Model Output Discussion

[nick sussex]

12z ens. for Warks.

http://charts.netwea...arwickshire.png

Op. run close to the mean and trending a little milder early next week.

Surprisingly quite a number of runs close together going well forward in view of the recent model somersaults.

Evening Phil

I would say at present the ensembles past 240hrs are going to be very unreliable, when you have a pattern change upstream and an expected AO going negative i often find they can flatline almost as if they just basically give up the ghost, so rather than implying agreement they IMO are often precursors to sudden scatter. Grouping ensembles in a typical zonal, icelandic low, strong azores high into FI would not be too much of a surprise, however with the current north hemipshere pattern they aren't really indicative of the possibly different scenarios that could occur in FI.

I'm slightly more happier with this evenings output from the ecm and gfs, we should remember that the azores high and also euro high just occasionally can help with certain patterns, also i see talk of the bartlett high on here this evening, no sign of this at the moment and if there was i would be the first to have a good moan about it!

[Glacier Point]

A strong flare up in convection has started over the western Pacific:

http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR/m.3d.html

NWP is responding to this through a typical MJO phase 6 type response:

http://raleighwx.easternuswx.com/MJO/DecemberPhase6500mb.gif

However, caution advised.

The all important Global Wind Oscillation may not necessarily agree with this.

Currently, the GWO has undergone a fast orbit towards phase 8:

http://www.esrl.noaa.gov/psd/map/images/gcm/gwo_40d.gif

... mainly due to falling mountain and frictional torques. Overall and relative angular momentum remains at or slightly above average however which is likley to restrict the vertical movement of the GWO. I suspect that a positive Asian mountain torque will drive the GWO back towards phase 4 quite quickly. Phase 4 composites place the trough closer to the UK with height rises over Greenland and a southward displaced jet stream.

Tonight's CPC made forecast for days 8-14 based on forecaster input, historical analogues and CMC/GFS Ensemble Means which I'd broadly agree with:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

Not cold and quite unsettled but a question mark against the extent of any ridge into Spain and also the focus for building heights is in the Svalbard - Greenland area of the Arctic. GFS Ensemble mean delivers quite some cold into eastern Europe and Russia thanks to a strong -AO projection:

http://raleighwx.easternuswx.com/models/gfsensemble/12zENS6-10day850mbTempAnomalyEurope.gif

http://raleighwx.easternuswx.com/models/gfsensemble/12zENS11-15day850mbTempAnomalyEurope.gif

[nick sussex]

Often when we see changes upstream this effects model reliability and this is shown with the latest verification stats.

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

The gfs and ukmo both dipping the most, but overall we see all models suffering, however the nogaps(fnmoc) has beaten the gfs for the last 3 days!

[SylvainTV]

Often when we see changes upstream this effects model reliability and this is shown with the latest verification stats.

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

The gfs and ukmo both dipping the most, but overall we see all models suffering, however the nogaps(fnmoc) has beaten the gfs for the last 3 days!

And I think that the "X" is the parallel GFS 00z run. It does "a little better" than the current GFS.

[bluearmy]

a strange evening in exeter. not often you see the T120 FAX looking more like GFS 12z than UKMO or ECM. (though to be brutally honest, it isnt like any of them re the individual shortwaves around us)

SYLVAIN - I note you're on here - any chance of the parallel GEFS for the next two weeks ??

Edited December 1, 2009 by bluearmy

[shuggee]

Anyone else spot Roger from American Dad right over the UK?

Ok - I'll get my coat...!

[cooling climate]

Well i've just looked at the 12Zs and then after reading some of the posts on here I had to check the models again.

Some silly posts on here especially those who are already writing off Dec.

We might not have any significant cold spell being shown within the reliable timeframe but the potential certainly remains. If you look at the +192 charts you can clearly see the models continue to prog a weak split PV which is in stark contrast to what we usually experience at this time of year.

Personally I feel its only a matter of time before this N blocking becomes established and we see LP systems track SE allowing the bitter arctic airmass to filter S/W. I continue to believe that a significant cold spell is on the horizon and the period im looking at is around 11-13th Dec. Infact im going to say that this coming Dec will be one that will be talked about for many years.

You get my vote.

From the 10th onwards I think things are likely to get very interesting indeed.

[Snowstorm1]

Who just passed out with gfs fi THE PUB RUN LIVES UP TO ITS NAME CHART OF THE WINTER SO FAR IS THIS

Edited December 1, 2009 by Snowstorm1

[SylvainTV]

a strange evening in exeter. not often you see the T120 FAX looking more like GFS 12z than UKMO or ECM. (though to be brutally honest, it isnt like any of them re the individual shortwaves around us)

SYLVAIN - I note you're on here - any chance of the parallel GEFS for the next two weeks ??

Nope, it has been postponed till January or more AFAIK. No parallel GEFS data are available for now unfortunately! I will add them as soon as they arrive (if they do ).

[Eugene]

http://www.wetterzentrale.de/pics/Rtavn3601.png - LOL

Yeah and has as much chance of coming off as ian brown forecasting a bitterly cold winter

[Polar Gael]

Who just passed out with gfs fi THE PUB RUN LIVES UP TO ITS NAME CHART OF THE WINTER SO FAR IS THIS

I think the pub run may have raided the festive drinks cabinet early doors before setting off down the boozer this evening.

I don't fancy the state of its head in the morning. It'll probably be full of Bartletts.

