Model Output Discussion

[Thundersquall]

Of the face of it the 12Z is a downgrade, as by T+90 the milder southerly flow has become established.

But.... is this the beginning of an evolution into a more Southeaterly / Easterly scenario? Well.... maybe,

as that High appears over Scandinavia at T+96 and our Low Pressure begins to pivot in an anticlockwise direction.

Looks like in reality, the Atlantic is going to try to win the battle by T+114.

So a cold snap, yes, however not a long-lasting one.

Edited February 20, 2010 by Thundersquall

[Joe Bloggs]

Tuesday looks like rain for most too..., turning mild in the SW.

http://www.wetterzentrale.de/pics/Rtavn784.png

http://www.wetterzentrale.de/pics/Rtavn7810.png

Snow definitely possible though across 'M62' corridor type area though, including Manchester and also parts of NI. By Wednesday the risk is pushed even further north, being reserved for parts of Scotland, it even turns too mild in the Central Lowlands by midday Weds.

http://www.wetterzentrale.de/pics/Rtavn1082.png Ouch, maybe a mild outlier?

[KTtom]

GFS is totally baffling at the moment. The difference at +102 is amazing compared to the 06z. The 06z had the low exiting the country on a west to east track just north of Norfolk, the 12z has it moving South to North and exiting NW Scotland!

Pretty amazing lack of consistancy.

[BornFromTheVoid]

Tuesday looking like a slight downgrade for Ireland at least. Sub -5C 850s clearing all but the very north. Still, more to watch for the rest of the week so fingers crossed!

Edit; milder sweeping the whole country. Very big difference to the 06z, hopefully not the beginning of a trend.

Edited February 20, 2010 by NaDamantaSam

[Harsh Climate]

Well if this run is to be believed, tommorows event is UPGRADED but wednesdays event DOWNGRADED lol (Edit: for my area)

Il take that with both hands, its whats happening within t24 hours that really matters not past 72 hours

Edited February 20, 2010 by Jed Bickerdike

[Cheese Rice]

GFS has made it pretty clear that after Monday it doesn't have a clue as to what will happen next, no doubt the next run will show something different.

[Thundersquall]

With the Greenland High in place on the 12Z up to at least T+126, the Atlantic weather systems can hardly win out for any prolonged length of time. What I mean by this is that this is not a pattern suggesting a return to any form of zonality. That Low Pressure to our SW will probably just mill about with nowhere for it to move. The Jet Stream is also in the wrong place for Atlantic dominance. That strong purple core of 162 knots plus simply dives SSE keeping well away from the British Isles.

Edited February 20, 2010 by Thundersquall

[andymusic]

Tomorrow's snow now appearing on the 12z GFS

http://www.wetterzen...cs/Rtavn184.png

http://www.wetterzen...cs/Rtavn244.png

Northern limit appears to be North Lancs/South Cumbria area

Judging by the projected dewpoints, Wales looks set to have a snow turning to rain setup, best chance of snow towards the NE towards Ruthin etc, by midday snow only likely Manchester northwards, anywhere south probably seeing rain.

By 18z tomorrow however there is some residual stuff left across the South Midlands/Eastern England, could be some snow on the back edge of the front.

Into Monday, precipitation only reaches Southern England now, not even reaching South Wales. Risk of temp snow is again aligned up with the northerly limit of the front, possibly the M4 corridor type of area, however by midday it looks like rain for just about everywhere as sub zero projected dewpoints become reserved for Wales, Northern England and Scotland...

It's only the GFS, so given the current disagreement amongst the output, possibly best to wait for the NAE and the UM before making too much judgement.

mind you the nae totally messed up today for Wales and the GFS was spot on - no snow - where as the nae progged snow

GFS has made it pretty clear that after Monday it doesn't have a clue as to what will happen next, no doubt the next run will show something different.

I'm with you on that assumption mate - 2 -3 days at most - look no further

[cooling climate]

LOL the difference between the 12z GFS run and the 12z UKMO run at t96

is ridiculous to say the least.

Before then though the two models have fairly good agreement on the low

along the channel with the snow risk much further south.

The GFS beyond t96 is a waste of time looking at imo.

[Harsh Climate]

As everyone knows this run goes wrong at around 96hours when the low goes too far north, opening the flood gates for much milder air.. http://www.wetterzentrale.de/pics/Rtavn962.png And by 120h the damage is done http://www.wetterzentrale.de/pics/Rtavn1202.png .

If we compare this to the last UKMO and ECM run, the gfs is verymuch on its own in this respect so unless ecm/ukmo backtrack later, I dont believe it. And from this winter allready, weve learned how wrongfully progressive the models like to be!..

ECM

http://www.wetterzentrale.de/pics/Recm961.gif

http://www.wetterzentrale.de/pics/Recm1201.gif

UKMO

http://www.wetterzentrale.de/pics/Rukm961.gif

http://www.wetterzentrale.de/pics/Rukm1201.gif

[Thundery wintry showers]

Looks pretty snowy for northern England over the next few days according to GFS 12Z, possibly in parts of southern England for a time on Monday/Tuesday as well. Again, potential for some of the biggest snow events of the season so far for the Midlands and northern England.

