Model Output Discussion 1200 hrs 30/09/14

[Frosty.]

I think the GEFS 12z mean is a little colder and more generally unsettled compared to the 6z mean in the T+240 plus range with temperatures much closer to normal and cold enough across northern high ground for wintry ppn, follow the isobars back to their source of origin and it's Greenland instead of the azores / southern europe. ..would make a nice change, veer them due north to the high arctic would be perfect. 

[MR EXTREMES]

I think the GEFS 12z mean is a little colder and more generally unsettled compared to the 6z mean in the T+240 plus range with temperatures much closer to normal and cold enough across northern high ground for wintry ppn, follow the isobars back to their source of origin and it's Greenland instead of the azores / southern europe. ..would make a nice change, veer them due north to the high arctic would be perfect. 

interesting ecm wants to give a cold snap then surface high frost fog more average temps

[MR EXTREMES]

interesting ecm wants to give a cold snap then surface high frost fog more average temps

lets not leave the gem out 

[knocker]

GEFS temps remaining above average until end of run including Europe and southern Scandinavia.

Edited October 27, 2014 by knocker

[Barry12]

Snow for Scotland is possible at day 8 if the ECM 12z verifies, it wouldn't last long though.

 

Edited October 27, 2014 by Barry95

[phil nw.]

Snow for Scotland is possible at day 8 if the ECM 12z verifies, it wouldn't last long though.

 

Yes the pattern is looking more mobile now Barry.

A typical Autumn outlook with the odd visit of colder air in the north before the next frontal system moves in from the west raising temperatures again.

With the mean track of the jet around or to the north of the UK a succession of ridges and troughs keeps things unsettled as we go into early November.

[Frosty.]

The models have been and still are showing a risk of a brief wintry snap during early november and the latest Ecm 12z run shows it too. a bit more tinkering and our first cold snap could be on the way,.i'm cheering for the dark blues  

[Snowboard Tennyson IOW]

Although I am keen to see this winter develop into a cold and snowy one I remain cautious, there are hints from reading posts and viewing models of November delivering something cold,however it's very much out of a reliable time frame (again). Last year gave continued false hope (say no more). The overall pattern is exciting though with lots of signals for potential Blocking, OPI a like.

[phil nw.]

Although I am keen to see this winter develop into a cold and snowy one I remain cautious, there are hints from reading posts and viewing models of November delivering something cold,however it's very much out of a reliable time frame (again). Last year gave continued false hope (say no more). The overall pattern is exciting though with lots of signals for potential Blocking, OPI a like.

Welcome STD pleased to have you aboard but do try to keep your views directly on the current charts in here.

OPI and Winter speculations are discussed in their relevant threads.

Thanks.☺

[ANYWEATHER]

Hints of something seasonal or even wintry as we move into next week....

[knocker]

A glance at this evenings ECM anomalies shows no shows no massive change in the outlook. A change from a very meridional flow to a more zonal one with a large wodge of colder air locked into the the NE Atlantic and eastern Europe. Little amplification in N. America or the PV.

Edited October 27, 2014 by knocker

[Cloud 10]

Some familiar differences between the GFS and ECM operational's at day 7 with the ECM having the more amplified pattern allowing Arctic air to penetrate down into the UK,and the GFS flattening any ridging around the Greenland/North Atlantic region very quickly,so no time for the cold air to spread down.

 

GFS..  ECM..

 

To amplify or not to amplify,that is the question.

[Barry12]

To amplify or not to amplify,that is the question.

 

We will find out on the 18z GFS

[Summer Sun]

A cold snap looks possible to start next week with some frosty mornings

 

 

Then towards bonfire night milder air begins to move back in from the west with some rain

 

 

So a colder start to next week with some frosty mornings before milder air looks to win out later on with some rain

[knocker]

The ECM monthly update. Little change to the current pattern. Temps average or above average.

 

[terrier]

So the ECM monthly update has updated for November. Showing temps average to above average throughout it's run. Think it's looking like another above average month overall again.

Edited October 28, 2014 by Polar Maritime
Or average as the Models show, Putting thoughts to one side..

[BlueHedgehog074]

Hard to tell whether it could be a one-off, but the GFS 0Z update seems to have brought the cold Northerly back to life for early next week...

