Winter Model Discussion 12Z 15/1/13 onwards.

[UV-RAY]

Im exactly the same Nick.

Quiet an unusual set up because normally you associate a front moving in from the Atlantic bringing milder temps but due to the pivoting front we actually see colder upper temps arrive from the E. Looking at the predicted temps when the front arrives it certainly won't be marginal because widely temps are below freezing and so are the dewpoints (-3C), upper temps across the E at -10C.

Where im dubious is how the front even manages to get to my region. Now history tells me it never makes it this far NE. Looking at the UKMO between +72 & +96 and im unconvinced whats its showing.

So for now I would say Wales, SW, W Midlands have plenty to be excited about but for the rest of us I would hold on a while.

Wise words indeed, for anyone who remembers winters from the last 20 years and beyond will be familiar with such a scenario. With such a stubborn block in place and as much as I would love to see what the models are showing, I can't help but feel that the Northern extent of any snow will be much further South than being modelled, please let me be wrong though. Edited January 15, 2013 by Sceptical Inquirer

[weather is fun]

Fantastic run of models tonight. Infact exceptional. Now a word of caution this looks like getting no further than the midlands for the snowfall. So us north of birmingham dont get too carried away by snowfall totals. As i think the front will fizzle out somewhere around the midlands. But south of there looks like getting a serious dumping if tonights gfs and ukmo prove correct

[kev238]

I haven't looked at the models but just read the comments. Have to say it sounds amazing on face value for many areas, with my area, Nottingham, potentially doing very well.

However, so often these fronts grind to a halt short of Nottingham and slide away, so I will reserve judgement, especially as the met office warnings for Friday seem to suggest just that happening at the moment.

Things will prob become clearer by end of tomorrow as to what Friday and Saturday brings. I remember February 2007, when a push from the south west was to meet with a cold wave from the north, in what was a very mild winter. For about four days we were forecast up to ten to fifteen centimetres, a south correction occurred at the last minute, and we got a few flurries. The next day, a band pushed up, unexpectedly and gave more than the previous day.

This illustrates how difficult these pushes from the south west can be with their northern extent.

The other point to make is that if these fronts push through this far, then almost inevitably it will mean less cold weather for a fair few places to the south west.

[fergieweather]

i read mods as 'models' - if its modifications its different, but which is it?!

Mods - Modifications

i.e., 12z NAE prog through Thurs considered outlier and currently discounted - but clearly if it was with support, it would have profound implications on rate of mild push into Friday etc. But UKMO-GM and GFS 12z's favoured as it stands. Very tricky, very high stakes down at Ops Centre.

[JOPRO]

10cm snow cover in the North Sea is indeed exceptional.

Maybe thats Settled on Sea Ice!!

[phil nw.]

Now we can see why the 2mtr temperature ens graphs have been suggesting close to or below freezing daily readings for the next week to 10 days.

The GFS and UKMO runs are both amazingly cold and snowy -the GFS for a lengthy period.

It shows what can occur with quite modest heights further north as long as the jet undercuts to the south of the UK.

One thing though the far south west of England and west Wales may see dew points rise above 0C after a while as some of the Atlantic air mixes into the system- thus making the snowfall there a temporary event.

For large areas of the UK though if this run verified snow would be falling for many and it would remain bitterly cold afterwards.

Edited January 15, 2013 by phil n.warks.

[from russia with love]

So what are the chances of snow from this front for Cambridge according to the latest set of models. Looks like a snowy gfs run and should be one of the coldest runs. Anyone who replies to this post will be of greatest help as i am travelling from cambridge to bristol early saturday morning.

[stratty]

So what are the chances of snow from this front for Cambridge according to the latest set of models. Looks like a snowy gfs run and should be one of the coldest runs. Anyone who replies to this post will be of greatest help as i am travelling from cambridge to bristol early saturday morning.

If the charts come off as shown - bloody good luck to ya!!!

Ensembles will be interesting reading to see where the 12z sits.............................

Edited January 15, 2013 by stratty

[weather eater]

Mods - Modifications

i.e., 12z NAE prog through Thurs considered outlier and currently discounted - but clearly if it was with support, it would have profound implications on rate of mild push into Friday etc. But UKMO-GM and GFS 12z's favoured as it stands. Very tricky, very high stakes down at Ops Centre.

Tricky, it would be great to be a fly on the wall in the Ops center if the ECM backs the UKMO and GFS, obviously the MO will not want to call anything to early we all know how quickly things can change.

[Weather Boy]

Can anyone more knowledgable please clarify why we are looking at a probable undercut in this scenario when we have a relatively weak block (1020 mb or so) coupled with a ferocious amount of energy in the Atlantic (even allowing for the GFS being OTT as it surely is in that regard)?

Is it because with low pressure over the continent, the energy looks likely to take the path of least resistance, and that is to be found to the south?

Compare this to December. Why does the Atlantic not just blast the little Scandinavia high aside, as it did then? Yes I am a little sceptical about the models, but I guess if even the GFS is starting to show that at fairly short range....

[Julian]

Mods - Modifications

i.e., 12z NAE prog through Thurs considered outlier and currently discounted - but clearly if it was with support, it would have profound implications on rate of mild push into Friday etc. But UKMO-GM and GFS 12z's favoured as it stands. Very tricky, very high stakes down at Ops Centre.

