Model Output Discussion - Stormy Period Inbound...

[bluearmy]

How did I forecast snow being quite possible between the 13th and 15th ten days ago then?

Snow has been looking like a possibility for a long time in a cold zonal flow but yeah charts change - they do tend to be much better with zonal condtions than blocking though so the 8 to 10 day charts won't be far wrong IMO.

https://forum.netweather.tv/topic/82124-model-output-discussion-into-2015/?p=3104240

Indeed mucka. And that New Year's Day post was made when the ECM jet was predicted to be about three hundred miles south of where it subsequently took it for the 6/10 days period. What is transpiring could have been more wintry if that ECM 00z quite had been correct with its jet lattitude.

It's not guesswork btw - that post was made purely based on the extended gefs and ECM eps. The ECM extended really have been good so far. I guess this means it's going to be wrong about the sinking cold trough now!

 

ADDED: just looking at the new extended eps and i note that the 552 height line is not into france from day 4 through 13, i always tend to judge a cold period re when that line is is suppressed far enough south so as to be into iberia.

 

nothing much to report (apart from the fact that it will be 'wintry' (if you count a severe storm as wintry) from tuesday onwards. once the thursday storm is through it will trend colder.  perhaps a slight 'warm up' as the vortex remnant heads se towards nw europe around day 9/10 and throws up a temporary sw flow ahead of it. even that could deliver a surprise depending on secondary features diving s ahead of it.

 

the back end of the run (day 14/15) shows an atlantic ridge headed east (very marked for that range) and with an established euro trough centred to our se by then, i expect that will amplify towards scandinavia. question then is - 'will it just sink across us (as per ian's meto thoughts from earlier) or can it be maintained to our west and keep the cold in place? the upstream system remains with a mobile look up to that point but i would say that by the end of week 2, the canadian vortex segment looks quite benign and it may be that the euro trough can hold its own.

 

interesting and at last, properly seasonal.  (this isnt a promise of widespread snowcover but over the next 2 weeks, the uk  will see more snowfall than over the past 22 months. (scottish mountains apart).

Edited January 11, 2015 by bluearmy

[john mac]

https://forum.netweather.tv/topic/82124-model-output-discussion-into-2015/?p=3104240

Indeed mucka. And that New Year's Day post was made when the ECM jet was predicted to be about three hundred miles south of where it subsequently took it for the 6/10 days period. What is transpiring could have been more wintry if that ECM 00z quite had been correct with its jet lattitude.

It's not guesswork btw - that post was made purely based on the extended gefs and ECM eps. The ECM extended really have been good so far. I guess this means it's going to be wrong about the sinking cold trough now!

 

ADDED: just looking at the new extended eps and i note that the 552 height line is not into france from day 4 through 13, i always tend to judge a cold period re when that line is is suppressed far enough south so as to be into iberia.

 

nothing much to report (apart from the fact that it will be 'wintry' (if you count a severe storm as wintry) from tuesday onwards. once the thursday storm is through it will trend colder.  perhaps a slight 'warm up' as the vortex remnant heads se towards nw europe around day 9/10 and throws up a temporary sw flow ahead of it. even that could deliver a surprise depending on secondary features diving s ahead of it.

 

the back end of the run (day 14/15) shows an atlantic ridge headed east (very marked for that range) and with an established euro trough centred to our se by then, i expect that will amplify towards scandinavia. question then is - 'will it just sink across us (as per ian's meto thoughts from earlier) or can it be maintained to our west and keep the cold in place? the upstream system remains with a mobile look up to that point but i would say that by the end of week 2, the canadian vortex segment looks quite benign and it may be that the euro trough can hold its own.

 

interesting and at last, properly seasonal.  (this isnt a promise of widespread snowcover but over the next 2 weeks, the uk  will see more snowfall than over the past 22 months. (scottish mountains apart).

That's not hard mate haha!! But let's hope so!!

