Model Output Discussion - 30th November onwards

[bluearmy]

We just having a chuckle on phone with UKMO about what certain newspapers will do to 'square' their recent/ongoing/interminable editorial line of late, versus the 12C Theta-W approaching Scotland in the UKMO-GM at T+144... ;-)

Isnt that a bit naive Ian. Most of the public will 'tar you all with the same brush'. They won't blame the papers. They think the papers are just reporting what 'you forecasters' have told them. Until the met office can convince the main tv news to allow them a slot to state their case, you won't get a wide enough public audience to appreciate what's really going on with the 'dodgy' agencies. I know this to be true cos i hear it in the office all the time. I get fed up defending the reliable forecasters and am actually frustrated that you can't find a way to make your case.I wonder if deep down, Exeter are worried that if they completely slate jm/JP et all and we get a frigid jan or feb then they'll look stupid? no one will care about the detail that there was only one cold month, not three.

[forecaster]

Does this show a Tropical Continental air source for the UK?

 

 

 

There will be a cross isobaric component to the flow (H->L), and also a general outflow from the high. So you might have a source from the Med, but this would be after that pattern persists for a few days. 

Isobars are not trajectories and figuring out the trajectory of the air is not as straightforward as eyeballing one isobaric map. 

[SMU]

I must admit for me today has meant nothing- I expect a BIG swing towards more inflection in the atlantic tomorrow & a better Scandi high-

 

Remember more inflection in the Atlantic will ensure more if not all energy goes under Scandi not over...

 

just like the NAVGEM 18z has started

 

http://www.meteociel.fr/modeles/navgeme_cartes.php?ech=6&code=0&mode=0&carte=1&archive=0

 

S

Edited December 3, 2013 by Steve Murr

[Catacol]

What ended up happening, over 2 weeks later was estimated to be a 1 in 250 year event. I could show similar charts from the last 26 years, and well, what followed became a nearly every year event for 22 years.

 

Quite right - a very rare event... but the point is that such an event DID occur and it will happen again. Of that there is no question. It wont be this year - at least I dont think it will be... but there again who knows what will happen in a few weeks time - and that is the point.

 

I'm not sure about your Maths though. The south of England has had significantly more than 4 cold surges in the last 26 years. 1997 to 2008 was a poor extended spell for winter in the UK: that is without question, but we have turned a corner since 2008 and blocking has reemerged. Even this year so far, with an early and powerful vortex, the QBO set westerly and a sun that has woken up a bit through the autumn we have still managed to get a meridional pattern and blocking of sorts. Nothing to be pessimistic about at all...

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

There will be a cross isobaric component to the flow (H->L), and also a general outflow from the high. So you might have a source from the Med, but this would be after that pattern persists for a few days. 

Isobars are not trajectories and figuring out the trajectory of the air is not as straightforward as eyeballing one isobaric map. 

 

OK Thanks for the answer. Still pretty mild for a few thousand metres up in winter, 0c isotherm at 3500m!

 

[Iceni]

Hope mods don't mind me responding to this, not really on topic, but worth remembering how December has often fayred in the not too distant future i.e. pre 08.

 

Yes December is much less likely to deliver wintry weather than Jan, Feb and even March. Recent Decembers have been quite unusual with much cold snowy weather (though we haven't been spared very mild weather neither, run up to christmas 08, early Dec 09, second half of both Dec 11 and 12 in particular). It has to be said the second half of Dec 09 and whole of Dec 10 saw very unusual synoptics for the time of year - quite exceptional and not the norm. I always say winter doesn't usually bite until after christmas, any cold before christmas is always a bonus - countryfolklore backs this up.

 

Going back to the 80's we saw a run of mild/very mild Decembers followed by cold/very cold weather in Jan and Feb, look at Dec 82, 83, 84, 85, 86 for evidence. Admittedly this wasn't the case with 87,88 and 89 - gosh the 80's were very poor for wintry weather in Dec, only 81 bucked the trend. Looking at the 90's and 00's prior to 08, only 95 and 96 brought nationwide lengthy cold/wintry weather in December for lengthy periods. Some years brought short sharp shocks, latter part of 93, 00, 01 and 05 for instance. Whilst others delivered cold high pressure scenarios at some stage, as recent as 06, 07, but also 92 and 02, or a minor snowy blip example Dec 8 1990, christmas day 04 in the north.

