Model Output Discussion - cold spell to end Autumn

[BLAST FROM THE PAST]

Northwestsnow....you will be wrong. 

 

NFTP

[northwestsnow]

Just now, BLAST FROM THE PAST said:

Northwestsnow....you will be wrong. 

 

NFTP

You dont think it will be corrected south Fred?

[feb1991blizzard]

I still wouldn't rule some parts of the South to get snow, It really wouldn't take that much of a shift at all to bring the SE into the firing line, a bit of a stretch of the imagination to bring the South West into the firing line obviously.

[bluearmy]

Just now, northwestsnow said:

You dont think it will be corrected south Fred?

I think he is taking issue with your comment re snow in the south 

[northwestsnow]

GFS does show the pattern amplified enough to bring another decent Polr maritime shot into the following week tho.

[northwestsnow]

1 minute ago, bluearmy said:

I think he is taking issue with your comment re snow in the south 

Oh ok - fair enough

[nick sussex]

I'm glad I'm not in the high risk area for any snow I don't think I'd be able to sleep and would stay up biting my nails till the next run!

The issue is effected by two key areas, near Iceland with any positive heights hanging on to help force the low se and upstream with shortwave energy spiralling around the main trough which gets ejected east into the Atlantic.

Its really a nightmare forecast. Putting aside slidergate the GFS still re-amplifies the upstream pattern and both the ECM and GFS agree on a big storm developing over the eastern USA.

 

 

[CanadaAl]

1 minute ago, bluearmy said:

I think he is taking issue with your comment re snow in the south 

Still all to play for but it is normally tough for anywhere in the SE to benefit from this setup unless there is already cold air. You really need a channel low type setup bringing winds off the continent to deliver the goods. However, as we've seen in the past it's a lot of 'nowcasting' at the time. 

[Methuselah]

Don't like the look of that much:

[feb1991blizzard]

Much more Amplification on this run - I can see the Easterly returning in FI.

[Allseasons-Si]

5 hours ago, ArHu3 said:

It's positive and predicted to stay positive for the next few weeks 

 

Sorry late to the session,been watching man utd match

ArHu3,that is the pacific north American pattern of which shows amplification to the west of the US and the wrong side of cold for the western side(wind of southerly origin) of the US,trough to the east of that,east US

here is the latest NAO/AO forecast,we would like to keep the forecasts for our side of the pond,looking at the latest from the NOAA,ridge western US,trough eastern US,amplified ridge in the Atlantic,trough over western europe so still nothing has changed in the last few days

the ens/eps at 240 and again nothing has changed much,still a marked trough into europe with ridge in the Atlantic,Alaska and to some extent scuasian keeping the trough over the BI from pushing east,so in that regard,still the sign of trough disruption close to our locale,so all in all pretty much as we were a few days ago,troughs aligning NW to SE

as for the segment of the pv over northeast Canada, the pna(Pacific north American ridge) west coast of N America continues to amplify meaning the trough in central US will dig further downstream amplifying the ridge in the Atlantic

i would take these charts that is churning out the last few days as exceptional to what we have whitnessed the last few years,and i sinserely hope that people get snow this year cos it's been hard to come by of late

i have enjoyed this forum the past few years,whether it be ups or downs,we cannot control the weather so don't let it control you

oh!!,just one final note regarding the slider,....where are we,oh!!,tueday,and we are trying to forecast a slider 5 days out,some seem to think that we are in friday mode,we are not and until then,we will have no idea of how it will turn out and that is pushing it,this will be a 48 hr event to see who will be in the firing line as regards to snow,infact i would pust it at 24 hrs,these slider events are very difficult to pin down.

as allways,happy model watching,there is a lot of twists and turns come winter

 

Edited December 5, 2017 by Allseasons-si

[tight isobar]

3 minutes ago, Ed Stone said:

Don't like the look of that much:

Big game player mid-december onwards!??

Some eye catching russian warmth!!

[Man With Beard]

Yet more promise of a colder long-term set up in the EC clusters tonight. 2 of the 3 clusters again build heights north - and a little east too.(this is D12)

In the shorter term ... D5 clusters have dropped the most southerly tracking "sliders", but the central England slider still very much game on.

