Model Output Discussion 01/09/17

[Allseasons-Si]

8 hours ago, snowray said:

Anyone notice the AO potentially falling like a stone as we go towards mid month?

Hi Snowray

that one is outdated 2nd Nov,here is the latest sets of AO&NAO,as you can see on the fourteen day forecast on the bottom right circled in black,you can see the mean(black line)to go negative

3 hours ago, bobbydog said:

anyone got a spare vortex?

this one is broken...

thats some siberian high!

No,too big to carry but you can have a piece of this

i have been looking at the 2010 re-analysis charts and you wouldn't think that a cold spell was coming,here is some steps to that cold spell from charts 1-7

1,this is the point at the time when you wouldn't think that a cold spell was on the way with a strong pv over the pole

2,the trough in the Atlantic start to get a neg tilt to it with heights starting to build into Scandinavia

3,4 the trough heads SE into the low countries allowing heights to build more to our north with ridge building into the Atlantic and from Alaska(pincer movement),the pv is forced to the siberian side

5,6 and 7 the holly grail

the archives for the charts above

http://www.meteociel.fr/modeles/archives/archives.php?mode=0&month=11&day=5&year=2010&map=5&hour=12&type=ncep

the latest 8-14 day 500mb forecast looks very similar to the gfs

Fantasic model watching at the moment and hope they continue

 

 

[bobbydog]

just an observation but some uncanny similarities in ridge placement -

and dates....

[bluearmy]

4 minutes ago, bobbydog said:

just an observation but some uncanny similarities in ridge placement -

and dates....

The difference being that the 1962 chart is real Bobby! 

[Man With Beard]

Just flicking through the 12Z EC ensembles at D11-D13, and the same story again - perhaps 70% of members develop significant heights somewhere to our north (variations between NW, N and NE), with the Atlantic pretty much dead or going underneath. Runs with a decent PV a bit like gold dust. 

Academic for now, but many runs with daytime UK maxima between 4C and 7C by the end of the ensemble period (so cold but still unlikely to lead to widespread lowland snow, which is what one would expect at this time of year).

I see the trend set by Thursday's EC46 counting down nicely at the moment, after a little wobble on Friday.

It's a bit like reporting that a train from London to Glasgow is still on time when it gets to Birmingham, though. It doesn't guarantee it will still be on time when it gets to Gretna Green!!

Edited November 5, 2017 by Man With Beard

[bobbydog]

2 minutes ago, bluearmy said:

The difference being that the 1962 chart is real Bobby! 

shhh!... don't ruin my fantasies...

[Dennis]

signs that a colder phase is growing

[nick sussex]

The GFS 18hrs run a good illustration of just how troublesome that small low in the mid Atlantic is.

Coupled with the GFS flatter upstream pattern this effectively causes the cold to get shunted further east next weekend.

 

 

[bluearmy]

Pretty good NH agreement between ec and gfs ops at day 9

[Met4Cast]

This is an absolutely incredible chart. Half of the Northern Hemisphere is dominated by high pressure, the vortex has been smashed to bits, Europe is going into the freezer.

Incredible from a Northern Hemisphere perspective, wow.

[-uksnow-]

6 minutes ago, bluearmy said:

Pretty good NH agreement between ec and gfs ops at day 9

Yep, and a freaky-large ridge over the near continent forming, the trend is our friend here especially for developments later into November. Though since my move to Oslo I might not be waiting quite so long..

 

Edited November 5, 2017 by -uksnow-

[Mucka]

Fascinating start to the crazy season.

I do love me some, "potential," and there is bags of that for around mid Nov onward.

Models good agreement on strong Atlantic ridge in 7 day range with Arctic high/Scandi ridge in 10 day range.

