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Model output discussion - the beast arrives


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Evening Guys  Officially signing off for the winter from my window - still all but 5 inches on the ground - have a great year ! Current   favourite   See

First rule of GFS model watching. Never trust a dartboard low....... But especially in this type of set up.

See you next Saturday then, Steve?

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41 minutes ago, Zak94 said:

h500slp.pngh500slp.png excellent, a significant increase in pressure over Scandinavia at 93 hours, forcing the jet stream to take a more southerly track. This is far from over!

Maybe I’m seeing things I barely see any difference! I think a negligible observation, however I do less of west based -NAO and a more inflated round Greenland high probably negligible too...

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So what would people forecast for thurs  be now,after looking at all the models.Even the met are not mentioning it in their video forecast this evening,seems it’s got everyone stumped lol:gathering:

Edited by SLEETY
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7 minutes ago, SLEETY said:

So what would people forecast for thurs Be now,after looking at all the models,even the met are not mentioning it in their video forecast this evening,seems it’s got everyone stumped lol:gathering:

It’s like Kryptonite no one wants to touch it! :D

For good reason as it’s still not sorted 3 days out.

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ok so lets look at bigger picture beyond Fridays low and where we trending.

I will use Icon to illustrate

18z-iconnh-0-120.png?26-18

 

12z-iconnh-0-126.png?26-12

trend is for vortex to be weaker displaced further south over Siberia. our low to go further south and weak surface heights developing to North east. over Pole we are seeing weak heights over Svalbard and each run the Aleutian ridge has a better attempt to gain latitude before it collapses. Now doesn't take great leap if trend continues to think that come day 7/8 that we may surface heights develop in Scandie at the same time the Aleutian ridge manages to get towards pole.

Models very slowly reacting to weaken Siberian vortex in response to second warming and also MJO going into phase 1?

 

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1 hour ago, nick sussex said:

And the low drama continues!

A flatter low as Phil just mentioned, this is better at keeping the colder flow ahead of it.

I really wouldn’t look past T96 hrs at the moment because as we’ve seen the models are making a real soap opera over this low.

You also have to factor in what the later output is showing , will that stay the same as they get closer in or will more forcing cause a southwards adjustment .

 

If the low flattens to much or stays too far to the south that would put the mockers on a notable blizzard for Southern England. We don't want it too stay too far away !

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I know this isn’t model specific but it is relevant to anyone dismaying about the events Thurs and Fri based on current output. 

I checked MetO for Swindon at 9pm or so and there was intermittent snow showing late Thurs and a bit of Fri. That’s now changed again to constant snow late Thurs, all of Fri and into Sat AM. 

To me this is a pretty clear indictation that, whatever the big 3 are spilling out, MOGREPS must be showing something else or a more favoured track of that low.

Hope that makes sense

 

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1 minute ago, Jemma Croton said:

I know this isn’t model specific but it is relevant to anyone dismaying about the events Thurs and Fri based on current output. 

I checked MetO for Swindon at 9pm or so and there was intermittent snow showing late Thurs and a bit of Fri. That’s now changed again to constant snow late Thurs, all of Fri and into Sat AM. 

To me this is a pretty clear indictation that, whatever the big 3 are spilling out, MOGREPS must be showing something else or a more favoured track of that low.

Hope that makes sense

 

H Jemma it does make sense but be cautious when viewing those automated forecasts . 

As for the attention seeking low to the sw we still need more runs because it’s a complicated set up.

It’s always a difficult juggling act for the outputs to work out the forcing from the north and the north ne movement of the low from the south .

50 to 100 miles either way can make quite a difference in terms of ground conditions.

 

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Surely the huge temperature difference between the bitterly cold air over the U.K. and the milder air associated with the low,is going to produce a mega blizzard somewhere ,hopefully the UK

At least the models FINALLY  agree that dense cold air is harder to push away than they  have been programmed to believe:gathering: 

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8 minutes ago, nick sussex said:

H Jemma it does make sense but be cautious when viewing those automated forecasts . 

