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Model output discussion - 5th December 2016 - Into Winter we go


Paul

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Posted
  • Location: winscombe north somerset
  • Weather Preferences: action weather
  • Location: winscombe north somerset
1 hour ago, Aaki Khan said:

Regardless Of Outcome One Must Enjoy The Epic Runs. #LaLaGaGa

Sorry If Moi Breaking Any Rules.:yahoo::cold:

Oh my ...it frightened me I won't be sleeping tonight ,:yahoo::yahoo::yahoo:day after tomorrow :bomb: interesting times ahead 

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

Seems a lot will come down to what impact the strong -EPO ridge has on the configuration of the eastern N American troughs; if the dive south of the jet on the east flank of the Pacific/Alaskan ridge can 'string out' the trough more N-S then there's an improved chance of a split jet scenario with impacts along the lines of what Steve M has been describing recently.

It is a historically tricky evolution for the models to resolve yet also a pivotal one; once it becomes set to happen (full model agreement at +120 for the overall progression) then then the rest of the output becomes about how long the cold stays with us. It's been too long since we were last in that position... fingers crossed for early-mid Jan 2017!

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Posted
  • Location: Bs249ej
  • Location: Bs249ej
18 minutes ago, Steve Murr said:

The ECM mean @240 certainly lends 'more' support to the OP than against- you wouldnt get that sort of wave up to greenland unless there was a majority vote-

The good news is with a Greenland high there is usually more margin of error in terms of cold air filtering south- rather than an easterly that has a small corridoor..

Anyway ECM op is 10/10 especially for the North- but it would only be the start...

wouldnt it be ironic if it was the start of a 1962/63 redux !!

can but dream,lol

 

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Posted
  • Location: Horton Heath , Eastleigh
  • Weather Preferences: Snow snow snow
  • Location: Horton Heath , Eastleigh
41 minutes ago, Dominic Carey said:

I have a feeling it will be a kaboom run just based on all the factors there were heading into this winter. How long do people think it be until warnings get issued?

Hi Dominic ...if weather warnings were issued based on model output we'd be inundated! It looks like it'll be getting colder but the finer detail (which would result in a warning if snow was forecast) can only be determined much closer to the event . 

Models will go be an indication of trend so I wouldn't get excited yet as I've learned from 6 or so years of lurking in this thread ...until theyre in the so called reliable (72 hrs or less) . 

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Posted
  • Location: Wakefield, West Yorkshire
  • Location: Wakefield, West Yorkshire
21 minutes ago, Steve Murr said:

The ECM mean @240 certainly lends 'more' support to the OP than against- you wouldnt get that sort of wave up to greenland unless there was a majority vote-

The good news is with a Greenland high there is usually more margin of error in terms of cold air filtering south- rather than an easterly that has a small corridoor..

Anyway ECM op is 10/10 especially for the North- but it would only be the start...

wouldnt it be ironic if it was the start of a 1962/63 redux !!

Stop it Steve!

On another note, someone said we're chasing Day 10 charts again. 192/216 are not Day 10 and for me that's where the interest is ECM wise.

Edited by Paul_1978
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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

Notable that at T240 the GEFS mean 500mb height anomalies are very similar to the ECMWF ENS anomalies. So there appears to be all round support for a cold northerly flow around the 7th January!

GEFS GEFS Mean Euro Height Anom 12z 28Dec for 07Jan.png ECM ENS ECM 500 12z 28Dec for 07Jan.GIF

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Posted
  • Location: st albans
  • Location: st albans
1 minute ago, Blessed Weather said:

Notable that at T240 the GEFS mean 500mb height anomalies are very similar to the ECMWF ENS anomalies. So there appears to be all round support for a cold northerly flow around the 7th January!

GEFS GEFS Mean Euro Height Anom 12z 28Dec for 07Jan.png ECM ENS ECM 500 12z 28Dec for 07Jan.GIF

Mslp and anomolies generally higher on the eps closer to the uk - which is evident out to day 15 aswell. 

