Model Output Discussion - 14th - 20th November

[mountain shadow]

Well the GFS 18z kicks the Euro trash high into touch and would bring the much needed snow to Scandanavia and The Alps. Very different from the ECM though. Too different I think.

[damianslaw]

GFS 18z is massively different to previous runs at around 150 hours onwards and better for cold and snow prospects however being such a difference I cant help but feel its likely to be an outlier. But its all interesting nonetheless.

GFS has a habit of latching onto a theme 240hrs + then play around with that theme in the medium term, only to revert back to what it was showing all along - so I'm not surprised to see it showing some amplification again.. It is the best model in my book when it comes to the atlantic and developments over NE USA it is after all an American model.. it is wrong to assume it will be an outlier. Indeed ECM is suggesting amplification as we hit December.. remains to be seen whether this will verify but if the models continue to show such a pattern in the coming 2-3 days then yes a change may be afoot for the new month i.e. some proper polar maritime air and temps slightly below average nothing exceptional but it would feel much colder than recently. Meto forecast also hints at such a pattern developing for December ..

Back to positives again - how good it is to see this thread alive and well today after weeks and weeks of it being in the doldrums - again thanks to the pattern change and the back of the euro high which was never going to deliver anything cold and snowy in the long term however much people were thinking an easterly may surface..

[mountain shadow]

Well well well. A Finish high at the end of the run. Big up to Glacier Point if that comes off.

[Strider]

The 18z is Lettuceing awesome for cold prospects compared to the 12zs... with such a dramatic difference though it can't be taken seriously until we see the esembles.

[Harve]

GFS 18z is massively different to previous runs at around 150 hours onwards and better for cold and snow prospects however being such a difference I cant help but feel its likely to be an outlier. But its all interesting nonetheless.

Yes, I'm not too sure how the low in the north sea just stops and deepens, which brings in the northerly. If there's an explanation for this then it's certainly encouraging, however.

[Costa Del Fal]

It is supported by the ECM in terms of the shift eastwards in the PV, this for me is a possibility, however the added amplification upstream has more of a question mark.

Indeed there a parts that say yes this run is possible and others that dont. Best run of the day anyway! Plenty of other facts to consider. NAO and AO dont support a cold spell for example.

[Mark Neal.]

+288hr look at that scenario if only we could have that aye

Anyway there are still the signs of some wintry stuff towards the end of this week in the mountains of Scotland and way out in FI, a chance of cold and snow, take it with a pinch of salt, nice to see it there though.

[Cheshire Freeze]

Very interesting run from the 18z tonight- probably more inline with the 12z ensemble suite than the 12z was. The end of the 18z highlights how it could be possible for the UK to experience cold even with a cold strat and PV over Greenland.....nice high latitude block to the east resisting the Atlantic flow. Are cold prospects all but gone for December?! Naaahhhhh, not yet.

[kold weather]

Ha well the 18z GFS develops a rather different solution!

I personally think its completely off-track with that solution and think the flatter jet solution of the 12z is probably closer to the mark (12z ECM probably is too far the other way)

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

If any run is going to throw up charts like this out of nowhere, its the 18z! Get ready for another 4 months of roller coasters!

Disclaimer: This will almost certainly not happen

Edited November 20, 2011 by RAIN RAIN RAIN

[chionomaniac]

Very interesting run from the 18z tonight- probably more inline with the 12z ensemble suite than the 12z was. The end of the 18z highlights how it could be possible for the UK to experience cold even with a cold strat and PV over Greenland.....nice high latitude block to the east resisting the Atlantic flow. Are cold prospects all but gone for December?! Naaahhhhh, not yet.

Yes, this run gives the maximum extraction of cold from a mid latitude high. The jet always runs over the top of the block so it is never sustainable but great to see.

[Backtrack]

A good 18z pub run tonight, brief topplers from the North/North West giving snow to higher ground in the North and East. Still no sustained sub 528 DAM though.

