Model Output Discussion - 23rd Jan - 12z onwards

[Roy]

I remember in similar situations to this, although there might not be snow in the south of the UK during the daytime, there's always a chance of polar lows coming south in the night time period when the temperature is lower. I've seen this happen a number of times in the past

[KyleHenry]

"Well I believe in Keyser Söze and the only thing that scares me is model fanatics"

Next weeks Northerly incursion is a direct result in the very short lag time between Troposphere and Stratosphere event unfolding.

Height rises N America around 26th Jan. Asian a Mountain Torque event by the 31st Jan. Polar Vortex displacement is garenteed .

Is it enough to indefinitely disrupt Polar Vortex? Unknown.

[Daniel*]

Ship is holding steady ECM T144

Good so far...

Edited January 24, 2015 by Daniel*

[ANYWEATHER]

I'm sorry, but you're wrong. Charts that are in the high resolution time frame should ALL be taken VERY seriously. Of course the professionals take them into account, how do you think the Met Office come up with the medium and long term outlooks? Granted they will use more than one model.  It's called a FIVE day forecast for a reason, and they can be made with reasonable confidence.

Now when talking about precipitation amounts or sunshine amounts, charts past the 72hr mark are useless yes, but when examining the upper air profiles for trends or to get a jist of the outlook over the next 5-7 days, each and every run counts.

 

Suggesting people calm down over a set of charts that are realistically WELL into the reliable time frame is just plain stupid.

 

Rant over. 

It depends though on the level of Shanon Entropy as Ian Ferguson has mentioned. High S/E = low confidence in the forecast  , Low S/E= High confidence in the forecast.

[J10]

Looking back to historic charts the following give heavy snow to low levels in the south.

 

 

Is there a source of historical data, which gives more information on historical events e.g. these type of charts.

 

 

I do think that some people tend to underestimate the snow potential from Northerlies as they live in areas, not effected by them.

 

With relation to the GFS charts they got very messy and the delayed the coldest air further south, something we didn't see in the ECM earlier. But what will the 12Hz show.

[ukpaul]

For comparison purposes

 

ECM 144h

 

UKMO

 

GEM

 

GFS

[Ali1977]

Surely cold enough for UK wide snow showers with the T168 ECM!!

[chris55]

ECM looking rather nice!!!!!!

[swfc]

Ridging in the atlantic not as good on the ecm at 160+ and little of a pressure rise towards greenland compared to this morning.Small low zipping threw ete .Still a good cold blast so far tho imo

Edited January 24, 2015 by swfc

[SMU]

Reviewing the ECM 144 it has

* A trough moving south over the uk ( look at the kink )

* low heights - circa 500mb thickness ~ 524 dam

* low uppers over england - as low as -8c in the SE

Thats certainly has wintry potential!!

s

[chris55]

ECM 168 Cold enough for snow for all!! And whats going to happen to the little potential "runner" in the Atlantic??? Undercut? Hopefully!

 

[Mucka]

JMA certainly brings in some colder uppers, maybe not so long lived though.

 

[J10]

ECM 12Hz, much better than GFS 12Hz, much cleaner looking and gets the cold into southern areas quicker.

Edited January 24, 2015 by J10

[Mark Neal.]

Reviewing the ECM 144 it has

* A trough moving south over the uk ( look at the kink )

* low heights - circa 500mb thickness ~ 524 dam

* low uppers over england - as low as -8c in the SE

Thats certainly has wintry potential!!

s

Good to see you being more positive mate, ECM looks pretty good! Plenty of instability in that flow.

Edited January 24, 2015 by Mark N

[Weathizard]

I would like to bank this run. Nice evolution, not quite as good ridging towards Greenland but general theme from the ECM is very solid.

 

BANK

 

[Ice Day]

That'll do nicely!

 

[TSNWK]

Short but harsh 3 day cold blast.. Not to be sniffed at folks.. It might topple over us at 216 and we then have a couple of days to severe frosts over the snow fields..

Ramp over.