Edited by bluearmy
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Posted
  • Location: Clayton-le-Woods, Chorley, Lancs
  • Weather Preferences: Snow
  • Location: Clayton-le-Woods, Chorley, Lancs

After the cold front clears South this weekend Fergie mentioned a possible low running in from the NW. Is this still a possibility or has it not materialised? 

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30 minutes ago, Steve Murr said:

The ECM mean @240 certainly lends 'more' support to the OP than against- you wouldnt get that sort of wave up to greenland unless there was a majority vote-

The good news is with a Greenland high there is usually more margin of error in terms of cold air filtering south- rather than an easterly that has a small corridoor..

Anyway ECM op is 10/10 especially for the North- but it would only be the start...

wouldnt it be ironic if it was the start of a 1962/63 redux !!

Hi Steve, a couple of days ago you were telling us to forget a greenland high... can i please just ask you what has changed in your view? im not trying to dig you out here it is an honest question as you seemed so addiment a few days back...what has changed in the output and what has caused that change.. just trying to learn so can see what to look for in future output

Regards

Edited by Guest
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
10 minutes ago, Paul_1978 said:

 

On another note, someone said we're chasing Day 10 charts again. 192/216 are not Day 10 and for me that's where the interest is ECM wise.

Agreed, the wheels are set in motion before day 10, I hope for all coldies sake that we end up with reloading cold shots similar to the Ecm 12z..it would really kick start this winter!:cold-emoji:

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Posted
  • Location: Camborne
  • Location: Camborne

Been waiting for NOAA to update but I think they must be on strike so a brief look at just the GEFS and EPS anomalies. There is nothing significantly different to the recent pattern to my eyes, although there are some variation within it.

In the 6-10 time frame still looking at the Aleutian ridge and the cold trough over SW North America. The Canadian vortex is not that well defined (far too early to dismiss it as it springs to life later) with the beginnings of a south east orientated trough. The other arm of the vortex rather diffuse but tending towards Russia. Thus we have an amplified Atlantic with the HP ridging NW but no agreement on the strength and orientation of the ridge which will effect the interpretation of the surface evolution vis the influence of the HP and the impact of systems as they swing around the high pressure and track SE bringing transitional wintry cold spells.

gefs_z500a_5d_nh_41.pngecm_eps_z500a_5d_nh_11.png

The tricky bit here is the next Atlantic wave propagates during this period with the aforementioned trough in the western Atlantic intensifying and triggering renewed ridging in mid Atlantic and it's this ridging along with the trough to the east that is causing differences in the det evolutions and the severity of the trough impacts at the end of the ten days as they track SE. Needs to be sorted.

ecm_eps_z500a_nh_11.pnggefs_z500a_nh_41.png

Looking at the 10-15 period no huge change but not surprisingly still differences but not with overall theme and the percentage play is still HP ridging adjacent to the UK with temps a little below average.

gefs_z500a_5d_nh_61.png

Edited by knocker
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2 minutes ago, Steve Murr said:

Hi mate

no worries highlighting that- I think you may find if you recheck that the posts were all about phase 1 of this approaching cold spell- 

Pre that ( pre even this cold spell appearing ) I have been highlighting a significant drop off in the zonal wind after the peak on the 27th/28th- heading down to average on the 4th- so certainly MLBs would be available -

The ECM OP is a clear HLB development - in conjuction with the -PNA high, the stratospheric zonal wind doesnt support it & actually the ensemble means have trended upwards again in the last 24 hours so ATM ironically a slightly less amplified MLB ( in the shape of a slightly flatter -PNA ride ) may be the form horse as opposed to the show stopping ECM, however the perk with that is it could deliver as cold, if not colder weather from the East centering the high over Scandi as opposed to Greenland -

In this scenario im happy to be wrong but thats my take ATM- ie not quite the stella ECM but the next best thing...