 

December 10 is also a case in point in itself - wintry weather quickly dissapeared and we saw a very mild 2 month period from second week of Jan. Quite similiar to Dec 81 and 96 which were followed by mild/very mild 2 month spells from mid Jan with very little in the way of wintriness.

 

 

The 'White Christmas' thing was due to Christmas Day being the 6th January as when the Julian changed to the Gregorian calender we lost 11 days. When I think - even over my lifetime - how much more likely snow and cold is in the early weeks of January, rather than the last week of December, it all fits.

Edited December 3, 2013 by Iceni

[Purga]

Another dire run from GFS & before anyone has a crack about 'surface cold' I'm paying heed to the upper air temps because without decent 850's we're in a No Snow zone.

I'm not sure what others want but cold dreary weather without any prospect of the white stuff doesn't float my boat.

BTW the bloke from Inverness looks pretty mild to me

Edited December 3, 2013 by Purga

[nick sussex]

An underwhelming GFS 18hrs run to end a disappointing day for those searching for some festive weather. The PV which was originally stretched in yesterdays outputs and further west has that hideous blob look and also a chunk is left to the ne.

 

The operationals are either overreacting today or picking up on a new trend, although the NOAA anomaly maps look more promising they can tend to lag behind when you get these sudden changes.

 

The ECM ensembles still look fine at least for some surface cold into the UK , I think that may well be closer to the mark but that still leaves the route to a more potent easterly quite difficult.

 

The opportunity IMO is really around the 144 to 168hrs mark because that's when we see that deep dig of the jet into the Atlantic, this is like the window opening because thats when you're most likely to see the high ridge north and you might also get a shortwave ejected south into Germany.at the same time, the problem across especially  the ECM and GFS is the positive tilt to the troughing at the key timeframe.

 

Theres a cut off point here in terms of how far east those low heights can extend  around Iceland if you're to get to an easterly once that's breached and you get energy going too far east the opportunity is gone.

 

IMO if there is to be any dramatic changes then we will see them around the 144hrs to 168hrs mark because that's the realistic window when the upstream pattern is still favourable and where we could squeeze out a bit more amplification.

[Interitus]

NOAA do it for you -it is in the upper air tools section.

 

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/model_guidance.php?dayin=11

 

These analogues are good, but it's worth remembering that they pattern match only over the Pacific/North American region, as statistically close matches over the whole Northern hemisphere are almost non-existent, hence some of the analogues are not always that accurate for our neck of the woods, but interesting nonetheless -

 

These 10 analogs are selected by performing a pattern correlation of the official forecast with observed maps in a 35-day time window centered on the centered date of the forecast, over the Pacific-North America region (60W westward to 175E, 20N to 70N), for observed maps from 1950 to 2010, and ranking the maps by their correlation scores. The 10-analog average map is then correlated with the original forecast over the PNA region, and the value of the correlation is listed in the upper left corner of the map

[fergieweather]

Isnt that a bit naive Ian. Most of the public will 'tar you all with the same brush'. They won't blame the papers. They think the papers are just reporting what 'you forecasters' have told them. Until the met office can convince the main tv news to allow them a slot to state their case, you won't get a wide enough public audience to appreciate what's really going on with the 'dodgy' agencies. I know this to be true cos i hear it in the office all the time. I get fed up defending the reliable forecasters and am actually frustrated that you can't find a way to make your case.I wonder if deep down, Exeter are worried that if they completely slate jm/JP et all and we get a frigid jan or feb then they'll look stupid? no one will care about the detail that there was only one cold month, not three.

The Met Office do get a main slot on TV: BBC Weather, many times a day. Plus ITV. I don't think Exeter are worried re sporadic occasions when LR pseudoscience 'forecasting' becomes reality: such are the vagaries of the business. But the other issue of the profession being tarred with same brush is an ongoing concern and rightly so. Anyway... back to the models!

[Cloud 10]

In the slightly more reliable timeframe,looks like the worst of the winds will be on Thursday

morning with 70 mph+ gusts in northern areas.

 

 

 

My crossing of the north sea in a canoe attempt will have to wait. 

[Catacol]

I have to say CH, I am not as optimistic as you are looking at the strat charts. Firstly, in todays Berlin output which is based on yesterdays 12Z ECM, the best that I can see is any height rises to our NE being positioned too far south and the residual Canadian vortex position also unfavourably positioned to allow further height rises any further north.