A very different outlook past midweek with south-westerlies and mild wet weather sweeping in across all parts. It would continue dull and damp for many under this setup although if the main frontal zone gets far north enough it may turn bright and showery and genuinely springlike in parts of the south. It goes to show how much uncertainty there is in the latter part of the forecast period but at the moment I am backing the milder air to gradually make it in from the south, albeit probably not as quickly as GFS 12Z indicates.

[Mark Bayley]

GFS

T96

T120

UKMO

T96

T120

UKMO keeps the low further south. Still not great though. Scotland would do ok along with northern England. GFS decides to have marginal in Scotland with rain for the rest of the UK (preceded by snow perhaps). Wouldn't bother about details consisdering the changes in the track of lows between runs! The Northern side of the UK seems favoured overall.

Edited February 20, 2010 by mark bayley

[igloo]

GFS has made it pretty clear that after Monday it doesn't have a clue as to what will happen next, no doubt the next run will show something different.

the usual trash from the GFS 4 runs a day all completely different from the last well the UKMO doesnt agree at +120 and it im guessing this evenings ECM will not either

[MR EXTREMES]

Looks pretty snowy for northern England over the next few days according to GFS 12Z, possibly in parts of southern England for a time on Monday/Tuesday as well. Again, potential for some of the biggest snow events of the season so far for the Midlands and northern England.

A very different outlook past midweek with south-westerlies and mild wet weather sweeping in across all parts. It would continue dull and damp for many under this setup although if the main frontal zone gets far north enough it may turn bright and showery and genuinely springlike in parts of the south. It goes to show how much uncertainty there is in the latter part of the forecast period but at the moment I am backing the milder air to gradually make it in from the south, albeit probably not as quickly as GFS 12Z indicates.

absolutely spot on gonna be some snowy events for a fair few but the alantic winning was always the most likely but it has to be said how tough its been to shift the cooler air.

but models still trending towards what alot have been saying for the last few days.

to be honest bring on spring maybe then we can start looking at easterlies in the summer lol.

but the models have been very consitant in the overall trend towards more spring like weather.

i also agree i would not right off totally some cold snap into the first part of spring its something that happens.

but its a wait and see moment.

Edited February 20, 2010 by badboy657

[Thundery wintry showers]

I think some are perhaps too quick to dismiss the GFS because it's not what most cold/snow lovers want to see? I do think it's being over-progressive with this, but we'll need to see the UKMO/ECM 12Zs before we can reasonably pass strong judgement on whether this is a case of GFS "going off on one" or the start of a trend. After all the last three GFS runs have mostly had the lows further south than UKMO/ECM.

I'd also like to note that if the milder air does come up from the south, it would be premature to write off the possibility of wintry weather from then onwards. With pressure staying high to the NW, even if mild air establishes over Britain it would only take a slowdown of the jet for cold air to filter back down from the north.

[Duane S.]

I have to say I'm a tad confused by this chart! Where's that PPN coming from in the South

[Derp Patrol]

Well.. so far it looks like a return for milder conditions from Wed/Thursday onwards. I must say that while some on here are looking for colder conditions, I certainly am not anymore. Looks like this will come just in time for the start of Spring as well

[Guest]

I have to say I'm a tad confused by this chart! Where's that PPN coming from in the South

Sometimes if you look at the comparable precip grid values they show as a "0" and that translates to blue/pink on the weather type map despite a "0" value for precip indicating that it will be dry. So it is just phantom precip. This is a common fault with all the models which pick up zero or negligible precip for some reason. I don't know why it can't be programmed out

Edited February 20, 2010 by CatchMyDrift

[Cheese Rice]

I think some are perhaps too quick to dismiss the GFS because it's not what most cold/snow lovers want to see? I do think it's being over-progressive with this, but we'll need to see the UKMO/ECM 12Zs before we can reasonably pass strong judgement on whether this is a case of GFS "going off on one" or the start of a trend. After all the last three GFS runs have mostly had the lows further south than UKMO/ECM.

I think even the snowiest of the runs were for the bin, at present nothing is certain after Monday as the models keep changing.

[Thundersquall]

I have to say I'm a tad confused by this chart! Where's that PPN coming from in the South

Please could you let me know where to access these NAE charts, so I can access them and see previous and later charts?

Many Thanks, TS.

[Harsh Climate]

UKMO 144h

http://www.wetterzen...cs/Rukm1441.gif

ECM 144h

http://www.wetterzen...cs/Recm1441.gif

Very springlike indeed....

Edited February 20, 2010 by Jed Bickerdike

[StewieEatWorld]

How long until we start to see the UKMO 12Z's? Or have I missed them...haha

[MR EXTREMES]

I have to say I'm a tad confused by this chart! Where's that PPN coming from in the South

thats a very confusing chart infact that would give snow on the southcoast but i for one think thats not a good chart for us id ignore that other than futher north.

[andymusic]

I think even the snowiest of the runs were for the bin, at present nothing is certain after Monday as the models keep changing.

I'm with you mate

[TEITS]

According to the NAE the 12Z GFS is wrong at +48. This makes the rest of the run pointless IMO.

Sunday/Monday looks very good especially for the Midlands.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/02/20/basis12/ukuk/prty/10022212_2012.gif