Model Output Discussion - cold spell to end Autumn

[MKN]

3 minutes ago, Steve Murr said:

Afternoon-

Things looking pretty set now for a tasty snow event for regions North of the M4 coridoor - Whilst the tracks have generally corrected south - we are now seeing minimal adjustments - Also if we look at the finer detail over the last 24 hours the Entry point over Ireland hasnt swayed to much, its the extension of the snow belt over the south - caused by the elongation of the trough - 

Monday is more concerning for a smaller concentrated area - so whilst there will be good coverage over a wide area sunday, Monday have some really focussed heavier bursts of snow along the boundary of the -1c isotherm-

Elevated areas in the SE could find rapid build up of heavy wet snow- but there will be a sharp cut off point to rain ( expected in Mid Kent )

Anyway - enjoy the snow if it arrives !!

 

S

North of the M4 is optimistic compared to the BBC who expect rain by 11am south of birmingham. Of course it may start out as snow further south but that probably wont last much past 8-9am.

 

[A.J]

2 minutes ago, warrenb said:

Interpretations is correct, at the ground it would be bitter, but aloft the air is quite mild.

you called it a 'warm high'....that is not a warm high, not in the slightest.....I certainly wouldn't call the 850hPa temps mild (0C or considerably lower in the vacinity of the UK).....Granted, there isn't bitterly cold upper air associated with that particular scandi-hi chart) but to describe it as 'warm' is certainly using creative licence in my book .....go forwards a couple of slides and look at the really cold air digging into central/west europe.....lovely! (and pure FI of course)

[stainesbloke]

12 minutes ago, MKN said:

North of the M4 is optimistic compared to the BBC who expect rain by 11am south of birmingham. Of course it may start out as snow further south but that probably wont last much past 8-9am.

 

That's not what the MetO are saying and the BBC still get their information from them. 

[V for Very Cold]

So..... enjoyed a snow day and came back to find the models have tumbled into the arctic!

anyone want to give me a quick summary of the next week??? Lol

[bluearmy]

Judging by that beeb chart, the new fax will have the low over the n midlands 

 

[JBMWeatherForever]

Looking forward to see what Sunday brings. The front currently forecast to be just south of IOM at the moment, but obviously a continuingly changing picture. Currently outside we have a conservative six inches, with a two foot drift in front of the garage. More snow even than in December 2010.

[A.J]

just a quickie (no charts I'm afraid) IIRC the GFS has been playing around the idea of a Scandy Hi and attendant easterly for a few runs out in deep FI....the start of a new trend?......can't remember for sure (it's been so busy in here) but haven't Steve, Nick and a few of the 'model thread big hitters' have mentioned about looking for this sort of trend to make it's appearence aroound these time frames?  (stand corrected if wrong)

[bluearmy]

New fax for 6am tmrw shows the convergance trough remaining in place through the Cheshire gap - going to be some big totals in the same places that saw accums today 

latest gefs mean shows less Scandi upper ridge late on in line with the 00z run 

Edited December 8, 2017 by bluearmy

[RobR]

2 minutes ago, bluearmy said:

New fax for 6am tmrw shows the convergance trough remaining in place through the Cheshire gap - going to be some big totals in the same places that saw accums today 

No eastward shift then?

[shaky]

8 minutes ago, bluearmy said:

Judging by that beeb chart, the new fax will have the low over the n midlands 

 

Ukmo has the centre of the low in east anglia!!so in nearly in line with early fax chart but further east!!

[Sperrin]

@bluearmy any thoughts on the fax in relation to Ireland? Models appear to show different ideas regarding how far the precipitation will make it. Looks like it'll get as far as mid Ulster to me.

[feb1991blizzard]

5 minutes ago, bluearmy said:

Judging by that beeb chart, the new fax will have the low over the n midlands 

 

Although the forecast may have been presented later, that graphic was updated much earlier, that its the same graphic used to issue the midday graphic for the Internet.

 

 

[I remember Atlantic 252]

4 minutes ago, bluearmy said:

New fax for 6am tmrw shows the convergance trough remaining in place through the Cheshire gap - going to be some big totals in the same places that saw accums today 

latest gefs mean shows less Scandi upper ridge late on in line with the 00z run 

Hopefully a bit further east for my location, just had heavy snow, always thought Sat am was best chance

[Snowmadsam]

1 minute ago, feb1991blizzard said:

Although the forecast may have been presented later, that graphic was updated much earlier, that its the same graphic used to issue the midday graphic for the Internet.

