Model Output Discussion - Stormy Period Inbound...

[TEITS]

So despite me saying a few days ago that the GEM had lost the plot and gone mad there are hints from the 18Z that it wasn't so bonkers after all.

 

The 18Z reminds me a little of what occurred during Jan 2013. What I mean by this is the models back away from the normal W-E movement of LP and we see sliders tracking SE. When this occurs you can sometimes see a weak area of high pressure develop to our N. Remember I said a while ago that you don't need mega high pressure to our N to bring cold to the UK!

 

Whilst this could be a blip or a new trend towards a colder, snowier outlook!

[john mac]

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

Happy days haha! We need to get some low heights into maninland Europe. Hopefully with that we can get some pressure building to the north east!!

[chionomaniac]

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

ECM has it at 6Z zipping along the south coast. 850's look to be in the region of -4ºC with a fair amount of precip on the southern flank. Possibilities....though very marginal.

 

[Jason M]

GFS Para run is very interesting tonight as it has some support from earlier ensemble runs and more notably the 12z gem ensembles.

GEFS will be interesting tonight. First bit of hope this evening for a very long time.

[Chris K]

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!

 

Just to add to what Shaky has responded, I did not think substantial snowfall was to be expected at lower levels in the South anyway (regarding Tuesday)? The main threat of some accumulating snow was for higher elevations Mendips/Cotswolds, some of the moors etc but even this depends on other factors.

 

The only time I have seen the word "significant" was with regards to Friday and what happens to the LP - low probability of anything significant for us further South at the moment..with more info by chio above and Ian's post below. It is at least a feature to keep an eye on over the coming days though, in addition to everything else getting thrown at us.

 

Some need to only scroll through a few pages back to get the latest info that we are lucky to get!

 

Brief update. High confidence now on snow for parts of W Country later Tues/Tues night. Several cm possible higher ground, notably (as it stands) Exmoor, northern Mendips Plateau; parts of Cotswolds. Likely the shower line (to Cb) extending down roughly M4 to give some surviving all the way towards London. Fairly high depth temperature should help prevent much low-lying accumulation. Different story on uplands aforementioned. Meanwhile, the troubling-looking 12z UKMO GM for Friday, which would yield substantial snow across SW/W Country, considered low probability. Low is most likely to head to Portugal, around the high, Exeter reckon. That's it from me for a while...cheers.

Edited January 11, 2015 by Chris K

[Mucka]

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.

 

 

So you were taking charts people were posting of a snapshot of 8 days away from one op run as being indicative of the weather for the next two weeks?

Plenty of people were talking about cold PM flow because that was what the MO broadly predicted. I'm not saying I knew something special, just that I didn't guess about snow possibilities, it was in the output - especially if you took all the output including ensembles together.

There would always be milder days and pinning down a specific day was too difficult at that range but it appeared the optimum conditions would be between 13th and 15th.

Here is the output from the 2nd from GFS for example for the 11th. But again you needed to take the output as whole into consideration. I know some people were exaggerating the milder interludes and poo pooing snow chances but a lot of others were talking up the possibility. (I could still be wrong and even if I am right I still got lucky because you can't really make decent forecasts that far out but you can outline the possibilities.)

As for the Azores high, perhaps you took some posts out of context because even I made a post much later about wishing someone would nuke it because it threatened to play spoiler but the cold zonal theme was very well signposted.

honest! 

 

[alexisj9]

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!

 

modeltracker.png

I've noticed many of those produce a wave over the south somewhere too, so that could raise winds and add more rain if it happens.

[Mucka]

GFS Para run is very interesting tonight as it has some support from earlier ensemble runs and more notably the 12z gem ensembles.

GEFS will be interesting tonight. First bit of hope this evening for a very long time.

 

Yes it is a very tantalising FI isn't it? Lots of (empty?) promises of MLB and perhaps even HLB thinking about setting up favourably for coldies.

Just one run but as you say it has been hinted at here and there in other output.

Certainly worth keeping an eye on the ensembles for any worthwhile signal developing.

Edited January 11, 2015 by Mucka

[Jason M]

Mucka

If you said a week ten days ago that it's a long way to cold you were surely right. I've heard a lot about cold zonal in recent weeks but the CET for January is almost 3c above the average. If that's cold zonal I'm curious to see what mild zonal is :-)

Reading both this and the CET thread there have been times when I think they must be referring to different countries :-)

Anyway, thankfully just a sniff of potential for some Arctic or CP air getting into the mix next weekend.

