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phil nw.

Model Output Discussion 1st January 2014-06z onwards.

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A very pertinent post by Nick F earlier this evening about one plausible scenario that could lead to even more rain. To that effect the 18z is very much the way we need to see the output trending, taking the low as far west and south of the UK (within reason) as possible as it heads se.

 

I wouldn't mind if the ppn falls as snow and accumulates then the freeze comes in, no flood worries there. Posted Image

Edited by Mucka

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Very COLD surface conditions on the 240hrs chart, especially for the snow fields, and even in the south lower than -4C is likely from that chart!

Posted ImagePosted Image

Edited by Panayiotis

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Yes, very much what I have been thinking and I continue to stand to the side of the more popular belief expressed and supported on here and think that the best possibilities for the cold backing west over our shores lie later than the time periods under consideration (and hope) on this thread. The 'cleaner' disruptive options are too far away to have confidence in based on the residual energy budget over the polar field (Canadian side) that is likely to be subject to 'slow kill' over the next two/three weeks or soPosted Image

 

If you have the time and inclination, is there any way you could simplify your last sentence for a newbie?

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If you have the time and inclination, is there any way you could simplify your last sentence for a newbie?

Simply that in terms of UK cold blocking prospects I think we need another bite at the polar vortex to reduce westerly energy sufficiently beyond the initial split indicated in the near term. However the process is well and truly underway and prospects at last show some good promise for the second half (especially last third) of winterPosted Image

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Not surprised GFS is going towards a more easterly solution, according to UKMO the MJO could head towards a strong phase 7, however it's still early days.

 

Here is the link:

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

 

Here are the MJO composites:

 

http://www.americanwx.com/raleighwx/MJO/MJO.html

 

So pretty interesting, the MJO composites suggest an anticyclone nearby with an easterly influence.

 

Of course it's not that simple, but I think these are signals GFS is picking up on and there is a good chance we will see more runs like this over the next few days.

 

Fine margins of course with potential cold but the GFS is the first interesting run of the winter within 192h (except for the early December northerly that didnt materialise), lets hope it persists and the MJO goes into phase 7 and other things start falling into place.

Edited by Quicksilver1989

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Simply that in terms of UK cold blocking prospects I think we need another bite at the polar vortex to reduce westerly energy sufficiently beyond the initial split indicated in the near term. However the process is well and truly underway and prospects at last show some good promise for the second half (especially last third) of winterPosted Image

 

Ah but you didn't fancy our Atlantic ridge much for the same reasons.

Then again I didn't get the trough disruption I was expecting so the reality seems to have fallen somewhere in the middle with the Atlantic ridge proving to be base camp ready for the second expedition and assent.

No way to know whether that second attempt will be successful but the output is going the right way and if that continues we should be fairly optimistic of our chances.

Of course the output is more likely to chop and change though.

TWT. 

Edited by Mucka

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Very happy with the output this evening. It is an evolving pattern therefore I would be less

happy if we saw fantastic synoptics at say t192 as this would evolve and change.

Hopeing for more upgrades tomorrow within this time frame.

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Ah but you didn't fancy our Atlantic ridge much for the same reasons.

Then again I didn't get the trough disruption I was expecting so the reality seems to have fallen somewhere in the middle with the Atlantic ridge proving to be base camp ready for the second expedition and assent.

No way to know whether that second attempt will be successful but the output is going the right way and if that continues we should be fairly optimistic of our chances.

Of course the output is more likely to chop and change though.

TWT. 

 

I do think your point about it falling in the middle is good one. I am rarely sold on this 'there can be no middle ground' outcome that is often posted in the lead up to an event.

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Hello 

 

As a newbie I have a question regarding air circulation around high and low pressure areas and how to interpret them on the various models.  I'm not sure if this is the right place to post but the site is fairly daunting with the sheer volume of message boards so apologies if I'm in the wrong place (please feel free to point me in the right direction).

 

Anyway the question is when looking at airflows hitting a low pressure area on one of the models output pages: how can you infer whether the Coriolis effect will dominate or the pressure gradient force?  Also I'm struggling with how to interpret the impact of friction on the Coriolis effect and whether I really need to consider it if the airflow is a westerly, given it's coming of the ocean?

 

I'm sure these questions betray my own ignorance but an answer would help me in interpreting model output even if it's "You are missing the big issue and focusing on a small/irrlevant one muppet!"

Edited by Trom

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http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-1-114.png?18

 

GFS control almost identical to the OP barring a tad more energy diving SE & the deep cold pool over Scandi a bit further SE...

 

Wonder how that evolves

 

S

Yes then ensembles look like the best for potential blocking thus far from GFS out to about day 5 so it will be interesting to see if that potential can be realised with more cold runs developing.

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Coldest london ens yet and assuming the cold cluster has the right solution, we will be seeing mean maxes of 1-2c in a day or so on the graph.

Something for the east coast to cheer with that little bit more undercutting which is entirely possible the control is the first MAIN run where the -10c isotherm gets in http://modeles.meteociel.fr/modeles/gens/run/gens-0-0-162.png?18 Just 7 days away- S

This evenings gem steve !

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What a control run from the gfs!!and all of it starts at just 96 hours!!slider lows and all!!

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Latest 120 hrs fax chart looks like a classic battleground over the UK scenario brewing.

 

Posted Imagefax120s (1).gif

Lowest WBFL is across northern areas Sat afternoon-night. Snow above 700m generally. Rain event elsewhere and totals hard to call (being closely monitored given ongoing sensitivity).

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Lowest WBFL is across northern areas Sat afternoon-night. Snow above 700m generally. Rain event elsewhere and totals hard to call (being closely monitored given ongoing sensitivity).

is there a chance fergie where the wbfl could lower even more and we see a battleground snow event more widely??

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Had a look at the ensembles individually, some looking very good indeed! A fair few get height rises to the north east, and an undercut with cold air making it to the UK.

 

Control  http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=0&mode=0&carte=0

Ptb 1, 2, 5, 6, 10, 11, 15, 16 and 20

 

Edit: Ptb 1 by far the best, as Steve illustrates below me! We also get a 48 hour snow event over the Midlands north Posted Image

Posted ImagePosted Image

Edited by Mark Bayley

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Knowing my luck I will miss all the cold and snow while I'm sunbathing in gran canaria! It actually may feel a bit cold Down in the canaryislands if some of the runs are to be believed!

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