Winter Model Discussion - Cold Hunting -12Z 06/01/13

[Mark Neal.]

I live just south of Oxford and on 19 20 21 Jan the netweather forecast is for a dewpoint of -1.4 winds of 53mph and 33cm snow.....all dreams of course...but nice ones!

Yes I wouldn't read too much into locationing of the Oxon area given model runs, usually the M4 north saying would be out, but looking at it even areas south of this would have some blizzard like conditions if the 18z GFS was to come off, obviously it is one run and given how its still a week away, big pinch of salt needed, we await the next chapter of weather model watching with both eyes firmly on the charts!

Edited January 7, 2013 by Mark Neal.

[Ice Day]

I can understand the euphoria tonight,...I can understand the caution.... especially from our more experienced members..... We have been badly bitten so often by these synoptics before and let down with a bang...... but

There is something different this time.... SSW??...... Will this be the key to a memorable winter.... I have a lot of patience and hopefully it will pay off.

If it goes the shape of the pear (which i think is unlikely), 60/40 is my guess of success, then i get a lot of pleasure from these sites:

Yes, we have all been here before, but when you have John Holmes posting the following, it does build confidence a little!!!!

there is less chance of mild stuff as we progress through the weekend and beyond than me winning the lottery and I don't do it!

Edited January 7, 2013 by Ice Day

[SMU]

http://modeles.meteociel.fr/modeles/gens/run/gensnh-21-1-168.png?18

A pretty good mean- shades of 20th Nov 2010....

S

[LomondSnowstorm]

GEFS mean is pretty stonking at +180:

It does tend to shift with the operational so perhaps not substantially more useful than the operational but it's very promising all the same.

[Dunstable Snow]

not the best run but we can expect to see upgrades soon.....

I read this and just had to laugh ! Still I suppose its much easier to laugh when we have just witnessed a run like that. That run certainly demonstrates how energy from the atlantic can really be our friend if the orientation and strenght of the cold block to the North and East is right as BA referenced earlier. Sat here 600 ft up in the Chilterns I would definately be snowed in for days if not longer. That all said we have had yet another day of model rollercoaster and fluctuating mood swings. I am seeking solace in JH's upper air anomoly charts which continue to show a very encouraging position and trying not to get too worked up by those bl..dy shortwaves notwithstanding the fact that one got us out of a potential hole on this latest run.

Keep up the great work everyone. I feel we are in for a very special few weeks of model watching and hopefully enjoying what the actual weather brings us. I think the autopsy on the winter of 2012/13 ( when it finally dies away in early May !) will be a fascinating read.

Cheers

[snowking]

Right well before I go to bed:

ECM32 control in the mid-long term offers a mean trough solution to our west (how refreshing) following brief cold this weekend/early next week.....then towards the end of Jan, we start to see more substantial heights across Greenland, with the mean trough pushed to our east (as it seems to meet energy heading south from Scandi - presumably a PV lobe) , introducing cold cyclogenesis with alternating N/E flow and a pretty blocked atlantic, before at the end of the run HP build over the atlantic into the UK and ridging up into Scandinavia.

Then again, if we cant look 96 hours ahead with any certainty, 768 might be pushing it a bit! Last ensemble suite suggested scandi height rises, lets see what Matt has to tell us in the morning!

SK

[Jason M]

agreed. this run is a mild outlier........

Lol, a quote made in jest but which may be fairly prophetic. Just run through the ensembles at 150 hours and they are fantastic. Some lovely runs in there with stronger scandi heights and a very strong signal now for Greenland height rises.

Must hold my excitement in check, but looking through the ensembles its quite difficult. Anyway I'll go away and write out Ian F s post a hundred times to calm down :-)

Jason

[Mark Neal.]

http://modeles.meteo...21-1-168.png?18

A pretty good mean- shades of 20th Nov 2010....

S

Good to see you pleased with the output currently Steve. Interesting times ahead, although caution required, I think it is important that we keep our feet on the ground, but also are not quick to dismiss it at the same time, enjoy what the weather charts are throwing up as it is better than constant weather systems encroaching from the Atlantic giving yet more rain to SW areas, it is slowly drying up for many flooded areas now and long may that continue! Great GFS ENS mean so far btw!

[Nick F]

Definitely uncertainties over the track of the shortwave this weekend, t+120 fax shows the low further north than ECM and GFS ops this evening - more akin to the UKMO GM but not that close:

Obviously the further north the low tracks SE, the further north the snow threat.

Edited January 7, 2013 by Nick F

[Timmytour]

And if the 18z does not include any SSW info just image what it could be like if it did. Now where is my snow shovel.....

Don't forget the SSW is usually welcome because it would disrupt a zonal pattern and offer a way out of it.

But it can easily, or so I imagine, disrupt a promising pattern so that we end up losing out just when utopia looks within reach!

