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Paul

Model Output Discussion - The Start Of Winter

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It is high that kind of sits between a Scandi and a Bartlett, so basically sits over Germany, so not a displaced Azores and not High Level blocking.

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It's a Scandi block which is South scandi based and covers part of Europe to the south. A traditional Scandi block will generally advect cold west via low heights to its South. A sceuro block will not because it has high heights stretching to its South. It can mean cold for us if there is cold air already entrenched to our southeast. It rarely means deep cold for nw Europe.

Nick L - re the mwto 30 dayer : I assume there could be ecm ens clusters at the end of week 2 which would clearly evolve to cold by the end of week 3.

However, we had this last jan when there was a potential SSW predicted for end of the month on glosea model and this caveat appeared on the 30 dayer despite the ecm 32 showing nothing. Imo, the appearance of this into the 30 dayer is strat related.

Edited by bluearmy

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Yes my thoughts to blue regarding stratt incorporated in there.

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There are rumblings of a major pattern change to much colder weather as we hit the new year. In the meantime, the models show a rinse and repeat generally rather cold and very disturbed pattern with a northwest / southeast aligned jet profile with Atlantic lows swinging SE time and again with frequent incursions of polar Maritimes bringing blustery wintry showers with a risk of thunder separated by slightly milder intrusions with heavy rain and gales. There is no sign of the weather settling down but on the other hand, nights will be cold and frosty at times during the pm outbreaks..early 2015 could be the turning point. :-)

Edited by Frosty.

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Yes - We don't know what the ECM strat output ENS longer range are showing but i can't believe that it is too dissimilar to this.

 

 

attachicon.gifNH_TMP_1mb_384.gif

 

Not an SSW and not even at day 10 but the way that this warming has been modeled and is reeling in it has the hallmarks of previous SSW's stamped all over it.

 

My only concern is the displacement type and whether the vortex will be totally crushed but if any one saw the tweet I made yesterday about EN post SSW NAO and NH average temps it is definitely something we want to see.

http://www.wsi.com/blog/energy/europe-more-of-the-same/

 

WSI graphic from the link NBLSB posted previously: ECM ensemble for 50mb at end of run. Their comment ....

 

"In the meantime, the ECMWF ensemble 50 hPa circulation, at the end of its run on the 24th December, shows the polar vortex still in place. The conclusion being that there is still no sign of stratospheric warming and by implication surface blocking and extreme cold."

 

My comment ....does that look like a Canadian warming?

 

50ECMWFPolarVortex.png

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Afternoon all,

 

Lots of speculation of what's going to happen out into the low resolution of the various model runs.The hear and now of the situation is that its cold and if you don't believe me  go for a walk and see for yourself,todays temps,

nmmuktempnew.png

60mph N/W gusts and we have a significant wind chill.

 

Modeling looks good for cold in the high res part,GFS indicative,

h850t850eu.png

Still looks great out to next Wednesday,

h850t850eu.png

After that take with a pinch of salt.

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http://www.wsi.com/blog/energy/europe-more-of-the-same/

 

WSI graphic from the link NBLSB posted previously: ECM ensemble for 50mb at end of run. Their comment ....

 

"In the meantime, the ECMWF ensemble 50 hPa circulation, at the end of its run on the 24th December, shows the polar vortex still in place. The conclusion being that there is still no sign of stratospheric warming and by implication surface blocking and extreme cold."

 

My comment ....does that look like a Canadian warming?

 

50ECMWFPolarVortex.png

I think we need to be very cautious until the stratospheric warming gets picked up by the ECM.

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Really exciting news regarding longer range developments today, what a tonic to read a colder trend could lock in during Christmas and more especially into the new year. I think there have already been signs of this in the far reaches of the gfs in particular with more of an Arctic look to the charts by then but even in the short to medium range it looks chilly and unsettled with temperatures averaging out a little below the seasonal norm so things are starting to look more encouraging for the long suffering coldies among us at last. :-)

Edited by Frosty.

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12z GFS similar to UKMet.

 

Pretty much the same pattern as we are now. Winds primarily from a North Westerly direction, temps below average with mainly snow on the higher hills.

 

As a positive, no sign of the Azores High moving into mainland Europe.

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The GFS is a dog's dinner  in FI and has been for the past several runs. It's almost as if there's no clear indicator for it to base its assertions upon. However the warming has been maintained in the strat and it's significant in as much as it's a prolonged and sustained one.....as Chiono has pointed out, perhaps the precursor to the predicted SSW.

 

I can't help but think that a rather favourable winter pattern may emerge at relatively short notice towards FI of future runs.

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The Parallel continues the trend.