S

Thank you for taking the time to explain and respond

Regards

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Posted
  • Location: Camborne
  • Location: Camborne

NOAA has finally updated and in the 6-10 and much as expected with strong positive anomalies mid Atlantic with ridging to the west suggesting very much the south staying relatively dry with systems tracking in from the NW and generally impacting the west and north west. In the later period a general relaxing of the amplification and the upper flow tending to back WNW
610day.03.gif814day.03.gif

Edited by knocker
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Posted
  • Location: st albans
  • Location: st albans
1 minute ago, Steve Murr said:

Hi mate

no worries highlighting that- I think you may find if you recheck that the posts were all about phase 1 of this approaching cold spell- 

Pre that ( pre even this cold spell appearing ) I have been highlighting a significant drop off in the zonal wind after the peak on the 27th/28th- heading down to average on the 4th- so certainly MLBs would be available -

The ECM OP is a clear HLB development - in conjuction with the -PNA high, the stratospheric zonal wind doesnt support it & actually the ensemble means have trended upwards again in the last 24 hours so ATM ironically a slightly less amplified MLB ( in the shape of a slightly flatter -PNA ride ) may be the form horse as opposed to the show stopping ECM, however the perk with that is it could deliver as cold, if not colder weather from the East centering the high over Scandi as opposed to Greenland -

In this scenario im happy to be wrong but thats my take ATM- ie not quite the stella ECM but the next best thing...

S

Or a split flow sending plenty of energy into the southern arm could promote a wedge ahead of it and create an effective griceland block which never gets really higher than s Greenland. Concern with this solution.would be clearing the euro heights and not seeing a west based -NAO 

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11 minutes ago, bluearmy said:

Or a split flow sending plenty of energy into the southern arm could promote a wedge ahead of it and create an effective griceland block which never gets really higher than s Greenland. Concern with this solution.would be clearing the euro heights and not seeing a west based -NAO 

Yes - not an ideal one that with the jet riding over the top....

lets see what the pub run brings

s

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl
16 minutes ago, More Snow said:

Hi Steve, a couple of days ago you were telling us to forget a greenland high... can i please just ask you what has changed in your view? im not trying to dig you out here it is an honest question as you seemed so addiment a few days back...what has changed in the output and what has caused that change.. just trying to learn so can see what to look for in future output

Regards

Hi mate. It's quite simple really, weather forecasting, professional and amateur alike, is guided by the models. The thing many people seem to forget is that the models are guided by the weather. Not the other way round. No matter what the models say at any given time, it is always subject to change within a matter of hours. Making sense of chaos is a funny old game....

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Well, it's been a generally mild winter so far but these current cold frosty nights are nice and we have our first arctic incursion on the horizon with hopefully more cold on the way during early / mid January!:)

Edited by Frosty.
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Posted
  • Location: Banbury
  • Location: Banbury
34 minutes ago, Choggy said:

Hi Dominic ...if weather warnings were issued based on model output we'd be inundated! It looks like it'll be getting colder but the finer detail (which would result in a warning if snow was forecast) can only be determined much closer to the event . 

Models will go be an indication of trend so I wouldn't get excited yet as I've learned from 6 or so years of lurking in this thread ...until theyre in the so called reliable (72 hrs or less) . 

We are miles away from any weather warnings , much water to go under many bridges yet

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

@Stewfox

Not good (read awful) 12z output for coldies from UKMO and GFS in the more reliable. Snow chances and cold upper air very limited and short lived. (yeah right) 

What's with the, "yeah right" comment? 

It was a perfectly accurate appraisal of GFS and UKMO 12z Op output and not the first time you had a little dig after quoting me - but then I guess fun posts are a good way of disguising personal digs.

 

 

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Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.

 

 

1 minute ago, bobbydog said:

Hi mate. It's quite simple really, weather forecasting, professional and amateur alike, is guided by the models. The thing many people seem to forget is that the models are guided by the weather. Not the other way round. No matter what the models say at any given time, it is always subject to change within a matter of hours. Making sense of chaos is a funny old game....

Well said re: the models. But even more reason that writing off cold for weeks at a time before the last of the Christmas turkey is binned could have been rather misguided. Lessons here for all if the cold spell comes off. Even for those who should know better.

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl
3 minutes ago, Banbury said:

We are miles away from any weather warnings , much water to go under many bridges yet

Unless it's frozen of course.... then it's not going anywhere...

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