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Model Output Discussion - cold spell to end Autumn


Message added by Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

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You know what - I havent seen 1 hopecast on here. People have put all their points of view across in a pretty good mannor- infact its been pretty good debate. The only post that sticks out a mile

Still coming slowly off a cautious fence Long term total global atmospheric angular momentum trends can tell you a lot about pattern changes due to the effects the rises and falls in global wind-

Afternoon All - A frantic few days on here with pages & pages of posts flying through in a matter of hours- I think we have 2 main discussion points at the moment-  1) The short to

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8 minutes ago, carinthian said:

Evening all. Our latest snow model has updated the amount of fresh snowfall with 33cm expected on Monday for our location in the Alps. As regards to Sundays snowfall prediction  back in the UK, a shift southwards in the higher percentage range . The experts we use think the slider may well be corrected again by UKMO tomorrow before firming up on snow prediction with-in the 72 hour range. Heaviest snowfall could well be on the higher ground to the NE of the triple point associated with the low pressure . So looking at the latest UKMO fax charts , that looks like NE Wales, Southern Pennines, and West Midlands . Some snow could fall to lower elevation later on Sunday night further south as the 250mb jet  sends the slider further south with a undercut of colder air again. A small warm sector , mainly to affect the SW . Looking further ahead they also indicate the second slider could go even further south and west, so Eire and SW England at risk of snow ( currently 20%) but could increase near the time. Mid Month still favour pressure rise to the NW later to NE towards Christmas but that's a long way off and a lot of weather for you guys to enjoy/endure. Good luck for those wanting snow!

You did call this brilliantly yesterday mate and mentioned the fact that the slider might slide further south and include more of the midlands and thats whats happened!!i also fully expect the ukmo to take it further south by tomorrow mornings run!!before that we got the cheshire gap snow situation to deal with!!fingers crossed!!also after looking at the ukmo at 96 hours i think precipitaion would remain as snow across the midlands northern england and east anglia as 850 temps never drop below -3 in these areas and taking into fact surface cold!!

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7 minutes ago, shaky said:

You did call this brilliantly yesterday mate and mentioned the fact that the slider might slide further south and include more of the midlands and thats whats happened!!i also fully expect the ukmo to take it further south by tomorrow mornings run!!before that we got the cheshire gap snow situation to deal with!!fingers crossed!!also after looking at the ukmo at 96 hours i think precipitaion would remain as snow across the midlands northern england and east anglia as 850 temps never drop below -3 in these areas and taking into fact surface cold!!

Hmmm dont be too sure shakster- APREGE joins UKMET/GEM in taking the low further north...

middle ground would suit me and you both!!

Edited by northwestsnow
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2 minutes ago, tynevalleysnow said:

Aparge looking good for most 

IMG_3627.PNG

Yes its a brilliant run!!

Better than GFS for more people too :)

but then again GFS is superb all the way out to the end!!

Edited by northwestsnow
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At T96 hrs upstream the UKMO has an 985 low compared to the GFS shallow feature. Because of that deepening this low runs more ne inflating lower heights over Greenland.

This dominos further and will effect the track of the next low into the UK.

NOAA will definitely be commenting on this later as it effects the New England states.

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1 minute ago, Summer Sun said:

I'm guessing GEM is underestimating the 850's?

gem-1-102.thumb.png.b1da237df9cd34859bff173705395fc5.pnggem-1-120.thumb.png.dbce6b96a07fed289b7e169ed16a075e.png

gem-1-144.thumb.png.b839e50eb7af872acc4f67a65bf5f030.pnggem-1-192.thumb.png.06c957e89d4696ea964ba11baa8566ff.png

gem-1-240.thumb.png.4d1cefa4d702086b37c7554480f6233f.png

Absolutely it's a known issue with that model, I don't understand why they cannot resolve the issue, 

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5 minutes ago, Summer Sun said:

I'm guessing GEM is underestimating the 850's?

gem-1-102.thumb.png.b1da237df9cd34859bff173705395fc5.pnggem-1-120.thumb.png.dbce6b96a07fed289b7e169ed16a075e.png

gem-1-144.thumb.png.b839e50eb7af872acc4f67a65bf5f030.pnggem-1-192.thumb.png.06c957e89d4696ea964ba11baa8566ff.png

gem-1-240.thumb.png.4d1cefa4d702086b37c7554480f6233f.png

The GEM is a dreadful model to be honest, once a few years ago it picked out a pattern before the big 3 and now everyone still uses the poxy thing! 

It can go in the same basket as the good old BOM imo!

Edited by Weathizard
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1 minute ago, Weathizard said:

The GEM is a dreadful model to be honest, once a few years ago it picked out a pattern before the big 3 and now everyone still uses the poxy thing! 

And yet:

cor_day5_HGT_P500_G2NHX.png

The "big 3" is actually ECM/UKMO/JMA with the GFS/GEM neck and neck trailing behind. Of course, on a day to day basis any one of those models could verify better than the others, but over a month the order is clear.

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3 minutes ago, Yarmy said:

And yet:

cor_day5_HGT_P500_G2NHX.png

The "big 3" is actually ECM/UKMO/JMA with the GFS/GEM neck and neck trailing behind. Of course, on a day to day basis any one of those models could verify better than the others, but over a month the order is clear.

Possibly but are these charts on a global scale? I never really understand how you can measure the accuracy of weather models with data as surely it varies, certain models are more accurate for certain areas in the globe ect.

IMO the GEM is utterly useless when it comes to 850's and more generally on our side of the pond.

Edited by Weathizard
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Cold ens tonight with a lengthy period of below average temps the only uncertainty is how much snow we will see in the coming weeks

Black line is the 30 year average for those not familiar with the below chart

gefsens850London0.thumb.png.994746c2485efb8e6a0c8f12689ea4cb.png

gefstmp2mmaxLondon.thumb.png.c3d659f670f6ec3a7a8c09db43f69836.png

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10 minutes ago, Weathizard said:

Possibly but are these charts on a global scale? I never really understand how you can measure the accuracy of weather models with data as surely it varies, certain models are more accurate for certain areas in the globe ect.

IMO the GEM is utterly useless when it comes to 850's and more generally on our side of the pond.

There's a model bias page you can check for that:

http://www.wpc.ncep.noaa.gov/mdlbias/

You can put in height, temp at various levels, etc. There's nothing really conclusive to my eye. 

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35 minutes ago, V for Very Cold said:

This Is model watching at its best.... I must just remember to get off the PC and check what’s happening outside! :yahoo:

 

When it does snow, people will miss it because they will be in here posting about when it will stop or where the next lot is coming from:rofl:

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