Model Output Discussion - 26Th Dec 21:25-->

[mesocyclone]

Looking at sat24 there is a monster system spreading in as far south as southern Portugal with the northern section stuck in the Atlantic on a level as far north as the boarders.

It looks like the band is starting to move into a lateral position that would cause extreme weather whether it's snow or rain as it would be continuous for some.

To me the image is akin to one of the big "perfect"storms the USA gets with flooding rains in the south and blizzards in the north . Not seen lightning in it but it looks like very deep convection.

Can see why it would turn into a mess if it stalled and filled.

http://www.sat24.com/

[BLAST FROM THE PAST]

I posted yesterday in the indepth thread that I believed the 'spoiling' SW over Norway was being overplayed...it seems some models today agree with that. I believe that once the cold pattern is in play the SW UK and Eire will be the battleground zones [mainly]. As even in the past great winters it may take second bite for snow to be around in the south, BUT when it does and the cold digs in it will be very hard to shift. Jetstream to remain on very southerly track and all that can do is bring big chances of cold and snow.

BFTP

[nick sussex]

Before the evening model runs start coming out a quick look at the latest verification stats which show a drop across the board over the last few days, with the ecm still ahead and the gfs, gem and ukmo dropping sharply, the gfs showing the steepest decline.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz6.html

Edited December 27, 2009 by nick sussex

[aspire27]

Before the evening model runs start coming out a quick look at the latest verification stats which show a drop across the board over the last few days, with the ecm still ahead and the gfs, gem and ukmo dropping sharply, the gfs showing the steepest decline.

http://www.emc.ncep..../html/acz6.html

When are the next important model runs due out?

[Solar Cycles]

When are the next important model runs due out?

Rolling out as we speak!

[aspire27]

Rolling out as we speak!

Oh right...thanks.

[conor123]

Well the GFS isn't backing down at all, if anything the low is even further north

[Frosty.]

I posted yesterday in the indepth thread that I believed the 'spoiling' SW over Norway was being overplayed...it seems some models today agree with that. I believe that once the cold pattern is in play the SW UK and Eire will be the battleground zones [mainly]. As even in the past great winters it may take second bite for snow to be around in the south, BUT when it does and the cold digs in it will be very hard to shift. Jetstream to remain on very southerly track and all that can do is bring big chances of cold and snow.

BFTP

Nice post Fred

A lot of the problems on here...pages and pages of it continue to revolve around the gfs going against the grain and I have to say i'm not too optimistic we will see any of those wonderful sudden upgrades the gfs is famous for, it seems to be digging it's heels in here but hopefully by posting this I will be proved wrong. reverse psychology

[Duane S.]

Before the evening model runs start coming out a quick look at the latest verification stats which show a drop across the board over the last few days, with the ecm still ahead and the gfs, gem and ukmo dropping sharply, the gfs showing the steepest decline.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz6.html

Good spot. The only one that hasn't taken a nosedive is the ECM.

I posted yesterday in the indepth thread that I believed the 'spoiling' SW over Norway was being overplayed...it seems some models today agree with that. I believe that once the cold pattern is in play the SW UK and Eire will be the battleground zones [mainly]. As even in the past great winters it may take second bite for snow to be around in the south, BUT when it does and the cold digs in it will be very hard to shift. Jetstream to remain on very southerly track and all that can do is bring big chances of cold and snow.

BFTP

I posted the same earlier today.

I think that if this was a true knife edge situation, which is not really the case here, or at least won't be once proper blocking to the N becomes established, then such a shortwave in that location could well be make or break for us. If it does act as a spoiler this time around it should only be a temporary inconvenience, no more.

[Troubleatmill]

GFS has the low at a better angle coming in on the 12z, think this is going to be a better run

[Geordiesnow]

Good spot. The only one that hasn't taken a nosedive is the ECM.

Past performances imo mean nothing. Your team could be on a 10 match losing run but you beat the team at the top of the table, same with the models, just because the ecm is at top of the performance charts does not mean it is more right than the others. We shall see though.

If the low is progged to be as similar as the GFS is showing, then credit must go to the UKMO which has been fairly consistant of this being the case.

Good run for NE Scotland thus far, it would seem on this run so far, it is this place that could potentially see alot of snowfall thanks to the colder air and convective showers.

Edited December 27, 2009 by Geordiesnow

[BLAST FROM THE PAST]

I really think that the south [south of Oxfordshire, Gloucestershire etc] will not get snow from the approaching storm. I think back edge will come into play as it passes through and it won't be until the 3rd say when the fun and games come into play nationally. There are some important timings to come through Jan with very heavy snow and bitterly cold events but I believe that the SW and Eire will be the zones in the battle ground. Cold/v cold to bitterly cold to dominate the first 3 weeks of Jan with the warm up towards the last week. Peak energy period with very stormy period/heavy snow very high winds from 14/15th onwards for a few days is still strongly on the cards. Far south west could be cold rain event. Now no more model watching for me for a couple of days when the picture will be clearer for the New Year. For me whether it snows for New Year is not of importance as I think it will follow very shortly after.

BFTP

[Liam J]

better angle of attack from the low for northern england, as shown on the 12z gfs, -5 850's are over northern england northwards with a strong easterly wind creating blizzards in the true meaning..

better angle of attack from the low for northern england, as shown on the 12z gfs, -5 850's are over northern england northwards with a strong easterly wind creating blizzards in the true meaning..

