Winter Model Discussion 12Z 09/01/13> The hunt for cold ?

[Met4Cast]

I'm not sure that's correct buddy. Here is a quote from Liam Dutton's recent blog:

"Most weather computer models tend to focus on what happens in the lowest part of earth’s atmosphere (the troposphere) because this is where weather happens.

As a result, they are not very good in taking into account sudden stratospheric warming events as they occur so much higher up. Also, the link between stratospheric warming and blocking high pressures is a relatively new discovery in meteorology, with research ongoing.

The Met Office has tackled this problem by developing an additional model, called GloSea4. It takes into account what is going on higher up in the stratosphere in an attempt to better predict the effects it may have on the weather lower down."

Yup - The models are just picking up on the Trophospheric reaction to the SSW, rather than the SSW itself.

12z is rolling, lets hope for a better run!

[Coast]

perhaps the mods should post the link to the moaning thread before the model output images hit this forum

Great idea! If your post is actually not about the models, it will be moved or removed and maybe you should look to see if this thread is more appropriate:

[nick sussex]

Does that mean they don't think that shortwave is correct?

There is a degree of uncertainty with how quickly a front clears the eastern USA and this ties in with the differences between the models.

In terms of the southern USA shortwave for the timebeing they're happier with the ECM ensemble mean which clears a separate low ene without a shortwave hot on its heels.

We'll see very soon!

[mcweather]

I hope the mods don't mind but I thought it might be appropriate to put two of GP'S posts from the old thread this morning in at this point in the hope that we all may be able to maintain a sense of perspective about what appears over the next few hours.

Firstly post 677

If I could allay a few fears here..

The 10 hPa and 100hPa operational 06z still looks consistent with overall strat developments, and general signal for ridge in the NE Atlantic locale.

t300 GEFS mean height anomaly very well defined, ridge signal eastern side Greenland and deep trough over Europe including UK.

The operational GFS and some ensemble members maybe picking up a reasonable idea for shortwave development between Iceland and Greenland, which makes next week's forecast that bit more problematic. Clearly the quicker the cold uppers become embedded the better for snow prospects next week. Interestingly NOGAPS which had championed this idea has now binned it 06z. Just demonstrates the massive spreads that currently exist in the North Atlantic in the medium range and large scale inter-run disagreement in NWP.

That doesn't alter the general trend here. Cold to begin this weekend, continued signal for a slight moderation in this before cold becomes more aggresive once more, timed for second and most significant downwell from the SSW. Note how the GEFS and also ECM ensembles begin to re-intensify cold beyond day 10.

Bottom line - don't mistake a tendency to moderate cold next week (and undoubted model variability to expode that out of all proportions) with a failed cold spell.

secondly post 688 answering a question from Bradley the mole

@GlacierPoint Thanks GP, interesting that nogaps 00z picked this up and dropped it on 6z. Just a quick question, are you leaning towards ECM or GFS at this stage regarding next week.

70% ECM 30% GFS

happy model watching everyone

Edited January 9, 2013 by mcweather

[bradymk]

I didn't realise how similar the ECMWF and GEM were this morning, time for the 12z GFS

[Staffordshire]

Got a feeling there will be a northward movment of satardays snowfall, manchester brought into the firing line more, also the block being much stronger and stalling the front for longer

Edited January 9, 2013 by Staffordshire

[Snowman31]

what time are we looking out for the shortwave?

[Harsh Climate]

Cold air 50 miles further west on saturday than 6z, good start

[Skyraker]

That is some energy going into the lower half of the jet.

[Met4Cast]

T60.. signs of the jet splitting across Southern Greenland..

[-uksnow-]

what time are we looking out for the shortwave?

T90ish is crucial

[Southender]

Looks like that pesky Shortwave is cropping up again over S.Greenland.

[Weathizard]

Certainly looks a better angle of attack at 66 for the north, considerably colder uppers.

Higher pressure over Greenland as well as the ridge a few hundred miles further north.

Edited January 9, 2013 by Weathizard

[Harsh Climate]

Light snow showers moving into lincolnshire/yorkshire saturday afternoon

[AWD]

Here comes the Shortwave time;

Edited January 9, 2013 by AWD

[MrSunshine]

Saturday's low pressure seems to be tracking further North on the 12z GFS run, bringing more Northern cities like Manchester & Leeds into the firing line rather than the more Southern Cities, interesting times ahead...

[warrenb]

The tilt on the Azores high is better, shooting towards Greenland.

[chiffer]

Not been model watching for sometime still don't have the chance now. Is the pv split?

[P-M]

Light snow showers moving into lincolnshire/yorkshire saturday afternoon

And up the eastern UK towards the Borders surely looking at that....?

[Snowly does it]

At T72, shortwave in evidence, however things to the West look slightly better. Watch what happens around GL and the mid Atlantic to T96

[Southender]

Shortwave spolier again @ 78

[Ali1977]

Nogaps upgrading the cold

[Snowly does it]

T78. Houston......

This is going to go pear shaped I think, looks like we are being short waved into submission

[Summer Sun]

Shortwave spolier again @ 78

Sorry but whats a shortwave?

[Methuselah]