Model Output Discussion 29th December - Into mid-Winter.

[ANYWEATHER]

As some have said on here in recent days its been a very blocked Autumn and start to Winter, but blocking around the UK needs to be in the right place to deliver the goods Just look at 1963 for the UK with record breaking cold making it the coldest winter since 1740 .....whilst Greenland bathed in there warmest winter.   Back to now , the Ecm shows some potential for cold , gfs  really looks like it needs to shunt the high pressure build to our south far away from our shores to deliver anything wintry. Its only the start of Winter folks , what really is the point on righting off winter from computer models which change from day to day , our weather is amazingly complex and in a million years time we will be looking at the weather and still clueless of what the future weather holds. There will be lots of surprises for everyone this Winter, sit back and enjoy.....after all it does not need to be that cold to SNOW.

[bobbydog]

1 hour ago, Backtrack said:

Coming from a realistic point of view- isn't it unlikely that our entire longitude position across the entire earth is affected by a cold outbreak? Below average in a ring around the earth. Chart seems unlikely, surely?

Which bit is unlikely? The fact that there is a ring of cold around the earth? Or that we are in it? 

[Seasonality]

1 hour ago, feb1991blizzard said:

If its via an in initial polar maritime flow from the NW then its the much maligned GEFS ensembles that picked it up first on new years day morning.

Ok. Then first in the publicly available operational runs within a reasonably verifiable time frame. And we don't of course have full access to UKMO output so can't say for sure if they didn't pick it up. No pleasing some 

[tight isobar]

As again the wrap -around of heights/Russia' and forcing of diverting systems (Atlantic) 

Converging into relevant formation of westerly advection and bringing deeper cold into the equation. .

Are being hinted at on raw -output. 

Further pressing of the eastern seaboard ridge now also becoming favorable! ?...

Scandinavian height basis into thepole are at ppresent going up in percentage. ....lets hope further output evolution smells this !

[nick sussex]

I've done my best guess looking at the limited view of the UKMO at T168hrs. Its likely that the Russian ridge backs west in between the low over the south of the UK and low heights to the ne. The ridge is likely to mean a se flow over the eastern North Sea. I've probably got the ridge influence a bit too far west into the UK but you get the idea. The deep troughing over Greenland we can tell by just enough from the limited UKMO view that the isobars are curving ne to the west of the UK.

 

[knocker]

Tonight there is some discord between the anomalies albeit nothing major.

Upstream no problem with the high pressure over western Alaska, an active Canadian vortex still with he trough orientated south west and a flat upper flow across the U.S. with a strong jet leaving the eastern seaboard. It's downstream where the problem arises as the ecm has a stronger mid Atlantic anomaly and ridging (the NOAA and GFS are more zonal) and thus, although all three have a trough/lobes running east from the vortex via Greenland to connect to the trough in the east, this ridging ensures that they track sharper SE than the other two and thus possibly have a more severe impact on the UK vis some transitory wintry weather. This is something the det runs will need to sort in the next couple of days to finalise the weather for next week, Worst case scenario all of the UK with have bouts of wind and rain , better, confined to the west and north. Temps a little below average

Now where are we going with all this? We are still looking at a pattern change upstream with retrogression and weakening of the Alaska HP to be replaced with a broad low pressure area but still with an intense vortex and a flat flow across the US. Downstream pretty zonal across the Atlantic in general with some retrogression of the trough  to the east with a suggestion of a positive tilt but that isn't unanimous. From a cold perspective looking at all of this iit s again the GEFS which offers some hope and finishes once more with ridging NE into Scandinavia with the deepening trough to the south. This would indeed be a route to tapping into cold in SE Europe but it needs much more support to consider seriously. So for now it looks like a continuation of Pm shots with the north being more in the firing line.

Edited January 3, 2017 by knocker

[bluearmy]

The good news for nick s is the high anomolies are gone from France within eps high res! The spreads show a cluster of members pushing a ridge east from the azores ridge through c France but let's hope they go by tomorrow. 

The story in the 10/15 stays the same with the low anomolies to our east and across into Iberia arcing around the Atlantic slightly high anomolies to our west . Not too dissimilar to the GEFS. The end of the run has the Russian high anomolies edging west  into ne scandi 

[There's a storm a coming]

4 minutes ago, nick sussex said:

I've done my best guess looking at the limited view of the UKMO at T168hrs. Its likely that the Russian ridge backs west in between the low over the south of the UK and low heights to the ne. The ridge is likely to mean a se flow over the eastern North Sea. I've probably got the ridge influence a bit too far west into the UK but you get the idea. The deep troughing over Greenland we can tell by just enough from the limited UKMO view that the isobars are curving ne to the west of the UK.

 

Looks a good guess for what the 168hrs shows but more importantly what do people think the next step would be?

