Model Output Discussion - 8th - 14th January

[Zenarcher]

My view on the weather models this evening,

GFS

The GFS has moved the low slightly further down at 120 hours. 4 other models disagree with this and place it slightly more West and closer to Greenland however the UKMO is probably the only model that backs this position up but only just. Going to 144 hours out to Saturday afternoon where things change for every model. The GFS shows high pressure trying to connect to our North East with a low situated to the West of the UK. Also the low heading into the Atlantic has been downgraded a touch since this morning and also its pushed the ridging up in the Atlantic a bit like what many other models suggest. At 168 hours the PV is still causing problems and so is the jet stream bringing down the Atlantic ridge and the GFS is on its own here with this solution. However looking in deep FI the GFS does show excellent cold weather but then that is FI.

ECM

The ECM does have good model agreement up to around 120 hours after this the support starts to drop. So where did it all go 'wrong' for the ECM? Around 144 hours to 160 hours some changes were made and this affected the outlook completely.

A chart below at 156 hours comparing the ECM 00z and 12z run,

Marked on the graph,

1. Changes to the low entering the Atlantic.

2. The low pressure has been made much deeper.

These changes have stopped the blocking from taking place and basically afterwards the UK is under high pressure for a few days.

JMA

It shows similar to the ECM with the high pressure to our North East just trying to reach out at 144 hours only to be knocked away leaving the UK with high pressure but no blocking.

GEM

Another model that's showing something along the line of the ECM but again due to the PV over Iceland and Greenland its stopping the blocking from getting down.

NOGAPS

Perhaps the best model this evening for showing cold weather with PV not as strong giving higher chances of a blocking.

UKMO

Its the only model on its own at 120 hours but gives some new hope I believe maybe later on.

Overall the models have good agreement up to around 96 to 120 hours. Beyond that they all take a different path some similar to others but no definite choice has been made yet. Some models like the GEM, JMA and ECM are good for mild weather fans but for cold weather fans its not looking as good as yesterday but changes can still be and will be made either for the better or for the worst.

[legritter]

looking at all of todays charts i half expected to be where we are now . but i would not be surprised if ECM is much furmer over the following days . its deeling with a big pressure rise , whether its to the n/e or north , and dont forget any orientation that is to be forecast will come much nearer the time .also looking at GFS , i know its knocked alot but it still keeps churning out ,plenty of highs ,north and east ,.so i think 3/4 days to still be patient ,but i think the big news of tomorrow could be met update . good model watching ,im of for a break ,cheers gang

[snowray]

I agree JS, strange how both GEM and ECM got conned together and both went all out on the Easterly and GFS was also showing up lots of potential with the Azores/Euro high finally getting the boot. Talking about boots, something must be afoot, with conflicting signals being fed into these model super computers starting to cause ripples down the line. At least we never had the scenario of ECM on board, then GFS, then UKMO coming close, all gone 2 or 3 days later at T108/T120, this is pure agony.

I know there is often a lot of talk about which model is the most accurate and UKMO only goes out to T144 of course, and there are charts that highlight the stats. But in my opinion the true value of a model is when it can acurately spot a patern change, be this at T120/140/164, any old cannon fodder model thould be able to spot a strong PV and raging zonality as we have seen over the last couple of months. Last winter GFS picked up on the late November Easterly way, way out and stuck to it's guns, now that was pure quality.

All eyes on 18z, a few more surprises I wonder?

[bluearmy]

the models aren't conned fellas. they just run based on that data thats fed into them. the data today has made the jet that bit stronger which doesnt allow the trough disruption to be effective in pumping enough WAA northwards for long enough to build the block. who knows if the jet forecast will be different tomrrow. unlikely seeing as we are 24 hours closer to the disruption. however, its just computers crunching numbers, not a door to door fraudster !!

back to reality (thats a joke by the way) and slowly but surely the mean trough is dropping closer and closer to the uk post T300 (NAEFS + GEFS) with the jet sinking sw and losing a bit of its oomph. the period around the 20th continues to look significant. note that the ecm control becomes a slack easterly at this juncture. the nwp may well tease over the next few days, especially if the AO continues to head negative beyond next weekend. something could pop up before the period around the 20th, given the polar profile.

[phil nw.]

The NAO days 8-14 500hPa forecast chart

still shows low hts.to our North west,though weaker.There`s just enough energy flowing across to our north discouraging any holding ridging to our NE-towards Scandi.

The stubborn Azores High still lurking,maybe a bit further North.

One notable aspect is higher pressure towards the far side of the Arctic ridging well in towards the pole supporting the idea of a weaker vortex,possibly ready to be displaced.

We look to be in a better position for height rises over the pole than we were say a week ago.

Edited January 8, 2012 by phil n.warks.

[Matty M]

Remember folks if the 18z is a corker do not get carried away....

We are at a crucial time in the medium to long term.

The cherry might not be bite this time but we need to have a few blocks still in places when or if

the first bite misses. What we don't want is the jet trundling through well into Scandy.

[SMU]

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Long ECM ensembles-

Control Cold again at day 13- Below freezing by day- but it cant be snow because it might offend OP

S

[Matty M]

18z isnt far away but the low at the tip of greeny isn't giving the right amount of passage for the High over Europe to push north.

The major problem in my eyes seems to be that on the earlier runs the Arctic High wanted to play ball, get inflated and head into Scandy, the latest runs arent showing this thus there isnt enough strength there to battle the jet.

Oh well!

Looks like the party is happening on the other side of the world and we are not invited!

Night folks. 18z is disinteresting with the PV still LOCKED over Greenland although good signs over the Arctic

for the longer term.

[January Snowstorm]

18z is very close to something special

144hrs is most certainly FI

I think the pattern is definatly changing, possibly for the remainder of Winter

The cold, perhaps sever cold is coming, just a matter of how quickly!