Cold not assured but with high and mid lat blocking the "potential" is certainly there for cold and snow second half of November

 

Edited November 5, 2017 by Mucka

[Cheshire Freeze]

Usually with the sort of charts on offer in the circa day 10 timeframe, I'd be getting a bit giddy. That is one huge Siberian HP and is usually a harbinger of all things winter. However, I have a nagging feeling we'll see the 'pretty patterns' of the progged shredded vortex dry up pretty sharpish as we head towards December. We need to see warmings of the strat if we're to prevent the upper strat uniting with the trop to bring the usual December dirge.

Unfortunately there is little sign of this at the moment. So those getting carried away may want to keep their excitement in check. It's pertinent to note that most of the 'legendary' years kicked of with a Canadian warming early doors...

Last year served as a lesson to us all just how quickly the trop vortex can ramp up once zonal winds increase.

Edited November 6, 2017 by CreweCold

[Daniel*]

1 hour ago, Daniel Smith said:

This is an absolutely incredible chart. Half of the Northern Hemisphere is dominated by high pressure, the vortex has been smashed to bits, Europe is going into the freezer.

Incredible from a Northern Hemisphere perspective, wow.

Not quite while it looks pretty, seems messy for our part of the world. I do not feel it will exert a pattern change for our isle perhaps if it was more amplified to our west with a more negative tilt, lows could zip southeastwards and herald something much colder. The blocking is not where we ideally want it we're too far west - did we not see the same last winter or the build up? I'd prefer the vortex on the Eurasia side, looks free to crawl back to its spiritual home. Europe is not going in to the freezer on the basis of GFS 18z chilly but not overly cold, however we're seeing firm support for AO to take nosedive, we want to see the NAO going negative too it has greater infulence for us, what the ECM eps depicts although not significantly so. Certainly been a number of years since, I've seen such interest raised early into the proceedings.  

 

[Daniel*]

32 minutes ago, CreweCold said:

Usually with the sort of charts on offer in the circa day 10 timeframe, I'd be getting a bit giddy. That is one huge Siberian HP and is usually a harbinger of all things winter. However, I have a nagging feeling we'll see the 'pretty patterns' of the progged shredded vortex dry up pretty sharpish as we head towards December. We need to see warmings of the strat if we're to prevent the upper strat uniting with the trop to bring the usual December dirge.

Unfortunately there is little sign of this at the moment. So those getting carried away may want to keep their excitement in check. It's pertinent to note that most of the 'legendary' years kicked of with a Canadian warming early doors...

Correct me if I'm wrong CC - excitement was generated last winter over a Canadian warming which did transpire? The winter which followed was hardly in the style of 1962/1963! 

[Cheshire Freeze]

Just now, Daniel* said:

Correct me if I'm wrong CC - excitement was generated last winter over a Canadian warming which did transpire? The winter which followed was hardly in the style of 1962/1963! 

Hmmmmm it was a very very tenuous one!

I believe the strat guys gave a reasonable analysis as to why it didn't quite cut the mustard

[feb1991blizzard]

Better aligned trough up the side of western Greenland on this GFS run.

Edited November 6, 2017 by feb1991blizzard

[feb1991blizzard]

Early chance for Mr Murr to test out his altitude?

[Duane S.]

Very interesting charts on offer at the moment. Something's certainly brewing going into the final third of the month. Some very good heights showing consistently in the higher latitudes.

i would side with Crewe though in that, ideally, we would like to see some decent upper atmospheric warming to mitigate the inevitable U wind increase as we head towards winter. Else the vortex is likely to get its act together sooner rather than later. That said... not having a rampant W-QBO certainly helps in keeping the PV at bay that bit longer and weaker.

[knocker]

Still a pretty fair agreement between last night’s 6-10 anomalies.

The key features of the pattern upstream, strong N. Pacific ridge and vortex N. Canada with associated trough eastern Pacific,

Downstream a lobe has broken off from the vortex and tracked east to northern Scandinavia linking to trough running south to the eastern Mediterranean. This is flanked by the east European ridge and small high cell over Franz Joseph Land.

Thus a strong westerly upper flow out of N. America and across the Atlantic but veering a tad NW in the east under the combined influence of the Azores HP and the trough to the east/south east.

So remaining unsettled with temps a little below average.

