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Paul

Model Output Discussion - 10th Jan Onwards

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Block is stronger this run. A 1035 surface high too.

 

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One of these days/years we're going to get an Easterly that upgrades closer to time.

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I measured 0.00cms, stalled 5 miles to my west, bet Gnosall and places got a pasting, you not mean south side of house? wind from S

No north side. Drifting snow settles in the shelter of objects that break the force of the wind.

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I believe things are falling into shape gradually and the models will increasingly show us the way into a cold spell beginning sunday/monday.

T132 holds the key for me in the GFS 12z....there's a little less movement east across the Atlantic and colder air coming down into Siberia

 

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I'm optimistic that, as tick becomes tock and T132 becomes T129, T126, and T123 on future runs, it will develop into the prospect of a cold easterly blowing its way towards us at T120

Then it will all go bosoms up! Posted Image

So....the T132 becomes T126.....and we see a continuing improvement in the position with a greater pooling of cold air and a further restraint in the eastward movement from the Atlantic

Posted Image

 

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Ah, go on then, one more time... I don't think I will ever tire of watching that through frame by frame!

 

Still waiting to see the definitive cataylst towards pattern change to rear its head in the general output. No wiser tonight unfortunately. I wonder when it does (presuming it will before March is out...) whether it will be pretty sudden?

I agree, I kept copies of all the N Hemisphere 500mb charts from that time! It was awesome!

 

Two of the most famous cold spells began pretty abruptly; December 1962 and January 1947, but on those occasions, everything worked out perfectly - not something that happens very often! We too often are right on the edge of the cold, with it maddeningly close across the Channel, or lurking just to the north.

 

I am still amazed at the strength of the mid-level flow across the Atlantic that we've been having. But given the intensity of the polar vortex, as evidenced by the extraordinary cold in the States, it's hardly surprising we've had such a powerful jet. Stratospheric temps have been remarkable too - minus 90C at one point last month at 30mb!

 

However, things across the US are a bit more temperate, one can only hope the jet either weakens considerably or changes trajectory - to our south!

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The ECM mean is clearly showing the block being pushed back way to the east

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The strength of the intensifying vortex to the NW and the bulging Azores HP is too much to resist. I think it's game over for any proper cold let's face it.

What Februaury may bring is another matter.

I don't claim to have any great skill at model analysis but I pay scant attention to mean charts as they are only as good as the ensembles that make them up. I appreciate that tonight's ECM mean is probably reasonably representative of the ensembles but that's not always the case, as one or two runs can skew the mean considerably.

Take this set of numbers : 4,4,4,4,4,100,4,4. The mean is 16 but you can hardly say that it is representative of the sequence!

Edited by Chalk Serpent
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Even with the disruption the high just cant push west can it 132hrs?Not strong enough or in the rite position for me

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Is that the longest lived shortwave/trough in history sat over Ireland for 5 days?

Edited by Mucka
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Even with the disruption the high just cant push west can it 132hrs?Not strong enough or in the rite position for me

Better position for the next low, day 6 onward sees the Atlantic ridge reamplify and this time the high is much closer to us so watch the next system head south east.

*DISCLAIMER*

Of course this is the GFS so the energy will blatantly go north east just for the lols

Edited by Captain shortwave
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The 18z  run still shows the Scandi high gamely having another facedown with the Atlantic trough-that cold air to the ne closer on this run

http://modeles.meteociel.fr/modeles/gfs/runs/2014011518/gfsnh-1-120.png?18

snow for the N.Isles and the far ne Scotland with -8C uppers around at that point.

 

The block not going easily.

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Now this run says we are only a gnats **** away from some potential for snow and some actual winter weather! Will it or wont it? 

I might as well play pin the tail on the donkey with these models on this possible Scandi high and more pronounced blocking on this latest run.

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I don't claim to have any great skill at model analysis but I pay scant attention to mean charts as they are only as good as the ensembles that make them up. I appreciate that tonight's ECM mean is probably reasonably representative of the ensembles but that's not always the case, as one or two runs can skew the mean considerably.Take this set of numbers : 4,4,4,4,4,100,4,4. The mean is 16 but you can hardly say that it is representative of the sequence!

