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Model Output Discussion - 10th Jan Onwards


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Its a much better orientation than the earlier 00hrs run, still probably a stalemate but at least the high looks in  better shape.

 

Yes, definite improvement, however if my limited knowledge is right, the SW/NE angle is going to make an undercut unlikely/difficult?

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Its a much better orientation than the earlier 00hrs run, still probably a stalemate but at least the high looks in  better shape.

Unfortunately on this run the initial low over Italy becomes cut off very quickly unlike previous output which sends near enough all the energy straight over the top

You can see this at day 4

Posted Image

Notice the warm air wrapping around the Sicilian low, the low will struggle to push south east.

Posted Image

so many small variables to think about with weak ridge and shortwaves all over the place. Hideous chart but one i think won't verify

Edited by Captain shortwave
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The 06z GFS run is very different to the Euro runs as early as t60 so hard to say

what fantasy trip its taking us on.

 

I noticed that on the 0z as well, the differences at 72 hours out is incredible.

 

Here is the 0z GFS at 72hrs:

 

Posted Image

 

And the 0z ECM at 72hrs:

 

Posted Image

 

The ECM has a detached 990mb low our side of that mid-atlantic ridge, while the GFS has it still merged with the parent low the other side of the ridge. Also of note is the little feature near Shetland on the ECM which is more pronounced than on the GFS.

 

Incidentally the 6z GFS moves everything eastwards a little, with a 5mb difference from the 0z over Greenland and the block north of Scandinavia moving towards Svalbard. Just goes to show how volatile the situation is at the moment in the models.

 

Posted Image

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So now the energy is all going over the top? this run has me very confused

 

Posted Image

 

Yes a very messy picture, I think it's safe to say the models are as confused as us past +144 h. No point looking at detail beyond.

 

Posted ImagePosted Image

Edited by Polar Maritime
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Unfortunately on this run the initial low over Italy becomes cut off very quickly unlike previous output which sends near enough all the energy straight over the top

You can see this at day 4

Posted Image

But a look at the jet profile shows all the energy heading S/SE towards SW Europe, however before the jet dives southeast, its quite away north which is keeping pressure low close to the NW too. As I mentioned in my last post, really need the upper flow upstream to become more favourable. Good point by John at keeping tabs on the H500 flow rather than concentrating on individual surface lows with regards to what may happen ahead.
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This is the ECM and GFS for the same timeframes.

 

ECM 00hrs run to 168hrs:

 

post-1206-0-34509800-1389436638_thumb.gi

 

GFS 06hrs run to 162hrs:

 

post-1206-0-52203200-1389436688_thumb.pn

 

The flatter pattern also allows the deeper purple low heights to encroach further se, compared to the ECM which because of the more amplified pattern there helps to pull these further nw.

 

Just some news about perhaps the disagreement between the GFS and others with the low in the earlier timeframe, this from the diagnostic discussions this morning.

 

MODEL SPREAD OPENS UP ON MONDAY AS ADDITIONAL ENERGY COMES ACROSSCANADA AND DROPS INTO THE NORTHERN/CENTRAL U.S..  THE OLD ECMWFWAS QUITE BULLISH HERE AND HAS COME INTO BETTER AGREEMENT WITHOTHER 00Z OPERATIONAL MODELS BY BACKING AWAY FROM ITS VERY STRONGSOLN.  THE GFS MAY PROVE TO BE A BIT ON THE FAST SIDE BY 14/06ZWITH ITS SFC LOW SCOOTING OUT INTO IL WHILE THE 00ZECMWF/CMC/UKMET WERE BACK IN THE EASTERN DAKOTAS.  THE MODELS DOSHOW A SOMEWHAT STRONGER MID/UPPER LEVEL JET THINK THERE WILL BE ALITTLE MORE DIGGING WHICH CAN SLOW ITS EASTWARD PROGRESSION.For newbies that's another of those terms they love to use over there, digging meaning the jet further south and which would help to add a bit more amplification.

Edited by nick sussex
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We've gone from this,

 

Posted Image

 

To this..... in just a few short days.

 

Posted Image

 

Is there any chance of this flipping back to what was showing on the 8th Jan in the next couple of days?

You're probably better making the comparison with the ECM/UKMO blend, I think the odds would favour the more amplified upstream solution, that still doesn't however mean we're going to see a long draw easterly unfortunately.

 

I think theres a chance however of imparting some colder air in from the se which could undercut the precip, its not too much of a leap of faith to get to that from the ECM/UKMO trend but its a much bigger step to then get the pieces in place to deliver that cleaner easterly flow.

