Model Output Discussion 18th Nov.2013-12z onwards.

[summer blizzard]

Chart of the year...

 

[Nick L]

Chart of the year...

 

 

I often see these charts posted but I have no idea what they show! I don't speak fluent German unfortunately...Is it simply potential temperature at 850hpa?

[BLAST FROM THE PAST]

Hi Gibby

Most are 'excited' I reckon because of some cold shots however long/short despite the vortexy vortex. I think most have expectations in right area I guess.

 

 

SB....stop that..Gibby is right, expectations are rising again!!!!!!  Its only chart of year if it came to fruition

 

 

BFTP

Edited November 27, 2013 by BLAST FROM THE PAST

[Frosty.]

Even in the short term, there is nothing mild, even when the atlantic air spills around the top of the high we have cold at the surface with max temps of 5-7 celsius and widespread slight frosts, and then it turns much colder and wintry from the northwest, not bad eh

[Mapantz]

I often see these charts posted but I have no idea what they show! I don't speak fluent German unfortunately...Is it simply potential temperature at 850hpa?

 

It's the Theta E chart basically, it takes the dew point into account as well as air temperature.

Edited November 27, 2013 by Mapantz

[Frosty.]

I often see these charts posted but I have no idea what they show! I don't speak fluent German unfortunately...Is it simply potential temperature at 850hpa?

das wetter ist very cold..ja ja ja wunderbar

[The Giant Daddy Jackpot]

Gibby, I fully agree with your prognosis. With a strong zonal influence and no sign of any blocking heights to our NW or NE, this looks like another very short lived spell and Dec looks increasingly like being an average one.

Edited November 27, 2013 by Sussexwalker

[gottolovethisweather]

IMO despite some optimism this morning I can't see any excitement to be gained from the 10 day mean chart of ECM. High pressure to the SW means there is no way cold will last a day or two on that synopsis.

 

http://www.wetterzentrale.de/pics/Reem2401.gif

 

Yes Gibby, I certainly respect your views  and you may well be correct come verification time. I largely believe the excitement is based more on the potential from say the 3rd December and into the even deeper period of the second week of December and beyond. The excitement from the voiciferous majority (mildies and those whom couldn't care less excepted) is due to being pleased that we are to see the end of High Pressure domination.

 

Anyway, let's move on as this NOT a discussion based around one's individual's analyses over another, it should be about what the various NWP outputs are suggesting, and December is only just around the corner now.

Edited November 27, 2013 by gottolovethisweather

[EML Network]

Chart of the year...

 

for cold yes...but that's a typical ''wishbone'' chart.

 

Good for those along the East Coast, Scotland, NW Coasts and N.Irlenad but that would likely be dry for most...still I agree it looks a peach.

[summer blizzard]

I often see these charts posted but I have no idea what they show! I don't speak fluent German unfortunately...Is it simply potential temperature at 850hpa?

 

It's the Theta E chart basically, it takes the dew point into account as well as air temperature.

 

This.

 

In winter and with high pressure especially it tends to be a much better guide of surface temperature and inversion potential than the standard upper air temperature charts.

for cold yes...but that's a typical ''wishbone'' chart.

 

Good for those along the East Coast, Scotland, NW Coasts and N.Irlenad but that would likely be dry for most...still I agree it looks a peach.

 

True but the air-mass is extremely cold so as a fan of extremes i'd love to see how low some of the sheltered Glens could go.

[Frosty.]

I fully agree with that prognosis. With a strong zonal influence and no sign of any blocking heights to our NW or NE, this looks like another very short lived spell and Dec looks increasingly like being an average one.

Give it chance, I think the alignment of the jet will be conducive to enable wintry reloads from the nw / n.....there is the potential for a noteworthy wintry spell here followed by more further upstream.

[Duane S.]

I am intrigued to see how this is going to play out...

 

Growing signals of the vortex moving back west at the same time as the increased likehood of a strong ridge appearing from over the other side of the Arctic. Now if we could get an amplified enough wave 2 response, we could have a truly severe cold spell thrust upon us. Although my money would be on it not being a particularly long lasting one.

 

Also, even though not really showing on the FI charts right now, watch this space as I think we could then be looking NE for the Mid December to Xmas period thereafter.

[Nick F]

I often see these charts posted but I have no idea what they show! I don't speak fluent German unfortunately...Is it simply potential temperature at 850hpa?

 

It shows the equivalent potential temperature (theta-e) at 850hPa, which is not the same as the forecast temperature at that level. Some links that may try to help understand theta-e:

 

http://www.theweatherprediction.com/habyhints/162/

http://en.wikipedia.org/wiki/Equivalent_potential_temperature

[Newberryone]

Well...the Gfs 06z op run would deliver rather more than standard uk December weather for sure, looks more like Dec 2010 to me, snow all over the uk, severe frosts and a bucket full of ice days followed by a frosty high to hard pack all that deep snow.

I admire your optimism but hasn't it been stated a countless number of times that the Gfs 06 op run has the least amount of data hence overall less likely to verify. 

I'm sorry but my money's with Gibby on this one..

 

 IMO despite some optimism this morning I can't see any excitement to be gained from the 10 day mean chart of ECM. High pressure to the SW means there is no way cold will last a day or two on that synopsis.

 

http://www.wetterzentrale.de/pics/Reem2401.gif

[MPG]

I admire your optimism but hasn't it been stated a countless number of times that the Gfs 06 op run has the least amount of data hence overall less likely to verify. 

I'm sorry but my money's with Gibby on this one..

 

IMO despite some optimism this morning I can't see any excitement to be gained from the 10 day mean chart of ECM. High pressure to the SW means there is no way cold will last a day or two on that synopsis.