The latter period is not particularly clear cut. Still a strong N. Pacific ridge, and tending to positive anomalies on the Russian side of the Arctic,  but no agreement on the orientation of the Canadian vortex and associated troughs but the percentage play  is still a trough to the NW with a zonal flow across the Atlantic so still remaining changeable and temps still a tad below normal.

 

[northwestsnow]

6 hours ago, CreweCold said:

Usually with the sort of charts on offer in the circa day 10 timeframe, I'd be getting a bit giddy. That is one huge Siberian HP and is usually a harbinger of all things winter. However, I have a nagging feeling we'll see the 'pretty patterns' of the progged shredded vortex dry up pretty sharpish as we head towards December. We need to see warmings of the strat if we're to prevent the upper strat uniting with the trop to bring the usual December dirge.

Unfortunately there is little sign of this at the moment. So those getting carried away may want to keep their excitement in check. It's pertinent to note that most of the 'legendary' years kicked of with a Canadian warming early doors...

Last year served as a lesson to us all just how quickly the trop vortex can ramp up once zonal winds increase.

Wise words old bean

Still, im feeling positive we will see a seasonal start to winter- METO seem keen on quite the opposite of the zonal express we have seen in recent Decembers- but back to the original point, its just a watching brief as this juncture.

[Dennis]

Jetstream : North signs 

Edited November 6, 2017 by Dennis

[knocker]

Today and tomorrow.

Broadly speaking you can divide Britain south of the Borders down the middle into west and east. All will start fine and bright with frost in many places but the west will quite quickly cloud over as fronts approach from the north west. This process will be a tad quicker in N. Ireland. Scotland will also start clear with temps as low as -6C in places but rain will quickly move, heavy at times, and becoming quite windy. Overnight and Tuesday the front(s) will track SE bringing rain to all then a clearance and a showery W/NW behind.

a quick run through of this morning's ecm

Wednesday sees  a low track east south of Iceland bringing rain and quite strong westerlies to Scotland whilst a ridge encroaches NE further south This attempts to consolidate but by 00 Friday a frontal system with associated waves orientated SW>NE has tracked around the HP to the south west and is already impacting north west Scotland. This sees the start of renewed amplification of the Azores to the west resulting in the front tracking south , with sporadic rain, over the UK in the next 24 hours

With the amplification continuing apace 48 hours later, 00 Monday, there is a broad trough area to the east from N. Scandinavia to N. Africa (with the colder air well into the latter) and the Azores ridging well north just to the west of the UK. Thus the latter in a cool, showery (wintry in the north) northerly airstream

From this point normal service is resumed with the eastward tracking energy suppressing the ridge with fronts impacting the north west early Tuesday.

Temp contour and anomaly

 

[carinthian]

On ‎01‎/‎11‎/‎2017 at 09:27, carinthian said:

We have trouble brewing in the Alps for Sunday and into the following week. Classic freeze thaw conditions with freezing level this coming weekend ranging from 3000m down to 1500m. An active front has been forecast to stall over the Alps with copious amounts of rainfall. We in our location have a fine mesh model prediction of 26mm during Sunday which could turn back to snowfall. Cold air under cutting warm air above makes for Genoa Cyclonenis likely. This is shown on the ECM models out into next week with further pulses of heavy rainfall probably heaviest on Thursday before the energy slowly dissipates. A nightmare scenario for our piste preparation planners with freeze /thaw conditions and lots of precipitation.

Following on from the above post, all the predicted charts have come to fruition. Snowfall arrived exactly on time and fine mesh predicted totals spot on for out location at 1650m asl. Looking at the present 850mb profile ECM chart below, just shows how borderline it is between rain and snowfall in the Alps. We are just on the cold side of the Genoa Cyclonenis . Snowing here heavily this morning with freezing level at 1300m and now forecast to stay at below 2000m for the rest of the week.

C

[Dennis]

Zonal winds

[mulzy]

Way out in FI, but this is certainly not normal for mid November.