briggsy6
28 December 2022 17:32:51
Daily Express and others forecasting snowmageddon as US storms cross the Atlantic to Blightly. Clearly these journos  no nothing about meteorology as if they did would understand that the Atlantic modifies the cold to such an extent that all we end up with is lots of cold rain. But then why let an attention seeking headline get in the way of the facts eh?
Location: Uxbridge
doctormog
28 December 2022 17:38:00
The north south split seems to be continuing on the most recent output with only brief milder blips up here in a cool theme overall. Nothing like the wintriness from earlier in the month looks likely though and milder further south. You’re welcome to our cold rain if you like.

The main theme however as has been mentioned is the mobile, westerly and unsettled picture with strong winds and rain (and northern hill snow) never far away. 
Bow Echo
28 December 2022 17:43:55
 I'll probably get shot down for saying it, but the outlook  at present does not look to my eye like a flat zonal pattern with no interruptions. There are periods of zonality, yes, oscillating with more semi meridional interludes, both at 250mb and surface levels. I'd certainly call it mobile, with the usual sine waves on the spaghetti as depressions develop. But there is to me no absolutely raging zonality. Now I'm surely going to be called for reading it wrongly, but thats how it seems to me. Any time such a n intermittent pattern of zonal mixed with meridional kicks in, there are always surprises that can follow. But being the weather and fluid dynamics it will now go completley laminar I'm sure...
 
Steve D. FRMetS
Burton Latimer, Kettering, Northants


Saint Snow
28 December 2022 18:48:50
Originally Posted by: briggsy6 

Daily Express and others forecasting snowmageddon as US storms cross the Atlantic to Blightly. Clearly these journos  no nothing about meteorology as if they did would understand that the Atlantic modifies the cold to such an extent that all we end up with is lots of cold rain. But then why let an attention seeking headline get in the way of the facts eh?



It may be a lazy representation but it's got some tenuous basis. Most of these frigid plunges that extend far southwards are the result of a buckling jet, which is one key ingredient of what the UK generally needs for cold. With lows that hit the UK coming from the west (mostly cyclogenesising - I'm sure that's not a proper word - off the US/Canada coast), it's an easy assumption to make. 

Martin
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Saint Snow
28 December 2022 18:50:49
Originally Posted by: Bow Echo 

I'll probably get shot down for saying it, but the outlook  at present does not look to my eye like a flat zonal pattern with no interruptions. There are periods of zonality, yes, oscillating with more semi meridional interludes, both at 250mb and surface levels. I'd certainly call it mobile, with the usual sine waves on the spaghetti as depressions develop. But there is to me no absolutely raging zonality. Now I'm surely going to be called for reading it wrongly, but thats how it seems to me. Any time such a n intermittent pattern of zonal mixed with meridional kicks in, there are always surprises that can follow. But being the weather and fluid dynamics it will now go completley laminar I'm sure...
 



I agree with you. 

Zonality relates to a specific set-up, which isn't what we have at the moment. 

Martin
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A TWO addict since 14/12/01
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Aneurin Bevan
dagspot
28 December 2022 21:59:00
Ben Rich  ‘Succession of fronts, mild and wet with teen figures, only occasional cold spells for far north well into New Year’
Sounds pretty zonal to me
Neilston 600ft ASL
DEW
  • DEW
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28 December 2022 22:06:19
Eye candy for the end of January
https://www.wetterzentrale.de/topkarten.php?map=1&model=cfs&var=1&run=12&time=792&lid=OP&h=0&mv=0&tr=24#mapref 
 
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Chichester 12m asl
tallyho_83
28 December 2022 23:26:21
Originally Posted by: DEW 

Eye candy for the end of January
https://www.wetterzentrale.de/topkarten.php?map=1&model=cfs&var=1&run=12&time=792&lid=OP&h=0&mv=0&tr=24#mapref 
 



Maybe in response to this SSW? - Seems to be a persistent theme now toward the end of the runs where by temps @ 10hpa rise significantly after the 1st week of January: - Here's for hoping anyway?! 🤞

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ballamar
28 December 2022 23:35:44
Decent potential end GFS op run, heights building in the right places. At least something to keep an eye on if any support. Energy could slide but like CFS changes nearly every run!
GEFS might show a little more interest
UncleAlbert
29 December 2022 00:38:00
Originally Posted by: ballamar 

Decent potential end GFS op run, heights building in the right places. At least something to keep an eye on if any support. Energy could slide but like CFS changes nearly every run!
GEFS might show a little more interest


Regarding the posts on the UK getting US weather and also on zonality, perfect zonality never happens does it?  That's the only way we would get an air mass directly from the other side of the pond, which as stated would be considerably modified even with the direct route.  If there was such a set up there would be no anticyclones nor depressions en route.  Conversely the perfect meridional flow never happens either so I in reality we can only talk in degrees of either state and currently I would say that we are experiencing a set up that has a fair degree of zonal bias.  I know that I may be stating the blatantly obvious, but of course we have to bare this in mind when using these terms.
Gandalf The White
29 December 2022 00:41:22
Originally Posted by: tallyho_83 

Maybe in response to this SSW? - Seems to be a persistent theme now toward the end of the runs where by temps @ 10hpa rise significantly after the 1st week of January: - Here's for hoping anyway?! 🤞

UserPostedImage





Although it looks quite impressive, that isn't a SSW: it's neither 'sudden' nor has sufficient warming.  To propagate down into the troposphere and influence weather systems there needs to be a sudden 'jolt' exerting downwards pressure. There also needs to be a wind reversal and that's not appearing in the forecast charts.

