Model Output Discussion - 21st - 28th November

[Liam J]

GFS continues to bomb a very deep depression for the end of the week, 940-945hpa centre tracking close to Northern Scotland with severe gales widespread over Northern Britain. I'm sure things will change before hand but should it continue in future outputs or even take a more southerly track than we could be looking at an exceptional wind storm event.

The depression is not without support either.

Edited November 27, 2011 by Liam J

[ukpaul]

In the high res looking more like the ECM but GFS tries to throw a low across the south later which I'd be surprised to see remaining in future runs. ECM looks more convincing to me but maybe this is GFS's halfway house on its way to the actual result.

[Grimsby Snow Lover]

Looks to me as if the PV has split,please correct me if I am wrong. Pressure also seems higher over Greenland too, shame its from the very last chart of the 18z GFS

http://hw.nwstatic.c...384/npsh500.png

Just to add a bit of spice to this FI chart, Mark Vogan is still pretty bullish of a pattern change around the 15th-20th December to something even colder as the PV is displaced. I know this is a minute straw to clutch at but it is something I will be look for over the next week or so.

Edited November 27, 2011 by Grimsby Snow Lover

[Zakos]

I was expecting the GFS to downgrade the snow potential for the early december cold snap, but, it has instead increased it. Very interesting. ECM also upgrading the snow potential. It's stil out of the reliable time frame, but I hope this upgrade trend continues. I think has a realistic chance of veryfing IMO,but I won't get my hopes up unless the cold spell has not dissapeared by tomorrows 18z...

[nick sussex]

Wow!, a very exciting 18z so far. A disturbed week, getting colder and windier with an extremely intense low pressure system tracking north of Scotland. One to keep an eye on. Following this system the air is polar in source and with a trough moving up the channel, severe flooding for parts of the south with heavy snow on its northern edge.

We all couldn't wait for the euro high to disappear, hopefully not a case of be careful what you wish for.

Yes let's hope it's one of those overblown GFS lows and is downgraded or disappears altogether.

Personally I've never understood the fascination people have with severe storms, for obvious reasons given past history down here in sw France I detest them!.

Overall I think theres quite a lot of uncertainty regarding the likely transition from this unsettled spell to the Azores high ridging ne in terms of how far north this gets.

[snowlover2009]

http://hw.nwstatic.co.uk/gfsimages/gfs.20111127/18/189/ukmaxtemp.png

http://hw.nwstatic.co.uk/gfsimages/gfs.20111127/18/189/h500slp.png

http://hw.nwstatic.co.uk/gfsimages/gfs.20111127/18/189/h850t850eu.png

http://hw.nwstatic.co.uk/gfsimages/gfs.20111127/18/189/6hrprecip.png

http://hw.nwstatic.co.uk/gfsimages/gfs.20111127/18/189/prectypeuktopo.png Probably snow over high ground or to low levels at times.

But wow, the biggest snow storm ever. I would love this to happen! It is rare to get a perfect synoptic like this, to get snow, with a low tracking south of the uk and bring all that precipitation and wind, along with cold temperatures and cold uppers for snow.

[damianslaw]

Yes let's hope it's one of those overblown GFS lows and is downgraded or disappears altogether.

Personally I've never understood the fascination people have with severe storms, for obvious reasons given past history down here in sw France I detest them!.

Overall I think theres quite a lot of uncertainty regarding the likely transition from this unsettled spell to the Azores high ridging ne in terms of how far north this gets.

GFS is verygood at picking up shortwaves and secondary low development in the short term - however, the chart is beyond the reliable timeframe so remains to be seen whether they continue to show such a feature in coming runs. One thing that we must take into account is how deep the low pressure system that tracked to the n of scotland became on friday - it deepened rapidly and caught many forecasters out - perhaps GFS may well be onto the right theme, the temp differentials between the atlantic and those very cold SST's near greenland would enable such a low to develop, indeed if things verified as shown then a particularly nasty event would unfold with severe gales very heavy precipitation that could very quickly turn to snow in places with a bit of height - we've had very benign conditions in recent winters with few storms - mother nature may well be about to bite back..

[Mark Neal.]

So the 18z keeps up the hints of snow in FI, but will this continue?,great to see even very far out of the reliable time frame,synoptics which would see a few on here happier than what we have right now,improvements are taking place i believe and we could be onto something in FI(hopefully).

[nick sussex]

I doubt there would be enough embedded cold at the surface, highest ground perhaps might see some snow out of that low on the northern flank.

But who needs that much drama over a bit of snow, the strongest winds would be on the southern flank of it, where the rain is! So whilst peoples roofs are getting blown off and power cuts break out and the inevitable tragic deaths if this storm was to catch a jet streak then we can all be happy for people being able to sledge down a high hill!

Even if I was still living in the UK and looked to be on the northern flank of the low, and even though I love snow it would be thanks but no thanks!

As people have obviously gathered storms are a touchy subject for me so apologies if this post comes across as throwing my toys out of the pram!

[kold weather]

Right here is a new thread folks, probably first true model thread of the winter!!

[Nick F]

Looks like the Euro trough which sets-up mid-week in place of the vacating Euro high might be a little more stubborn to move on on this evening's runs - particularly evident on the ECM operational. This is good news in that it keeps the jet on NW-SE tilt, keeping the British Isles under Pm air for longer.

Only really in FI does the trough move on allowing the Azores ridge in, so perhaps not particularly mild as we head through early December, though no noteworthy cold either, but some snow events possible for northern areas perhaps as the colder air interacts with some deep depression tracking east/SE under the strong jet.