Model Output Discussion 01/09/17

[karlos1983]

12 minutes ago, blizzard81 said:

This is what I feared this morning. The Arctic high is a very fickle beast. Like a beautiful woman, the opportunity must be seized quickly as she won't be hanging round for long. 

Classic, that’s where I’ve been going wrong 

[blizzard81]

3 minutes ago, bluearmy said:

Eps AO/nao combo now bottoming out around -2 before recovering to neutral by end week 2. The heady days of -4 not seen for several runs now.

I wonder if this will  be reflected in the next ec46 update. Or will it continue to lead us up the northern heights garden path like it did last year. 

[nick sussex]

US state forecasts. Low confidence past next Wednesday.

Main uncertainty is depth and speed of low progression there, this impacts on the Atlantic pattern so it’s hard to have too much confidence in current outputs until that’s resolved.

[snowbunting]

I remember the gfs in 2009 picking up the cold signal out in Fl only to drop it and then come back with the signal at 7 days out... it wasnt wrong either!  

Seems 2017 might be a reapeat. It dropped the signal for a second cold plunge next weekend in favour of something more Zonal... weather bomb... storm. 

For this on the 12z run.  I wonder if it will stick to this. 

[bluearmy]

19 minutes ago, blizzard81 said:

I wonder if this will  be reflected in the next ec46 update. Or will it continue to lead us up the northern heights garden path like it did last year. 

The ec 46 bottomed out at -2 aswell although it trundled slowly back to neutral around Dec 13th. 

[nick sussex]

One of the biggest areas of contention upstream is the handling of this low pressure circled red from the 12hrs runs:

ECM                                                                     GFS

And from the horses mouth US forecasters admit one of the GFS's failings:

A significant shortwave will dig into Northern California
and eject east quickly deepening once it crosses the Rockies by
Friday/Saturday. The GFS is similar in recognizing the system...
but is trending to keep the energy farther north...with less
amplification of the system until it is nearly east of our area.
The GFS is both a day faster and farther north with the rapid
development of the H500 and sfc lows. This is a pretty typical
bias of the GFS beyond 120 hours.

This flat bias is often why the ECM is preferred across the USA compared to their own homegrown model . Though of course the ECM has its own issues.

Edited November 10, 2017 by nick sussex

[blizzard81]

5 minutes ago, snowbunting said:

I remember the gfs in 2009 picking up the cold signal out in Fl only to drop it and then come back with the signal at 7 days out... it wasnt wrong either!  

Seems 2017 might be a reapeat. It dropped the signal for a second cold plunge next weekend in favour of something more Zonal... weather bomb... storm. 

For this on the 12z run.  I wonder if it will stick to this. 

Let's hope for a repeat this year. Many people forget the gfs victories and ecm failures. Ecm has had many failures, especially over the last 5 years. 

[Hocus Pocus]

26 minutes ago, bluearmy said:

Eps AO/nao combo now bottoming out around -2 before recovering to neutral by end week 2. The heady days of -4 not seen for several runs now.

Just goes to show anything past the 7-10 day timeframe should come with a government  health warning. On a positive note a blocking feature towards our N/NW is still the form horse but where it sets up is still undecided and for how long looks even more indecisive. 

[northwestsnow]

Its really interesting - the models are making fascinating viewing.

I actually thought the EC mean at day 10 looks good-

So, all to play for and plenty of lovely dry and cold weather for walkers like myself to enjoy this weekend- will need the thermals!!

Must admit im suprised (pleasantly) by the tweets ive just read on the tweets thread,polar north westerlies by next weekend? Im not sure im seeing that??

Edited November 10, 2017 by northwestsnow

[knocker]

And the conclusions of this evening's NOAA disussion

PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD 300 PM EST FRI NOVEMBER 10 2017 6-10 DAY OUTLOOK FOR NOV 16 - 20 2017

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO GOOD MODEL AGREEMENT ON THE EXPECTED CIRCULATION PATTERN, AND GOOD AGREEMENT AMONG THE TEMPERATURE AND PRECIPITATION TOOLS.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE TO GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS ON THE 500-HPA CIRCULATION PATTERN DURING WEEK 2, OFFSET BY MODERATE TO LARGE SPREAD AMONG THE ENSEMBLE MEMBERS.

Edited November 10, 2017 by knocker

[feb1991blizzard]

12 minutes ago, nick sussex said:

One of the biggest areas of contention upstream is the handling of this low pressure circled red from the 12hrs runs:

ECM                                                                     GFS

And from the horses mouth US forecasters admit one of the GFS's failings:

A significant shortwave will dig into Northern California
and eject east quickly deepening once it crosses the Rockies by
Friday/Saturday. The GFS is similar in recognizing the system...
but is trending to keep the energy farther north...with less
amplification of the system until it is nearly east of our area.
The GFS is both a day faster and farther north with the rapid
development of the H500 and sfc lows. This is a pretty typical
bias of the GFS beyond 120 hours.

