237 replies to this topic

[feb1991blizzard]

ECM not looking too good post 168 im afraid, it's really not looking too good now, lets just hope the ensembles paint a different picture, or i feel the Met Office 15 dayer will be amended tommorow, and not for the better either.

[karyo]

Overall, there is less blocking in the 12z ECM. A step in the wrong direction!

It doesn't even give the decent northwesterly that the UKMO brings at 120 hours.

Then a questionable chart right at the end of the run with some surface cold. http://www.meteociel...map=0&archive=0

Karyo

Edited by karyo, 18 January 2012 - 18:59 .

[Gavin D]

ECM ends under high pressure

[Weather wizard]

Tim Bland, on 18 January 2012 - 18:55 , said:

Looks ok at 216. An Atlantic ridge, lower heights over Spain and lots of cold to our north and east. Wouldn't take many tweaks to make it a great chart - - see above ^^^^^

Yes but look at the PV over Greenland again Grrrrrrr!!!!!!

[Cloud 10]

UKMO and GFS very similar at 96hrs.

http://www.wetterzen...ics/Rukm961.gif

http://www.wetterzen...cs/Rtavn961.png

ECM not so similar!

http://www.wetterzen...ics/Recm961.gif


Quite a cold day on sunday with wintry showers in north-western areas if gfs and ukmo
are correct.

[mulzy]

Tim Bland, on 18 January 2012 - 18:55 , said:

Looks ok at 216. An Atlantic ridge, lower heights over Spain and lots of cold to our north and east. Wouldn't take many tweaks to make it a great chart - - see above ^^^^^

Agree Tim - the ECM 240 is not a terrible chart - a few tweaks and we're in business.

Anyway it's all FI.

[danm]

ECM ends on an interesting note, gives us something we haven't seen in any outputs recently - that of a retrogressing high from the Azores up towards Scandi. Some fairly cold uppers at the end. Unfortunately the PV is strong over Greenland, so if the run continued past t240:



.....it could well have just turned into a sinker.

[Tim Bland]

Weather wizard, on 18 January 2012 - 18:58 , said:

Yes but look at the PV over Greenland again Grrrrrrr!!!!!!

Yes whilst the PV is still in that position there is no where for that ridge to go / progress. At least there is some lower pressure to our south and if that PV backs west it could be game on. Still lots to play for IMO

[mountain shadow]

THE EYE IN THE SKY, on 18 January 2012 - 17:19 , said:

At the moment if we are to see a prolonged cold spell i.e Met O forecast then in my opinion it will arrive via blocking to our NE rather than Greenland. If you notice the Met O say NE/E,lys but if it was a Greenland HP N,lys are also possible.

True, but we are not going to get a ne/e unless we first get a block into southern Greenland, however temporary to slow down the jet enough to allow the Russian High to ridge west.

As it is, despite the PV shifting to the other side of th pole, we still cannot seem to get proper blocking into Greenland enough to stop the jet pushing through into the GIN sea.

The teleconnections and 500mb height anomalies do however support this, so maybe the models aren't picking up on it.

Has anyone link to the ensembles for the place in Greenland?, always a good place to start looking for blocking.

[feb1991blizzard]

And when the AH finally decides to play ball and we get some sort of falling heights over mainland Europe, then what spoils it, yes you have guessed it, a dirty great PV re-emerging over GL.

[nick sussex]

Hard to know what to make of this run, but regardless I still think its to the ne that any pressure rises are going to come from.

The Canadian high can amplify the upstream pattern and even with a strong looking segment of the PV if you get enough dig south then the jet should bounce ne in the Atlantic.

I just can't see a Greenland high happening initially, the first stage has to be from the east or ne and we do see that Iberian low which is a good thing to support any ridge.

[Cloud 10]

mountain shadow, on 18 January 2012 - 19:03 , said:

True, but we are not going to get a ne/e unless we first get a block into southern Greenland, however temporary to slow down the jet enough to allow the Russian High to ridge west.

As it is, despite the PV shifting to the other side of th pole, we still cannot seem to get proper blocking into Greenland enough to stop the jet pushing through into the GIN sea.

The teleconnections and 500mb height anomalies do however support this, so maybe the models aren't picking up on it.

Has anyone link to the ensembles for the place in Greenland?, always a good place to start looking for blocking.

greenland ensembles (nuuk)

[feb1991blizzard]

Zakos, on 18 January 2012 - 19:07 , said:

the met have made this bold statement clearly not based on any op runs that we have acces to. What makes you think that theyre going to downgrade the cold risk based on models they have already disregarded, and which continue to be inconsistent? And besides the gfs ensembles are clearly leaning towards a noteable cold spell anyway.