Not much support from other models, though, with models such as the GEM 0Z going for more of a milder Westerly flow during that period:

So it could still turn out to be a failed mission for this Artic Maritime incursion. One thing I have noticed, though, is the GFS trys to hold back Low Pressure to our West allowing a gap to develop between the Low Pressure to our North-East and the Low to our West. There also seems to be an amplified ridge from the Azores high filling that gap and, as such, helping a Northerly to occur. Most other models have the Low to our West quickly merging with Low Pressure trying to go to our North-East/East - this of which kills of chances of a Northerly developing. This is something that would likely need to be kept an eye on for future runs as it could have an affect on whether a Northerly develops or not. It does help as well to see ridging of High Pressure occurring to our West to help hold back approaching Lows to the West.

If the GFS does verify, then there would probably be wintry showers possibly falling to some fairly low levels to the North. Some of these showers probably likely to stream through the Chesire Gap towards the Midlands for a time, too, though with wintriness to them likely to be restricted for hilly areas. Even if the Northerly becomes terminated, a nice little surprise their for the cold and snow fans this morning!

Edited October 28, 2014 by DiagonalRedLine

[IDO]

So as the GEFS were strongly hinting at last week, and not a shock bearing in mind the time of year, the flatter more zonal pattern is upcoming. GEM this morning is a prime example:

 

D6:   D8:  D10: 

 

GFS op after D10 continues the theme just currently messing about with the placing of the jet:

 

D12:  D16: 

 

Its a case of grin and bear it for the next few weeks at least, as the PV establishes itself, and keeping an eye on any signal as to where it will rest, and to check to see if the Strat. can help. The D16 NH chart shows a rampant PV:

 

 

The models have been hinting now and then at a possible PM incursion but the ensembles have not supported this, with a flatter pattern and the jet not sinking south enough even if it is only a transient shift south. The ECM has now come in line with the ensembles this morning with a very flat westerly flow:

 

D10: 

 

As things stand I cannot see anything cold for most of November from any of the LR models. Of course this can change however experience tells me once this type of pattern sets in it can take weeks for a change.

Edited October 28, 2014 by i'm dreaming of...

[Yarmy]

'Wet' is a reasonable summary the ECM 00z from T120 onwards. The last frame shows a nasty looking depresssion as 2 Atlantic lows merge over the British Isles:

 

 

Never particularly cool/cold, but hints of a pattern change? The semi-persistent-large-area-cyclone-that-dare-not-speak-its-name is still quite fragmented.

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY OCTOBER 28TH 2014.

NEXT UPDATE WEDNESDAY OCTOBER 29TH 08:00

THE CURRENT GENERAL SITUATION. A cold front will move steadily SE across the UK today and tonight to become slow moving over Southern England tomorrow. A ridge of High pressure will move in across Northern Britain from the West tomorrow.

MODELS-2 WEEK HEADLINE  Less mild and changeable weather with rain and showers at times mostly in the North at first extending to all areas later. Some short drier and cooler periods are possible too.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream currently across NW Britain weakens over the coming days as a High pressure ridge buckles the flow North around the UK. It then ridges North over the Atlantic and then dives South over the UK to set up a Low pressure trough over the UK next week with the flow to the South then. A simplified West to East flow easing North over the UK is then shown later in Week 2.

GFS Today's operational run shows Low pressure moving ENE close to NW Scotland over the coming weekend with increasingly unsettled weather already over the North finding it's way down across Southern Britain too over the weekend. After a short cool interlude early next week thereafter we see changeable conditions under a Westerly flow, strong at times with some transient ridges of High pressure bringing occasional brighter and drier spells in between the bands of rain. Brief cooler periods under the ridges continue to be possible but generally fairly mild conditions are shown to persist.

THE GFS ENSEMBLES.  The GFS Ensembles differ on two aspects from the operational in a general agreeance on the basic theme. Firstly the very unsettled phase from the weekend is shown to last longer with colder air entrained to start next week before the predicted ridge moves in and lastly there is greater emphasis on mild amd less unsettled conditions over the South to occur towards the end of the run as High pressure builds up again towards the South and bathes the UK in mild SW winds yet again.

UKMO. UKMO today shows Low pressure between Scotland and Iceland at the weekend moving East and maintaining a changeable West or WSW flow across the UK with all areas at risk of rain or showers at times with temperatures falling and returning to near average across the South.

