I can guarantee a cold easterly starting about the 21st February as I have to go to Liverpool for 5 days. Law of Sod!

 Well, circa 20% chance of significant high cell retrogression towards the end of next week... the downward trend in mean EPS 850hPa temp and GPH shows very well in 12z EC plumes (e.g. For Reading or Exeter), with some markedly colder members in an ever-widening ENS spread by then... so, can't *yet* discount further colder outbreaks of Pm/Am air into next 10-15D on. It's not the favoured f'cast outcome into medium range, but for now can't be discounted either.     

fergie post from last night for thos who have not read it

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS

THE CURRENT GENERAL SITUATION A large anticyclone will move slowly towards NW Britain with a cold and freshening ENE flow across Southern England tomorrow.

MODELS-2 WEEK HEADLINE A lot of benign and quiet weather is expected across the UK with light winds and plenty of cloud but some sunshine or clear spells with some frosts at night especially in the South. Daytime temperatures close to average.

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow now climbing North of the UK and weakening the European trough as High pressure near the British Isles ensures it stays North of or over Northern parts of the UK for most of the period.

GFS OPERATIONAL The GFS operational today shows High pressure domination throughout the duration of it's run. The centre drifts around, over or close to the UK throughout the run providing a very variable set of weather at the surface impossible to predict. Dry weather is guaranteed with few places seeing any rain or snow. Cloud amounts will be much harder to predict with some clear or sunny spells leading to overnight frosts and fog while daytime temperatures should reach average levels especially over the North but it could be rather chilly in the South at times if a drift of wind from Europe develops.

THE GFS CONTROL The GFS control run offers nothing any different with no real trend away from the UK based High pressure shown from this run either.

THE GFS CLUSTERS The GFS Clusters show an amazing 90% support for High pressure to lie close to SW England or just to the SW of that point in 15 days time. This means Northern areas will see the strongest breezes from the west or NW and the frost risk becomes restricted towards the South. The remaining 10% of support a UK trough with High pressure well out in the Atlantic.

UKMO UKMO this morning shows High pressure close to NW Britain slipping slowly South to Southern ireland by the end of the weekend before moving it slowly East across the UK next week. Quiet and benign conditions look likely for all with a few breaks allowing a little sunshine by day or frost at night while the general theme will revolve around light winds, cloudy skies and temperatures not far from average.

THE FAX CHARTS The Fax Charts are replicated from the raw data showing the UK under slack winds revolving arouns a large and intense High settling near to Ireland by early next week cutting off the cold feed of East winds over the South to begin with.

GEM GEM shows High pressure domination too with the same tricky mix of conditions at the surface revolving around cloud amounts and temperature values overnight dependent on cloud cover. Pressure falls slack for a time later next week as the High declines for a time but returns later to put us back to square 1 in 10 days time.

NAVGEM NAVGEM holds High pressure just to the West for a while before it drifts slowly across the UK and away to the SE declining slowly later next week. Winds will be light and variable throughout. Some sunshine is possible under a generally rather cloudy period with patchy frost and fog patches where skies clear by night.

ECM ECM offers the most interest this morning if its a return to cold weather your looking for as it too shows High pressure drifting across the UK and away to the SE next week but linking then to a build of pressure to the NW and opening the door somewhat to another cold plunge from the North late next week and the weekend.

ECM 10 DAY MEAN The 10 Day Mean this morning indicates that High pressure will most likely lie close to the South of the UK next week and beyond. Conditions will slowly recover to fairly average temperatures and rather cloudy weather overall with patchy rain at times in the North.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend from all models remains focused on anticyclonic weather being dominant over the UK for the foreseeable future.

