Spring Model Discussion 18Z 6/3/13 onwards....

[SMU]

There is growing support for a PV lobe to get shunted into the heart of Scandi at day 8 ( 192 ) with the -20c isotherm circulating within that-

we are seeing SOME runs creating a SW movement of this circulation- as a result a few -10's / -12's & -14's now cropping up within the ensemble suite-

Im sure if we searched hard enough- maybe even a -16c-

So this weekend & into Monday presents us with 24-30 hours of snow potential then slightly less cold- with another potential reload from the east at day 8 with similarly cold air entrenched...

S

[Panayiotis]

There is growing support for a PV lobe to get shunted into the heart of Scandi at day 8 ( 192 ) with the -20c isotherm circulating within that-

we are seeing SOME runs creating a SW movement of this circulation- as a result a few -10's / -12's & -14's now cropping up within the ensemble suite-

Im sure if we searched hard enough- maybe even a -16c-

So this weekend & into Monday presents us with 24-30 hours of snow potential then slightly less cold- with another potential reload from the east at day 8 with similarly cold air entrenched...

S

Yes with the PV lobe over Scandi, cold is never far away. Lets see what the ECM 12z shows! Edited March 7, 2013 by Panayiotis

[Summer Sun]

12z ensembles lots of scatter from the 14th which is expected at this range

Aberdeen ensemble looks fairly stable

[LomondSnowstorm]

12z ensembles lots of scatter from the 14th which is expected at this range

Aberdeen ensemble looks fairly stable

Staggering to see the ensemble mean staying at -5C for most of Scotland for the entire run, through to the 23rd of March.

[Panayiotis]

Staggering to see the ensemble mean staying at -5C for most of Scotland for the entire run, through to the 23rd of March.

But remember the average for the time of year is around -4C/-5C, (red line).

[snowmadchrisuk]

12z ensembles lots of scatter from the 14th which is expected at this range

Aberdeen ensemble looks fairly stable

The Ensembles have decided to go mad about precipitation on the 11th (Mon) that is the first time I have seen them do that to that extent for London..

Edited March 7, 2013 by snowmadchrisuk

[BLAST FROM THE PAST]

Well, no HP 'building' from the south, our Gavin will have to wait a tad longer . On a serious note that UKMO is excellent, and the GFS isn't too shabby either...a nice move up again from 00z and may we see an 'upgrade' of snowfall anticipation??. Looking forward to see what the ECM brings......here we are...

This t96 chart - now that is Dartmoor, Bodmin, and Exmoor a place not to be.

BFTP

Edited March 7, 2013 by BLAST FROM THE PAST

[Snowman.]

Snowy.

Its also trying to suck in the Shortwave which could keep heights up.

Edited March 7, 2013 by SN0WM4N

[AWD]

Nothing springlike as you would hope for when approaching mid March. I would expect some low double figure temperatures being present in Mid March for the southern half of the UK but instead we have a possible Ice Day on Monday;

Followed by less cold, but still colder than average temperatures later next week;

The GEFS for London clearly show the upper air temperatures struggling for the foreseeable with the mean never getting above 0c at all, and only rising above -5c in FI;

causing surface temperatures to be below average for the south for the foreseeable future, typically around 5c with some days a bit colder and some a bit milder;

and even when we do have the less cold air temperatures later next week, the windchill will keep things feeling rather cold for mid March anyway, taking the edge of any soaring high single figure temperatures parts of favoured southern England might briefly hit;

Even by the end of next week, the projected Dewpoints are below freezing widely;

The conditions and feel of the weather is going to be cold for March all next week. Yes, the coldest temperatures will only last for the first couple of days, but will still remain below average for most, if not all of the week. Whilst the basic GFS temperature maps might show a 6c/7c/8c for southern England at some point next week, once you factor in windchill, Dewpoint values and any cloudcover, that MAX temperature will not feel all that great for the time of year.

Also, when factoring in any snowfall potential, there is a lot more too it than just cold uppers. In early Spring, evaporative and nocturnal cooling play a big part in conditions. I assume the GFS temperature maps don't take this into consideration (correct me if I'm wrong please) so when any shower cells pass over, the temperature will plummet due to lack of solar input etc and conditions for convective sleet/hail/snow become ripe again, but not for settling, lasting snow obviously.

