Model Output Discussion - 26th December - 1st January

[kev238]

Meanwhile there looks like there could be another storm approaching for Tuesday. Hopefully, this one will produce some interesting weather; the potential is there for it to cause high winds across a wider area but the tracks of these storms can be difficult to predict until the last minute!

[bobbydog]

as a cold lover myself, i'm finding the 'cold/mild' argument getting a little tedious. cold snowy weather is not guaranteed in this country and is more of a rarity than some people seem to think. we seem to be experiencing 'normal' winter weather so far, for the location of our country. we have had mild, cold, snow, rain, hail, fog, wind, calm weather, stormy weather and anything else i may have missed, some where in the country at any given time this winter, so its hardly been boring!

as it happens, some less boring weather is on the way in the earlier timeframe. the GFS has been showing the low, due to arrive tuesday, taking a slightly more southerly track on each run. as it stands at the moment, whilst not a hurricane, it could bring some very strong winds on a countrywide scale. lets not get so bogged down in what may or may not happen this winter, that we miss what is actually going on outside!

[Robbie Garrett]

GFS is good, where else is the high pressure going to come from?? It's transferring further north. I may be wrong but this is exactly what happened in early november last year. Well according to ECMWF! Definitely some progression forward, and in that way it has to be mild, wasn't early November 2010 mild? If people such as GP, are saying that there is an upcoming pattern change, these are the trends in the short-term that we are going to hate in order to get to this pattern change right?

HP ridging north is a pattern change as far as I am aware.

[Bobby]

GFS is a big mild outlier again, why is it doing this all the time?

ECM was somewhat of a mild outlier this time too.

[Jason M]

Hi All

A glimmer of hope :o !!

Just looked through the ensembles and some def signs of hope in amongst them. Massive caveats of course in that we are talking about ensemble members at 300 hours away, but at least something to be interested in.

There are still a few horrors in amongst them (including my own personal nightmare / theory which shows the high sitting over the top of us). The 850s are never massively cold despite some great synoptics as there is nothing cold to tap into, but a few of the runs would evolve colder down the line.

Jason

[keithlucky]

At last the met have change there outlook to colder and drier towards the end of the month congratulations

GP in on your winter outlook.

[nick sussex]

Regarding the continued GFS operational runs in terms of being mild outliers, this is probably to do with the drop down in resolution.

The ensembles have had days now to switch to support the operational run and because they haven't budged I'd ignore the operational run past 192hrs and look more at the GEFS clustering and mean for the later output.

[phil nw.]

bloody iPad!

Anyway Phil, the Alaskan ridge could be very important. Will the vortex be able to resist it in it's slightly weaker state?

Two runs now .........................

Lol,Yes first signs that the 500hPa pattern is responding.Early days but that`s the sort of timeframe we should be looking at for response to the first warmings,which were at the top of the Strato.pre-Xmas.

The first stage-the Euro troughing still looks well modelled-

http://www.wetterzentrale.de/pics/Rtavn1441.png

we need that next step now-upstream to add buckling to the flow.

[SLEETY]

Is their some software fault with the gfs at the moment.It keeps throwing out mild outlier after outlier time and time again.

Yet if you look at all the ensemble runs they are actually trending colder in the long run..

Very odd and and its beginning to lose it's credibility again.

Edited December 30, 2011 by SLEETY

[Duane S.]

Regarding the continued GFS operational runs in terms of being mild outliers, this is probably to do with the drop down in resolution.

The ensembles have had days now to switch to support the operational run and because they haven't budged I'd ignore the operational run past 192hrs and look more at the GEFS clustering and mean for the later output.

Yep, completely agree. This GFS operational versus ensembles has been ongoing for a few days now. I don't ever remember such a consistent run-on-run disparity. And like you say, the longer it lasts the more likely you would expect the former to follow the latter eventually?

That said plenty of times i've see the op be on the colder side against warmer members, only for the wayward members to suddenly switch to the op's way of thinking, so it is a tricky one to call.

Here's Rome's SLP according to the 06z, yet AGAIN way above the majority..

Edited December 30, 2011 by s4lancia

[NorthernRab]

Very odd and and its beginning to lose it's credibility again.

It never really had much to begin with.

[jpwild]

Does this mean we can discount the mild looking charts then that have been posted along with the views of the posters?

[Duane S.]

Does this mean we can discount the mild looking charts then that have been posted along with the views of the posters?

Of course not, why on earth would you want to do that? There are plenty of reasons why 'mild' charts could win out, in the same way that colder scenarios could...

[Robbie Garrett]

Where is the MetOffice update?

[snow drift]

Where is the MetOffice update?

Its out and suggesting high pressure near or over us towards the end of the month. There are indications from the model output that this is the way it could lead. I would not bet against them.

[kev238]

Yes, a change in the text from the met office.. Mentioning a return to temperatures close to average or slightly below by the end of the forecast period ( pretty much end of January). Reading between the lines, as stated above, high pressure close by to the uk.

[Robbie Garrett]

Yes, a change in the text from the met office.. Mentioning a return to temperatures close to average or slightly below by the end of the forecast period ( pretty much end of January). Reading between the lines, as stated above, high pressure close by to the uk.

Found it.

Towards the end of January there are indications that temperatures may fall closer to average, perhaps slightly below at times. High pressure may become more influential, resulting in precipitation amounts falling below average in places, with more in the way of sunshine and increasingly widespread overnight frosts.

Now for this HP to ridge further north towards Greenland or Scandinavia.

[Bristawl Si]

Yes, a change in the text from the met office.. Mentioning a return to temperatures close to average or slightly below by the end of the forecast period ( pretty much end of January). Reading between the lines, as stated above, high pressure close by to the uk.