MY THOUGHTS Not a lot to be said about this morning's output as all models are agreed upon a sustained dry and bright period of weather with a lot of cloud and temperatures not far from the seasonal average though frosts and patchy frosts at night will be possible almost anywhere at anytime. Amounts of cloud will determine whether there is frost or not and this will be the forecasting nightmare for the whole period as the High drifts over from the Eest and away to the SE later next week. The positioning of the High later next week may give rise to a greater chance of more sunshine as winds turn towards the SE and this could draw colder and clearer air into the South and East of England later next week. We also have to touch upon the ECM model this morning which although agrees on a declining High to the SE by the end of next week shows an interesting rise of pressure up to the NW late in it's operational run which could open the door to an arctic surge from the North again by next weekend although this is poorly supported from within it's ensembles at the moment. However and in Summary High pressure is sometimes more difficult to predict than Low pressure as they don't tend to follow any particular rules about movements and this can be poorly handled by models but what can be said this morning is that there will be very little if any rain or indeed snow over the next 10-14 days with a lot of quiet and settled weather with the main focus likely to be how much cloud determines how things will be at the surface in regards to sunshine by day and frost and fog by night.

Issued at 08:30 Thursday February 5th 2015

Well we have a straw from ECM to clutch at in FI this morning with us almost getting in on the next cold shot to Europe:

http://www.meteociel.fr/modeles/ecmwf.php?ech=216&mode=1&map=0&type=0&archive=0

If we can just get the high to retrogress a bit further NW it could be game on - a vast improvement from last nights run but no support from any other model yet so could be a one off or a trend. One to watch this evening, certainly any chance of avoiding weeks on end of mildish cloudy muck gets my interest at the moment.

Also what caught my eye is the GFS ensembles, first time I think I have seen a member this winter clearly reach -15, and again another member does it at the end of the run:

http://www.wetterzentrale.de/pics/MT8_London_ens.png

I wonder if something could be up?  Let's see if any later runs today build on this theme - maybe optimistic but as I said anything to avoid endless days of nothing weather!

The reason I am thinking along these lines, is that while the probability at any given time is low, the integrated time I am unsure about since there are multiple windows of opportunity for this to happen while the HP refuses to budge, indeed we have already missed an opportunity that was shown on the ensembles.

And given it only takes a small upgrade for the cold shot to happen, if we ever go down this line we could end up with a monumental shift in the ensembles perhaps over the course of a day, it hasn't happened quite yet though. 

I am with you Quantum. For as long as the usual zonal train is halted, anything can happen. We are not stuck in our normal rut and the current synoptics are laden with potential should the pieces of the jigsaw move in the right way.

I guess, the problem we have had is the persistence of vorticity over Canada - once that decays (if it does) then it is game on.

The ECM 00z is worth some interest this morning.

A lot has to fall into place for that ECM to come off for the Atlantic sector at least; low pressure becoming cut-off from the jet near the Azores on day 6, the U.S. low having a good orientation for building the mid-Atlantic high (preferably negative i.e. SE to NW) and the polar vortex splitting sufficiently to allow the high to reach toward the higher latitudes.

Of the other models, UKMO seems to have the U.S. low orientated favourably based on the day 6 chart but that's a rough extrapolation.

GFS has been coming close for a number of runs now - as usual it has sniffed out the idea of high pressure attempting to gain some influence over Greenland ahead of the others, but has struggled to produce more than variants on a toppling high scenario - though far from the 'conventional' type, as there's not enough momentum in the Atlantic to flatten the high and it sits over the UK instead - a consequence of westerly momentum being removed from the mid-latitudes by various torque events in the near future.

We need to see GFS lower the momentum further to help with getting a vortex split, and amplify the Atlantic flow more to help with getting the mid-Atlantic ridge to shift W then NW from the UK.

If that happens, then it's time to start sitting up and thinking about a possible sting in winters tail.

Not happening on the 06z. At least we get a continental feed

ECM op not supported by the ens

This is very interesting, as this maybe the link to what I was informed about yesterday by my METO informer. Fingers crossed it happens and we get a sting before the end of Winter!

This is potentially a massive development, and will be the hot topic today i reckon.

It comes very close at one point

Only the -10 isotherm there, I say only because you can bet that the GENS will have some sub -15s on it. 

But yeh, perhaps this isn't the time we get the upgrade, but the opportunities will keep on coming. 

