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Model Output Discussion 01/09/17


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59 minutes ago, mulzy said:

Extended eps not as good as last night.  Picking up a west based NAO signal.  Start of a trend or a blip?

I wondered about this and await the clusters to see if it has some traction but the persistence of the low upper anomoly across w Europe and low height anomoly makes me think that even if a greeny ridge does establish a bit further west, the euro trough could be broad enough to encompass nw Europe and deliver the milder air to our se. No doubt that the spread on uppers shows a rise in temps to our south on a sw/ne trajectory at day 10 so expect a cluster at T240 to show that. broadly, the NH pattern by day 10 which persists out to day 15 is a 3 wave standing - usually tough to break down in a hurry. 

Note that a the very end of the eps, a small circulation of vortex establishes in e Canada which will fire up the northern arm somewhat - should that be the case we will need substantial wedges of heights to our wnw to ensure that the jet is deflected into Europe to our south - high risk strategy but big rewards on offer 

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Good morning Gang ,Its great to be back reading the Posts on Net weather .My Wife passed away two weeks ago ,she had Pancreatic Cancer which spread ,but enjoyed life since she was diagnosed back in Ap

Good afternoon gang ,its nice to be back reading all the posts again ,although i have been lurking .(Thanks to all friends on here for my much appreciated messages over the loss of my wife recently ,T

So sorry to hear that mate Dont want to clutter up this thread but im sure i speak for everyone in wishing you the very best and hope you will be ok.

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3 minutes ago, bluearmy said:

I wondered about this and await the clusters to see if it has some traction but the persistence of the low upper anomoly across w Europe and low height anomoly makes me think that even if a greeny ridge does establish a bit further west, the euro trough could be broad enough to encompass nw Europe and deliver the milder air to our se. No doubt that the spread on uppers shows a rise in temps to our south on a sw/ne trajectory at day 10 so expect a cluster at T240 to show that. broadly, the NH pattern by day 10 which persists out to day 15 is a 3 wave standing - usually tough to break down in a hurry. 

Note that a the very end of the eps, a small circulation of vortex establishes in e Canada which will fire up the northern arm somewhat - should that be the case we will need substantial wedges of heights to our wnw to ensure that the jet is deflected into Europe to our south - high risk strategy but big rewards on offer 

120 -144 is the crucial timeframe now Blue- can we get that retrogression in the Atlantic to bring about the height build over southern Greenland?

UKMO says no, i hope EC is not over ramplifying again...:)

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1 hour ago, Newberryone said:

The PV obviously intent on setting up residence for Dec in its usual location so. ?

Talk about being miles off target?  Can you demonstrate that as I for disagree,

Again runs demonstrating cold continuing in varying degrees.  It is bound to get less cold at times but the opportunity for further surges of real cold remain very much on the table.  

 

BFTP

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1 hour ago, Gavin Hannah said:

 

Good summary. The ridge starts to take form over night tonight. This lasts the week and should continue to bring cold nights and days. Scotland looks good for further snowfall, esp on the high ground. Would expect fine settled weather everywhere else.  The end of the week sees slightly milder temperatures. But should still be fine and settled. The HP has parked itself to our west.  Further into FI, it goes for a mega reload, but takes a full week to get there. 

image.thumb.png.6d330ec6c2bc56158e07860a1eb4b776.png

As mentioned, the Atlantic is a no show. If we can keep the Atlantic shutdown, then this could be the pattern this month.  If we get a few reloads of this ridging, all it takes is for it to setup just right and it could put us in the freezer for a prolonged spell.

Roll on winter!!:cold:

 

 

 

 

Hopefully the pattern carries onto December and talk of mega reloads that shows itself in the GFS anomaly charts.....Two black hole together in the same chart....Can't be bad :)

gfsnh-12-336_tnq5.png

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I think an eruption has to have time to take effect, so that the ash gets trapped in upper levels of the atmosphere and this then brings temperatures down, it has to also circumnavigate the globe somewhat too - Karakatoa in 1883 is a good example of this. It was a huge eruption.

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41 minutes ago, karlos1983 said:

Question while it’s quiet if I may. can Volcanic eruptions have any impact on weather models?

Didn't that volcano in Iceland (with the funny name) erupt in 2009, which consequentely grounded a lot of flights because of the air bourne ash? 

Further to that, sunspots were low too, so I wonder if there's a link with an inactive Sun > active volcanoes > northern blocking and cold winters for north west europe?

Could it be volcano eruptions and their repercussions cause chaos with the models, such as we've seen recently?

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43 minutes ago, karyo said:

Large eruptions can certainly affect weather patterns. I am watching the Mount Agung eruption at the moment. So far, it is not a large eruption but this can change quickly.

Seems a change is likely, Mount Agung: Bali volcano activity prompts 'red warning' http://www.bbc.co.uk/news/world-asia-42126284

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8 minutes ago, Dancerwithwings said:

Hopefully the pattern carries onto December and talk of mega reloads that shows itself in the GFS anomaly charts.....Two black hole together in the same chart....Can't be bad :)

gfsnh-12-336_tnq5.png

Firstly remembering this is one chart way out yonder those charts can be very misleading. Where precisely would you put the surface high?

Edited by knocker
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9 minutes ago, northwestsnow said:

120 -144 is the crucial timeframe now Blue- can we get that retrogression in the Atlantic to bring about the height build over southern Greenland?