Unfortunately I feel this run is starting to sway towards GP's thoughts of pressure rising over Scandinavia, possibly leading to another Euro High. This really wouldn't be good, and could eat up 1/4 of Winter if it was to sustain itself again for a similar amount of time.

The real question I am asking myself here though, is where the heck is the cold pooling to the East? We have literally nothing to tap into should be get an Easterly, it would just be days on end of North Sea murk.

Overall, an 'OK' run for cold fans, brief incursions from the NW giving snow to higher ground, overnight frosts and overall generally remaining average, or slightly below at times. A little concerning to see no cold pooling to the East, and the Euro High looks to try to rebuild.

[weather_it_will]

It's like somebody hit the weather with a large hammer on the 18Z GFS. Mild to cold in one blow!

Model watching just got interesting again.

[kold weather]

Yes, this run gives the maximum extraction of cold from a mid latitude high. The jet always runs over the top of the block so it is never sustainable but great to see.

Yep i think this shows exactly what we need to look for given the current state of the Stratosphere and La Nina. I think people should always remember that a cold Strat does NOT mean we can't have cold spells, maybe even very cold spells if we tap into a pool, it just makes it very hard to sustain them beyond say 4-5 days unless you pull the upper high over the UK itself.

[Zakos]

The GFS has been toying with a cold spell these last few days in FI. And now, finally, there is a forecast for a significant cold spell outside of FI. Im not saying its going to be this severe, or even if it will occur, as it is still out of the reliable time frame. But, this is the best GFS run we have had in terms of cold since last winter IMO. Im very confident of some kind of cold spell as we enter December, even if it is just a fairly brief northerly toppler.

[Cheshire Freeze]

Yes, this run gives the maximum extraction of cold from a mid latitude high. The jet always runs over the top of the block so it is never sustainable but great to see.

Yeah, at least SOME people will possibly see some snow, even if it is on hills above 500m in the north!

Also, good to see the general intimation that a rather large warming of the strat is likely to take place after Christmas.....Late Jan and Feb could be extremely interesting model watching wise.

[nick sussex]

Indeed there a parts that say yes this run is possible and others that dont. Best run of the day anyway! Plenty of other facts to consider. NAO and AO dont support a cold spell for example.

Yes I can see a plausible way to get that higher resolution output, more amplified upstream pattern and eastwards movement of the PV. As for the lower resolution output , if that verifies I will go and light a candle at Lourdes and start going to Mass!

I'd stick the post 192hrs output of the GFS in the shredder, I can't see that verifying no matter how much I'd like it to.

[phil nw.]

Yes 18Z illustrates perfectly my post earlier about Northerly Topplers.

Even with a strong vortex if we get enough amplification in the flow where it benefits us then we can get a shot of Polar air well south into the UK.

However as Chiono. said with the jet riding over the top this wont sustain for long.

Edited November 20, 2011 by phil n.warks.

[BLAST FROM THE PAST]

18z is a classic example of why I posted earlier to wait and see what will develop. Only early last week it seemed no end to the euro block. My viewpoint was that we would see colder feed set in for last week of Nov, models for sure heading that way. Is 12z right? is 18z right? GFS ECM? Watch and allow the models to develop this week.

Re not sustaining, maybe any cold shot won't initially. However, I think the hemisphere is starting to shift towards a real cold shot down the line and i think there is a whammo down the line this winter....that thought remains firm.

BFTP

Edited November 20, 2011 by BLAST FROM THE PAST

[kold weather]

Right here is the next thread guys, this one is closing very soon!!

[Ruzzi]

I have looked through his Youtube pages and can't find any newer video that is less than 2 months old so I don't know where Brian found this one. Its a shame as I find Mark Vogan very interesting to listen to. I will keep my eye out for any new videos he posts.

Yeah he is an interesting character, with some very interesting opinions and viewpoints. Much appreciated mate!!