In fact there is another 'near miss' with the -10 line once again visible.

not much support from Iceland Pressure forecast for height rises north of the UK... However there is significant scatter after 7 days time to at least keep it open as a discussion item

a post from tamara on NW that's needs translating ????????   

The upper anomaly charts are a good guide on the basis that one interprets them in terms of factors that make them liable to change and doesn't take them at face value in the same way as happens with NWP output.

For quite some now I have been discussing the atmospheric circulation pattern and the symmetry of the GWO orbits which continue to suggest cyclical amplification phases. This theme is as strong to day as it has been in recent weeks and whilst we can distrust the over amplification tendencies of the ECM (f.e) which cannot and should not ignore the trend it suggests which is entirely in line with expectations.

The difficult issue remains timing, and of course, whether the next phase of Pacific retrogression bears fruit for the the UK at all. Neither of these questions can be answered with any degree of certainty at all - but I for one still have high confidence in the macro NH pattern leading us to further polar incursions later this month.

GWO as anticipated is creating a second +EAMT which is going to supplement a displaced vortex our side of the pole - as previously mentioned. Large +frictional torques and MT are inevitably going to be followed by corresponding -torque/MT through Phases 8/1 and 2 the other side of the pole which are a high signal for Rossby wave driven Pacific retrogression followed by downstream amplification in the Atlantic. Exactly the same as repeated increasingly through the winter.

There should be no surprise if this signal contiunues to wax and wanes in intra day NWP but don't let that fool anyone. I would also ignore the fact that just a small percentage of post 10 day ensemble data reflects this signal..currently.   It is obscured by a rather obfuscated MJO signal - however, the MJO itself comprises a percentage of the AAM/GWO budget and it is this signal which will be a large decider in the behavioural direction of the MJO.  

The upcoming MLB quiet period is indeed very much a holding pattern - but I don't personally buy any longer term suggestions that this is any sticking pattern through the remainder of February into March.

Stratospheric forecasts support the direction of travel of the vortex our side of the pole. We simply await the trigger for that upstream amplification and the floodgates should open. Its a case, for me at least, of when that happens rather than if it will

On that basis, the upper anomaly charts will evolve naturally in response to that signal. What they currently show has no bearing at all on that process.

More model output required, as they say, to keep a watching brief over this

http://www.atmos.alb...wo/gfsgwo_1.png

Let's play a game of Spot The Difference.

The GFS for right now:

And at 384 hours . . .



 I think it is time for me to admit defeat and stop being like Moby Dick chasing after a whale (snow) and take a back seat from my facebook forecasting duties for a while.

I'm not being in a sulk or anything like that, in fact I am appreciating charts like this as it means I can be getting on with things rather than obsessing over phantom snowy outlooks or worrying about Atlantic cyclogenesis bombing their way towards us whenever I do my forecasts in the morning.

So, with that to mind, that has a  from me, especially as the daylight grows longer with each passing day.

Taking the latest GFE Ensemble at face value - it's looking very barren for the next couple of week (after tonight down here).  Let's hope the factors that Tamara is highlighting do come into play, otherwise it's snowless for a while down here.

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=292.44000244140625&y=179.67999267578125

Hi all,

Here's today's video update;

Hint's Of Retrogression Later Next Week;

http://www.gavsweathervids.com/

Very cold air could be close to us in the next 8-10 days so needs watching.

Less interest on the 6Z unfortunately, though I think we will continue to get these patterns thrown at us for a while in the minority on the GEFS, hopefully it will come to something. There is one very impressive 6Z ensemble though.

Its usually "Jam Tamara" if you look at how many of those types of "possible factors that could come into play" forecasts that have been issued this winter you start to look at credibility issues.....

"Jam Tamara"...like it

I credited you last time.  Its a classic, so true.

Shame I can't make royalties on it...I'd fly to Bjiorli to see some snow with the proceeds

UKMO looks a little more interesting but looks like the high cant go anywhere for 10 days