[bluearmy]

good point john. (seeing as one flake would probably suffice) !

 

im confident that even waltham abbey will have seen lying snow before the fortnight is out!

[Paul]

Thought it would be interesting to see how the GFS has handled the midweek storm - at face values all of the last 12 runs (right back to Thursday) have been there or thereabouts, but then when you consider the difference a hundred miles or so makes when it comes to the outcome on the ground, and that's the headache with these deep low's!

 

 

 

[john mac]

good point john. (seeing as one flake would probably suffice) !

 

im confident that even waltham abbey will have seen lying snow before the fortnight is out!

Hope your right mate! ECM 12Z at least shows plenty of opportunities. Just wondering if the Azores high can keep further west for a long enough.

[Cloud 10]

So whats the day 10 story re the Azores high?

 

 

Lots of daylight between the ECM 12z ensemble mean and the NAEFS at day 10,with the ECM being the most wintry run of the season so far with the azores high sent packing.

 

NAEFS..  ECM..

 

 

NOAA won't be happy in their discussions tomorrow!

 

NCEP= confused.com   http://www.hpc.ncep.noaa.gov/discussions/pmdepd.html

[Barry12]

Interesting

 

[Long haul to mild]

Hope your right mate! ECM 12Z at least shows plenty of opportunities. Just wondering if the Azores high can keep further west for a long enough.

Really could do with seeing more signs of height rises to our North East to get a pattern in that would finally deliver something in the "not seen a single flake since March 2013" East and South East (apologies for an outbreak of IMBYism there!)

At the moment there are very few signs of that and Fergie's earlier post about anticyclonic weather sinking south allowing SW's at the end of the month and into February isn't very encouraging either!

However, that's a long time away and certainly the models are showing that there are some possibilities in the coming week or two, with unexpected features likely to crop up at fairly short notice.

[johnholmes]

re this week and the predicted storm, I posted this in that thread but it will fit well in here I reckon, serious issues with wind do seem likely although just which urban area will be worst affected is not yet clear. This assuming it does not weaken in the actual event.

 

the latest Fax, link below shows for 12z Thursday their view this evening; the low is some 5mb deeper than the last 12z position and about 3 degrees SW.

http://www.weatherch...momslp.htm#t120

Whether the actual track will end up as currently shown or a bit north or south we will know by early Wednesday I would suggest. By then we can use basic meteorology to track a fairly accurate path without a computer model.

It does look like severe gale force winds or even higher for a wide swathe of urban UK, just which urban area being worst affected is not yet totally clear.

For example the 'gradient' or distance between the isobars on the latest Fax suggests a speed of 80 knots over areas of W/NW Yorkshire, so mean speeds at least half that with gusts possible to or even in excess of this, especially if there are any 'lee effects'. This would be when an inversion in the frontal zone develops just above the tops of the Pennines forcing the air through a much narrower depth of air than if a normal atmosphere was present.

Edited January 11, 2015 by johnholmes

[terrier]

Well just catching up after a busy Sunday. Still seems that the gfs wants to bring in another vicious Storm mid week. But before then it seems like some surprise snowfall for many. And not just the usual suspects. The one thing I did notice tonight was the update from Ian regarding the ec32 day update going for w/sw winds as we move into feb. Not great but I guess still time for a change.

[Woollymummy]

Is all this new change big enough to qualify as a "cold heart" or do we need to see sustained cold into February? I still want the OPI to win...,

[johnholmes]

I think too many are getting hung up about the wind direction Ian quoted. I read it as being in conjuction with surface high pressure. To me he perhaps left things a touch in the air for whatever his reason with no comment about where the high might be actually located. If you read the 16-30 day Met outlook, which has hardly changed for over a week, they have consistently mentioned the weather being calmer at the end of the period, I quote the last sentence below

However towards the end of this period, drier and more settled conditions may start to become a little more dominant, especially across the south.

[knocker]

 I believe the METO take but the both the GFS have ir running further north which would be better.