[The Enforcer]

ECM 12z does look very cold, however, there is still need for caution:

 

 

 

Will need to see dew point information, which will only verify inside T+24.

Edited January 24, 2015 by The Enforcer

[IDO]

The ECM op at D9 flatter, like its 0z mean tonight: 

 

To be expected and in line with the recent GEFS output of a 5-6 day cold spell.

[in the vale]

I think it is worth pointing out the obvious for those who may be missing it. Over the last 2-3 days the models have converged to provide a high degree of confidence in a cold spell over large parts of the UK. That's good, full stop. Which places will see snow and very cold temps has shifted around but where will actually benefit depends on the source of the flow. We have seen NW/N/NE scenarios and the mood of the forum has shifted hugely depending on which direction each run has sourced the upper air from.

 

Some posters (we know who they are) are entirely objective but the vast majority will call a particular set of outputs an upgrade or downgrade based upon where they live - entirely natural. I get excited by N or NW flows but quite unexcited by easterlies a) because there are generally too many factors that need to verify and b) because they don't generally help me (N. Wales) with snow (cold, yes). However, I am excited if John from Norwich gets snow and look at their pictures of it with a smile on my face. My advice is to look at the posters location before reading their words. I have done this here for years and almost always gives you as accurate a picture of what the models are ACTUALLY showing than what their words are saying. Daniel's post above (#331) is a great example of being objective - he lives in London but seems excited by a chart which would give him much less than me. Good for you matey.

 

There is stunning potential in the short, medium and longer term for many of us - but I do understand how each run consumes some posters entirely, only for the same folk to appear again a few hours later saying there has been a major downgrade. We are only human after all! From all models and wider teleconnections, Feb 2015 has the potential to be remembered for a good few years. Potential is all we have right now and I've already banked that and am very content!

[Ice Day]

At 216 the northern hemisphere looks like a crocodiles face.............I'll get my coat!

 

[Iceberg]

EC is just stunning all the way though tbh, however if we stick to T144, a Steve says there is a front moving down, IMO there are a couple of surface features (i.e upto around 8000ft) coming down the country, as we get closer, history (and far too much model watching), tells us that the warmer sector and colder sector in these features amplifies down to around T48-72 region. With the amplification comes rain and sleet for areas west of the features centre and heavy snow just to the east. These features also tend to move west a bit as well imo.

With that in mind a forecasting would be very concerned with *snow potential* atm, particularly for areas east of devon and west wales and west of say the M1.

A wide area atm, which will get narrowed down, but dry this aint.

[Mark Neal.]

EC is just stunning all the way though tbh, however if we stick to T144, a Steve says there is a front moving down, IMO there are a couple of surface features (i.e upto around 8000ft) coming down the country, as we get closer, history (and far too much model watching), tells us that the warmer sector and colder sector in these features amplifies down to around T48-72 region. With the amplification comes rain and sleet for areas west of the features centre and heavy snow just to the east. These features also tend to move west a bit as well imo.

With that in mind a forecasting would be very concerned with *snow potential* atm, particularly for areas east of devon and west wales and west of say the M1.

A wide area atm, which will get narrowed down, but dry this aint.

Thanks for your updates on surface features,precipitation etc.. very handy to hear. Hopefully someone will post some preicip charts for ECM when they come out. 

[Cheshire Freeze]

The ECM op at D9 flatter, like its 0z mean tonight: ECH1-216.gifEDH1-240.gif

To be expected and in line with the recent GEFS output of a 5-6 day cold spell.

Flatter? The Canadian side vortex is draining away, eroded from both sides. Looks a completely different ball game to what we've had all winter in my eyes. Looks like the opening scenes of a major pattern change to me.

Edited January 24, 2015 by CreweCold

[sunnijim]

Quick question as i'm viewing the latest runs on my phone,are we seeing air sourced from a 'true' arctic source yet (Northerly) ? they look like they bend into a 'not too cold' (severity wise) Russia,hence the nashing of teeth regarding marginal snow events again...