 

gfsnh-0-264.png?12

 

gfsnh-1-264.png?12

 

-10's in Scotland, -8's spreading south. 

Edited by SN0WM4N

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GFS (p) FI is a decent illustration (though far from ideal)  of how the pattern may flatten for a few days but it should amplify once more as the PV and core trough moves to our East and interacts with the Siberian/Russian high it will force lower heights South with the winds more predominantly from the N/NE rather than W/NW which could give us a cold snap and if the pattern is backed far enough West and the trough deep enough we could see some MLB following behind though currently the upstream modelling does not support this. There are a couple of potential spoilers as well and the cleaner the transfer of the lobe of PV from West to East the better off we will be.

 

gfsnh-0-234.png?12

 

However after this wintry blast that could be the next with the potential for some more widespread low level snow. A long way out at the moment but for those who feel there will be an increasingly less cold mobile westerly flow in the run up to  Christmas it may provide some cheer, at least in model land over the coming days.

Edited by Mucka

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 I kind of disagree with that statement of WSI. Firstly, I would not be looking at 50hPa for the first signs of an SSW - 50hPa is possibly the last place to start to look as the warming would start at 1hPa - so without looking there you cannot say there is no sign - perhaps there isn't on the ECM but I doubt that as well. And why ?- well look at the vortex shape - even at 50hPA it is obviously affected by a wave 1 displacement - I would be looking for what is causing that, and it wouldn't surprise me that if anyone has a 1 hPa mean chart then the answer will be found there, with evidence of a warming that could be the first signs of a January SSW.

The strange thing about it is that the ECM ensemble mean looks almost identical to the GFS at the same timeframe, when clearly there's a significant warming going on at the upper levels of the stratosphere:

post-9298-0-58888100-1418231031_thumb.gi

Of course that's not to say that the higher warming is also necessarily there on the ECM ENS, but it certainly isn't inconsistent with what we've been seeing on the GFS op.

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The GFS-P also showing the cold plunge for the end of the week.

-10C uppers just reaching the far north of the UK with the snow risk on low ground in N.Scotland and more extensively on any high ground.

post-2026-0-14119000-1418230647_thumb.pnpost-2026-0-08215800-1418230661_thumb.pn

 

A decent cold shot considering the quite modest pattern with little if any overall ridging. 

 

 

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The GFS is a dog's dinner  in FI and has been for the past several runs. It's almost as if there's no clear indicator for it to base its assertions upon.

 

hi cc... i must admit i find this remark rather odd. the gfs in fi to my eyes looks quite consistent in predicting a bog standard westerly regime. if a mobile unsettled westerly is a dogs dinner then fair enough! id have thought its assertions are based on current jet projections. timing of cold/mild sectors of course will vary but the trend is pretty clear for now.

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Model and strat related.The 2010 severe cold spell wasnt picked up on the models when the the mo were sounding cold and snow from the n/ne,if i remember correctly.

I know a pattern change may happen end of month/beg jan,so if the models are showing a tosh mild fi for the mxt 2/3 wks and mo outlook brings cold chances nearer,i know i will be a tad excited lol.

Forget my above comment lol.Ian you big tease.

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Not much cheer in GFS ensembles for those who want a white Christmas but still a long way out. I have been saying that I fancied some blocking to start showing up in the <10 day charts (so by Christmas day) by mid month but starting to look like that will be bust at the moment. (reverse psyche?  :pardon: )

I still see a window of opportunity for a more amplified pattern to reestablish itself last 3rd Dec even if GFS doesn't but then I may be more bias than GFS:clapping:

 

Edit:

 

Just read Fergies post, that should keep spirits up for now.

Edited by Mucka

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hi cc... i must admit i find this remark rather odd. the gfs in fi to my eyes looks quite consistent in predicting a bog standard westerly regime. if a mobile unsettled westerly is a dogs dinner then fair enough! id have thought its assertions are based on current jet projections. timing of cold/mild sectors of course will vary but the trend is pretty clear for now.

Not odd at all if you view the synoptic progression holistically from a NH perspective. The PV comes under huge stress....you can see this as it never centres around any one place for an extended period of time. It ebbs, flows, consorts etc etc yet the UK stays under a slack westerly flow with no strong jet stream to produce any zonality of note. Will the day 10-14 charts look like that come the time?? Not a chance IMO.

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BUT recall the highlighting of 'conflicting signals' post-December expressed in previous UKMO seasonal discussions and I must reiterate that this element remains. So it's going to take a while into this month before we see whether GloSea consolidates certain signals.

fergie could you give us anymore information on the potential snow event for north midlands northern england Friday morning!! Gfs has that low crossing through the midlands tomorrow night and now ukmo/ecm have it crossing the same path aswell!!

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