 

 

That's correct. The BBC use 6 hourly "shows" as they are referred to on Weatherscape XT. BBC will next get guidance at 6pm this evening, then again at 10. 

I'm still thinking a 30 mile shift southwards, but remains to be seen

[BleakMidwinter]

7 hours ago, shaky said:

Before you know it these snow accumulation charts will look like the ecm one lol!!ecm forecasting 8 inches+ of snow for central england and wales!!

Uh... well, Telford (Shropshire) at 150m asl has had over six inches today, so...!

The charts are startling. I keep assuming they won't pan out, but at present, well, they are doing!

[feb1991blizzard]

3 minutes ago, Snowmadsam said:

That's correct. The BBC use 6 hourly "shows" as they are referred to on Weatherscape XT. BBC will next get guidance at 6pm this evening, then again at 10. 

I'm still thinking a 30 mile shift southwards, but remains to be seen

That's why ive seen many a discrepancy with forecasts been issued with model data that's out of date, annoyingly though I think the internet graphic, the one you switch between yourself with the slide scale is only updated twice a day at 2 days or more out, however, all that changes soon anyway because upto 36 hours they use 1 hour gaps, because upto 36 hours is updated wuth the same model as the MO map forecast, cant remember if its UKV or UK4.

[feb1991blizzard]

As you are with arome now coming into range.

[bluearmy]

12 minutes ago, RobR said:

No eastward shift then?

ref the current rough in the irish sea, nope, staying put. telford might be cut off before sunday's snow arrives!

[chris55]

With regards to the track of Sunday's low and associated snow potential I would be very impressed if the MET/BBC or any charts for that matter have this bang on and 100% accurate.

They have the best info and charts but at the end of the day, with such a finely balanced system regarding snowfall, and with such fine margins over a tiny section of the globe I would say to anyone 'whithin' the risk zone, and that's from Bristol ish up to Manchester ish, sit back, relax, and have a good old fashioned Radar/lamppost watch come Saturday night/Sunday. 

Its so easy to get caught up in the small changes run to run, but the system is incoming and what will be will be regardless.

 

 

 

Edited December 8, 2017 by chris55

[TEITS]

1 hour ago, Catacol said:

 

Until then a lot of NW airstreams with occasional northerly.... so cold/cold but not a big freeze.

That above is what I disagree with. The trend in my opinion is to lose the NW airstreams and be replaced by a milder W,ly flow.

[snowking]

6 minutes ago, feb1991blizzard said:

That's why ive seen many a discrepancy with forecasts been issued with model data that's out of date, annoyingly though I think the internet graphic, the one you switch between yourself with the slide scale is only updated twice a day at 2 days or more out, however, all that changes soon anyway because upto 36 hours they use 1 hour gaps, because upto 36 hours is updated wuth the same model as the MO map forecast, cant remember if its UKV or UK4.

It's the later (UKV) - although it's chief forecaster modified fields which are shown rather than the raw UKV output I believe

Edited December 8, 2017 by snowking

[bluearmy]

given the importance of giving good guidance for sundays 'event' it would be disappointing for the bbc to be issuing forecasts which are out of date or not in line with most up to date thinking. I wonder if ms lear mentioned that the area of snow could be south of this chart ?

anyway, latest euro4 is bang in line with its 06z chart and exactly the same as gfs12z at T42 with pressure centre placement. snow line costwolds across to Bedford/luton at that timescale

T48 the low e midlands/wash. snow line drifting n a little so s midlands across towards Peterborough and then up to just west of Norwich. interestingly, this shows accums all the way to the nw of Norfolk.

some kind soul can post this from weather online

Edited December 8, 2017 by bluearmy

[Snowyowl9]

Theres going to be some serious disruption to sunday Mondays snow strong easterly winds are showing drifting on hills especially.

Looking at the shropshire area for winds.

http://www.xcweather.co.uk/

Then a strong NEly further SE Monday quite an impressive setup.

http://wetterzentrale.de/pics/Rtavn721.html

 

[MKN]

Fair way North

[bluearmy]

ec 12z op has the two low centres exactly as gfs 12z T48 so hardly any divergence from the script on the ops we see.

 

Edited December 8, 2017 by bluearmy