Model Output Discussion 29th December - Into mid-Winter.

[MidnightSnow]

6 minutes ago, MrNooo said:

You spend all winter searching for charts such as these and when they appear in FI (which is what they are) some of you dismiss them in an instant, you couldn't make it up.

I think some are just cautious after having their fingers burnt all winter. We've seen some epic charts but nothing has come to fruition yet. (Except obviously the poverty rain/snow event this Thursday/Friday.)

Hopefully these charts are still showing in a few days time.. this forum will be in meltdown 

[radiohead]

Precip charts for easterly on the 12Z ECM look quite light during the period of cold uppers. Though there are some streamers going inland at times, it's mostly light coastal stuff. Of course it's deep FI and subject to lots of change. Impossible to forecast snow this far out.

[Nick L]

11 minutes ago, Steve Murr said:

In terms of IF the ECM landed as is tonight the question of snow showers has arisen-

The timestamp 168 proves the time where the deepest convection would form

SSTs

 so the important factors here are -

*The low heights the further SE you go with lowest values into Kent as you would expect of 536 DAM

* Upper air temps & SSTs combine to deliver around 18c thermal gradient 

* The flow allignment is perfect to pick up moisture off the North sea-

As a result the emphasis on this chart would see widespread snow showers across the E,SE & the South with the northern extent tapering off North of the humber - the further N & W you go the drier it gets, SE Ireland may pick up some convection as well- 

Looking close the SE especially kent sees a nice kink in the flow prolonging the showers into a more defined period of snow edging WSW -

The 192 chart is very similar with just a slightly weaker emphasis on the convection meaning slightly weaker shower streams however even at 168 -192 you could accumulate significant amounts of snow depth with 1:12 ratios...

S

Just to support this, the 3-hourly ECM precipitation charts show plenty of showers, particularly later on. Discussing such details at this range is futile anyhow!

Edited January 10, 2017 by Nick L

[Snowy L]

1 minute ago, radiohead said:

Precip charts for easterly on the 12Z ECM look quite light during the period of cold uppers. Though there are some streamers going inland at times, it's mostly light coastal stuff. Of course it's deep FI and subject to lots of change. Impossible to forecast snow this far out.

Do you have precip charts for Friday? Hopefully ECM is still showing that secondary low.

[stewfox]

50 minutes ago, Jonan92 said:

OMG

 

Look at Greenland

Greenland has gone green !!! on 20 Jan

Blue 18 Jan

Blue Mauve 15 Jan 

I recall Green 14 Jan 1963

13 Dec 2010

15 feb 1986

 

 

[Frosty.]

15 minutes ago, snowice said:

I need new fingers . Thread moving so fast. Great ECM,As Frosty has said.  First cold blast in 48hrs,all the talk of the easterly I nearly forget the upcoming ONE

Yes let's not overlook the initial cold blast, there could be some serious snow up north and most of us should see wintry ppn and very cold frosty / icy nights..even talking about significant wind-chill factor making it feel sub-zero. The Northerly followed by an Easterly would be a dream come true and would make up for last winter's horrors!. Fingers and toes crossed that the Ecm trend will be our friend 

[winterof79]

3 minutes ago, Snowy L said:

Do you have precip charts for Friday? Hopefully ECM is still showing that secondary low.

ECM not making anything of the secondary low at present and also takes the Depreesion on Friday in a little too far East

[chris55]

27 minutes ago, nick sussex said:

NCEP just updated. Good news.

SO OVERALL...THE 12Z AND 00Z ECMWF APPEAR TO BE THE BEST FIT
OVERALL TO THE PREFERENCE AT ALL FORECAST HOURS...BUT THE 12Z
UKMET/CMC LOOK REASONABLY SIMILAR TO THE ECMWF. CONFIDENCE IS ONLY
AVERAGE GIVEN MODEST CHANGES FROM RUN TO RUN AND MODERATE ENSEMBLE
SPREAD.
 

Thankfully no room for the GFS! Remember this is just the short term but crucially this is where the differences start with the GFS and effect events  in the ne USA and ne Canada and downstream the ridge in the Atlantic.

Who actually writes this analysis? And why do they insist on using capital letters throughout? I assume it is from an individual senior forecaster interpreting what they see from the data suites, something comparable to the UKMET, which is worth looking at, though the use of capitals does annoy me!!

[sunnijim]

What happens next?

From past experience in these situations,

Either: The GFS suddenly flips and produces a "snow fans dream run", in line and better than recent ECM output,either 18z tonight or 00z imo.

Or GFS produces steller Snow fest run just as the ECM flips to a more benign solution!

Edited January 10, 2017 by sunnijim

[Nick L]

2 minutes ago, chris55 said:

Who actually writes this analysis? And why do they insist on using capital letters throughout? I assume it is from an individual senior forecaster interpreting what they see from the data suites, something comparable to the UKMET, which is worth looking at, though the use of capitals does annoy me!!

They're from NOAA. NOAA organisations have traditionally used capital letters, all to do with how their forecasts used to be transmitted via telegram I believe, and even some of their existing communications can only deal with caps. They are finally and gradually starting to use lower case letters now though! (Those who are interested in US storms will have noticed it in the SPC outlooks).