Edited December 5, 2017 by Man With Beard

[Geordiesnow]

5 minutes ago, Snowy L said:

Dont be so sure of corrections further south. Last week we all thought Thursdays low would be corrected south, but its actually been corrected North and by quite a distance too.

Indeed although its a slightly different situation set up this time but for those saying it could edge further southwards and westwards basing on past experience are probably saying that because in their heart they want that too happen and I would rather that occurs also as it gives more room for error.

Couple of things that may work in our favour is the models are forecasting a ridge ahead of this weather front coming in so given cold air and lighter winds on Saturday night, it will be cold at the surface, if the front comes in at dawn then despite unremarkable upper air temps then any PPN could fall as snow. Also the models are forecasting fairly low thicknesses which I believe is a plus for those wanting too see wintry PPN although I don't know the full technicalities of this.

I'm still wary it will all be a bit too flat though, past experiences does actually suggest weather patterns get shifted eastwards over time and if the flow is too flat like the 18Z kind of suggest then we may get too much milder air coming in unfortunately.

[northwestsnow]

18z MUCH better into FI with a scandy high pushing the jet SE - thats more like it!!

[Methuselah]

I'll take this as a trend; it's shown up a few times:

[bluearmy]

2 minutes ago, Man With Beard said:

Yet more promise of a colder long-term set up in the EC clusters tonight. 2 of the 3 clusters again build heights north - and a little east too.(this is D12)

In the shorter term ... D5 clusters have dropped the most southerly tracking "sliders", but the central England slider still very much game on.

There is one cluster (largest)  which takes the point of the upper trough further south into Brest. 

and I am delighted to see the return of proper clusters behind day 10!

btw, the pub run has a great lower res!

 

[karlos1983]

Let me just reassure you, and if you live any further south than me you are gonna be getting wet! I have had snow from a northerly, north westerly an easterly, north easterly and a south easterly. However a Westerly, South westerly and southerly I have not. 

I don’t live in the north east or north west and never have done, so couldn’t possibly say for those locations.

I’ve had Thundersnow from a northerly !! 

Myth busted!

Edited December 5, 2017 by karlos1983

[Frosty.]

There is a lot to like about the 18z with plenty of cold wintry weather, especially further north with elevation bringing snow at times too..choc full of potential and a very cold arctic blast just around the corner..not looking good for those who prefer swly zephyrs  after tomorrow / thursday.

[northwestsnow]

1 minute ago, bluearmy said:

There is one cluster (largest)  which takes the point of the upper trough further south into Brest. 

and I am delighted to see the return of proper clusters behind day 10!

btw, the pub run has a great lower res!

 

18Z FI is fabulous Blue and the first GFS operational i have seen bring this into play (scandy height rises).

The charts toward the end would bring in a very cold high with temps absolutely plummeting !!

 

[tight isobar]

5 minutes ago, northwestsnow said:

18z MUCH better into FI with a scandy high pushing the jet SE - thats more like it!!

And for the sanity of my fellow south/south-east'erners,..

If output/synoptics keep playing out this signal....

It may well be the likes of you persons north-north west/west....that begin to look on in envy!... 

??night!

Edited December 5, 2017 by tight isobar

[feb1991blizzard]

I think we can all see where this would be going with that height profile and -10 to -12 isotherm poised.

[Allseasons-Si]

Yes blue,if the heights are strong enough to our east/NE,that will deflect the pv over the NE Canadia back NW,something to beckon with as we go along.

[northwestsnow]

Just now, feb1991blizzard said:

I think we can all see where this would be going with that height profile and -10 to -12 isotherm poised.

BEAUTIFUL chart Feb- East winds for christmas week!!

[Glacier Point]

Gfs may be a little progressive in the extended, but make no mistake, the evolution is perfectly plausible towards height rises to our north.

For the second run, gfs op has retrogressed the North Pacific ridge. This effectively releases the anchor on the North American trough, allowing it to drive eastwards and southwards, this is how the deck falls - Pacifc ridge first, blocking to our north then follows,