About 5 out of 20 GEFS members suggest a strong scandinavian block with uppers cold enough for a deep cold spell being advected into Britain, and when you consider that 10 of the 20 members are tweaked towards a colder outcome, hardly compelling evidence, the fact is the Met office mentioned it but said its not the favoured outcome, but you would think some OP runs would have looked better by now, at least in FI, after all FI charts usually bring in phantom Easterlies even when there is no decent background signals, which there is at themoment.

[phil n.warks.]

Slowly the N.Atlantic pattern is changing but with disagreements in the output beyond 4-5 days it`s uncertain wrt the exact detail beyond this range.

Let`s look at the 3 main models at T144hrs.



We can see the pieces of the vortex spilling down from the north but the way the troughing is handled is slightly different.The GFS pushes more energy east into Scandinavia and W.Russia showing a flatter milder outlook.The Euros. both dig the troughing more south but the ECM keeps it further West than the UKMO.
If we look at the overall picture though there are similarities.
The Azores High finally giving ground and extending N.West out into the Atlantic in tandem with the jet moving south.
The vortex altough modelled differently is continung to show as a weaker feature.
To get the troughing digging south as modelled it`s inevitable we will see varying temperatures as the flow will contain milder and colder air in the north westerly flow. We can`t get straight to a bitter cold set up from where we are now without this.
Just to underline the uncertainty the GFS Ens. graph shows a wide spread quite early on.


The Op.run very much on the milder side,the mean around -3C.

So in the short term an unsettled north westerly type with variable temperatures but beyond the weekend there`s much to be confirmed.

[nick sussex]

The ECM actually gives me a bit more optimism, even with a poorly tilted trough it still manages to stick some energy se into Iberia and people shouldn't panic if a piece of the PV appears over western Greenland.

Follow the output in the NH perspective where will the energy go from that PV?

In terms of the UKMO further outlook theres no way this run diminishes the odds of some much colder weather,

[Weather wizard]

The op was an outlier for having high pressure in the med it seems
http://www.netweathe...ensviewer;sess=

Edited by Weather wizard, 18 January 2012 - 19:22 .

[feb1991blizzard]

I can see why people are saying that the 240 chart is promising but that PV isnt going anywhere fast, if it was then yes, that chart would potentially ne a stonker by 288, but looking at the strat thread, the re-emergence of the PV looks likely again now, wheras i thought we had kissed good by to it looking at recent runs.

[john mac]

As GP said earlier the AO and NAO are forecast to drop from +2 values to -1 in the space of 4 days and this is why the models are struggling so much with the current pattern change.

I know its hard and its been frusrating but we just need to be a little more patient. GP speaks with alot of confidence in his posts and i for one am convinced that we are going to see a decent prolonged cold spell very soon.

Also don't forget, he said expect the unexpected lol!!!

Edited by john mac, 18 January 2012 - 19:30 .

[ANYWEATHER]

Zakos, on 18 January 2012 - 19:07 , said:

the met have made this bold statement clearly not based on any op runs that we have acces to. What makes you think that theyre going to downgrade the cold risk based on models they have already disregarded, and which continue to be inconsistent? And besides the gfs ensembles are clearly leaning towards a noteable cold spell anyway.

Met-Office have pointed out that this could go either way, Cold/Mild, to be honest the a very safe Forecast.! From the Latest output, it seems there is growing confidence that January could well be pretty Snowless ,Nationwide, apart from the obvious places! If I was to pick a model for anything resembling cold in the Next ten days it would be the Ecm with High pressure in Situ across the Nation leading to some Sharp Frosts . But thats a long way off and I would suspect from past experience the Gfs is on the Money.

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[Gibby]

In summary tonights runs continue to show mixed output. GFS keeps things basically westerly themed with troughs crossing Eastwards at times delivering mild interludes with outbreaks of rain alternating with colder showery weather when some snowfall could occur in the North. Further out in FI Low pressures continue to be present up to the NW with high pressure developing over Central Europe backing winds towards the South. Though technically mild a light flow from continental Europe ould mean eastern areas be rather chilly at times if more settled. UKMO shows that cold zonality is likely with rain or showers at times with the emphasis on slightly colder than average conditions with snow on Northern hills at times. ECM also brings cold zonality though late in its run High pressure moves NE from the Azores in very chilly air allowing frost and fog to become big factors by 240hrs as it crosses the UK.

Nothing too exciting tonight from the operationals or the GFS ensembles though the High pressure on the ECM 240hr chart could be a precursor to something as it is moving NE towards Scandinavia and may provide a catalyst for the jet to undercut as Low pressure buffers up to it in the days that follow.

Incidentally, a Greenland High is not the be all and end all. Many a cold spell has occurred with a Scandi High and Low pressure near Greenland as Long as pressure becomes Low over southern Europe. Its on the boundary between a cold european airmass and the warm atlantic depressions that often produce our heaviest if sometimes transient snowfalls like we used to get in the 80's from breakaway channel Low's.

Edited by Gibby, 18 January 2012 - 19:43 .