THE FAX CHARTS  The Fax Charts show another marked and unseasonably mild warm sector developing over the UK later this week between Low pressure to the NW and High pressure over Europe. The Atlantic fronts then are shown to make inroads across the UK at the weekend with cloud and rain bringing a slight drop in temperatures over the mild South then.

GEM  GEM today shows a Westerly flow across the UK for the next 10 days or so once the current very mild SW flow finally loses it's grip over the South at the weekend. This will then ensure cloud and rain at times for all in strong winds mixed in with some brighter and showery weather. Temperatures will then be close to average over all areas.

NAVGEM NAVGEM shows an unsettled phase at the weekend when the current very mild air finally gets pushed away from Southern Britain. Two or three days of rain at times in blustery West then NW winds then bring cooler air down across the UK next week as a ridge crosses the UK from the West.  

ECM . ECM really ratcheets up the Atlantic influence from this weekend as deeper Atlantic Low pressure streams in from the West at the weekend and becomes fed by reinforcements moving in from the West next week to set up a large and deep Low complex across the UK with strong to gale Westerly winds making it feel cool with plenty of squally heavy showers and longer spells of rain for all areas in temperatures no better than average by the end of the run.

THE ECM ENSEMBLES  The ECM Ensembles today show a typical Autumn pattern and while not as harsh with the extent of Low pressure as it's operational it does show Low pressure to the North of the UK, High pressure over the Azores and a broad and unstable westerly flow across the UK bringing spells of rain and showers to all areas with temperatures close to average.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend is still for Atlantic driven weather to continue across the UK though with more risk of some heavy rain at times reaching the South of Britain too wth time in somewhat lower temperatures than of late.

MY THOUGHTS  Not much to say this morning that has not been said already as the theme of Atlantic driven weather remains through the next couple of weeks across the British Isles. However, one of the main differences in the weather will be the inclusion of Southern Britain to much more regularly join in with the wind and rainfall that the North has experienced over recent times. This will lower temperatures more towards the seasonal average as the air source becomes more North Atlantic based rather than from the Azores. In among the unsettled and changeable pattern will be some cooler and drier phases when overnight frost and fog patches could occur on a local basis. That leaves us two weeks from now with the weather still looking Atlantic driven from the long term models and as a result I can see little indication as yet that fog, frost and snow will feature in any notable way across the UK apart from the hills and mountains above 3000 feet.

[shaky]

Well the models are showing the northerly to be pretty potent once again!!if things are changing this early on regading the northerly then I wouldnt be too confident what happens afterwards!!!the last few frames of the ecm would feel decidedly chilly though and the pv is still all over the place so the organisation of the pv is still not guaranteed yet!!Although eventually it will happen cos its suppose to anyway at this time of the year!!

[knocker]

A Nor'easter for the weekend. Perhaps much snow for New England. I thought a little titillation.............................

 

[Polar Maritime]

Yes this Model'd Northerly shot could produce some heavy snow for parts the Highlands. I'm sure detail will change at this time-scale.

 

Edited October 28, 2014 by Polar Maritime

[IDO]

Yes this Model'd Northerly shot could produce some heavy snow for parts the Highlands. I'm sure detail will change at this time-scale.

 

 

 

Yes early days. Neither GEM or ECM support this at that time frame:

 

 

 

The GEFS mean does support a transient cooler upper  flow, along with the control, but how potent that will be even if GFS is right?

 

 

 

Aberdeen:   London :

[Nick F]

Latest synoptic outlook from me for the next 14 days:

 

http://www.netweather.tv/index.cgi?action=news;storyid=6254;sess=

 

Briefly colder north today and tomorrow, but flow turning southerly across all areas by end of the week, perhaps 20c reached again in the SE on Friday. Cooling down across all parts by Saturday as a cold front sweeping east clears the SE, then changeable over the weekend, showers in places. Uncertainties, as already discussed here this morning, with regards to potential northerly arriving Tuesday, as we've seen, ECM and GEM having none of it from there deterministic runs, 06z GFS like its 00z predecesor, still going for it. Could be first significant snow of the season for northern hills. But the northerly not likely to last long in what is an increasingly mobile flow next week.

Edited October 28, 2014 by Nick F