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phil nw.

Model Output Discussions 12z 30/11/16

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Ouch, I have to admit latest ec run is not pretty :(, that ridge from europe to greenland on the 0z is not opening amplifying but closing instead and no green bubble to the south either, only a light orange one :( I have to concede, things won't get better until at least the 12th

 

ECH1-168.GIF?04-0ECH1-168.GIF?00

Edited by ArHu3

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Evening All. Well there may be a Big Black Mild Dark Cloud this evening, over the model output but alas the model output in the last couple of weeks have given us snowmaggedon to cheesy very mild charts ! The charts at T+240 both from ecm and gfs  tonight would give us just about anything but deep cold. We need the Euro high to disappear....Waiting......

raised-eyebrows-o.gif

chocolate-teapot1.jpg

freezing.gif

europe high.png

europe highx.png

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Pretty uninspring ECM mean tonight, but the spreads show the potential at 144-168 for a greater window of ridge building perhaps - 

Screen Shot 2016-12-04 at 20.32.58.png

Screen Shot 2016-12-04 at 20.32.43.png

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All you need is a thin slither of heights to the north of three UK and boom.

Any decent set up can spring within 5 days or so.

Look at historic charts.The best set ups for me are low pressure dominated with weak heights doing their job.

A strong decent scandi or Greenland high doesn't go amiss lol.

Love this place.Hats off to you all.

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14 minutes ago, snowwman said:

Bingo! Exactly what I wanted. Thanks muchly!!

That's 65N, a bit too far north :(

Edited by ArHu3

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15 minutes ago, bluearmy said:

Whilst peeps are looking at upper strat zonal wind forecasts (which will likely have little effect in the trop for some time if at all),  back in the trop, the  extended eps build the Atlantic high anomoly between Scotland and Iceland in the 10/15 day period. Low anomolys establish s Europe and more than just a hint of a med circulation by day 15. We stay under weak high anomolys and high upper anomoly goes pretty quickly. Infact, carinthian will be pleased to hear that low upper anomolys establish quite widely over Europe. the picture at day 15 doesn't N look too different to the GEFS at the same time and trending closer to the previous ec 46 output. 

The trending is post day 12 - where there is a drop down to normal T2ms over debilt- so perhaps some hope then however as we know that could evaporate overnight-

the control run doesnt really agree..

IMG_9845.PNG

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Important to remember that the late Nov-early Dec potential was almost entirely down to an overdone stratospheric event (SSW in the case of GEFS - which failed to quite materialise), with tropical forcing not being in the right place to help much.

This time we're working with a weaker yet potentially more influential stratospheric event plus increasingly helpful tropical forcing,  so one can't assume things will play out like they did last time.

Edited by Singularity

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5 minutes ago, Steve Murr said:

The trending is post day 12 - where there is a drop down to normal T2ms over debilt- so perhaps some hope then however as we know that could evaporate overnight-

the control run doesnt really agree..

IMG_9845.PNG

Isn't this this mornings run? If so I'm thinking we could have improvement like on the GEFS.

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3 minutes ago, Ali1977 said:

Isn't this this mornings run? If so I'm thinking we could have improvement like on the GEFS.

Knmi doesn't do gfs, only ecmwf and their own hirlam model and its successor harmonie(<= very good short term, fine mesh model)

Edited by ArHu3

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The anomalies of late have been in pretty good agreement, particularly in the 6-10 range and they still are this evening. This gives one overall confidence in the outcome if not the specific day to day detail. So a quick resume of where we stand.

The Aleutian HP is still with us along with the vortex lobe N. Canada, with associated trough south of Greenland, which between them has initiated an Arctic plunge into north west Canada. Thus the flow is flat across the southern States with a strong jet exiting into the Atlantic. Here the upper flow remains in the westerly quadrant as the European high  pressure has slipped south east of the UK.

Ergo a continuation of unsettled weather with systems tracking NE so the west and north west more prone to the unsettled weather with the SE still remaining under the influence of the HP. Given the course of the airstream temps quite good and above average.

610day.03.gifecm_eps_z500a_5d_nh_11.pnggefs_z500a_5d_nh_41.png

In the 10-15 period things get slightly more iffy although they are all in the same ball park. NOAA is keen on keeping a weak trough mid Atlantic with a weak negative anomaly whereas the other two are not. They both have positive anomalies across the Atlantic with the GEFS indicating the stronger ones in the Iceland area but, and this may turn out to be important, both are indicating ridging to the south west of the UK and the surface high would be in this area. Temps under this scenario would be around normal. The EPS T360 anomaly is not a million miles from the GEFS 5 day except it has much more emphasis on the LP to the SSE

814day.03.gifgefs_z500a_5d_nh_61.png

Edited by knocker

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Things can and will change over the next week or so. I think the following sums up where we are

1) Predictions of an early Dec cold shot haven't worked out. Many inc the Met were inaccurate

2) The vortex remains in a weakened state and surely it's only a matter of time before another opportunity comes along.

