Model Output Discussion 17th Dec.2013-12z onwards.

[Cloud 10]

gfs 06z very representative of the ecm extended ens although the ridging into greenland is overdone on that op run. (however, doubtful the transient ridging would show on the ecm mean though and several recent control runs have amplified mid atlantic like that)

 

Today's long range met-office update certainly with a colder theme.

 

UK weather forecast - Met Office

 

 

Maybe "game time" is just around the corner.

[CanadaAl]

Looks like the GFS has been on the Mulled Wine! Merry Christmas everyone!  

[Summer Sun]

Latest AO update shows more members going negative than positive from early January

 

Edited December 25, 2013 by Summer Sun

[bluearmy]

isnt that AO/ NAO forecast just a graphical representation of the GEFS ?  

 

if so, a neg AO is likely with that polar high whilst the NAO could remain neutral and we could still have cold via a euro trough. i am beginning to think that we could have a situation where the battelground between cold and less cold air is in our locale as the trough disrupts around us and drops the lows into europe. that will be fun model watching !! 

[Snowman.]

New warming?

 

[Mark Bayley]

isnt that AO/ NAO forecast just a graphical representation of the GEFS ?  

 

if so, a neg AO is likely with that polar high whilst the NAO could remain neutral and we could still have cold via a euro trough. i am beginning to think that we could have a situation where the battelground between cold and less cold air is in our locale as the trough disrupts around us and drops the lows into europe. that will be fun model watching !! 

 

but could also produce some pretty good snow events, if it was to occur. although as you state, fun model watching, if not a little nerve racking. Heres hoping the models keep with the wintry theme.

[IDO]

isnt that AO/ NAO forecast just a graphical representation of the GEFS ?  

 

if so, a neg AO is likely with that polar high whilst the NAO could remain neutral and we could still have cold via a euro trough. i am beginning to think that we could have a situation where the battelground between cold and less cold air is in our locale as the trough disrupts around us and drops the lows into europe. that will be fun model watching !! 

 

 

Yes, this ties in with the trend that was enhanced on the GFS 06z. The clustering:  

 

Those 30% in Cluster 2 represent the more zonal positive AO whilst we have 10% showing a very disrupted UK trough and the slight favourite (Cluster 1) would also be interesting.

 

Notice the change from the GFS 0z, that I found to have a more muted trend: 

 

Lets hope that the 06z isn't an outlier and we can see more clustering like this.

[Mark Bayley]

Definitely hints that the weather may turn more wintry as we head through the first half of January. Although i'd agree with BA that a battleground between the cold and less cold air is going to establish near us, if it does. There are some promising signals in the stratospheric outlook, with strong wave breaking events over the next few weeks (i.e. deflection of rosby waves into the strat, see CH's post for a great overview http://forum.netweather.tv/topic/78161-stratosphere-temperature-watch-20132014/). 

Wave break two> Wave break one >

Also note some warming, and possible further warming>

Although nothing spectacular, with zonal winds remaining pretty strong 

This shouldn't be enough to cause a disintegrated polar vortex, and sustained prolonged cold, but will no doubt lead to some disruption before probable reformation. 

 

The MJO remains in relatively low amplitude, and thus wont have much impact. GFS and UKMO go for a weakish phase 8, which gives us this composite, supporting height rises towards Greenland. 

(http://www.americanwx.com/raleighwx/MJO/MJO/JanuaryPhase8500mb)

Ensembles show good support for -AO.

I'd suggest, based on the current output, that some sort of battle ground is likely up close to the UK as we progress through the first half of January. Low pressure systems pushing south into Europe, across or below the UK, which as we know can lead to some pretty interesting conditions to those north of any lows! Ensembles already starting to look colder

Edited December 25, 2013 by Mark Bayley

[Gaz1985]

Friday's low is still nasty for the northern half of UK, Happy Christmas everyone hope santa brought you what ya wanted 

 

[Eskimo]

Going to be a good GFS run!

[shaky]

Going to be a good GFS run!

what makes you say that??

Going to be a good GFS run!

what makes you say that?