Thanks again for your input Ian.

This really is a "devil if you do devil if you don't" situation for you guys wrt calling an event for Friday/Saturday.

[Timmytour]

The NAE is a big surprise - Thursday now another snow event for central/western areas - rain into the SW. Has this just come out of nowhere or have a missed something?

However, the pressure pattern for Europe hasn't changed too much - a little further east but not much:

NAE:

UKMO:

And still looking good for undercut on Friday/Saturday

Edit: just seen note from IF above - well, we shall see!

Who's that fella walking behind the front on the NAE? Looks like he knows he's let it go too soon and is walking after it to pick it up and have another go

[Methuselah]

Mods - Modifications

i.e., 12z NAE prog through Thurs considered outlier and currently discounted - but clearly if it was with support, it would have profound implications on rate of mild push into Friday etc. But UKMO-GM and GFS 12z's favoured as it stands. Very tricky, very high stakes down at Ops Centre.

Thank you for that, Ian. It's clearly a forecasters' nightmare...

[randomwalk]

Who's that fella walking behind the front on the NAE? Looks like he knows he's let it go too soon and is walking after it to pick it up and have another go

Must be the Chief

[Jason M]

Thank you for that, Ian. It's clearly a forecasters' nightmare...

Yep, worth noting as well the METO 120 & 144 charts started to pick up the undercut first and was promptly discounted as an outlier. Outlier doesnt always mean wrong and if NAE was in our favour we wouldnt be discounting (not that its exactly a disaster :-) )

Jason

[mickpips]

Our 'independant' ex met office forecaster for Yorkshire 'Paul Hudson' has made it quite clear the uncertainty for the weekend but states at some point that a disruptive amount of snow can be expected this weekend , and timing currently varies from Saturday night through to Sunday night but likely to turn to rain into Monday away from higher ground. With next week being unsettled and 'less cold' with periods of rain and snow to hills... take from that whichever model output you require, but I'm assuming he still has contact sources at the MO

Edited January 15, 2013 by mickpips

[johnholmes]

Hi John, .... What exactly should I be looking at here.... soo many options on Extra.

try these

msl and rainfall

msl and dewpoint

uk and 850mb temperatures

wet bulb temperatures

freezing level

max and min temps

I could go on but that should give you a 'feel' for how each run is dealing with the weather patterns as far ahead as you wish to go. Maybe stop at T+144 sometimes even before then for reality.

enjoy

[swfc]

Our 'independant' ex met office forecaster for Yorkshire 'Paul Hudson' has made it quite clear the uncertainty for the weekend but states at some point that a disruptive amount of snow can be expected this weekend , and timing currently varies from Saturday night through to Sunday night but likely to turn to rain into Monday away from higher ground. With next week being unsettled and 'less cold' with periods of rain and snow to hills... take from that whichever model output you require, but I'm assuming he still has contact sources at the MO

have you a link?.thanks

[Glacier Point]

12z GEFS beginning to amplify in the mid Atlantic.

Comparison with yesterday at the same time we can see the anomalous ridge extending further north on todays day 9 comapared to yesterday's day 10.

That is important because it delays the eastward progression of the longwave trough exiting the eastern US (exceptional cold coming there) and sharpens the trough over Europe, increasing the chance of further undercutting shortwaves and a more substantive eddy developing when the jet relents (which invariably end up strengthening heights over Scandinavia). We can see this is trend today for a renewed surge or perhaps 2 surges from the NE.

[fergieweather]

Our 'independant' ex met office forecaster for Yorkshire 'Paul Hudson' has made it quite clear the uncertainty for the weekend but states at some point that a disruptive amount of snow can be expected this weekend , and timing currently varies from Saturday night through to Sunday night but likely to turn to rain into Monday away from higher ground. With next week being unsettled and 'less cold' with periods of rain and snow to hills... take from that whichever model output you require, but I'm assuming he still has contact sources at the MO

Yes - that's the UKMO view into next week as based on 00z output but we await updated version circa midnight based on 12z runs.

[Snowman.]

Even though we have this event this Weekend what's happening with the PV?

Do you think after a sort of mild 'blip' we could be sent into another cold blast or raging PV?

[Polar Maritime]

Even though we have this event this Weekend what's happening with the PV?

Do you think after a sort of mild 'blip' we could be sent into another cold blast or raging PV?

Read GP's post above.

[Barry12]

Yes - that's the UKMO view into next week as based on 00z output but we await updated version circa midnight based on 12z runs.

Hi Ian, whats your take on the chinese model - cma?

[mickpips]

have you a link?.thanks

No , he was was giving his daily views Live on Radio Leeds, he does tend to give his views quite often on the differences when there thrown up between the GFS and the UKMO outputs

[Skyraker]

This is model related.. trust me...

As others have hinted , this model output is similar to Jan 1947... As much as I love snow and cold, the following makes sober reading.

"The winter is also cited as a factor in the devaluation of the pound from $4.03 to $2.80, Britain's decline from superpower status and the introduction of the Marshall Plan to aid war-torn Europe."

You can google it , but here is the link. (There are models in there)

http://en.wikipedia.org/wiki/Winter_of_1946%E2%80%931947_in_the_United_Kingdom

Mods, feel free to move this to ramp/moaning if need be.

Edited January 15, 2013 by Skyraker