3) It's 3 weeks to Christmas. We won't have a clue how this will turn out for at least another 10 days.

4) Weak la nina or neutral favours a colder weather type.

So plenty to be positive about and plenty fun and games along the way!

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6 minutes ago, Steve Murr said:

The trending is post day 12 - where there is a drop down to normal T2ms over debilt- so perhaps some hope then however as we know that could evaporate overnight-

the control run doesnt really agree..

 

The control is probably v cold for s uk under a slow moving high. De bilt too close to the onshore flow off the n sea to have an inversion. 

Anything in the 10/15 day period could evaporate overnight but the close agreement with the GEFS output over the Atlantic and Europe is notable and also with the past four ec 46 runs ignoring the most recent one which we already knew could be skewed by questionable early stages of the run over the Pacific. Since fridays 00z eps came out, the appetite to build Atlantic anomolys again has beeen consistent. the period post the 19th was always the ec46 starting point for advecting cold over us. and yes, we know it didn't see the strength of the mild week upcoming. 

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44 minutes ago, ArHu3 said:

That's 65N, a bit too far north :(

It's in agreement with this:

 

http://ozonewatch.gsfc.nasa.gov/meteorology/wind_2016_MERRA2_NH.html

 

and is more detailed, so I'll take it.

I should add that as Bluearmy has said, there is a long time- lag between 10hPa and the troposhere, and, furthermore, there may be something of a trop- strat split this winter.

 

A note on ECMWF, and I can't find much to complain about- a split trop vortex with opportunities for Atlantic ridging, GFS ensembles are quite keen on said ridging for just beyond this timeframe, and 4 GFS opperational runs yesterday into today, provided us with said height rises by day 16! That's not what I would call poor model output.

Edited by snowwman

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More long faces in here tonight than at an undertakers' convention. Can I offer my take on where we are now?

I used to wonder why there had been no really cold December since 1890. The question was answered in 2009. 119 years!  December rarely does cold until the last week. So still time for it to step up to the plate. Patience and yes more runs....:)

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4 minutes ago, Weathervane said:

More long faces in here tonight than at an undertakers' convention. Can I offer my take on where we are now?

I used to wonder why there had been no really cold December since 1890. The question was answered in 2009. 119 years!  December rarely does cold until the last week. So still time for it to step up to the plate. Patience and yes more runs....:)

There had - 1981.

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Well I would be happy with surface / faux cold like we currently have beyond the upcoming mild spell with a return to frosts and freezing fog..which is what the GEFS mean and MO update is continuing to indicate for second half December..as long as it becomes seasonal again it will be alright!:santa-emoji:

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22 minutes ago, January Snowstorm said:

Things can and will change over the next week or so. I think the following sums up where we are

1) Predictions of an early Dec cold shot haven't worked out. Many inc the Met were inaccurate

2) The vortex remains in a weakened state and surely it's only a matter of time before another opportunity comes along.

3) It's 3 weeks to Christmas. We won't have a clue how this will turn out for at least another 10 days.

4) Weak la nina or neutral favours a colder weather type.

So plenty to be positive about and plenty fun and games along the way!

Never a truer word spoken

 

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30 minutes ago, Bristle boy said:

Are weather model outputs born at the start of the garden path?

The models were good with the forecast  of the high and the mild spell coming up. Of course some like GFS flip flop but not for long.

The background signals and mid range forecast (14 days +) have been taken at face value, hence the disappointment.  Another air frost here tonight the 8th in the last 2 weeks, well above the long term average which is reflected in the low CET values. 

 

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18 minutes ago, Frosty. said:

Well I would be happy with surface / faux cold like we currently have beyond the upcoming mild spell with a return to frosts and freezing fog..which is what the GEFS mean and MO update is continuing to indicate for second half December..as long as it becomes seasonal again it will be alright!:santa-emoji:

Yea all depends were the high sets up in events like the above we had grey skies for over a week until last night were we manage a patchy frost, if it was a good surface high covering all of uk i would be happy with that but if its just half the country reaping the rewards then no thanks.

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2 minutes ago, Summer Sun said:

e98c4d12-5352-43de-9034-03e5f0a61475.png

 

What would this mean?

I think this winter is akin to 2005/6 or 2008/9 - mild pockets intercepted with cold. January and February are the proper cold months. December is just the last bits of Autumn being gunked out. 

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