Edited December 27, 2009 by james12

[Snowaddict]

A definite improvement on the 12Z GFS evolution, much better in terms of the flow, with colder air further south towards Day 3...

Snow risk extending across all of Ireland as well as many parts of the UK & Wales also..

This is a definite trend in the immediate term towards the overnight ECMWF 00Z evolution in my opinion.

Also, very good to see ECMWF leading the pack in terms of verification, this is important and I think the nosedive in the others indicates the uncertainty with the upcoming pattern.

SA

[snowmadchrisuk]

Well no backing down from the GFS really. Rain for the Midlands from that run , and the South west can get there t-shirts out 12 degrees on Tuesday and Wednesday in Cornwall. We really needed to see the GFS doing a backtrack even a slight Southward movement would have done fro a start but it hasn't happened. I really hope that the other models don't start heading towards the GFS this evening as you have to give the GFS credit for being consistent for the last few days with this low.

[Geordiesnow]

Lol, you better hope the UKMO/ECM saves the day because this cold snap/spell is soon turning into a cool spell with alot wind and rain. I think the term flooding could well be a word commonly used in the next few days and not the S word.

As i say though, UKMO has shown similar with the low pretty much over us and starting to fill and people dismissed this in hope of something better. At this moment in time, what the GFS is showing has to be the form horse, mostly because the UKMO has indeed in previous outputs have shown something similar.

[Liam J]

excellent gfs rolling out now, NE flow 850 -5 to -8 over much of the uk, low pressure to east driving showers and snow accross wide areas looking good unless you have to travel for new year!!

[yamkin]

Very interesting GME 12Z 108h & 132h

[rich1]

excellent gfs rolling out now, NE flow 850 -5 to -8 over much of the uk, low pressure to east driving showers and snow accross wide areas looking good unless you have to travel for new year!!

Hmm..bit dump down here but it does appear to get there eventually, a little bit of a hint of a climbdown but still being stubborn as regards midweek and beyond. A bit frustrating still but so long as the ECM doesnt back down, remain a bit more hopeful for the new year period

looking at the temp projections for new years day however, a slightly better run this one so far. Not great in the short term but 1 degree on NYD at midday isnt bad I guess

Edited December 27, 2009 by rich1

[snowking]

Very bizarre update from the Met Office this afternoon for East Anglia tuesday through thursday:

Becoming windy with sleet and snow moving up from the south on Tuesday and lasting through Wednesday. By Thursday things pick up with some sunshine but still feeling cold.

Now from what I can see from the latest data chances really east of the M1 of snow during midweek are very slim even going by the ECMWF consensus. Would Ian Ferguson perhaps be around and happen to know when the Met Office get access to the updated ECMWF runs? I could only assume from this a shorter term upgrade from their own model is responsible because the 12z GFS with the different angle of the LP in the north sea certainly prevents snowfall further east so its definitely not the GFS that they go with (a positive sign given that ideally for longer term gain we still could do with the LP's attacking from further south than at present)

SK

[Eugene]

Well no backing down from the GFS really. Rain for the Midlands from that run , and the South west can get there t-shirts out 12 degrees on Tuesday and Wednesday in Cornwall. We really needed to see the GFS doing a backtrack even a slight Southward movement would have done fro a start but it hasn't happened. I really hope that the other models don't start heading towards the GFS this evening as you have to give the GFS credit for being consistent for the last few days with this low.

Yes it would be nice to get some proper warmth, too chilly this weekend to be considered warm here, unfortunately not lasting long on GFS 12Z with a cold new years.

http://www.wetterzentrale.de/pics/Rtavn1201.png

[Geordiesnow]

A definite improvement on the 12Z GFS evolution, much better in terms of the flow, with colder air further south towards Day 3...

Snow risk extending across all of Ireland as well as many parts of the UK & Wales also..

This is a definite trend in the immediate term towards the overnight ECMWF 00Z evolution in my opinion.

Also, very good to see ECMWF leading the pack in terms of verification, this is important and I think the nosedive in the others indicates the uncertainty with the upcoming pattern.

SA

You must be looking at different outputs to me and everyone else then because this run has showed the -5 air to be slightly further North again!

NE Scotland and perhaps Cumbria looks like the place for snowfall that would be disruptive, elsewhere, it would be a snow turning to rain event unfortunately, IF this run occurs.

[West is Best]

What on earth is going on with the GFS? That secondary low of 985mb at T102 200 miles off the Brest peninsular (a development on the last two runs) bears no relation to any other model outputs.

Either it's spotting something none of the others are, or it has totally lost the plot. Given the recent ensemble scatter at the relevant time I suspect the latter. Look for this low quietly to get ditched in the next 36 hours, and with it for the initial low to be placed further south.

Could be a very bad moment for the GFS this ...

Edit - just seen Nick's post about how the GFS is having a big decline in accuracy.

Edited December 27, 2009 by West is Best

[yamkin]

excellent gfs rolling out now, NE flow 850 -5 to -8 over much of the uk, low pressure to east driving showers and snow accross wide areas looking good unless you have to travel for new year!!

For the same 84h period, GME 12Z is also looking very good

[Snowaddict]

FANTASTIC UKMO @ T+60 - T+96!!

http://www.meteociel.fr/modeles/ukmo2.php?nh=&ech=72&carte=1021

It has the low much further south & look at T+96... A very strong easterly flow..

Excellent output to T+96 in my opinion..

It's all trending in the right direction so far!