With warm sectors caught in the flow midweek, the freezing level and Dewpoints do get moderated somewhat, so snowfall midweek will become less of an event;

But by the end of the week, they become favourable again;

Showing how difficult it is to forecast and how upper air temperatures, especially at this time of year, are only one small detail to consider.

So a lengthy below average spell of weather looks likely for most of next week, with a briefer very cold spell at the beginning of the week. With so much to consider regarding convective snowfall, its my opinion that its too early to look at that with any meaning and seriousness. I would suggest to take the GFS PPN type charts with a pinch of salt however.

Edited March 7, 2013 by AWD

[snowmadchrisuk]

Snowy.

Its also trying to suck in the Shortwave which could keep heights up.

Very Snowy to my eyes ... really blown up the low to the SW

[bluearmy]

The phasing of the small shortwave to our east and the cold front delays the southward clearance somewhat on sunday, especially further east. i wonder if that might spring a little surprise ?

[Snowman.]

ECM looks like the UKMO. GFS going its own route.

Edited March 7, 2013 by SN0WM4N

[Summer Sun]

Well, no HP 'building' from the south, our Gavin will have to wait a tad longer .

BFTP

Indeed non in the reliable but I found it in FI

Edited March 7, 2013 by Gavin.

[Captain Shortwave]

ECM looks like the UKMO. GFS going its own route.

I think heights are better over Greenland, probably closer to the GEM solution.

T144

Scotland, central/eastern England still under -8 uppers

Edited March 7, 2013 by Captain shortwave

[bradymk]

http://www.meteocent...rope.html#model some of you may like this, extended version of NMM hi res model. Not sure on the accuracy but here it is, you can view other variables aswell as precip. Look how cold the 850's are on it for Monday, -15c nearly reaches land. Also shows the potential precip in the east on Monday but still probably underestimating convective potential. Edited March 7, 2013 by bradythemole

[Mucka]

Any warm sector pushing through as the flow turns more to the North being kept further West on this ECM run (more GEM than GFS and the Op was again on the milder side of its ensembles in the mid term so it looks more like staying cold through next week after a bitter start to the week)

[Snowman.]

Heights strong north still, possible reload from NE.

[Snowman.]

STILL COLD at T168.

[Tom Jarvis]

another easterly coming up on the ecm!!!!!

[nick sussex]

The phasing of the small shortwave to our east and the cold front delays the southward clearance somewhat on sunday, especially further east. i wonder if that might spring a little surprise ?

Looking at the latest fax chart you might get that surprise,it looks a close run thing but I think theres a good chance that rain could turn to snow.

At this range though that might change, a difficult call, maybe the UKMO will mention it but highlight a lot of uncertainty.

It's funny the same shortwave which helps the UK with the transition to cold, ends up becoming a nuisance later as it takes a tour of the north Atlantic.

Edited March 7, 2013 by nick sussex

[chris55]

Very Snowy to my eyes ... really blown up the low to the SW

Yes SMC, although the Low to the south west has been consistently modelled to skim to the south of the UK, surely there is a slim chance any frontal activity associated could just push inland enough to produce a South West snow event!

[bradymk]

Yes SMC, although the Low to the south west has been consistently modelled to skim to the south of the UK, surely there is a slim chance any frontal activity associated could just push inland enough to produce a South West snow event!

I would say it is too far south west currently. Also as my post was hidden away somewhere, http://www.meteocenter.eu/WRF-forecast/EU/Europe.html#model some may like this, extended version of NMM with precip, temp etc

[snowmadchrisuk]

Yes SMC, although the Low to the south west has been consistently modelled to skim to the south of the UK, surely there is a slim chance any frontal activity associated could just push inland enough to produce a South West snow event!

I was thinking more it might enhance PPN rates over our area , If it does get any further North though , given it is Monday, a Classic SW Snow event could well happen .. Worth keeping an eye on cause recent runs are making it closer and deeper.

[Planet Stow]

http://www.express.co.uk/news/uk/382590/Britian-braced-for-eight-inches-of-snow-as-winter-roars-back

[Cheshire Freeze]

Energy heads SE again!

Could be a 'get your snow boots on' moment at 216 hrs

Edited March 7, 2013 by CreweCold