 

http://www.wetterzentrale.de/pics/Reem2401.gif

Which data is it missing then? Think you have that completely wrong. Gibby just issued his winter forecast with no mention of cold in December, currently the models are trending towards something from the North so maybe he's panicing! lol.

Edited November 27, 2013 by MPG

[Cheshire Freeze]

Yep no sign of cold.....cold, cold where are you cold?!........Oh, wait

 

 

Edited November 27, 2013 by CreweCold

[Gibby]

Morning Gibby,

 

It still remains cold, the HP isn't exactly a scorcher either, perhaps the far SW possibly touching double figures, while everyone else remains in single digits and cold frosty mornings. 850's -10C.

 

But with respect you are using GFS charts to back up data supplied by ECM and those temperature profile map readings are as useless as a chocolate fireguard at that range but hey ho everyone to their own.

[Yarmy]

I admire your optimism but hasn't it been stated a countless number of times that the Gfs 06 op run has the least amount of data hence overall less likely to verify. 

I'm sorry but my money's with Gibby on this one..

 

 IMO despite some optimism this morning I can't see any excitement to be gained from the 10 day mean chart of ECM. High pressure to the SW means there is no way cold will last a day or two on that synopsis.

 

http://www.wetterzentrale.de/pics/Reem2401.gif

 

It has been stated countless times, nonetheless it isn't true. At least according to any objective measure (i.e. verification stats).

[Newberryone]

Which data is it missing then? Think you have that completely wrong. Gibby just issued his winter forecast with no montion of cold in December, currently the models are trending towards something from the North so maybe he's panicing! lol.

Re: missing data on the Gfs 06 op run I'm afraid I'd have to refer you to one of the more experienced and knowledgeable members on this forum in order to give you a comprehensive answer. However, you must admit this is not the first time this has been stated about this particular run. I can honestly say hardly a day goes by that this whole "lack of data issue" isn't brought up by someone or other.

[Summer Sun]

The final run of ECM Op looks a wee bit cold

 

 

Ensemble for the same time

 

 

Anomaly

 

[chionomaniac]

Yep no sign of cold.....cold, cold where are you cold?!........Oh, wait

 

 

 

I don't think that anyone has said that there is no sign of cold, CC. More so, and Gibby is right here, - there are no signs in the current output of long term sustained severe cold for the UK - ie the such that favourably positioned HLB's would produce. Any one who suggests otherwise is kidding themselves. That does not mean that we will not see a spell of below average temperatures - in fact I believe that December will come in slightly below average due to the NW/ SE orientation of the jet stream and those further north are likely to see some tempreratures cold enough for snow at times.

 

There were a couple of good posts from CH and SM earlier that mentioned the stratosphere and wQBO and how that colder oulooks are still possible in spite of the current stratospheric conditions, but sustained HLB's are unlikely in the immediate.

[Frosty.]

The GEM was the first model to spot this cold and unsettled trend and then all the others slowly climbed aboard, if the gem has nailed this, it will go even higher in my estimation.

[SLEETY]

an Fergusson â€@fergieweather13m

Colder spell expected later next week may last somewhat longer than initially suspected but longevity & influence to S UK very uncertain.

 

looks like met are more confident now of a more prolonged cold-spell,for most of the country

[SMU]

Do people actually understand what the MEAN chart is- its being misread by every single person this morning including Gibby.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2013112700/EDH1-240.GIF?27-12

DAY 10

 

shows the UK in a North West flow with an amplified wave in the atlantic which is 'seemingly' toppling the high-  even at that juncture half the UK is on the northern side of the polar front ( similar to Feb 79 which had copious amounts of snow events)

So snow for the North rain for the south would seem likely-

 

However the Mean is only half the story- You need the clustering to be clear what the form horse is likely to be- & at this stage a multitude of solutions are available-

If you use the operational & MEAN blend then you come up with a more acute pattern.

 

If you just take the mean you will have around 30 runs with a highly amplified pattern & that low sliding across the cold air to the SW of the UK, you will have 20 runs that would take the atlantic low across Scotland returning milder air.-

 

Hence the mean is in the middle- however the low ( if there is one -) will only take one track- & this is where you need the cluster data from the ECM, because the cluster data will probably show more emphasis on amplification- the mean however just waters down the signal because the 20 or so runs that take a different track.

 

As said ANY of the solutions could be right, so it is POOR form to forecast a return mild weather at this point, as it is to be 100% certain that the cold will be prolonged-

Its the type of pattern where a drop in the ocean in weather terms IE 250 miles will mean make or break for the UK.

Very foolish & misguided to take the mean in isolation today without presenting the whole picture-

So note :IM not saying it will be either - however with the Aleutian high lurking into Canada this will SLOW any feature down moving up the east coast & either cause it recurve earlier allowing to come off the states at a more southern latitude or even bend inwards to the interior.

 

No polar blocking = fast solution = good bye prolonged cold-

 

That's why the Aleutian high is so important to the longevity of the cold.

 

S

Edited November 27, 2013 by Steve Murr

[SMU]

 

an Fergusson â€@fergieweather13m

Colder spell expected later next week may last somewhat longer than initially suspected but longevity & influence to S UK very uncertain.

 

looks like met are more confident now of a more prolonged cold-spell,for most of the country

 

I think I mentioned IF twitter this morning-

 

Obviously the ECM clustering & decider models are 'seeing' more amplification....

The reason around the uncertainty for the south is explained above-

 

Amplification & tilt of jet could see the whole of the UK in sustained cold or just half of it ( the North) if the pattern is flatter than expected.

 

S

Edited November 27, 2013 by Steve Murr