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Model output discussion - 5th December 2016 - Into Winter we go

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ECM this morning is quite a sight. If we can really go from this... 

ECH1-0.GIF?26-12

To this... 

ECH1-240.GIF?26-12

In the space of 10 days I think there will be few complaining. I hope Sidney got a warm jumper from Santa yesterday. 

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13 minutes ago, fergieweather said:

Worth noting that UKMO prognosis for January has shifted now. They suspect PNA may be influential; GloSea5 has moved over weekend to suggest anticyclonic/blocked regime will dominate throughout Jan, with milder interludes only occasionally and temperatures generally lower than average. Although severe cold is still considered unlikely, they note that currently around 25% of yesterday's EC EPS members and several GloSea5 members allow reorientation of the block (principally expected to the W) to shift such as to bring a Pc flow. GloSea5 keeps the broadly +ve MSLP anomalies all the way to the end of January, maintaining a colder theme compared to climatology.

Deja vu, or on the money this month? We watch with interest... but gloves & scarves ready from next weekend (at least that initial bit of the story comes with high confidence, albeit cold front timing has wide error margin of 12-24hrs).

Forgive my ignorance Ian but what is a Pc flow? 

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6 minutes ago, Tony Beets said:

Forgive my ignorance Ian but what is a Pc flow? 

Polar continental

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25 minutes ago, fergieweather said:

Worth noting that UKMO prognosis for January has shifted now. They suspect PNA may be influential; GloSea5 has moved over weekend to suggest anticyclonic/blocked regime will dominate throughout Jan, with milder interludes only occasionally and temperatures generally lower than average. Although severe cold is still considered unlikely, they note that currently around 25% of yesterday's EC EPS members and several GloSea5 members allow reorientation of the block (principally expected to the W) to shift such as to bring a Pc flow. GloSea5 keeps the broadly +ve MSLP anomalies all the way to the end of January, maintaining a colder theme compared to climatology.

Deja vu, or on the money this month? We watch with interest... but gloves & scarves ready from next weekend (at least that initial bit of the story comes with high confidence, albeit cold front timing has wide error margin of 12-24hrs).

So rather than the high out west drifting SE more drifting east and slightly further north? Hence Pc flow. Or am I completely wrong? Just trying to learn.

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Its been clear for a few days we are going to get two pulses of heights into the western Atlantic, likely in response to forcing in the Pacific quadrant; that wave remains active for about 7 days (no change from yesterday:

gensnh-0-1-144.pnggensnh-0-1-324.png

It has always looked better placed for the US trough to provide the UK with a better chance of cold rather than previous shots this month. We get the first amplification next weekend; bringing us three days of sub-zero uppers; ECM D7:

ECM1-168 (1).gif  GFS D10: gfs-0-240 (2).png London Pressure: graphe4_1000_306_141___Londres (2).gif

Then around D10, further height rises to the west brings us the best chance of snow^^^

However still much uncertainty re the initial height rises cross and inter-model and they make huge differences with respect to longevity, potential and where the second ridge/trough combo sits. The London ensemble pressure chart highlights this. No point speculating further than that as variables within the D10 envelope make the ensembles pretty useless after that. I suspect the second ridge will topple as the Pacific wave subsides and whether we can get a wedge of heights favourably placed in the flow to prolong a colder pattern is the question? 

We are clearly heading for an extended period of below average upper temps, from D7 to at least D15; just need some luck to make this period worthwhile for a UK wintry outlook.

 

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7 minutes ago, That ECM said:

So rather than the high out west drifting SE more drifting east and slightly further north? Hence Pc flow. Or am I completely wrong? Just trying to learn.

Obviously I cannot speak for IF but I would read that as heights building to the NE and thus a NE/E flow over the UK

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5 minutes ago, That ECM said:

So rather than the high out west drifting SE more drifting east and slightly further north? Hence Pc flow. Or am I completely wrong? Just trying to learn.

Rather than the ridge staying out west and bringing a wnw mean flow, it may drift further nne and bring a ene instead. the ridge staying out west would mean more pm source. If it gets further ne then it becomes pc. all indicative at the moment and a broad background against which to predict the likelihood of general conditions. 

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I think it's fair to say that the initial n and ne flow for the new year had to be pulled out like teeth from the gfs with most runs quickly sinking the high. However now the meto ecm and more and more the gfs seek to be increasing the instability of the flow down the east side of the high, keeping it in place and quickly allowing the extension of the waa around Greenland. 

Fantastic models though this morning and only a couple of days until the detail of snow showers and how cold etc. 

Re glosea glad it's come on board the potential and likelihood of the Jan pattern has been discussed on here just before Christmas, based on the model output so it's good to see glosea catching up ;)

Edited by Iceberg

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Must say I was'nt expecting a ECM run like that:fool: cold from the first with an interesting evolution of northerlies. Hp far enough west this time.

Edited by Matthew Wilson

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1 minute ago, Matthew Wilson said:

Must say I was'nt expecting a ECM run like that:fool: cold from the first with an interesting evolution of northerlies. Hp far enough west this time.

Yes it's much better than yesterday, here's hoping..I haven't had anything to ramp so far this winter..hope that's about to change!:D

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I know I am not allowed to make comparisons but the 240h ECMWF 

ECH1-240.GIF?26-12

 

does remind me a bit of these setups

 

 

 

archivesnh-1962-12-28-0-0.pngarchivesnh-1978-12-31-12-0.png

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Exciting models this morning! Cant wait for some GP/Steve murr thoughts! Ukmo has suddenly become a LOT more amplified at 144,for me ita all about getting that ridge into southern greenland at said timeframe and we are in the game at last! 

I do hope it isnt a false dawn! 

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Very nice NH profile from ECM @ 240hrs

ECMOPNH00_240_1.png

Main PV lobe thinks'maybe I'll take a trip from Siberia to check out the UK for once'!:D

GFS ENS aren't too shabby P10 being a beaut

GFSP10EU00_354_2.png

Seriously though there is a lot of scatter and to get perspective, we could always end up with P13

GFSP13EU00_300_2.png

:closedeyes:.

There is a lot more of interest for coldies that's for sure and increasingly so as we move on  towards the New Year.

Hope you all keep having a great Holiday and here's to a frigid New Year! :cold::D

Edited by Purga

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And some may scorn and it may be an old wives tale but my grandpa said in  his experience mist and fog during Dec was an indicator of much colder weather down the line. It might be nosense but its been quite foggy recently...Anyway, steve murr has just arrived so will prepare the stage for a murr ramp..:D

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The ext EPS this morning is indicating a trough over Scandinavia, mild ridging in the Atlantic thus an upper flow from the WNW with temps a little below average. Pretty mundane fayre.

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Just now, knocker said:

The ext EPS this morning is indicating a trough over Scandinavia, mild ridging in the Atlantic thus an upper flow from the WNW with temps a little below average. Pretty mundane fayre.

There must be a clustering within indicating a colder N'ly flow unless the London graph does a complete flip because a lot on the 12z were showing temps not much above freezing which for London isn't indicative of a mundane WNW flow

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Pressure is going to be noteworthy on wednesday:shok: If you wake up with a headache then this might be a possible cause. 4mb off the record for December.

IMG_0901.PNG

IMG_0900.PNG

Edited by Matthew Wilson

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