Thats why we have spreads CS. Should take care of your scenario.
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Yes I went into one this morning over its push east of the Azores high! its not likely because the overall pattern is expected to keep this displaced to the west, and also bear in mind those comments from NCEP re the GFS, that should call into question how much energy it throws east. It's very finely balanced at the moment and I'm still remaining positive.

post-19044-0-07824100-1389824544_thumb.jpost-19044-0-31089700-1389824622_thumb.jpost-19044-0-69254100-1389824632_thumb.jGfs18z certainly closer to Euros tonight, Azores high westwards correction. Encouraging?
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Looking a tad chilly in the NE states......AGAIN.......not that I'm at all jealous Posted Image

 

Posted Image

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Two of the most famous cold spells began pretty abruptly; December 1962 and January 1947,

While the actual start of the long sequence of cold days was pretty abrupt, isn't it fair to say that the easterly had already flexed its muscles earlier on during both winters in a way in which, sadly, it hasn't managed to do this winter?

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Synoptically interesting run but no chance of anything overly cold due to the high subsiding away to the SE and the warm temperature profile over the continent.

As soon as it hits low res within about 12 hours the Atlantic goes turbo charged and its zonal until spring :-) It may be right but I'd ignore it on this run.

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Day 4 fax compared to the day 5 fax reveals big differences off the eastern seaboard in just 24 hours. yesterday had a wound up system over newfounland at 970 mb. Today has a far weaker one at 990mb 500 miles further east. Thats the human interpretation of the models at days 4/5.

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Looking further ahead, you can see the PV becoming much weaker and less organised on todays runs.

Posted ImagePosted ImagePosted ImagePosted Image

We should be looking for these trends if you want an increase chance of colder weather:

Edited by Panayiotis
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 While the actual start of the long sequence of cold days was pretty abrupt, isn't it fair to say that the easterly had already flexed its muscles earlier on during both winters in a way in which, sadly, it hasn't managed to do this winter?

 

yes both December 1962 and December and early January 1946/47were different to the last 6 weeks.

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CC - YOU DONT NEED DEEP COLD - ITS JANUARY !!!!!!!!!!!!!!!!!!!

 

yes, the first disruptive trough cannot draw a decent undercutting soueaster because the continent isnt cold enough. that will not be the case on the second or third disruption.  some of our best snowfalls have been those where the situation was a knife edge one.  we really could see a decent snow event next week. by the same token, we could fall the wrong side by a degree or so or a hundred miles. its getting to that kind of set up - honestly.

Ok maybe I used the wrong term by saying deep cold what I ment to say was a pattern in the next

10 days or 9 from tomorrow where the pattern is conducive for snowfall and  low laying snow.

I would rate our chances as 10% at the very best.

I think many are flogging a dead horse here. Beyond day 10 and things may start to change quite

rapidly. This strat warming is looking better and better for some fireworks come February.

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Day 4 fax compared to the day 5 fax reveals big differences off the eastern seaboard in just 24 hours. yesterday had a wound up system over newfounland at 970 mb. Today has a far weaker one at 990mb 500 miles further east. Thats the human interpretation of the models at days 4/5.

Hello. Is that a postive or negative upstream change for Uk coldies..

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Lots of high pressure around on the latest GFS, but still too much energy coming out of the states to allow it to settle in a decent position for cold. It's unable to push north and unable to push up to the north east, instead it could land slap bang on top of the country which is a bore fest of a different kind.Posted Image

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Hello. Is that a postive or negative upstream change for Uk coldies..

Theoretically negative as the deeper system should drive a larger ridge ahead of it and sharper trough over here. However, not sure it makes a great deal of difference looking at the subsequent charts on the ukmo run.
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I don't claim to have any great skill at model analysis but I pay scant attention to mean charts as they are only as good as the ensembles that make them up. I appreciate that tonight's ECM mean is probably reasonably representative of the ensembles but that's not always the case, as one or two runs can skew the mean considerably.Take this set of numbers : 4,4,4,4,4,100,4,4. The mean is 16 but you can hardly say that it is representative of the sequence!

Yes basic stats says we need standard deviation and mean to describe a distribution, well a normal one at any rate.

 

Are the ensembles normally distributed or do they show skew from time to time.  Also is there any measure of deviation from the mean reported?

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