Model output discussion - winter proper underway

[Iceaxecrampon]

GFS 00z

Hmmmm.....

[Frosty.]

Essentially, in a nutshell its a mild rather cloudy week ahead with mist / hill fog, a little patchy rain here and there and temps around 11 c but in any sunshine the temps will be boosted towards the mid teens celsius, around 60f..not particularly wintry I think its fair to say.  

[knocker]

The ecm det.run this morning is consistant with what it has been hinting at vis the anomalies, albeit rather more gung ho. Jus prior to Xmas day it has a very strong jet, 170kt region, running up the eastern seaboard courtesy of the mid west cold trough, which then exits across the Atlantic towards the UK with the Azores HP relegated south west. Ergo this scenario would portend a windy and unsettled Xmas period

9

A quick look at this mornings GEFS which hang on to the Azores influence more than is indicated by the ecm det run but do eventually head in the same direction

Edited December 17, 2017 by knocker

[Weather-history]

25 minutes ago, Frosty. said:

Essentially, in a nutshell its a mild rather cloudy week ahead with mist / hill fog, a little patchy rain here and there and temps around 11 c but in any sunshine the temps will be boosted towards the mid teens celsius, around 60f..not particularly wintry I think its fair to say.  

I still don't see this 60F in the charts, if anything, it looks less mild to me this week. 

Edited December 17, 2017 by Weather-history

[Frosty.]

32 minutes ago, Frosty. said:

Essentially, in a nutshell its a mild rather cloudy week ahead with mist / hill fog, a little patchy rain here and there and temps around 11 c but in any sunshine the temps will be boosted towards the mid teens celsius, around 60f..not particularly wintry I think its fair to say.  

I should just add that today and tomorrow will be fairly chilly days across at least the southern half of the uk with a risk of frost and ice overnight as a ridge of high pressure builds across the uk, it's a very cold start this morning further southeast for example but the large mild plume lurking out in the atlantic is set to bathe the uk from tuesday with potentially exceptionally mild temps in the 14/16c range for favoured spots....according to stav danaos!!

Edited December 17, 2017 by Frosty.

[blizzard81]

Looks like the Atlantic will be back with a vengeance for the end of December. No sign yet of heights building to the north east in a way that will affect us. We just have to hope the models are over cooking the pv to our north west. At least Xmas day looks seasonal. 

[NO LONGER POSTING]

In December 2010 didn't we see a similar thing? We had a very cold December and lots of snow even had lying snow on Xmas day, but after all that was over it was very hard to get the cold back in, if at all. Correct me if I am wrong but sometimes a good start to winter doesn't mean it persists through to the end 

[blizzard81]

1 minute ago, Surrey said:

In December 2010 didn't we see a similar thing? We had a very cold December and lots of snow even had lying snow on Xmas day, but after all that was over it was very hard to get the cold back in, if at all. Correct me if I am wrong but sometimes a good start to winter doesn't mean it persists through to the end 

Yep, Dec 2010 was exceptionally cold and snowy up until Xmas. Like this year, we were in la nina enso state. 

[knocker]

Ive been musing about the PNA this morning as one does on a Sunday. The clue really is in the name. The forecast pattern over North America is suggestive of a typical postive PNA with the Alaskan ridge and cold tough in the mid west buy downstream not so much at all.

No trend to positive heights over Greenland and in fact the southerly advection of colder air from thr Arctic is more general in the east, courtesy of the Canadian vortex, and into the NW Atlantic which leads to the suppression of the Azores HP and allows the strong jet leaving the eastern seaboard to cut a swathe across the Atlantic.

The mean PNA this morning from the GEFS is negative

[West is Best]

Well there's no doubt that the Azores high is being pulled west: something showing up clearly on the runs. The problem is that it's insufficiently dynamic at the moment to ridge north into a true mid-Atlantic block. So the best we get are meridional incursions (better than nothing). Great for the Scottish ski industry but a bit 'meh' for the rest of us.

However, there are tantalising hints of what could happen, see here with the ECM T240 which is exciting, and the ensembles continue to offer a huge range of possibilities at really quite short range.

[northwestsnow]

Looks like the weather is going to turn very unsettled acc to the 00z runs!!
Our hope is the jet sinks south after day 10- EC is better then GFS for me- 

[West is Best]

9 hours ago, meh said:

I wouldn't want to be a farmer on the Somerset Levels if some of these GFS FIs come to fruition.  

Hopefully the drainage channels are in good nick(!)  

I believe they are called rhynes 

[northwestsnow]

GFS00z op still going for quite a substantial warming at 10Pha  - it starts around 

192

And carries on to the end-

caveat being its GFS but something to keep an eye on 

[karlos1983]

5 minutes ago, northwestsnow said:

GFS00z op still going for quite a substantial warming at 10Pha  - it starts around 

192

And carries on to the end-

caveat being its GFS but something to keep an eye on 

Yup, it’s been showing this for quite a while this time, and it has been getting closer, so to see it inside 192 is encouraging. 

Liking the ecm this morning, potentially not miles away from showing some interest for coldies!  

Certainly the pick of the bunch at D6-7

Edited December 17, 2017 by karlos1983
Typo

[tinybill]

talk about t not knowing what going  to happen on the big day if the models keep changeing!

[northwestsnow]

Actually EC is about the best of the longer range output this morning- GEM is dreadful, with a captial D!!