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Because of the large differences in the 06z run at a very early time frame I would lean

more towards what the Euro's are showing and due to their encouraging output out to

t144 I think there is a reason to feel a little more optimistic prior to this afternoons runs.

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Just picking up on a point you raise in your post OMM-that is the lack of ‘significant amplification of the upper flow from n America’.

 True to a point. However something equally, if not even more important is shown on the anomaly charts and has been consistently for several days, that is the distance apart of the main troughs you see in the link below

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

 

Thanks John, this is a very helpful and informative description.

 

Anomaly charts are not something I refer to as a matter of course, although I can clearly see the benefits and what you explain makes much sense. With me, I tend to look at the overall current pattern and for features that stand out, based on what I have seen from historically similar situations, and compare to the model output to see if it looks realistic. Not exactly scientific I readily admit!

 

You make some very valid points on model reliability beyond a few days. I never cease to be amazed at how quickly the output can change, that together with the remarkable differences in output between the different models themselves sometimes.

 

These last few weeks have surprised even me in terms of the intensity of both the jet and attendant LPs. In 47 years, I don't ever recall seeing a 926mb LP that close to mainland Britain, as happened last month. Although I have no scientific rationales for saying this, it inclines me to think the pendulum will swing to the other extreme before the winter's out. Maybe it's just my own perception, but it seems as if extreme weather is becoming more common. But that's another subject altogether!

 

Thanks again for taking the trouble to explain anomaly charts, I shall refer back to your postt in future.

 

 

Edited by OldMetMan
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mentioning it for no other reason that it exists - the london ecm ens  still showing colder couple days around the 20th and thereafter, there is still some pretty cold clustering evident. fairly wide spreads though but no sign of mild at this juncture (i'm sure the possibilities will start to appear soon).  averages maxes around 5c but that more likely to be 3c or 7c, depending on what transpires.

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Metoffice seem to think we will get some sort of SE flow undercutting as they go for hill snow mid week. I think it's too much of a "leap of faith" to think we will SE a full backtrack to what we saw a few days ago though with a clean easterly. Onwards and upwards though, once the models settle down we can start the hunt for the next cold snap / spell. Overall though a disappointing winter so far for cold fans.

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mentioning it for no other reason that it exists - the london ecm ens  still showing colder couple days around the 20th and thereafter, there is still some pretty cold clustering evident. fairly wide spreads though but no sign of mild at this juncture (i'm sure the possibilities will start to appear soon).  averages maxes around 5c but that more likely to be 3c or 7c, depending on what transpires.

 

 

Yes the ECM mean suggests a continental feed the further s/e you are: T240 post-14819-0-02766300-1389439908_thumb.g

 

For next Saturday the GFS (06z) and ECM mean:

 

post-14819-0-84215100-1389439980_thumb.p   post-14819-0-27358700-1389439958_thumb.g

 

Only subtle differences; the ECM has more energy entering the trough than the GFS and the pattern is further east with the GFS. Neither look like the Easterly we were forecast a few days ago!

 

Both the GFS op and Control on the 06z look too progressive when compared to the mean, with respect to the AH ridging.

 

However the T240 06z mean is poor for cold:  post-14819-0-98603500-1389440226_thumb.p post-14819-0-33910500-1389440254_thumb.p

 

Still no relenting in the trend away from wintriness.

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^^^ I have heard that the lady is in the cab on the way home:

 

  fergieweather
Hey @Claire7Carter, your 'Say No to Snow' t-shirt clearly having impact if v latest Met Office assessment into 10-15d period proves correct
11/01/2014 11:49
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If we take todays 6z gefs mean temp anomaly, and compare it with 6z mean from 2 days ago, we see the decline away from a negative anomaly for the UK and western Europe. We see the cold has been shunted further north east on the latest output. Both graphics cover the same time period - Jan 14 thru 19th

Posted ImagePosted Image

Gefs mean temp anomaly, 6z 09/01, 6z, 11/01

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^^^ I have heard that the lady is in the cab on the way home:   fergieweather Hey @Claire7Carter, your 'Say No to Snow' t-shirt clearly having impact if v latest Met Office assessment into 10-15d period proves correct11/01/2014 11:49

Well there you have it. MOGREPS is clearly completely dropped the idea of decent cold and snow for to next couple of weeks. Time for a break, This one is gone folks.
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^^^ I have heard that the lady is in the cab on the way home:

 

  fergieweather

Hey @Claire7Carter, your 'Say No to Snow' t-shirt clearly having impact if v latest Met Office assessment into 10-15d period proves correct

11/01/2014 11:49

 

I think anyone seen sporting that t-shirt should be deported!!! lol That does say though 10 to 15 day timeframe so maybe we can scrape some interest before then.

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