As for the attention seeking low to the sw we still need more runs because it’s a complicated set up.

It’s always a difficult juggling act for the outputs to work out the forcing from the north and the north ne movement of the low from the south .

50 to 100 miles either way can make quite a difference in terms of ground conditions.

 

Always read them with a pinch of salt sweet. Just thought it might help some with the dismay xx

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Very quiet this morning :D

Both UKMO and GFS have the low further West on the 00Z runs. Slightly colder flow is maintained across much of the UK but for most of us we are stuck in no man's land.

Could be worse, although not what most of us want to see.

GFS: Rtavn1201.gif

 

UKMO: Rukm1201.gif

Edited by essexweather
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Initial low still oval shaped on Friday on GFS at T84:

gfs-0-84.png

gfs-1-84.png

Cold holds until next week, uppers below 0C even in the south on Wednesday T192:

gfs-1-192.png

gfs-0-192.png

UKMO more rounded at T72:

UW72-21.GIF?27-05

 

Edited by Mike Poole
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As I feared the dreaded mixer is back.

Milder air into the south in 72hrs on the GFS 

gfs-1-72.thumb.png.38d51fb523325436013a99c24643384f.png

Hate to say half the UK is into milder air after t72 ukmo and GFS swing back to quickly remove cold but northern England and Scotland remains cold for the rest of the runs.

Still here in balmy Portsmouth the snow is falling so it's still a bonus for down here disappointed to lose it quick.

Shame the second warming event came so late maybe February would have been a great wintry month.

Anyway I do now believe the fat lady is singing and for half of the uk at least it will turn milder or should I say average.UW72-7.thumb.gif.35e35c3257f617e6073f331cc90ec012.gif

The only crumb of hope is that met office has the low elongated like some have said more easterly influence to start but this low must stay south of UK for it to benefit for longevity.

 

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What a shambles,gfs has been utterly clueless in this position of the low pressure ,look where it is now compared to earlier runs.

 

Be surprised if they didn’t  give it completely overhaul ,

Like has been said before,probably only hit SW before retreating away S ,don’t think their be a big blizzard across the S now,maybe just SW,at most.

 

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21 minutes ago, MR EXTREMES said:

As I feared the dreaded mixer is back.

Milder air into the south in 72hrs on the GFS 

gfs-1-72.thumb.png.38d51fb523325436013a99c24643384f.png

Hate to say half the UK is into milder air after t72 ukmo and GFS swing back to quickly remove cold but northern England and Scotland remains cold for the rest of the runs.

Still here in balmy Portsmouth the snow is falling so it's still a bonus for down here disappointed to lose it quick.

Shame the second warming event came so late maybe February would have been a great wintry month.

Anyway I do now believe the fat lady is singing and for half of the uk at least it will turn milder or should I say average.UW72-7.thumb.gif.35e35c3257f617e6073f331cc90ec012.gif

The only crumb of hope is that met office has the low elongated like some have said more easterly influence to start but this low must stay south of UK for it to benefit for longevity.

 

To be honest I still think it's an upgrade to what we've been seeing in the last couple of days with the low being sent up across the uk and further north. We're starting to see the GFS model the cold pool and how it is slowing down the low and shallowing it. Don't get me wrong, an easterly trajectory would be far more favourable but the 0c isotherm only tracks inland briefly before being pushed south again on Saturday. Maybe i'm in denial but i don't think the fat lady has sung yet. I think late weds/thurs would be time to call it. I'm seeing echos of Jan 2013 happening. Low was modeled to send southerlies but with only 96 hours ahead, the negative tilt was picked up and there was a big snow event and the cold won (20 January 2013). I've added the models for comparison:

gfs-2013011600-0-108.png?0 gfs-2013012000-0-12.png?0  Left: 0z, 16th January, Right 0z 20th January. 

Maybe not the best example but it shows how the models struggle with cold pools. 

Below is the diagram for the clusters for the 0z GFS (Cambridge). So far the op is on a milder track compared to the other members 

Diagramme GEFS

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