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Model output discussions pm 31/12/15

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3 minutes ago, karyo said:

Everything I see in the models today is in agreement with the met office update from yesterday. A possibility for a brief cold spell preceded and followed by mild weather. 

You forgot to mention wet also with above average rain fall for the west there is no mercy when it comes to mother nature.:wallbash::wallbash:

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16 minutes ago, karyo said:

Everything I see in the models today is in agreement with the met office update from yesterday. A possibility for a brief cold spell preceded and followed by mild weather. 

Incorrect and wrong thread but there forecasts do not state mild at all.

More average temps in-fact. Please continue with meto discussion in the relevant threads, Thanks. 

Edited by Polar Maritime

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im surprised that some more seasoned chart watchers are getting despondent about that individual runs show.

the mean upper trough is expected to shift eastward, the uk is likely to get flooded with cold pm air. but this scenario is often not one that lasts. so expecting a lengthy cold spell out of the emerging possible synoptical pattern is pretty unrealistic imho. especially when you throw in to the mix a re-emerging azores high , which is only of use (for cold) if it links with the greenland high. if it doesnt, then the jet will steer systems over its northern flank and over the uk.

personally id be surprised if this expected cold snap lasted longer then around 3-4 days.

 

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1 minute ago, mushymanrob said:

Personally id be surprised if this expected cold snap lasted longer then around 3-4 days.

Which is what's expected during a cold spell and that's what the models are showing before heading back to something average. Not the balmy temps of late.

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As for the reload in the 6z, we often see the GFS doing that in the far FI as it doesn't pick up the shortwaves at this range and the northerlies look like happening quite easily. When the event moves in the semi reliable timeframe, shortwaves and weaker heights further north spoil our chances.

Edited by Polar Maritime

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Don't think we have really learnt anything after the 06z either way, waiting for the ensembles to give an idea, hopefully a few more than the 00z will be tending cold and not a few less

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It certainly look colder next week with some wintry showers around

gfs-1-174.png?6gfs-1-198.png?6gfs-1-222.png?6gfs-1-252.png?6

As the week progress the high builds over the UK more so becoming much drier for a time

gfs-0-252.png?6

Edited by Summer Sun

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As a boy in the New Forest in the 50/60's I longed for snow. There were barren years, but it often seemed to arrive around half term in February. Current charts  suggest some cold interest, but if we want an early snow fest it will have to be a virtual one.

Edited by Polar Maritime
To move discussion on..

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More shortwave drama, I would have banked these charts a few days ago, when the mother of all storm was shown, even if it's only a quick northerly I would take that then high pressure to dry us all out, long term the PV is in ruins and all the signals point to chances a plenty for cold and some white stuff come late Jan early Feb. :cold:

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14 minutes ago, karyo said:

As for the reload in the 6z, we often see the GFS doing that in the far FI as it doesn't pick up the shortwaves at this range and the northerlies look like happening quite easily. When the event moves in the semi reliable timeframe, shortwaves and weaker heights further north spoil our chances.

Hi Kayro

I'm merely taking what I see from the output at face value, regardless of its historical verification. It certainly helped me when I was a "beginner" and I was not sure what could happen looking at the broader NH picture/profile. It wasn't until I saw these potential reloads get scuppered by shortwaves nearer to the time etc, that I started to get a bit more experience of Model watching as to what you state. You are more than likely correct RE the Shortwaves and the GFS tendencies to deal badly with what looks like a clear cut Northerly, but it can be a lot to take in for beginner's.  

Cheers

Karl 

  

Edited by Polar Maritime
To move discussion on..

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4 minutes ago, karlos1983 said:

Hi Kayro

I'm merely taking what I see from the output at face value, regardless of its historical verification. It certainly helped me when I was a "beginner" and I was not sure what could happen looking at the broader NH picture/profile. It wasn't until I saw these potential reloads get scuppered by shortwaves nearer to the time etc, that I started to get a bit more experience of Model watching as to what you state. You are more than likely correct RE the Shortwaves and the GFS tendencies to deal badly with what looks like a clear cut Northerly, but it can be a lot to take in for beginner's.  

Cheers

Karl 

  

No problem Karl, I got excited on numerous occassions in the past to be treated with disappointment in the end. Of course, occassionally those charts can come off but the percentage is sadly low.

Edited by karyo

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I must say, that I've never been fussed by all the 'shortwave hysteria'. I appreciate model 'downgrades' can be somewhat tiresome; but computers cannot 'downgrade' the weather...:D

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Well looking at the GEFS Purbs at +180 timeframe it is hard to argue we won't see a northerly and much colder conditions of some sort next week. 

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=180&code=1&mode=0&carte=1

Scrolling through them all is not disheartening in the slightest. Purely talking for our cold next week, not the prolonged nature of it. 

 

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Nothing to get to phased about this morning' as evolution to cold is just that...evolving! 

The recent modelling of possible split-polar vortex via cross polar flow has somewhat diminished "given" however waa into point Greenland still remains optimistic. Large lobe stagnant vortex in/and around top Canada remains the fly in the ointment' in thw craved Atlantic block.

This is still very much open for function as the NCEP stress in last night's analysis. And as things stand it an open book in regardsto getting a window of opportunity to get heights into that area (greenland) atm its threading a rope through the eye of a needle scenario. ...but as again coming model evolution could turn the rope into a cotton thread' and send waa to meet the Arctic high...then a whole different nw euro/uk picture will evolve......and tge root to cooling be comes the root to the freezer! 

Resolve is not nearly there ....yet!

gfsnh-0-360.png

gfsnh-0-384.png

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For reference in terms of what I said - there has been significant change in the models ( most notably the GFS ) which swung the cold west- all that was missing was a higher amplitude wave in the atlantic

Projected GFS day 6 thurs 1pm

gfs-0-138.png?12

 

Probable verification

gfs-0-48.png?6

 

Upper Air projected

gfs-1-144.png?12

 

Upper air probable verification

gfs-1-66.png?6

 

For London then I make that a swing 8 degrees & for most 4-6 degrees.

Not quite enough for the full on Cold & snow-  but you would have to be Stevie wonder not to see the difference.

 

 

Edited by Polar Maritime
To move discussion on..

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One thing the models have definitely underdone is the MJO. Numerous forecast modelling has had it little amplified and returning to the COD. 

Yet it continues now fairly well amplified into Zone 7 through 8.

I wonder therefore if the Atlantic ridge next week will prove more resilient. 

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Only just catching up with the outputs. Putting aside the debate re shortwaves which I'm sure you'll be relieved about given my past obsession of them!

The ECM quite disappointing this morning, it moves that lobe of PV west across Greenland and this isn't want we want to see.

Unfortunately there is no agreement between the big 3 upstream at T144hrs. The GFS 00hrs run was quite nice because the idea of a shortwave dropping se from Greenland is a possibility.

We're not seeing deep and amplified low pressure upstream to deliver some WAA into Greenland , we really need a good interaction between south/north streams of the jet over there and one system running ne up the west side of Greenland.

Overall it still looks on course to become colder, I think to prolong the cold without a proper Greenland high is going to need some more upstream amplification to help pull back the PV and allow some shortwave energy to run se under the UK with the Arctic high hanging on to the ne.

 

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