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


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If the  GFS and UKMO do verify then the potential for disruptive snow initially from the Midlands Northwards Monday-Wednesday thereafter those further South, must be high on the agenda for next week. What is quite remarkable is how quickly this has upgraded from a block to our East  and being a slow burner to a potential wintry week ahead.

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Well I wanted to sit back this year and watch the models whilst reading the posts in this thread but I can't help posting in exitement. Model watching has been painful of late and now we are heading through the new year we are being spoilt!

 

The GFS 12z is by far the best for decent cold and a snowfest for a hell of a lot of peeps with the snow being driven well inland from the east. 

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014010812/gfs-2-192.png?12

 

Beautiful, bring it on. Mind you, still time for it go pairshaped yet.

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If the  GFS and UKMO do verify then the potential for disruptive snow initially from the Midlands Northwards Monday-Wednesday thereafter those further South, must be high on the agenda for next week. What is quite remarkable is how quickly this has upgraded from a block to our East  and being a slow burner to a potential wintry week ahead.

 

Thats winter for you things can change rapidly if everything falls into place

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I think I'd prefer the UKMO way from an IMBY perspective but any of the models look nice at the moment given the recent weather pattern.

Amazing how quickly things have turned around, a shortwave will probably appear from nowhere and ruin everything soon enough!

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Based on History alone that line is likely to be further South West come T0...... 90% always is in a battle ground scenario, that's what the ECM 00z overnight with the colder 144 chart could be favourite...

 

Summer sun where is your Euro temp anomaly chart today Posted Image

S

 

http://forum.netweather.tv/topic/78936-model-output-discussion-1st-january-2014-06z-onwards/?p=2889380

 

:)

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i am an absolute newbee.But reading this thread has been very exciting.Lots of knowledgable folk in here.Keep up the good work its a great read and interesting getting peoples differing views,though everyone now seems to be going for cold! which is great news.Living in Liverpool its a bit of a downer but if we get snow anywhere close by a trip will have to be made

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Wouldn't it be coincidental if it were to snow next Friday, exactly a year after many people's first snow last year.

What I was thinking!! A clear example of when the models underestimated a Scandi block was last year, with a very similar setup...

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If you must worry about how long something will last which has not even happened you should read the guide for forecasters on Scandi highs posted by JH yesterday. It clearly states that the longevity of the block does not depend on its size. Quote 'The intensity of the anticyclone on the day of formation has no effect on persistence'. The main factor is the  mobility to the East of the block. There are then someguidlines as to what factors affect the persotence of this set-up. I reattached it in case you did not see it yesterday.

Posted ImageEmpirical rules for scandinavian high to developc.doc

 

This was also borne out last January when we had a small block with central pressure of only about 1015 mb which proved quite resilient. 

Posted Imagearchives-2013-1-20-0-0.png

 

http://www.meteociel.fr/modeles/archives/archives.php?day=17&month=1&hour=0&year=2013&map=0&mode=2

 

It is the orientation and placement of the block which is most important in my view.

thank you very intresting read thanks jh. and to be fare I remember the block last winter and indeed it was very robust.

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Can anyone help me, What is the thick black line between yellow and green called? And why is it relevant (i.e. bolded in this way)

The black line is the 552 dam contour (of the 500 hPa surface) - highlighted as the approx. median value to trace major troughs/ridges in pattern.
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Ignoring the long term trends for now for the reasons Ian described above (although I must say there is little evidence of anything "mild" for the foreseeable), the GEFS highlight the split conundrum well next week;

post-12721-0-89406800-1389204214_thumb.jpost-12721-0-38215600-1389204236_thumb.j

Still enough members suggestive of a "non easterly" there to give the option respectable credence. However, with the Op & Control supporting the cluster that do go "cold" for the past 4 GFS runs now, you have to at this stage, favour the easterly happening rather than not.

850hpa and PPN detail is irrelevant at this stage until the positioning and tilt of any pressure build in the GIN corridor is accomplished. This will then dictate the true source of any continental airmass we are to receive.

Hopefully Ian could share the 12z Met Office assessment with us (or what pieces he is authorised too) later tonight to see what, if any, changes are apparent compared to the earlier publicised medium range forecast today. Although off course, we still await the all important EC date though, which could influence that greatly.

Edited by AWD
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GFS 12z ensemble showing a clear trend to something cooler during next week

 

Posted ImagePosted ImagePosted Image

 

All over to ECM now

"Something Cooler"? on those graphs I would have said "Something very much colder"Posted Image

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gem the last chart is messy but the rest our beautiful

Posted Image

 

Messy can be good! A chart that doesn't necessarily scream potential can often deliver snowfalls!! GEM overall an absolute peach tonight! 

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Anyone fancy pointing out the Positive differences of ECM @ 72 V GFS 72

 

ECM

http://www.meteociel.fr/modeles/ecmwf/runs/2014010812/ECH1-72.GIF

 

GFS

http://modeles.meteociel.fr/modeles/gfs/runs/2014010812/gfsnh-0-72.png?12

 

Not noticeable unless you look at both.

 

Answers on a postcard!

Stronger heights over the Pole? :D

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Anyone fancy pointing out the Positive differences of ECM @ 72 V GFS 72 ECMhttp://www.meteociel.fr/modeles/ecmwf/runs/2014010812/ECH1-72.GIF GFShttp://modeles.meteociel.fr/modeles/gfs/runs/2014010812/gfsnh-0-72.png?12 Not noticeable unless you look at both. Answers on a postcard!

EC has SW/NE tilted pressure to our north.
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Anyone fancy pointing out the Positive differences of ECM @ 72 V GFS 72

 

ECM

http://www.meteociel.fr/modeles/ecmwf/runs/2014010812/ECH1-72.GIF

 

GFS

http://modeles.meteociel.fr/modeles/gfs/runs/2014010812/gfsnh-0-72.png?12

 

Not noticeable unless you look at both.

 

Answers on a postcard!

 

Trough disrupting slightly further S&W & slightly more amplified, slightly higher heights to the N, and quicker advection of colder uppers to the E/NE.

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Anyone fancy pointing out the Positive differences of ECM @ 72 V GFS 72

 

ECM

http://www.meteociel.fr/modeles/ecmwf/runs/2014010812/ECH1-72.GIF

 

GFS

http://modeles.meteociel.fr/modeles/gfs/runs/2014010812/gfsnh-0-72.png?12

 

Not noticeable unless you look at both.

 

Answers on a postcard!

 

 

Higher heights over svalbard, low in atlantic is also slightly further south and west. The whole pattern seems very slightly further west.

 

 

 

 

Dan 

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Time for one of my paintjobs!

 

Posted ImageUN144-21.gif

 

Okay upstream circled red is the amplified wave, the arrows the direction of travel, the low to the west of the UK will react to this wave as it approaches, it will force energy to disrupt se reinforcing low heights over the Med as this happens the cold will get pulled in from the east.

They look very similar to me with the UKMO wave looking just a little more amplified.

The result would be the same though.

ECM out to t96 looking great.

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