In line with GP's forecast, basically

[Weather Boy]

Yes, a change in the text from the met office.. Mentioning a return to temperatures close to average or slightly below by the end of the forecast period ( pretty much end of January). Reading between the lines, as stated above, high pressure close by to the uk.

.....which is pretty much what the ops run of the GFS has been modelling for some time (although +216 which is roughly where the ridging into the UK starts in the 06z can hardly be regarded as the end of January).

Strong indications, I think (at least if the ops run has its way) that once we get this stormy and unsetled spell out of the way after next week, we'll see some more settled conditions spreading from the south.

We've all seen models drop ideas that they've held pretty conistently at much shorter notice than that, but this one does have the backing of the Meto.

[phil nw.]

Does this mean we can discount the mild looking charts then that have been posted along with the views of the posters?

The next 10 days continue with a fairly typical Westerly pattern with temps. around the norm-some milder days,some colder but nothing out of the ordinary.

If you see the Op.run it looks a mild run against many of it`s members.

http://www.wetterzen..._London_ens.png

Mild charts will show some days in this changeable pattern.but you could just as easily pick a colder chart from the output.

Edited December 30, 2011 by phil n.warks.

[snow drift]

The next 10 days continue with a fairly typical Westerly pattern with temps. around the norm-some milder days,some colder but nothing out of the ordinary.

If you see the Op.run it looks a mild run against many of it`s members.

http://www.wetterzen..._London_ens.png

Mild charts will show some days in this changeable pattern.but you could just as easily pick a colder chart from the output.

A fair amount of rain as well. Not my cup of tea but needed especially if we are heading for a dry period towards the middle to end of month.

[J10]

http://forum.netweat...etweather-blog/ <- Latest Ski Blog

However this features a synoptic analysis using GFS charts over the next 7 days, which should be informative.

Synoptic Patterns and Progression

As for much of the winter we seem to be stuck in a +NAO pattern, with low pressure over the Northern Latitudes with a temporary Surface High over Greenland but with a vigorous Polar Vortex above this. There is low pressure over Scandinavia feeding in cool or cold North Westerly winds over much of Europe (including the Alps). The Azores High has ridges a long way North East edging into western Europe including the UK, starting to feed in mild to very mild over the UK after a cool start.

The general +NAO pattern will not change over the next 7 days, but within this, there will be warmer and cooler periods of weather as we will see below.

Saturday will see the Azores High Pressure (1036mb) a bit further south, but still feeding mild SW winds of a Tropical Maritime airflow into the UK and the rest of Western Europe including the western half of the Alps. Low Pressure over Scandinavia with NW winds keeping it very cold here, and remaining cool over the rest of Eastern Europe for the time being.

Sunday sees the whole pattern edge east, with the milder SW flow over most of Europe and into Southern Scandinavia, remaining cold over Northern Scandinavia and cold also for SE Europe. the Winds over the Atlantic turning more of a NW direction and colder air flooding south, so tuning cooler over the UK later.

Monday sees Low Pressure again dominating the scene over the Atlantic, and now over Greenland , with winds more of a flatter westerly direction, but with the cold air pumped south into the Western Atlantic previously, this should feed moderated Polar Maritime air over the UK, so cool or cold here. Mild further east over most of mainland Europe with SW winds, but staying cold over the far north of Scandinavia and Russia.

Tuesday sees things unsettled on a zonal flow, NW winds pushing into the UK , so cool or cold again, and perhaps stormy over northern areas for a time. South westerly winds over Europe (including the alps), so generally mild, but slightly cooler further north and east, remaining cold over Northern Scandinavia.

Wednesday, sees more a flatter Westerly flow on top of the Azores High to the south, cool over much of Northern and Western Europe (including the Alps from yesterday's NW blast). Milder towards Southern and Eastern Europe, remaining cold over Northern Scandinavia, and turning milder again from the west for the UK, as a Tropical Maritime airflow sets in for a time.

Thursday and Friday a bit uncertain at this stage, the zonal pattern remains set with a mix of cool/cold Polar Maritime air and milder Tropical Maritime air, with perhaps a more general period of Tropical Maritime air around the weekend over the UK if the Azores High Pressure pushes further North East as currently suggested.

[Crystal Memories]

Hi Can anyone shed some light on what the weather is going to be like in the Austrian Alps from the 7th till 14th Jan as from what i can make out from the maps so far looks like there will be increasingly mild air turning any snow at low levels to rain and maybe even higher up the mountains am i reading this right?

[cooling climate]

Lol,Yes first signs that the 500hPa pattern is responding.Early days but that`s the sort of timeframe we should be looking at for response to the first warmings,which were at the top of the Strato.pre-Xmas.

The first stage-the Euro troughing still looks well modelled-

http://www.wetterzen...s/Rtavn1441.png

we need that next step now-upstream to add buckling to the flow.

Heights building on the Alaskan side pushing into the Arctic have

been showing up on the far reaches of the GFS extended output for

the past couple of days now. They are now being modeled inside the

t 300 time frame which is showing some consistency in the modelling.

My previous few posts have alluded to this as these heights will usher

in the start of the northern hemisphere pattern change we will see mid

January onwards.

[weathe20]

Heights building on the Alaskan side pushing into the Arctic have

been showing up on the far reaches of the GFS extended output for

the past couple of days now. They are now being modeled inside the

t 300 time frame which is showing some consistency in the modelling.

My previous few posts have alluded to this as these heights will usher

in the start of the northern hemisphere pattern change we will see mid

January onwards.

This pattern wont last. Signals are a foot for a pattern change to cooler conditions mid Jan.

NAO heading into neautral and slightly negative. The mean AO is heading to negative.

Ridging in the Atlantic bring N, NW air flow, with troughing across eastern europe.