[snowmadchrisuk]

Going to be a good GFS run!

Not so sure yet, Monday's low is making more inroads and quicker , Arctic High is 10mb lower pressure , still it's early days yet and remember the 12z is usually progressive. 

[snowmadchrisuk]

Not so sure yet, Monday's low is making more inroads and quicker , Arctic High is 10mb lower pressure , still it's early days yet and remember the 12z is usually progressive. 

Secondary low on Tuesday that wasn't there on the 6z, let's hope it reinforces the heights instead of mucking it up .......

 

[SMU]

http://modeles.meteociel.fr/modeles/gfs/runs/2013122512/gfsnh-0-156.png?12

 

A strong signal now for back door heights to push NW into Eastern Greenland-

 

12z looks better as it seperates the main low & the jet allowing shortwaves to come across the south - which in turn will allow the parent high to be sucked back west!

 

good run reinforcing the heights- now at just 144...

 

S

[snowmadchrisuk]

http://modeles.meteociel.fr/modeles/gfs/runs/2013122512/gfsnh-0-156.png?12

 

A strong signal now for back door heights to push NW into Eastern Greenland-

 

12z looks better as it seperates the main low & the jet allowing shortwaves to come across the south - which in turn will allow the parent high to be sucked back west!

 

good run reinforcing the heights- now at just 144...

 

S

 

Some worrying rainfall totals for next week in order to get there though ....... 3 days of non stop rain showing next week . 

[Ali1977]

Another very nice looking FI....prob is that it is in FI

[Zenarcher]

Another nice end to the GFS FI today,

 

 

Min temps would reach around -4c in some parts along with snow. Still very far out but I haven't seen FI charts look this good for a long time.

Edited December 25, 2013 by weathermaster

[Cheshire Freeze]

All roads leading to cold on the GFS op runs at present. AO to go negative, NAO perhaps following, potentially significant snow events in the new year and all looking bang on cue......

 

 

Merry Christmas!

[Jason M]

Another nice end to the GFS FI today,

GFSFI.png

Min temps would reach around -4c in some parts along with snow. Still very far out but I haven't seen FI charts look this good for a long time.

Mostly cold rain on that chart. 850s of -3 to -4 with maritime sourced air.

Europe is very mild indeed at present and although some of the Synoptics in FI look good its mostly rain / slushfest.

Jason

Should add that detail doesn't really matter that far out. It's always worth cross referencing good looking charts with the 850s.

Edited December 25, 2013 by Jason M

[EML Network]

Satellite image captures Santa making his way home

 

Edited December 25, 2013 by EML Network

[Cloud 10]

Mostly cold rain on that chart. 850s of -3 to -4 with maritime sourced air.

Europe is very mild indeed at present and although some of the Synoptics in FI look good its mostly rain / slushfest.

Jason

 

Its actually more of a snow-fest.

 

[Jason M]

Its actually more of a snow-fest.

 

gfs-2-360.png

Moot point really, but GFS low res massively over eggs snowfall. I'll stick with rain/sleet fest but we will never know as it won't verify anyway. The point I was trying to make (badly) is just that people need to not get sucked in by charts without checking the 850s.

[snowmadchrisuk]

Its actually more of a snow-fest.

 

gfs-2-360.png

ENSEMBLES are not as good on this run with no hardly any supporting a ridge of heights out to +180 .. let's see what they now do in FI

[LomondSnowstorm]

The synoptics are what matter at this stage anyway - of course it's not helpful that continental Europe is relatively mild at the moment and ideally we'd probably rather have a trough dropping south into Scandi from the Arctic to establish a better cold pool, but the important point is that we're starting to see positive anomalies over the Arctic and a slow but steady southwards movement of the jet and, subsequently, of troughing features:

[bluearmy]

the gfs ridge at day 7/8/9 (whenever its shown) has not had much ecm support. no worries as the catalyst for the jet to come southeast appears to be a ridge coming off the eastern seaboard around day 10 which pulls the azores high nw. so if we can be patient, winter arrives a couple days later anyway.

Edited December 25, 2013 by bluearmy