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Model Output Discussion - The Run In To Christmas


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Whilst I agree with Ian that the met office shouldn't "scare" the public with warnings of snow etc I don't see why they can't just forecast the most likely scenario!? Their latest forecast (below) fof the period Boxing Day to new year bares no resemblance to any of the models / means we can see! Can Ian update us as to whether this fits in with models he can see ie MOGREPS ?

"Showers will likely ease during Boxing Day. Thereafter, it is thought it will be generally windy throughout with further spells of wet and mild weather, interspersed with colder, showery conditions. "

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It's a little unusual for the METO to say anything further than 5 days, and for Boxing Day that means 21st December, another 3 days away from now. They have clearly been forced into something they don't normally do because of the Christmas issue.

 

With a pattern change and uncertainty in the models I suggest that 5 day rule is even more important. There are still too many variables in the mix. I don't think we will start to see a firm-up on the Christmas period until the model outputs this Saturday and Sunday, perhaps even Monday morning.

 

However, with all those caveats in mind, a colder spell does seem very likely. 

Edited by West is Best
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A quick question for those who have a far greater understanding of this than I and apologies if this is not right forum for this question. Why is that America can forecast their Winter snow and weather (be it vast snow storms or just a harsh very cold period) a lot further ahead than us? Or like us, could their models be showing a raging snow storm (equivalent to our Easterly say) and then this get dropped within a very short window, like 72/48 hours. 

 

Thanks in advance  :friends:

As someone who has a lot of close family in Colorado I can assure you that forecasters do *sometimes* get it wrong, but it is much rarer. This is because weather in a continental climate is much easier to forecast at medium range than in a maritime climate. 

 

Usually snow forecasts for the CO resorts are pretty accurate at 3-5 day range. 

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A quick question for those who have a far greater understanding of this than I and apologies if this is not right forum for this question. Why is that America can forecast their Winter snow and weather (be it vast snow storms or just a harsh very cold period) a lot further ahead than us? Or like us, could their models be showing a raging snow storm (equivalent to our Easterly say) and then this get dropped within a very short window, like 72/48 hours. 

 

Thanks in advance  :friends:

Theres a greater margin for error in the USA because you're not dealing with the moderating effects of an ocean unless you're on the west coast.

 

In the USA a westerly for example circulating around low could still deliver some very cold temps, they of course still have problems with low tracks and who gets the snow,  it looks like they can make longer range calls but the fine detail still isn't possible.

 

So for example longer range can say a cold push se but with a country that vast some States might miss out. I think the problem in the UK is the media often take a higher probability as a forecast so one comment from the UKMO gets turned into a statement of fact.

Edited by nick sussex
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Fully understand the MetO's concerns and conservative approach but my personal opinion is that they should at least add caveats that there is a possibility of colder weather. As it is it reads like they are pushing mild zonal conditions after boxing day which while possible does not represent the output we all have access to.

 

"Showers will likely ease during Boxing Day. Thereafter, it is thought it will be generally windy throughout with further spells of wet and mild weather, interspersed with colder, showery conditions."

 

Why no caveat that there is the possibility of a colder spell of weather developing?

 

Surely if such sensible forecasts outlining the prospects of future conditions are misconstrued or misinterpreted that is neither the MetO's responsibility or main area of concern?

I would rather be fully informed of weather prospects by a public service than it worry about political correctness.

Edited by Mucka
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Fully understand the MetO's concerns and conservative approach but my personal opinion is that they should at least add caveats that there is a possibility of colder weather. As it is it reads like they are pushing mild zonal conditions after boxing day which while possible does not represent the output we all have access to.

 

"Showers will likely ease during Boxing Day. Thereafter, it is thought it will be generally windy throughout with further spells of wet and mild weather, interspersed with colder, showery conditions."

 

Why no caveat that there is the possibility of a colder spell of weather developing?

 

Surely if such sensible forecasts outlining the prospects of future conditions are misconstrued or misinterpreted that is neither the MetO's responsibility or main area of concern?

I would rather be fully informed of weather prospects by a public service than it worry about political correctness.

But they have mentioned colder, showery conditions, they probably feel that is enough at this moment in time .

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A quick question for those who have a far greater understanding of this than I and apologies if this is not right forum for this question. Why is that America can forecast their Winter snow and weather (be it vast snow storms or just a harsh very cold period) a lot further ahead than us? Or like us, could their models be showing a raging snow storm (equivalent to our Easterly say) and then this get dropped within a very short window, like 72/48 hours. 

 

Thanks in advance  :friends:

 

Because it's a big continental mass and the fact that you've not got 5 different air masses trying to fight for supremacy. Polar, Polar Maritime, Tropical Maritime, Polar Continental and Tropical Continental. So many different forces at work make for variable and unpredictable weather.

 

I'm originally from Perth in Western Australia and the weather forecasting there is far easier and very seldom wrong.

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not sure why people are disregarding the ukmo outlook...

 

'becoming mild wet and windy' is an option and has been shown on several models, the ecm in particular and yesterdays gfs 06z.

theres only potential in fi for a cold spell to develop, it has never been set in stone, so dont be surprised if faith in fi will be misplaced (not only in fi but in cold rampers too :nonono: )

 

 

Well in fairness, at this stage Colder blocked condition seem the favorable course of event. i.e. More likely than Mild and wet. Backed by at least 4 models at this stage. And not FI either, beginning as early as +150. 

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Well in fairness, at this stage Colder blocked condition seem the favorable course of event. i.e. More likely than Mild and wet. Backed by at least 4 models at this stage. And not FI either, beginning as early as +150. 

 

i accept that a colder spell is the most likely solution, and the 500mb anomaly chart i posted supports that. i think the main question is just how amplified an 'event' itll turn out to be. i did think when the gfs first showed a big freeze it was overstating the severity of the cold, and by contrast the ecm was understating it. the cold spell might well just turn out to be nothing much out of the ordinary. its too early yet for any degree of certainty.

but id suggest it is fi... as i understand fi it starts when uncertainty starts as opposed to a fixed time.

 

edit

btw im not suggesting the whole outlook beyond crimbo is wet and mild... the models do not support that, but some suggest more of what we have now, mild/cold spells, unsettled.

Edited by mushymanrob
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Won't be long though, Ian before the Metoffice will have to give out reasonable warnings so that those who plan to travel over the Xmas period are forewarned. ( Just keep the b word out of the forecasts!) The worst thing about the upcoming possible synoptics is that the likes of Madden will claim success and I find that really frustrating.

 

Agreed, but luckily still a week away and balance between windy-wet versus windy-snowy far from clear yet, if indeed situation eventually warrants warnings in formal sense. Still low confidence on outcome.

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Got to say I don't like that shortwave/low pressure that the GFS develops on this morning runs, it does alter the output somewhat and we know how that can harm any chances regarding cold weather. 

 

Its still too far out to be certain, its all still too far out for me but there are hints for sure of something perhaps more significantly colder on the horizon. 

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Yes big changes at D8 with a much flatter upstream and a push east:  post-14819-0-27915100-1418898833_thumb.p post-14819-0-55611300-1418898842_thumb.p

 

HLB to MLB looking the 06z trend?

Edited by i'm dreaming of...
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What happened to the cold charts....METO right not to be too excited by the cold possibilities looking at the 06Zs.  Actually the GFS P still looks good.

Edited by Ali1977
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I think we're going to get an in-between solution here (ECM and GFS P)

 

gfsnh-0-198.png?6

The lows don't merge on GFS P like ECM

 

ECM1-216.GIF?18-12

Edited by Vivian
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