[BLAST FROM THE PAST]

Storms, cold, snow, rain this week.  This month has a lot more to come too and as is hinted in FI with GFS, imo effects of the SW we've had to come as well.  Not bad really is it

 

BFTP

[Mucka]

Mucka

If you said a week ten days ago that it's a long way to cold you were surely right. I've heard a lot about cold zonal in recent weeks but the CET for January is almost 3c above the average. If that's cold zonal I'm curious to see what mild zonal is :-)

Reading both this and the CET thread there have been times when I think they must be referring to different countries :-)

Anyway, thankfully just a sniff of potential for some Arctic or CP air getting into the mix next weekend.

 

Hi Jason.

 

I said there was decent chance of snow between 13th and 15th in cold zonal flow.

RE any cold pattern setting up from mid month, I gave it about 20% chance around the same time.

 

The CET includes a very mild spell before the cold zonal conditions kicked in which was just this weekend! 

I think a better indicator of whether the zonal flow is cold is the CET during this period - from 10th to 15th but of course cold here is a relative term. A cold zonal flow is often just below average because of the milder phases where the cold air gets mixed out as the next system rolls in and the nights are often milder.

 

Some of it is pure misunderstanding but some of it is frustrated coldies deliberately misconstruing posts. There was hope of some form of pattern change after mid month for a short while to a colder pattern via an Atlantic ridge but we have seen that fold unfortunately.

All we can do is hope we see some transient snow in this spell and the output improves and picks up on a new blocking signal.

 

Talking of signals, interesting control run on the way out.

 

Edited January 11, 2015 by Mucka

[Trom]

It's interesting to note that the charts showed dispersion from 11th of January onward for about a week.  This gave the opportunity for cold outcomes.  It's nice to that as we've arrived at this date that opportunity seems to have verified.  I'm certainly not claiming clairvoyance as all I saw was the volatility.  Not deep cold but that was never on the cards, but for cold we got the best outcome on offer.  Now we are here at that range on the GEFS ensembles the trend seems to flatten with less dispersion going forward.  That sees us getting cold to the 15th and then flattening.  ECM better if you want a continued downward trend.

Edited January 11, 2015 by Trom

[SE Blizzards]

ECM 12Z ENS FOR LONDON

 

 

Mean Temps around  3c / 4c from the 17th and not really rising all the way to the end.

Now, that is a cold set of ENS considering that's for London.

 

And whisper it quietly, some Easterlies are starting to show up on the GEFS at Day 9 / 10.

 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=228

Edited January 11, 2015 by SE Blizzards

[lorenzo]

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..naefsnh-0-0-240.png  ECM..EDH101-240.gif

 

NOAA won't be happy in their discussions tomorrow!

 

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

 

ECM raises the bar further later in the EPS suite too, the Barents -  Kara low problem dispatched and wave 2 / wave 3 activity back up and running. 

 

Edit - getting my seas mixed up - blame Sig Hansen.

Edited January 11, 2015 by lorenzo

[Jason M]

Taken from the GEFS the chart below doesn't look much, but this is what a cold chart looks like, rather than the insipid North westerlies we have been chasing

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=336&code=17&mode=0&carte=0

Nothing marginal about the uppers here

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=336&code=17&mode=1&carte=0

the issue then becomes one of precipitation, but if anything fell under this chart it would be white :-)

Liking tonight's charts, let's see what the morning brings.....

[bryan629]

ECM @ 240

 

GEM @240

 

GFS @240 ( the worst of the bunch)

 

GFS (P) @ 240

 

 

JMA @192

 

All of the above have one thing in common... a busted up Polar Vortex...!!   ok .. all differing in their own right, but a theme is there.

each model is picking up on a signal of sorts and each model is fragmenting and dispacing the PV at best to the other side of the hemisphere or at worst the gfs@240 as shown.

 

I beleive it has been a rollercoaster ride over in the strat thread, and i wonder now because of what is being modelled out on the above way out in FI , if its conceivable that recent warmings have been mis understood or misinterpreted in some way or another.

The reason i ask is because of what Tamara said a few weeks ago about the rubber band being stretched and how long it would take to snap.

 

To my eyes, these are very good looking charts ( apart from GFS@240) because with a PV being modelled to break up and/or bugger off elsewhere it gives our part of the world a chance to pop in and out of the freezer in one shape or form via hight rises North or North East of here,

I do realise that some models as i have posted are not reliable , but i also realise that each model is showing a pretty much similar theme and may be completely different come tomorrows runs.

 

putting that aside, and perhaps wandering off topic... the storm modelled for Wed/Thurs looks very potent , please take care , those wind gusts look pretty dangerous... especially if you find yourself being chased by a squadron of low flying wheely bins

 

 

 

 

 

 

 

 

 

 

[Mucka]

Hello?