Edited January 10, 2017 by Nick L

[winterof79]

8 minutes ago, stewfox said:

Greenland has gone green !!! on 20 Jan

Blue 18 Jan

Blue Mauve 15 Jan 

I recall Green 14 Jan 1963

13 Dec 2010

15 feb 1986

 

 

How very dare you miss this Bad Boy

[Rob K]

14 minutes ago, Steve Murr said:

@Seasonality - The control isnt bias corrected its run ( IIRC ) at the same lower resolution as the ensembles without any pterbation bias -which is different to the known bias of the OP as that bias isnt deliberate, the ENS are-

I wonder how many people know ALL the ENS have bias applied at T0 !!

Heres the UKMO 168-

EASTERLY!!

S

That is the ECM 168 chart, Steve.

 

This is the UKMO 168 chart:

 

[Chris K]

5 minutes ago, chris55 said:

Who actually writes this analysis? And why do they insist on using capital letters throughout? I assume it is from an individual senior forecaster interpreting what they see from the data suites, something comparable to the UKMET, which is worth looking at, though the use of capitals does annoy me!!

To answer the capitals bit, forecasts produced for operational requirements, such as for the military, have this format as well. I think it is just a policy standard dating back for producing internal messages using Teletype machine.

Nick beat me to it

Edited January 10, 2017 by Chris K

[weirpig]

1 minute ago, Nick L said:

They're from NOAA. NOAA organisations have traditionally used capital letters, all to do with how their forecasts used to be transmitted via telegram I believe, and even some of their existing communications can only deal with caps. They are finally and gradually starting to use lower case letters now though!

Lol nick  i do believe what you say is true although they have only been using capitals for six months before that it was a series of dots and dashes . 

[Man With Beard]

I see many picking out the precip charts from ECM - can I add a few "marginal" events to keep an eye on. 

Obviously Thursday (could be MEGA for the south if things fall correctly)

Then Friday - marginal rain/snow running down the east (I think GFS has this as snow)

Then Sunday/Monday, an almost stationary front over central/western areas. Uppers look a bit high, but will the cold air influence as the front is pushed back? Interesting!!

  

Finally, a very non-marginal event apart from on the immediate east coast (and maybe not even here) - on Tuesday, the little disturbance in the North Sea works into southern parts. Snow for sure, and it works its way down into the SW

  

In fact, I wonder if Cornwall/Devon could be the place to be if we get a straighter easterly, with winds down the channel

Not worried about uppers increasing a bit - they're coming straight off snow fields in Europe.

 

 

Edited January 10, 2017 by Man With Beard

[damianslaw]

Well has the ECM got it right? Notable how the last runs of GFS have followed ECM suite, which has been very consistent with its continued easterly output. The trend to an easterly continues in force. Looking at the northern hemispheric picture it all appears to be due to a major switch in the shape and position of the PV, which is forecast to elongate - stretch so to speak towards north pole, with major ridge development taking place over USA, and the flip from a aleutian ridge to an aluetian low, all this aids warm air advection into the Pole across greenland clearing a path for the mid atlantic ridge to build quickly NE. 

Jetstream profile forecasts showing the jet taking a closed circulatory path having s-bended through europe, with some form of cut off low feature developing over central/southern europe, before breaking into small pieces all over the shop - indeed the energy appears to be wiped out of it, probably helped by the much warmer uppers coming off the eastern USA seaboard.

Short-term, weekend is proving very tricky to call, after the cold NW plunge Thurs-Fri with potential for trough features, there does appear to be some form of frontal feature from the atlantic breaking through, but not convincingly simply fizzingly due to rising pressure. I haven't looked at the FAX charts for a long time - always the best when trying to pick out features in unstable polar outbreaks, and today's shows a frontal feature moving through on Saturday in cold uppers, so a potential snow event from the west, with perhaps back edge sleety rain.

We are certainly at the best point in the winter so far for a potential sustained cold outbreak (timing exactly the same as Jan 2013... mmm 2 week cold spell thereafter..)

[stewfox]

5 minutes ago, winterof79 said:

How very dare you miss this Bad Boy

That doesn't look like a  'Greenland' to me ?

 

[karlos1983]

Not a bad mean at 192

Edited January 10, 2017 by karlos1983

[Iceberg]

Are stunning ecm ens mean at t168. Just stunning with the vertical west waa and under cut. 

[Ali1977]

Just now, Iceberg said:

Are stunning ecm ens mean at t168. Just stunning with the vertical west waa and under cut. 

Awesome ENS mean, surely some stunning members and massive support

[Captain Shortwave]

ECM ens

      

      

Best set of ens yet, we do try to get an easterly even on the mean and it remains cold throughout though mainly settled. There are probably some mean easterlies in the set. Signs of potential retrogression perhaps at day 10, this shown more on the anomaly charts. Low heights over central/southern Europe potentially migrating westwards too.

 

Edited January 10, 2017 by Captain Shortwave

[The Beast From The East]

Fantastic ECM again but can anyone remember which Model was most on the money when the 2010 cold/snow spell when it started counting it down from about 10 days out I believe?? 

[winterof79]

4 minutes ago, stewfox said:

That doesn't look like a  'Greenland' to me ?

 

Apologies it was a few days later

 

[karlos1983]

2 minutes ago, Captain Shortwave said:

ECM ens

      

Best set of ens yet, we do try to get an easterly even on the mean and it remains cold throughout though mainly settled. There are probably some mean easterlies in the set. Signs of potential retrogression perhaps at day 10.

 

Finally heights drop in Europe, and low and behold we have cold potential. Cracking few days it has been. Retrogression would just top it off..

[doctor32]

Whole of the ens under the ZERO line throughout run.

Mean a steady -5 to end

Edited January 10, 2017 by doctor32