 

ecmwf100f240.gif

 

This is backed up somewhat by the latest GFS charts:

 

viewimage.png

 

 

I don't think that the wave 2 activity will be strong enough to weaken the vortex sufficiently.

 

Agree on Wave 2. My post earlier did declare the likelihood that blocking would not set up far enough north, and that the wave 2 warming forecast over the US may not be strong enough to substantially impact the vortex. Nothing wrong with a slightly optimistic slant on it though... :-) - and who knows - that warming may end up stronger than currently forecast.

 

However I do think that the forecast wave 2 warming will help to push the vortex away from Canada and hence I do see the possibility of height rises over greenland later in the month. A Scandy block at proper high latitude in the next 2 weeks is a long shot - I think I have been pretty consistent in declaring a murky mid lat omega type affair as the most likely.

[SW Saltire]

 

BTW the bloke from Inverness looks pretty mild to me

That is fine, if you had said upper temps aren't condusive to snow. However, in all your posts you have said it was going to be mild

Did one of your posts on the ecm not say "get the t-shirts and shorts out" thus contradicting your claim that you are only comenting on snow potential.

Also, even in this post you have said that inverness will be mild, why, because you see a blob of yellow and think mild and northern rab has repeatedly said that may not be the case in reality...

In the slightly more reliable timeframe,looks like the worst of the winds will be on Thursday

morning with 70 mph+ gusts in northern areas.

 

gfs-0-36.png

 

 

My crossing of the north sea in a canoe attempt will have to wait. 

Some of the graphs in the regional thread by lorenzo show it to be far more severe than 70 mph, widely in the 80s if not more

Edited December 4, 2013 by SW Saltire

[Mucka]

ECM London ensembles, still a strong signal for a MLB and a gentle cooling trend from mid month

 

 

It would be nice to see some really cold members clustering from mid month tomorrow.

[bluearmy]

The Met Office do get a main slot on TV: BBC Weather, many times a day. Plus ITV. I don't think Exeter are worried re sporadic occasions when LR pseudoscience 'forecasting' becomes reality: such are the vagaries of the business. But the other issue of the profession being tarred with same brush is an ongoing concern and rightly so. Anyway... back to the models!

Barely enough time to make the forecast ian.london ecm ens the coldest since........... probably march!

[radiohead]

ECM London ensembles, still a strong signal for a MLB and a gentle cooling trend from mid month

 

 

It would be nice to see some really cold members clustering from mid month tomorrow.

 

 

Thankfully ECM and GFS op runs seem to be going off on one from day 9 if not earlier.

Edited December 3, 2013 by radiohead

[phil nw.]

The 12Z anomaly charts suggest a very dry period over the next 2 weeks or so with a high never far away from the UK/W Europe.

The movements of the main features over this period suggests to me that days 9-10 are where the furthest north any block will likely be then signal eases south after that on the naefs.

http://www.meteociel.fr/modeles/naefs_cartes.php?ech=0&code=0&mode=0

http://www.meteociel.fr/modeles/ecmwf.php?mode=101&map=0&type=1

No real appetite from tonight's outputs to develop an easterly yet-more mid-latitude heights seem to be the favourite for much of the period near the UK.

We can't rule out some continental cooling from a south easterly drift after the milder spell early next week but i can't see any support for any deep cold from the east in this set.

[Mucka]

Thankfully ECM and GFS op runs seem to be going off on one from day 9 if not earlier.

 

 

Yeah both above the mean from around then so could just be coincidence the Ops are picking out milder runs. I'll be worried if UKMO goes the same way tomorrow even if the ensembles remain fairly solid as it would start to look like a trend but otherwise today not that much has changed other than a further move away from a quick Easterly being built, looks like we might need to go the longer way around and wait until after mid month to potentially draw in any cold uppers. 

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=297&y=130&run=18&runpara=0&type=3&ext=1

Edited December 3, 2013 by Mucka

[Jimmy0127]

Yup.... Thankfully some of us have learned not to care a jot whether it's a mild, average or cold outcome and to then concern ourselves wIth 12-72hr forecast issues. All interesting whatever the outcome...!

 

But you are clearly somewhat interested:

"UKMO view (just chatted with them) remains as before: i.e. for Scandinavian block to establish after next week's milder (for some, notably so) phase and a progressively colder return from SE/E thereafter.  