 

 

UKMO sticking with the cheeky channel low. Not on GFS output but let's hope ECM can back it up.

 

No joy with the storm being downgraded I'm afraid, especially GFSp, ouch!

 

 

UKMO has the strongest winds further South.

 

 

So other than interest in the storm, upcoming snow chances and what is happening in FI, we have a fundamental disagreement about whether the shortwave coming off the Eastern seaboard develops or not. GFS and GFSp make nothing of it and send it packing to Portugal while UKMO and GEM develop it and have track East across the South of the UK or channel.

Edited January 12, 2015 by Mucka

[legritter]

Hello?

 

 

UKMO sticking with the cheeky channel low. Not on GFS output but let's hope ECM can back it up.

would be nice ,potential hopefully ,alot of weather to get through and this could be what some lucky posters are dreaming of . 

[Mucka]

Some GFS ensembles have picked up on the idea of developing that low and pushing it East rather than South though to different effect. It could happen though.

Otherwise the vortex not looking very "vortexy" in GFS deep FI among some ensemble members and how about this to cheer coldies up.

 

 

It could happen, right?

 

GFS ensemles Central Egnland

 

Edited January 12, 2015 by Mucka

[Jason M]

Hmm, disappointed with this mornings charts tbh. Last nights pub run and ensembles seemed to be really developing a theme for something more interesting via an easterly. This seemed to be building on the gem ensembles and a few other hints. There were some good charts inside 10 days as well.

I think a big step away from that this morning. There are a few decent charts still and mucka highlights one of the better GEFS but overall the only objective view in MY OPINION (before anyone gets narky :-) ) is a continuation of zonal hell out to the end of the month. Taken as a whole the output looks flatter and more zonal across most time frames. Still some hints at the end of FI but that's where they have been for days now.

I stress there are some decent charts still floating around if one looks hard enough ie the GFS P isn't a disaster, and the METO 144 has the channel low still (albeit hard to tell without 850s whether that would be anything other than cold rain). My pessimism is really because I feel last nights trend isn't being developed this morning.

[bluearmy]

The 7/10 day period looking a bit messy with a fair range of solutions. Will the 10/14 day prognosis remain the same from the ECM extended?

[Man With Beard]

Looking at the storm for Thursday, it doesn't look like a record breaker in terms of gusts, probably in the 80 mph range which IMBY was a regular occurance last year, but what needs watching is a line of gusts that is appearing that goes directly south to north (take GFS this morning) which could bring 60-70 mph gusts across all areas. Of course at this stage its still too early to give exact intensity so between 50 and 80 mph can't be ruled out. In short, everyone will know about this one.

On to the snow, Tuesday/Wednesday's south west event still firmly on judging by EURO4, though am I right that the same model made a bit of a pigs ear of Saturday's northern snow event? After a break for heavy rain on Thursday (possibly a flood risk in places), snow risks return next weekend with a number of small secondary lows threatening to form within cold air - couldn't possibly make a decent forecast on those just yet.

Longer term, GFS busts the vortex completely whilst ECM by D9/D10 still appears to have the vortex stuck to the NW but hold on is that high pressure building to the north east...?

[picog]

 

 

GFS ensemles Central Egnland

 

 

 

2m temp are chilly but not especially cold looking, especially at night. 850s look v borderline for snow — isn't it -5C or below for snow ideally?

[Captain Shortwave]

UKMO the best run by a mile this morning with regards for next weekend and beyond.

Day 7 and beyond would be fun with heights building to our north and low pressure upstream moving south east into southern Europe.

Shame the UKMO is on its own for this, the other models take that low towards Portugal and build the Azores high over the top of it, this creates the unfavourable pattern later on which allows the westerlies back in for an arbitrary period of time.

[IDO]

It always looked borderline for snow at sea-level from the second front tomorrow, due to the uppers only getting to -4c by tomorrow afternoon into the area required. So it really does look like a hill to mountain snow event tomorrow in the W/SW: 

 

 

Some disturbances in the flow for Tuesday evening into Wednesday but small features so more miss than hit for most. The uppers will be better for snow to lower levels by then.

 

The hi-res models just getting into the frame re the storm and the initial track is as so: 

 

 

 

With uncertainty re the short wave in the Atlantic UKMO/GEM -v- ECM/GFS then from D6 it remains variable for surface conditions. The four models take:

 

 

 

 

 

GEM at D10 now has more influence from the Azores so more TM than of late. The GEFS at D12 are showing several clusters and it is apparent that the breakdown of the strong zonal flow is proving difficult for it to model. It does look like the Azores will try to edge north/NE so maybe a N/S split later with the south less influenced by the jet? Then from there other possibilities may manifest.