Charts courtesy weatherbell

 

Edited January 11, 2015 by knocker

[fergieweather]

I believe the METO take but the both the GFS have ir running further north which would be better.

Charts courtesy weatherbell

We await another assessment shortly from Ops Centre based on their 18Z output. The 12z stuff didn't look at all pretty with inland gusts widely to 50kts.

[fergieweather]

We await another assessment shortly from Ops Centre based on their 18Z output. The 12z stuff didn't look at all pretty with inland gusts widely to 50kts.

No significant changes at this juncture from UKMO albeit clearly development later Weds remains a key uncertainty with regards to wind strength detail/distribution. Ditto PPN phase across S England late Tues; ditto what unfolds later Fri. So little to add until tomorrow.

[Barry12]

No significant changes at this juncture from UKMO albeit clearly development later Weds remains a key uncertainty with regards to wind strength detail/distribution. Ditto PPN phase across S England late Tues; ditto what unfolds later Fri. So little to add until tomorrow.

 

Whats the snow risk for the north on Tuesday?

[Mucka]

Definitely scope for some widespread snowfall around the 19th as well.

 

 

If we can get a good slider or disruption SE then it is game on and interesting to see that weak ridge appear.

GEM was the first to toy with that the other day I think.

If it gains strength it would be nice for coldies.

 

Scandi highs can pop up in short notice with such situations (low probability granted but something to watch)

Edited January 11, 2015 by Mucka

[Captain Shortwave]

Definitely scope for some widespread snowfall around the 19th as well.

 

 

If we can get a good slider or disruption SE then it is game on and interesting to see that weak ridge appear.

GEM was the first to toy with that the other day I think.

If it gains strength it would be nice for coldies.

Interesting that both the operational and parallel are playing with this scenario (albeit with a different starting point around day 7)

GFS op

Not far from something good, slightly better heights to our north and we would be in business.

Edited January 11, 2015 by Captain shortwave

[bluearmy]

Where will this fella be come Friday?

[john mac]

image.jpg

Where will this fella be come Friday?

Ian said the MO think it will head towards Portugal!! Hope it's a channel runner though!!

[shaky]

No substantial snowfall showing on the models this evening for most low lying areas. No severe warnings issued by the met office either for snow...

as ian fergie said warnings to be expected regarding snow tomorrow!! Wind is the main concern at the moment!

[Eugene]

How did I forecast snow being quite possible between the 13th and 15th ten days ago then?

Snow has been looking like a possibility for a long time in a cold zonal flow but yeah charts change - they do tend to be much better with zonal condtions than blocking though so the 8 to 10 day charts won't be far wrong IMO.

 

 

On January 2nd people were posting charts for Jan 10th showing a stronger euro high just to our south saying it's a long way to cold, yet what happened is many in northern england saw snowfall on Jan 10th/11th with the potential for more tuesday and later in the week.

[bluearmy]

Ian said the MO think it will head towards Portugal!! Hope it's a channel runner though!!

I think Ian was speaking about the small depression following later. This little feature seems to be a potential troublesome one.

[Mark Neal.]

I think Ian was speaking about the small depression following later. This little feature seems to be a potential troublesome one.

Troublesome in regard to potential surprise snowfall? 

[BLAST FROM THE PAST]

Looking ahead what am I anticipating....well fortunately its not developing in too mild a month or indeed outlook, some pretty chilly weather on and off to come. I'm also/really focussing on my period 20/21. Another stormy spell around then, LP/s likely not to be as deep but could be more of a player/s as I anticipate developments to our E/NE [could be a HP or it could be heights trying to build] to induce a more southerly track with even sub lows going into near continent thus affecting more of the UK [direct hit] and a negative tilt so a SE'ly flow could develop.

 

 

 

Above is my musings in seasonal thread, 18z GFS is interesting indeed

 

 

BFTP

Edited January 11, 2015 by BLAST FROM THE PAST