook but maybe not the straightforward evolution to a high pressure dominated period showing this morning.The ECM modelling a little less keen  on holding the Atlantic jet at bay with some energy still coming through.

 

On a footnote October height anomalies to the north and east,especially early in the month, are not unusual as we have a number of recent examples since 2000-as a look back in the archives will show.

 

Certainly for cold lovers it's nice to see the first real upper cold air infiltrating south into Russia around the block but for newcomers this pattern has no bearing on Winter one way or the other.

As much as i and many cold seekers would love this setup in a few weeks many of us know things can quickly change as the Atlantic jet fires up later in the season.

Meanwhile i hope the GFS is the current way forward and we can get a nice settled little spell of Autmnal weather to finish off September.

[Gavin Hannah]

I think many of us have been burned too many times by the Jet to take 'odds - on' trends at face value. It seems we need to load the dice in our favour to get those magical moments to fall just right.  Ideally, we want the sort of HP setup in image two to take hold late december.

[summer blizzard]

A note of caution regarding easterlies now. If it's even ESE or any further north then we ain't burning that cloud off quickly at this time of year away from the west of the UK.

[Frosty.]

The Gfs 6z through FI shows quite a blocked pattern with high pressure to the NE of the uk and low pressure well to the SW / S with a feed of warm Ely/SEly winds from the very warm continent being drawn northwest across the uk bringing unseasonably warm conditions to much of the uk with temperatures into the high teens to low 20's celsius through late september and early october, judging from the warm temps across the southern half of the uk, there would be plenty of sunshine to come...you could almost call it summery, indeed, it is summery, it's certainly not autumnal! 

Edited September 18, 2015 by Frosty.

[knocker]

Noted Phil but looking at the 00z GEFS upgrade and the ECM ens anomalies they are both more or less on the same page except for the weak trough central Europe and the positioning of the HP. How far east to take the HP is a theme in the ext period with the GEFs more inclined to keeping it nearer the UK.

Charts courtesy weatherbell

Edited September 18, 2015 by knocker

[Frosty.]

i hope the GFS is the current way forward and we can get a nice settled little spell of Autmnal weather to finish off September.

Here here, I hope the gfs 6z is the way forward as it shows an unseasonably warm and largely settled late Sept / early October (see previous page for 6z charts). The current expert view is around mid October onwards to possibly bring about a change to unsettled Atlantic weather across most areas but more especially the n/w, the s/e to still have spells of pleasant weather

Edited September 18, 2015 by Frosty.

[Polar Maritime]

This evenings 12z GFS run is certainly showing the Atlantic push much stronger than the lunch-time run towards Months end.

 

                   6z                                                        12z

Edited September 18, 2015 by Polar Maritime

[ANYWEATHER]

After a lovely early Autumn weekend for just about all, and we cant moan as the good weather is on the weekend ! Next week looks decidedly unsettled. The models have been great in predicting this weekends fine spell, but not so good on predicting next weeks weather. I refuse to believe that high pressure will dominate by the end of the month. I would love a traditional quiet autumn spell, but models are really in a mess after late next week in there predictions.....    

[summer blizzard]

Just to highlight one particular model difference tonight (though not in our neck of the woods yet), GFS barely registers and kills TD10. Euro has it a 960mb hurricane headed for the Azores by day 10.

[knocker]

Interesting that the 12z anomalies rather reverse the midnight analysis. Then the ecm was pushing the HP east but now the GEFS has subsided the ridge over the UK and pushed the Atlantic trough further east. The ecm is having none of this and in the extended period maintains the HP in the eastern Atlantic, without significant ridging, and continues to diminish the influence of the trough to the west. Obviously these differences will need to be resolved before confidence can be justified but I'm a bit suspicious by the change in the GEFS. Be interesting to see what the T574 makes of it, I'm reading the NOAA 8-14 to being similar to the ecm

http://www.tropicaltidbits.com/

Edited September 18, 2015 by knocker

[knocker]

The GEFS (P) at 1800z  brings the upper trough east reaching it's furthest extent by Sunday but then it begins a retrogression back to the western Atlantic with a helping nudge from the Azores ridge.From then on it goes into a death spiral leaving a general area of HP tin the eastern Atlantic with the main HP further east with LP southern Europe and N. Africa, Keep the faith bunnies.

Charts courtesy weatherbell

 

[bluearmy]

Ecm ens mean at day 10 pretty strong on the ridge in our locale. We've seen this modelled to some extent quite a bit and then the upper trough has made inroads closer to the time. Think we'll see a decent block verify this time but where it settles is open to question.

[Frosty.]

Ecm ens mean at day 10 pretty strong on the ridge in our locale.

Indeed, what a lovely Ecm 00z ensemble mean @ T+240 we have this morning and the Gefs 00z mean looks even better. I think  we are going to see a change to settled and pleasantly warm conditions by the end of next week onwards but with chilly nights and increasing risk of overnight mist and fog patches.

Edited September 19, 2015 by Frosty.

[Due South]

El nino not the big driver for UK Winter. Cold pool in North Atlantic, close to position in 2009 much bigger factor ( Big Joe B ) Twitter

[knocker]

Ecm ens mean at day 10 pretty strong on the ridge in our locale. We've seen this modelled to some extent quite a bit and then the upper trough has made inroads closer to the time. Think we'll see a decent block verify this time but where it settles is open to question.

 

I would agree but as to where it settles well....................................................

http://www.tropicaltidbits.com/

[Frosty.]

The Gfs 6z shows an increasingly blocked pattern with high pressure becoming centred to the NE or N of the uk dominating low res, with no atlantic threat but low pressure to the south occasionally edging north creating stronger Ely winds across the south for a time but generally lighter further north. In the meantime, this weekend looks fine with a ridge of high pressure but next week becomes more unsettled from the northwest with showers and longer spells of rain but the longer term signal is for increasingly settled conditions to become established through late sept / early oct with pleasantly warm sunshine but with chilly nights and a risk of mist and fog.

Edited September 19, 2015 by Frosty.