Tasac

[nick sussex]

2 minutes ago, There's a storm a coming said:

Looks a good guess for what the 168hrs shows but more importantly what do people think the next step would be?

Tasac

Thanks, it would be great if the stingers at the UKMO just gave us the full UKMO output at T168hrs. In terms of next step we'd probably expect some trough disruption as the troughing over Greenland moves east so probably low pressure angled nw/se into the UK. I think at the moment its hard to see a true easterly flow. Possibly the best outcome would be a battle ground scenario.The thing to look out for if the UKMO is too bullish is taking the more middle ground scenario of the ECM and if the ridge to the east can extend over the top of the troughing over the UK at T168hrs.

Of course we do need the GFS to backtrack from its flat pattern. I'd be shocked if its correct because we're not even talking a shortwave drama, its simply upstream with the low track further west  and deeper closer to the east coast USA and that ridge to the ne. This is all within T96hrs.

[There's a storm a coming]

1 minute ago, nick sussex said:

Thanks, it would be great if the stingers at the UKMO just gave us the full UKMO output at T168hrs. In terms of next step we'd probably expect some trough disruption as the troughing over Greenland moves east so probably low pressure angled nw/se into the UK. I think at the moment its hard to see a true easterly flow. Possibly the best outcome would be a battle ground scenario.The thing to look out for if the UKMO is too bullish is taking the more middle ground scenario of the ECM and if the ridge to the east can extend over the top of the troughing over the UK at T168hrs.

Of course we do need the GFS to backtrack from its flat pattern. I'd be shocked if its correct because we're not even talking a shortwave drama, its simply upstream with the low track further west  and deeper closer to the east coast USA and that ridge to the ne. This is all within T96hrs.

Thanks nick for your reply and thoughts, I'm sure the GFS will start backtracking most probably starting with the 18z. As it all starts on the southeast coast of USA is there any news from them on what model they prefer

Tasac

[nick sussex]

1 minute ago, There's a storm a coming said:

Thanks nick for your reply and thoughts, I'm sure the GFS will start backtracking most probably starting with the 18z. As it all starts on the southeast coast of USA is there any news from them on what model they prefer

Tasac

You're welcome.I'm still waiting for the latest NCEP State forecasts update.

[karlos1983]

34 minutes ago, nick sussex said:

I've done my best guess looking at the limited view of the UKMO at T168hrs. Its likely that the Russian ridge backs west in between the low over the south of the UK and low heights to the ne. The ridge is likely to mean a se flow over the eastern North Sea. I've probably got the ridge influence a bit too far west into the UK but you get the idea. The deep troughing over Greenland we can tell by just enough from the limited UKMO view that the isobars are curving ne to the west of the UK.

 

After that Arsenal result, I'm of the opinion anything is possible. 

Top doodle Nick 

[Stuie]

36 minutes ago, There's a storm a coming said:

Looks a good guess for what the 168hrs shows but more importantly what do people think the next step would be?

Tasac

Etch-a-sketch?

Seriously, not a bad shout Nick.

[winterof79]

39 minutes ago, There's a storm a coming said:

Looks a good guess for what the 168hrs shows but more importantly what do people think the next step would be?

Tasac

The Azores High to lose its sad mouth and eyes as it is pushed out of the picture

Edited January 3, 2017 by winterof79

[knocker]

23 minutes ago, There's a storm a coming said:

Thanks nick for your reply and thoughts, I'm sure the GFS will start backtracking most probably starting with the 18z. As it all starts on the southeast coast of USA is there any news from them on what model they prefer

Tasac

The NWS the ecm their take on the 6-10

Quote

TODAY'S NUMERICAL MODEL SOLUTIONS ARE IN GOOD AGREEMENT ON THE 500-HPA FLOW PATTERN PREDICTED OVER THE FORECAST DOMAIN. ALL OF TODAY'S MODELS PREDICT AN ANOMALOUSLY STRONG RIDGE CENTERED NEAR THE WEST COAST OF ALASKA, A POSITIVELY-TILTED DOWNSTREAM TROUGH CENTERED ACROSS BRITISH COLUMBIA, A FLAT RIDGE ACROSS THE CONUS, AND ANOTHER TROUGH CENTERED NEAR THE EASTERN SEABOARD. ENSEMBLE SPREAD FOR MOST OF THE CONUS IS LOW TO MODERATE, AS DEPICTED BY THE LATEST GFS, ECMWF, AND CANADIAN SPAGHETTI MAPS, THOUGH MODERATE TO HIGH SPREAD IS INDICATED NEAR AND OFF THE SOUTHEAST COAST, ASSOCIATED WITH A PREDICTED TROUGH. THOUGH TODAY'S SOLUTIONS ARE ALL IN GOOD AGREEMENT, THE 0Z ECWMF ENSEMBLE MEAN WAS FAVORED, SINCE IT HAS SLIGHTLY OUTPERFORMED THE OTHER MODEL SOLUTIONS DURING THE PAST 60 DAYS ACROSS THE FORECAST DOMAIN.