 
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


DEW
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  • Advanced Member
29 December 2022 08:03:49
The WX temp charts are anything but stable. This morning's version has the ultra cold area in Siberia restored in week 1, and while Europe remains above average for that week, cold spreads well south to the Black Sea in week 2 as well as the rest of W Europe cooling down though to a lesser extent. Pptn more consistent, continuing in Atlantic coastal countries incl Britain, with some extension to the Baltic, and in week 2 down through France and onward to the Adriatic.

GFS Op - default W-lies but with interruptions, and not penetrating so far into Europe as shown yesterday. The interruptions may be based on LP coming down from the NW with cold N-ly spells (Sun 1st, 995mb Scotland weakly, Tue 10th 985mb E Scotland strongly) or HP developing from the S with mild SW-lies (Thu 5th 1040mb Spain-Norway, Sat 14th ditto)

ECM - similar to GFS in general pattern and specifically for Sun 1st (though LP centred over England) and Thu 5th (though ridge placed further E). This model then develops a very large LP centred 950mb SE Iceland which dictates the weather all the way down to the Alps

GEFS - temps up and down to match the above until Sat 7th (this variation most marked in S, the N having a flatter and cooler profile) after which little agreement between ens members, with a final spread on Sat 14th from 10C below to 8C above norm. Rain in one or other ens member from time to time, most probable around 1st and 8th, heaviest in W and lttle prospect of snow exc in far N.
War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
Brian Gaze
29 December 2022 08:25:14
Looks like a "choppy" zonal flow to me rather than a very flat one. The sine wave pattern is clear for the next week or so and beyond that it could simply be that the individual runs are bringing disturbances through at different times so the mean is being smoothed.

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Brian Gaze
29 December 2022 08:29:44
Also there are 23/31 runs dipping below -5C and only 3/31 going below -10C. Very similar to recent days and IMO no real sign of a significant cold period at the moment. 


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Brian Gaze
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UncleAlbert
29 December 2022 09:03:08
Originally Posted by: Brian Gaze 

Looks like a "choppy" zonal flow to me rather than a very flat one. The sine wave pattern is clear for the next week or so and beyond that it could simply be that the individual runs are bringing disturbances through at different times so the mean is being smoothed.

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Except to my eye, the lower plots in the later part of the run are the more stable ones, so in that way some sort of split?
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The Beast from the East
29 December 2022 09:35:34
Originally Posted by: Brian Gaze 

Also there are 23/31 runs dipping below -5C and only 3/31 going below -10C. Very similar to recent days and IMO no real sign of a significant cold period at the moment. 


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Pitiful. Just roll on spring and those warm sunny days. Hopefully a long fetch bartlett can set up at least for the south and we can keep those heating bills down
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doctormog
29 December 2022 09:38:08
Meanwhile up here it looks like it will remain on the chilly side in the coming days then a potential warm up to something milder for a couple of days then more average or below again beyond that. The latter (cooler) part has changed over the last day or so should be viewed with a lot of caution. 

https://modeles16.meteociel.fr/modeles/gensp/graphe_ens3.phpclim=1&x=&y=&ext=1&run=0&lat=57.2&lon=-2.25&runpara=0 

Overall though the pervading theme is unsettled. 
ballamar
29 December 2022 10:14:15
Scandi high at 150h on GFS op, nothing to get excited about though!
fairweather
29 December 2022 10:37:43
Originally Posted by: UncleAlbert 

Except to my eye, the lower plots in the later part of the run are the more stable ones, so in that way some sort of split?


​​​​​​​Sorry, could you explain  this to me. I don't understand what is more "stable" about the lower ones?
S.Essex, 42m ASL
UncleAlbert
29 December 2022 14:40:58
Originally Posted by: fairweather 

Sorry, could you explain  this to me. I don't understand what is more "stable" about the lower ones?



On the 850mb 0000hrs GFS ensembly around 6 of the members at around -5C or lower stayed at around that value for quite a few days rather than exhibiting the fluctuations we see from the passage of frequent troughs, possibly suggesting  the chance of a somewhat different pattern emerging, all be it near to the end of the run.  Of course this  has totally vanished on the latest run!
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