 

Its as you were wrt that trough you circled on the 18z so presumably another good run coming up but one we cant put any faith in!

 

9 minutes ago, northwestsnow said:

Its really interesting - the models are making fascinating viewing.

I actually thought the EC mean at day 10 looks good-

So, all to play for and plenty of lovely dry and cold weather for walkers like myself to enjoy this weekend- will need the thermals!!

It does but I always find with these projected cold spells that it depends on the trend, if i'd just flew back from a long holiday, landed in Britain and you'd offered me that as an ECM 240 mean on 10th November then I would have snapped your hand off, but its peaked and the trend is towards less blocked again, you can even start to see on some runs now the dreaded residual bits of shortwave energy over southern Greenland now, when you start to see that, its usually non-recoverable situation and game over.

[northwestsnow]

Maybe the north westerlies  for next weekend are not such a fanciful forecast- GFS18Z driving the 528 DAM line into north west Britain by next friday morning.

Snow showers across northern hills by next friday?

Edited November 10, 2017 by northwestsnow

[northwestsnow]

In fact 18z shows some heavy snow across much of the western facing pennines- probably be needing as a rough guess 300m + for snow but again, fascinating viewing.

[Had Worse]

98m above your head, you need a bigger hill.

[northwestsnow]

3 minutes ago, Had Worse said:

98m above your head, you need a bigger hill.

Aye, im not sure if 300m would be enough but the 528 DAM line is in the equation and besides- i have hills above 330m about 2 miles up the road.

Probably change tomorrow

Edited November 10, 2017 by northwestsnow

[feb1991blizzard]

1 minute ago, northwestsnow said:

In fact 18z shows some heavy snow across much of the western facing pennines- probably be needing as a rough guess 300m + for snow but again, fascinating viewing.

Yes, not wishing to be IMBY on the MOD thread but this area is one part of the country that illustrates the 300m line effect very well, that setup could well mean green 250m and 2-3 inches at 300m and you can see that on the hills, its amazing what moving from 600 to 1000ft does for your snowfall totals.

[Had Worse]

Just now, northwestsnow said:

Aye, im not sure if 30m would be enough but the 528 DAM line is in the equation and besides- i have hills above 330m about 2 miles up the road.

Probably change tomorrow

I'm facing the other side of the hill from stalybridge / carbrook and that is over 300m asl so if the cloud base is high enough, I might see that icing sugar you hinted at. (My way of avoiding the 'S' word) 

[phil nw.]

Keep to model discussion please guys-ta

[northwestsnow]

2 minutes ago, Had Worse said:

I'm facing the other side of the hill from stalybridge / carbrook and that is over 300m asl so if the cloud base is high enough, I might see that icing sugar you hinted at. (My way of avoiding the 'S' word) 

Aha yes i know that area well enough- the 18z really is of interest for those in our vicinity esp as there are hills all around us- top of Rippendon road at the Kings arms stands at over 400m so this run would seem them with a decent event

sorry phil will drop this- just thought 18z was relevant for snow chances.

Edited November 10, 2017 by northwestsnow

[Had Worse]

2 minutes ago, northwestsnow said:

Aha yes i know that area well enough- the 18z really is of interest for those in our vicinity esp as there are hills all around us- top of Rippendon road at the Kings arms stands at over 400m so this run would seem them with a decent event

You mean where the cross is and the drop down to shaw via Grains road?

Must get back on topic, I sense the models are sending a 2009/10 flavour, its a good direction to come from IMBY.

 

Edited November 10, 2017 by Had Worse

[Polar Maritime]

The GFS has consistently shown a N/W flow of types over the past few days. A better option tonight though.

 

 

[northwestsnow]

Just now, Had Worse said:

You mean where the cross is and the drop down to shaw via Grains road?

 

I do- anyway, 18z looks cold across much of NW Britain from late next week- hope its right!

[Man With Beard]

Lots of routes to a colder air source by D10 on tonight's clusters

Gateway for northerly influence appears pretty much gone by D15 though

[northwestsnow]

Getting that classic feeling watching 18z comes out!! Very cold air in place as the Atlantic tries to get in at 240

Edited November 10, 2017 by northwestsnow

[blizzard81]

3 minutes ago, Man With Beard said:

Lots of routes to a colder air source by D10 on tonight's clusters

Gateway for northerly influence appears pretty much gone by D15 though

Is this because the Atlantic breaks through?