 

[winterof79]

Low developing off coast of Florida closer to coast this run and earlier

 

Edited January 3, 2017 by winterof79

[There's a storm a coming]

13 minutes ago, knocker said:

The NWS the ecm their take on the 6-10

 

So if I read that right they are happy with the pattern across most of the usa apart from the southeast corner where there is a mod to high spread...typical that that's the bit we're interested in.

looks like the GFS 18 has moved a little closer to the UKMO and ECM although it's still a bit quicker

Tasac

Edited January 3, 2017 by There's a storm a coming

[tight isobar]

The 'now' impressive Pacific ridge. .becomes penultimate and pivatol to our finality. ..

The evolving Russian forming ridge..needs spike then cross link..then all roads lead to splt vortex/scandi block...

[booferking]

GFS slowly moving to the euros surprise surprise.

[Catacol]

Been away a day - and not great scanning of charts and signals tonight. We really are stuck in a rut for the moment - MJO remains weak as the pacific idles.... vortex profile has trended less disrupted in the last 48 hours, and we seem to be stuck with a Euro mid lat high that is the strongest global anomaly anywhere and seems a permanent feature.

Calendar says 3rd January - still not close to half way through winter. Lots to play for - delighted to see so little energy in the atlantic still. But we need something to change to get blocking to a higher latitude.

At the moment the -PNA profile in the US is not helping us because global amplification is generally so weak. With a bit more amplification I think it would help retrogress the pattern more dynamically, but not currently. However longer term forecasts are now suggesting an alteration of the long wave pattern as we approach mid month, and as others have pointed out the possible return of low pressure to the aleutians.

So where might the change come from? CPC yesterday updated their MJO report - get it at this link via a ppt and have a read....

www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.ppt

Slide 16 is perhaps our ray of hope. CPC assessment of the ensemble forecasts is that ECM is seeing a renewal of MJO activity in the Indian Ocean as we approach mid month. In layman's terms this means the very amplification we need. Suggested composite for initially a phase 6 transition is here 

Before moving more to here as we reach phase 7

 

(Note the need here to use non-Nino composites - some Nino composites were posted earlier today but we are no longer in a Nino phase....)

So - some grounds for optimism as we approach mid month. Note that these composites match the NWP suggestion of a return of the Aleutian Low... and as all strat grogs will know this offers potential of more strat forcing as we approach February. Again - as has been said ad infinitum - these forcings are not jaw dropping and we should not be jumping up and down in certain joy - but still time for a change, and still enough working in our favour to keep us on the edge of our seats....

Edited January 3, 2017 by Catacol

[feb1991blizzard]

very slightly better ridging towards SW Greenland in between the 2 troughs on the 18z, Surely Steve Murr cant pull this one off. Can he?

[Allseasons-Si]

Happy new year everyone,1st post of 2017

i have just had a doodle dandy with the mean charts from the ecm and gefs below at 240 hrs,i know it's FL,but there isn't much difference between the two on a macro scale only suckle changes,lets have a gander :-

1:red lines

the ecm has less amplification in the Atlantic sector but more so in the Asia/Siberian area,this tells me that there would be trough disruption heading south into Europe where as the gefs has a bit more ridging in the Atlantic but flatter Asian/Siberia ridge so which one would you take?

2:yellow arrow

they both show a source north of west so similarities there

3:brown line(Europe)

the ecm by far the more amplified of the two with trough digging further into the med lowering the height's there

4:yellow line(north America)

again the ecm is slightly more amplified with the trough digging a bit further south into the states than the gefs

5:black and white circles

there is not much difference,both showing the Aleutian trough/height's,the ecm a little more robust

so all in all the ecm mean(if it's correct) would produce the better outcome

p.s good analysis steve murr as always,and you have set a wheel spinning here,will we see this trough disrupt further west?

 

[tight isobar]

Nice evidence of binocular spread in pv...

In anoms and hpa. ..

Lets see ridge split. .then wrapping of height links....

Looking cushty..going forward. .

[SMU]

a near miss from the 18z however we are edging closer, we have limped forward with @T162 a low closing off over NW italy - the UKMO has it over England-

However on the 168 12z there was no closed low as the jet never got that far south-

Give the GFS another 18-30 hours ....

Edited January 3, 2017 by Steve Murr

[johnholmes]

Well the 70% of a coldish burst seems less likely to me looking at the anomaly charts. Usually the one nearer the mark is the NOAA outputs and they have gone for a flatter Atlantic flow, still the marked ridging/+ve heights west of Alaska. Also still showing +ve heights in the Atlantic. But the swing is towards less chance of a deep cold outbreak than a swing to a higher risk. The occasional Pm airmass getting well south but certainly no major cold outbreak on the horizon to me.

sorry no charts.