UKMO says no, i hope EC is not over ramplifying again...:)

Of course it is - stick with the ens mean. Wouldn't worry about ukmo day 6 anyway. It's just another variation on a theme. 

Btw, that day 10 ec op is hemispehrical cold weather porn - it won't verify like that ! 

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Extended EPS see maintenance of the UK trough with pressure over Greenland sustained. No sign of an azores high presence. At the very least this will produce a NW airstream - and perhaps northerlies on a significant number of days.

eps_z500a_b_nh_360.png

The question will be whether an easterly component can be sustained to bring any deep cold. There has been quite a lot of commentary about tepid northerlies - and loss of sea ice impact. Just looking at temperature profiles over Svallbard or Tromso it is pretty clear a northerly in early winter is going to struggle to deliver the right conditions for lowland parts so longer term we need more of an easterly component and this means higher pressure to our north. Scandinavian heights will be important in the longer term if this winter is to deliver a cold spell of note.

 

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1 minute ago, knocker said:

Firstly remembering this is one chart way out yonder those charts are very misleading. Where precisely would you put the surface high?

"charts are very misleading" ....Yes and absolutely, anything out in FI is misleading you don't have to remind us of that Knocker and the HP well slightly further east if you don't mind :)

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1 hour ago, summer blizzard said:

Note how even the colder parts of the vortex have become disjointed by day 10.

The breakaway portion over northwestern Russia, very interesting with the direction that is heading.

 

ECH0-240.GIF?26-12

If  the flow to the north east connects with the low over northwestern Europe then the uppers would soon plummet. All academic at that range, but nice to ponder what could be. 

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2 minutes ago, Dancerwithwings said:

"charts are very misleading" ....Yes and absolutely, anything out in FI is misleading you don't have to remind us of that Knocker and the HP well slightly further east if you don't mind :)

What I'm trying to remind you of is that from that chart you have no idea where the surface HP is. That is what's misleading before you try to get clever.

Edited by knocker
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6 minutes ago, Catacol said:

Extended EPS see maintenance of the UK trough with pressure over Greenland sustained. No sign of an azores high presence. At the very least this will produce a NW airstream - and perhaps northerlies on a significant number of days.

eps_z500a_b_nh_360.png

T

 

Not necessarily so. Looking at the same chart with contour lines on it you get a split flow with part under the Greenland ridge which is just norh of west over the UK/

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11 minutes ago, Catacol said:

Extended EPS see maintenance of the UK trough with pressure over Greenland sustained. No sign of an azores high presence. At the very least this will produce a NW airstream - and perhaps northerlies on a significant number of days.

eps_z500a_b_nh_360.png

The question will be whether an easterly component can be sustained to bring any deep cold. There has been quite a lot of commentary about tepid northerlies - and loss of sea ice impact. Just looking at temperature profiles over Svallbard or Tromso it is pretty clear a northerly in early winter is going to struggle to deliver the right conditions for lowland parts so longer term we need more of an easterly component and this means higher pressure to our north. Scandinavian heights will be important in the longer term if this winter is to deliver a cold spell of note.

 

Surely this chart indicates West based -NOA?

 

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3 minutes ago, bluearmy said:

Are we really debating a gfs day 14 op chart ??

I wasn't but I was wondering whether was some confusion again vis anomalies bot being a physical part of a contour chart. I men it has been know before. There seem to be a lot of wise guys around this morning who seem to think I'm bloody stupid

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GFS already backtracking now as the upper air cold pool expands over NW europe-

The SE corner doesnt lose the -6line

IMG_1364.thumb.PNG.3a01c7ced65e676a4d1d05d84758fb2f.PNG

where as the 00z had it over debilt-

s

Edited by Steve Murr
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3 minutes ago, knocker said:

Not necessarily so. Looking at the same chart with contour lines on it you get a split flow with part under the Greenland ridge which is just norh of west over the UK/

Agreed. I'm rather assuming that we will continue to see energy spill over the top rather than drop underneath but completely agree that a split, especially given heights profile over the US, is possible. In such circumstances height rises over Scandy become even more important for those looking for cold otherwise we end up with trademark Nina westerlies and a rather damp pattern. It is all finely balanced but the lack of a significant negative anomaly immediately to our west leaves me to stick with a best guess of surface atlantic ridge and jet mainly to the north. As ever - we will see with time.

Chilly pattern, sometimes cold.. but no snow for my back garden yet I fear. :-( Us south westerners get all the bad luck, eh?!

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2 minutes ago, snowblizzard said:

Surely this chart indicates West based -NOA?

A risk, given this is a mean chart but with that low anomoly over w Europe, would be a low risk

note that naefs keeps the Atlantic upper ridge further east compared to the eps. Splitting the difference wouldn't be too bad a result! 

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Good start to the 6z GFS, colder air holding on for much longer across the South-East, should se better retrogression on this one!

Edited by Captain Shortwave
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5 minutes ago, snowblizzard said:

Surely this chart indicates West based -NOA?

 

As an anomaly chart from the EPS suite that's rather hard to say - looking at individual stamps might be more helpful there. I'm using it as a general tool with one key conclusion - and that is that the vortex doesnt appear to be about to set up shop over Greenland which really would be a game over condition for anyone looking for seasonal weather. It's like building a jenga tower - every block and angle impacts on another and this is only one indicator.

BDC charts posted over on the strat thread are interesting this morning - especially as in my quest to learn more and more I havent really factored ozone into my thoughts too often. There is a forcing there that wont upset those with a love of white.

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