[Troubleatmill]

sorry just been said

Edited January 7, 2013 by Nick JB

[-uksnow-]

Viewed all ens out to 192, and i counted a mere 4 runs that dont bring cold to the UK or are about too, it is fairly late so give or take 1 but this is GOOD. The cold comes in many forms, raging easterly, GL blocks, MAH's, so much options, so few mild ensembles... a very GOOD night all

[The Northern Ramper]

Yes its exhausting!

It was knife edge stuff towards the end of the higher resolution output. Really its all to do with how the energy off the ne USA phases and a race then to get the ridge building over Greenland to exert some forcing on the pattern. Once you cut off the Azores high and get energy under the building ridge to the north good things can happen.

The GFS and UKMO do largely agree on the upstream pattern in terms of how the energy phases, its the ECM which is the real sticking point.

Lets hope it reads the script tomorrow and we see agreement on that more favourable upstream pattern.

The irony of you calling for a shortwave to scupper the high hilarious

[TEITS]

Last post from me tonight.

We always moan about cold being in FI so my attention is within +168.

Here is the ensemble mean at +96/+120/+168.

http://modeles.meteo...-21-1-90.png?18

http://modeles.meteo...21-1-120.png?18

http://modeles.meteo...21-1-168.png?18

So based on the above risk of rain on Saturday that could turn to snow before it clears S although the exact detail is uncertain. During Sun/Mon the risk of sleet, snow showers into E areas with the W remaining mainly dry. It will obviously be cold by day with a frost at night with the lowest mins more likely in W areas under clearer skies.

Beyond and I have no idea!

18Z ensemble mean suggests remaining cold and possibly turning even colder from the NE.

http://modeles.meteo...21-1-240.png?18

Edited January 7, 2013 by THE EYE IN THE SKY

[Paul T]

When there was a few dodgy GFS runs, people were saying post 120hrs is totally FI.

Now thats out the window, and all people care about is post 120hrs!

Its great to see these charts, but a pinch of salt is required at the moment!

[Tom Montalbano]

Viewed all ens out to 192, and i counted a mere 4 runs that dont bring cold to the UK or are about too, it is fairly late so give or take 1 but this is GOOD. The cold comes in many forms, raging easterly, GL blocks, MAH's, so much options, so few mild ensembles... a very GOOD night all

Agree, just been through all 20 members from the 18z up to t180 and great majority make more of the low west of Ireland tracking S.E. and acting as a trigger to pull more of a definite easterly on its northern flank, with pretty cold uppers. Just off to view the 2nd half of the run, ensemble wise.

Regards,

Tom

[Tamara]

SK update:That sounds a lot like deja vu and the sort of pattern we have seen through many recent months back to the summer, with blocking to the north or north west, but low pressure close by, or over the UK, without any polar easterly/northerly airsteam advecting south of the country - so effectively cutting off Arctic air as low pressure on the jet stream attempts to disrupt across the atlantic but never properly gets south enough deeper into Europe

Edited January 7, 2013 by Tamara Road

[Mark Neal.]

The GFS 18Z mean at 180hrs is superb!

Edited January 7, 2013 by Mark Neal.

[Dexter29]

When there was a few dodgy GFS runs, people were saying post 120hrs is totally FI.

Now thats out the window, and all people care about is post 120hrs!

Its great to see these charts, but a pinch of salt is required at the moment!

Absolutely, charts can't even nail this Friday to Sunday yet.

Looking at even minuscule detail for Monday and there after, is craaaazy and will only lead to more moans and groans because their blizzard showing for 19th January has disappeared.

[Cloud 10]

Some mouth watering ensembles to go with the op run,the ensemble challenge is on!

Anyone beat that?

[nick sussex]

The irony of you calling for a shortwave to scupper the high hilarious

Lol! yes it is ironic but its crucial to stop the Azores high trying to edge north at that point, thats why that shortwave was doing us a favour.

There are times when the Azores high can help but at that point in the output it was a pest.

[TEITS]

One more post tonight.

Ensembles upto +180 and you can see we still have some room for improvement with the initial E,ly with this arriving slightly sooner and being colder than the Op.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=314&ext=1&y=78&run=18&runpara=0

Finally delighted to see a 1020mb SLP mean around Iceland in the medium range.

[weirpig]

Anyone looking for the next iceage pert 2 is a cracker of a run (sorry cant post link)

[EML Network]

There some truly mouth watering runs on the 18z suite, I should imagine that little red line is going to be close to that magic - 5 throughout from + 120 onward

updated FAX trending in a similar way too ?

[ITSY]

Some of those runs (upto 50% or more not including the op and control) deliver some stunning synoptics for UK cold. Lets firm up before getting carried away, could still be a 'cold wobble' so to speak. Mean time, snow risk within the week. What a turn around within 7 days!