[Matty M]

18z is very close to something special

144hrs is most certainly FI

I think the pattern is definatly changing, possibly for the remainder of Winter

The cold, perhaps sever cold is coming, just a matter of how quickly!

18z is very close to something special

144hrs is most certainly FI

I think the pattern is definatly changing, possibly for the remainder of Winter

The cold, perhaps sever cold is coming, just a matter of how quickly!

You take your happy pills tonight JS!?

Looks worse than the 12z and looks like the jets about to go straight through us with the PV locked over Greenland!

[Geordiesnow]

18z is very close to something special

144hrs is most certainly FI

I think the pattern is definatly changing, possibly for the remainder of Winter

The cold, perhaps sever cold is coming, just a matter of how quickly!

Don't think its very close personally but the global pattern is changing thats for sure with a negative AO developing but as its been the case for most runs and most certainly recent runs, its not going to affect our weather it would appear.

Frustrating but its the sort of set up that can easily change but experience tells us it rarely changes into a cold fans favour though!

[mountain shadow]

http://www.knmi.nl/e...agse/index.html

Long ECM ensembles-

S

The lack of projected snowfall confirms pretty well that an easterly is not going to happen this shot.

[nick sussex]

The latest fax chart from the UKMO at 120hrs looks better than I thought it would, you'd think there'd be at least some WAA ahead of that Atlantic low.

http://www.meteociel.fr/modeles/ukmo2.php?ech=120&carte=2000

[igloo]

as said earlier unless the PV is smashed to bits we will be locked in this current pattern its been stuck there sinch november how long that will be is anyones guess but no signs of it moving anytime soon one thing for sure it will get busted eventually i just hope its not early spring

[on the coast]

Looks like the Jet is going to be very strong and spoil the cold party for a while yet. 3rd week in Jan could be the start of the change after seeing todays model runs.

[Beasterly]

A pressure of 11010 over Greenland??

http://176.31.229.228/modeles/gfs/runs/gfsnh-2012010818-0-174.png?18

[LomondSnowstorm]

The lack of projected snowfall confirms pretty well that an easterly is not going to happen this shot.

Not necessary, remember that these are for the Netherlands so an easterly wouldn't necessarily deliver any precipitation on that side of the North Sea. However, it's clear that support for an easterly this time round from the models is waning with each run that passes http://nwstatic.co.uk/gfsimages/gfs.20120108/18/168/npsh500.png

The models generally have a tendency to be a bit progressive in introducing pattern changes and with the stratospheric situation developing as it is it may not be an entirely false dawn but for the moment it looks like we may have to look towards the end of January for any favourable blocking to develop. But that might all change tomorrow again of course!

[snowingman]

.. as I have said for weeks... the old atlantic zonal pattern is NOT giving up!! all this talk of easterlies and split PV - nonsense - and the latest GFS 18Z confirms it once more !! any glimmer of cold has once more been zapped ! slightly not so very mild zonal but SWesterlies all the same, mild weather - NO SNOW and NO FROST! this must be a record now for mid winter - surely the mildest 6 week spell ever!!

[Jason M]

At 126 high pressure finally declines to our south.... King Bartlett is dead

http://www.meteociel...&ech=126&mode=0

At 186 all heil King Bartlett the second

http://www.meteociel...&ech=186&mode=0

Overall, dire 18Z run, zonal all the way with PV over Greenland, massive Azures high to the SW. Only one run of course, but the trend today is not our friend. Lets see what tommorow brings. Even with the better charts this weekend the Azures high has never been far away. Using the chicken and egg analagy, even if we get rid of the egg (PV) we might still be left with the chicken (Azures high), which will likely lay another egg (PV) which................ . Its all a bit 1988/89!

Jason

Edited January 8, 2012 by Jason M

[mulzy]

Strong PV around Greenland the feature of todays model runs. Deep cold still far far away I'm afraid. Mild trending to average sums it up.

[January Snowstorm]

You take your happy pills tonight JS!?

Looks worse than the 12z and looks like the jets about to go straight through us with the PV locked over Greenland!

It looks fine to me in the reliable timeframe.

Anything after 144hrs wont happen so i'm not bothered what it shows.

By the way Matty a little less sarcasm would be great, we all have our views and are entitled to them, tks.

[lukemc]

Hello again,

I was reading in the Stratosphere thread that Chroniomaniac was concerned about something called the E-P flux moving away from the pole rather than polewards, he was saying that even if we get a stratospheric warming (a major one) if the E-P flux is moving away from the pole it would make it less likely to get rid of the polar vortex - could this be what today's modelling has been picking up on (e.g. the GFS 18z keeping the PV in situ in response to that signal)?

However, I did find it puzzling that in the Stratosphere thread yesterday everyone was taking about an epic warming but today everything seems more cautious with these concerns emerging - if the Stratospheric output is so volatile how come we rely on it so much surely if it changes so much means that we can question its accuracy especially this far out?

Luke

[HotCuppa]

That PV is likely to stay entrenched where it is for the time being, possibly right through to the end of winter, thats something we probably have to come to terms with...nothing seems to be able to shift it For me there is no difference from being mild to slightly cooler conditions..no over night frost, and more rain..yuck

[SP1986]

Not sure why people have the expectation there will be no frost, there looks like being plenty next week, especially with the slack, high pressure conditions, into next week.

[davehsug]

Not sure why people have the expectation there will be no frost, there looks like being plenty next week, especially with the slack, high pressure conditions, into next week.

Because this looks like being a cloudy high SP? That was certainly the general theme from both week ahead forecasts today, with fronts-some old & decaying- never far away. I would reckon the high will need to come much closer to get a chance of anything other then a local frost & that doesn't seem to happen this week.