As far as EC is concerned i think the progression from day 10 will be to sink the jet south- but we really need to see some kind of amplification in the north Atlantic thereafter !!

[northwestsnow]

Last one from me this morning-

EC day 10 has some very warm 850s right up across the Arctic !!

 

[bluearmy]

We are seeing a propensity on here to be extrapolating from op runs post day 8. Once they get to this range they are more than likely wrong. some of the features they have showing will of course verify but which ones??  that's why, despite them getting a hard time in here, the ens means and anomolys are used. These verify on the upper pattern better than the ops after day 6. 

As far as the 00z suites are concerned, little evidence that cool to potentially cold zonality is avoidable. Possibly stormy but also possibly very wintry if the upper trough gets far enough south and we see runners in the base of the trough. Higher ground in the north will see snow in cool zonality in any event. 

How the amplified Pacific plays out remains the question - signs that we may see ridging towards kamkatchka but this likely to just pass back across to Siberia rather than get towards the pole. cross model ens guidance says we should be left with a polar high somewhere north/northeast of Alaska in a couple of weeks. Can this ridge across towards Greenland?  No evidence that the eps are at all interested in any scandi highs in two weeks. 

[northwestsnow]

12 minutes ago, bluearmy said:

We are seeing a propensity on here to be extrapolating from op runs post day 8. Once they get to this range they are more than likely wrong. some of the features they have showing will of course verify but which ones??  that's why, despite them getting a hard time in here, the ens means and anomolys are used. These verify on the upper pattern better than the ops after day 6. 

As far as the 00z suites are concerned, little evidence that cool to potentially cold zonality is avoidable. Possibly stormy but also possibly very wintry if the upper trough gets far enough south and we see runners in the base of the trough. Higher ground in the north will see snow in cool zonality in any event. 

How the amplified Pacific plays out remains the question - signs that we may see ridging towards kamkatchka but this likely to just pass back across to Siberia rather than get towards the pole. cross model ens guidance says we should be left with a polar high somewhere north/northeast of Alaska in a couple of weeks. Can this ridge across towards Greenland?  No evidence that the eps are at all interested in any scandi highs in two weeks. 

Yet again Blue i find myself agreeing with pretty much all your post

Cold zonality is my stab towards New year -ala METO outlook.

The problem with cold zonality is its very difficult to sustain with out some kind of blocking to the north- i also agree Febs Scandy high is not going to happen anytime soon.

The only hope as far as i'm concerned is some kind of buckling of the jet to allow some Height rises in the Atlantic sector..

Perhaps this is why Exeter are mentioning the north in regards to wintry potential towards NY...

Further on they mention milder interludes being reduced- they have to be seeing those height rises in the north atlantic to sustain a wintry pattern.

Anyway, thats defo the last one for me today lol..

Edited December 17, 2017 by northwestsnow

[bobbydog]

are we beginning to see some continuity at last? - from the ECM-

last two ECM runs looking very similar, allowing for the 12 hour difference. the jet digging south and the vortex being drained from greenland in the process. this could allow for amplification afterwards as @northwestsnow mentions. thats if there's anything left of us after that storm passes through!

 

[TEITS]

Very much agree with WIB this morning.

No doubts the output has improved because at one stage Xmas looked to be very mild with a SW,ly flow. Now we are looking at cool, cold depending on where you live. Whilst a majority are unlikely to see a white xmas, the higher ground in the N could well see some snow. Some will be disappointed but it could be worse. I remember Xmas in the past when temps have been 14C!

Beyond Xmas day and its possible the colder NW,ly outbreaks could push further S. Again any E,ly via a Scandi HP looks very unlikely this year. The Berlin ensembles are a clear example.

[tight isobar]

11 hours ago, tight isobar said:

Encouraging' developments via 18z..

The pacific monster ridge working favourably...

Canadian sector vortex diluting/and everything tranfering east.

Any height alignment behind this process would prove great for our part.

Synoptics to be eyeballing in the next 24hrs!!!

We are beining to see a pattern emerging now...and a reasinable one for the chance of a more seasonal xmas period.

The pv on a more promising migrate/placement!

And the possibilities of perhaps even better evolutions as we draw closer!!!

[Deep Snow please]

Looks like an incredibly high flood risk for the South East between Christmas and New Year going by the GFS.

Starts to deepen as it comes out of the Atlantic

Continues to deepen

And again - only this time it's intensifying even more, seems to be picking up quite a lot

However it could be possible for this to resolve to keeping that system bedded in over Scandinavia preventing the flood risk or perhaps - and this is really hopecasting, providing cold air for the low pressure that's currently flooding southern England (shown above) to give us one hell of a winter.

Edited December 17, 2017 by Deep Snow please

[swfc]

Alluding to teits comments they do make good points esp on regard to the east and scan

Imo the high pressure building to the east is in fact hindering the pv moving eastwards and slowing down the pacific heighths movement hopefully getting towards greenland.I think that would allow agreater chance of a better aligned jet as ba mentioned then a chance of cold shot.All in all tho id say anything past 7-10 days isnt worth a jott.Just to note that area of low pressure forming at150 hrs pf the esb on gfs is a real ball breaker!!!!!

Edited December 17, 2017 by swfc

[78/79]

1 hour ago, West is Best said:

I believe they are called rhynes 

First constructed  around the 16th century ,by I believe, Carthusian Monks , and later on developed by Dutch Engineers.