 

"Yup, 'could' being the key phrase given the timescale ahead. However, the notion of the colder block (with UK somewhere to western edge of it) remains the form horse they favour currently. I've not seen the DECIDER output behind it, but have perused the EC32, so can see the rationale being employed. Anyway, we watch with interest. The polarization of solutions past next week is very striking currently and it would be foolhardy to wholly write-off any solution (including the NCEP 'Winter Blowtorch') at this juncture, albeit the seemingly contractually-required return to a more zonal or Atlantic-dominated status-quo is a known GFS trait and one often highlighted by the senior forecasters at Exeter, as a note of caution for those perusing stuff progged out past T+240. But that doesn't mean it's wrong. We just don't know...

 

"We just having a chuckle on phone with UKMO about what certain newspapers will do to 'square' their recent/ongoing/interminable editorial line of late, versus the 12C Theta-W approaching Scotland in the UKMO-GM at T+144... ;-)" 

Surely accurate long range forecasting is a meteorologists goal? Especially when potentially hazardous weather is foreseeable. 

[SMU]

Who remembers the OLD days of forecasting Easterlies VIA the GFS ensembles

 

Warsaw, Berlin, Copenhagen > London.

 

You used to start with the Warsaw ensembles dropping through the floor & so on.

 

Lets start with the Warsaw & Berlin Ensembles from 12z.

 

Berlin- MEAN after the cold 3c.

http://www.wetterzentrale.de/pics/MT8_Berlin_ens.png

 

Warsaw- MEAN after the cold rising to 0c.

http://www.wetterzentrale.de/pics/MT8_Warschau_ens.png

 

Lets see what the 00z & 18z throw up-

 

at least 1 will be cold.

http://modeles.meteociel.fr/modeles/gens/run/gensnh-16-1-252.png?18

 

S

[NorthernRab]

Edit: slightly screw up there with the format of this post, please delete  

Edited December 3, 2013 by NorthernRab

[NorthernRab]

Another dire run from GFS & before anyone has a crack about 'surface cold' I'm paying heed to the upper air temps because without decent 850's we're in a No Snow zone.

I'm not sure what others want but cold dreary weather without any prospect of the white stuff doesn't float my boat.

BTW the bloke from Inverness looks pretty mild to me

 

 

 

 

Good to see you've managed to respond (sort of, in an indirect way) to criticism this time, if in a slightly rude manner - "bloke from Inverness" indeed! 

 

As you can see from the chart you've posted, high pressure is dominant over much of the south which could lead to fairly suppressed day-time maxes and the potential for frost and fog. No snow, but then no snow does not equal mild in this situation, it equals cold but dry. 

 

The isobars are more tightly packed for my location on this particular date, so SWrly winds are feeding in warmer air despite high pressure, leading to fairly unseasonal warm for my location in the Highlands and elsewhere in Scotland. All that would take would be a slight shunt of the high to the NW (which the euro ensemble mean currently points to) and we'd be under freezing fog 

[phil nw.]

Yeah both above the mean from around then so could just be coincidence the Ops are picking out milder runs. I'll be worried if UKMO goes the same way tomorrow even if the ensembles remain fairly solid as it would start to look like a trend but otherwise today not that much has changed other than a further move away from a quick Easterly being built, looks like we might need to go the longer way around and wait until after mid month to potentially draw in any cold uppers. 

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=297&y=130&run=18&runpara=0&type=3&ext=1

Yes if we are to get a cold easterly it will be beyond the current modeling i think.

We have a better chance from a blocked setup that's currently forecasted with a weak Atlantic than from a position of a mobile westerly pattern which is our normal December setup.

[Joe Levy]

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=185&y=179 (South West England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=254&y=2 (Northern England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=357&y=78 (East Anglia)

 

Whilst there is not too much in the way of deep cold shown in the 18z ensembles, bar the odd run here and there, there is a notable cool down towards the end, marked by an increased spread. If this trend is maintained, we may start to see the colder runs emerge as a more significant part of the ensemble, but equally we may not. All part of the fun!

 

EDIT except there is a more notable presence of cold runs in Eastern England, which does support the Scandi high idea

Edited December 3, 2013 by Joe Levy

[Panayiotis]

Latest CFS IS A BEAUTY!!!! 

Edited December 4, 2013 by Panayiotis