[Yozzer]

And here we go again! GFS has bipolar disorder at the moment, certainly making manic depressives out of many on here. Although we've seen eye candy in FI many times before, there does seem to be much more persistence in the appearance of these types of scenario recently. Maybe, just maybe... Anyway, off to stock up on supplies now!!!

[Thundery wintry showers]

Can I just say that the evolution from T+174 to T+228 (Atlantic low getting "swallowed up" NW-ward into nothingness) is the most implausible synoptic evolution that I have ever seen?!

The charts at the very end of the run are amazing- but also not particularly plausible either. Very rarely do you get such a huge mass of northern blocking.

[kold weather]

Well the basic evolution looks similar on all the models, we have a UK trough which just doesn't want to leave our shores, jet stream is just too potent right now, we will see height rises to the NE but for now its only going to lock us into a milder flow again. Eventually those lows in the Atlantic are going to have a break and when they do expect some sort of northern blocking to take charge, however there are many ways that could lead us there and one would be to have a fuax Bartlett...aka 1987.

[Cloud 10]

Another festival of northern blocking after+168hrs from tonights gfs 18z.

As soon as it gets past 180 hrs someone throws the winter armageddon switch.!

[chionomaniac]

Can I just say that the evolution from T+174 to T+228 (Atlantic low getting "swallowed up" NW-ward into nothingness) is the most implausible synoptic evolution that I have ever seen?!

The charts at the very end of the run are amazing- but also not particularly plausible either. Very rarely do you get such a huge mass of northern blocking.

It is almost as if that the GFS has decided to have the split vortex at T+228 and is working the synoptics in beforehand to fit in with this!

[snowray]

I'm sure that runs like this in mid to long range FI will pop up regularly throughout Winter. We have already had more than our fair share to be honest and not just from 18z. After this old carry on of recent days I am going to take all output past T72 with a pinch of old saxa, my sanity means more to me this year for some inexplicable reason, maybe I'm getting old.

[Severe Siberian icy blast]

And here we go again! GFS has bipolar disorder at the moment, certainly making manic depressives out of many on here. Although we've seen eye candy in FI many times before, there does seem to be much more persistence in the appearance of these types of scenario recently. Maybe, just maybe... Anyway, off to stock up on supplies now!!!

Well its a repeat of last night it seems , if we get this look for another 3 days then its deffinatly on to somethin , even the 12z wasnt that different looking at the pressure rises to our norh , i have a feeling about the next 2wks and behond but as far as every1 else is concerned its nothin more than a feeling so ones will argue my ''feeling'' , but time will tell , and im rather optimistic to say the least .

[Richie V]

Who just passed out with gfs fi THE PUB RUN LIVES UP TO ITS NAME CHART OF THE WINTER SO FAR IS THIS

I nearly swallowed my entire face when I saw that chart!

[snowray]

http://www.wetterzentrale.de/pics/Rtavn3601.png - LOL

Yeah and has as much chance of coming off as ian brown forecasting a bitterly cold winter

:lol:

Well everyone has their own idea of course. in fact these mega freeze scenarios, like what we are regularly seeing have as much chance of turning up at some stage this winter as they have in any winter past, present or future.

If your superstitious though think back, when was the Winter of discontent? 78/79 yeah, who was in government? Was there not a general election in '79?

Some people believe that history repeats itself.

[Iceni]

Who just passed out with gfs fi THE PUB RUN LIVES UP TO ITS NAME CHART OF THE WINTER SO FAR IS THIS

I was going through my local forecast on NWTV Lite — days of green and yellow dross when I got to day 16 and the icon values all turned blue! Just please let Christmas be cooooolllldddd Yummm!:D:cold::lol:

[Polar Side]

There does seem to be a different look about the models this year. In previous winters FI used to throw up the odd Northerly here and there that never had a long lasting look about them. This year so far, the models in FI seem to be keen on showing the holy grail type senarios with huge amounts of Northen blocking and bitter North Easterlies reminiscent of the late 70's and early to mid 80's.

Could this be our year at last ?

[snowray]

Can I just say that the evolution from T+174 to T+228 (Atlantic low getting "swallowed up" NW-ward into nothingness) is the most implausible synoptic evolution that I have ever seen?!

The charts at the very end of the run are amazing- but also not particularly plausible either. Very rarely do you get such a huge mass of northern blocking.

18z has done this sort of thing a few times recently, I was thinking exactly the same re that low. And the parallel run always starts with data thats about 24hrs out of date, I'm starting to give up on this model I must say.

[kold weather]

Well the ensembles are interesting, certainly some cold solutions in there akin to the 18z op run but also some really horrid runs as well that smack of a bartlett high, would be something else to have northern blocking and a southerly jet and still end up with a raging bartlett situation...I have my doubts about that as well as anything as extreme as the 18z op run as well for that matter.

[weather eater]

Can I just say that the evolution from T+174 to T+228 (Atlantic low getting "swallowed up" NW-ward into nothingness) is the most implausible synoptic evolution that I have ever seen?!

The charts at the very end of the run are amazing- but also not particularly plausible either. Very rarely do you get such a huge mass of northern blocking.

That was my thought, at t180 massive LPs, rather smaller HP over Scandinavia, then it almost looks like the Hp just sucks the LP dry, like some sort of weird 50s B movie. No sense getting elated or depressed by any model run at the moment, they just don’t seem to have a clue, good watching though.