Model Output - General Discussion

[snowmadchrisuk]

IT WILL BE ALONG WITH THIS !! meto have said thursday sleet / snow for low lying some are saying tuesday now again confused !! i must admit i`ve not enjoyed the forum this year as yet unlike others, too much bickering and confrontation!! i`ll try again later in the winter i think !! there you go frosty post gone !!

It's because the GFS 12z brought the Cold air in quicker (Tuesday) for the Midlands. And this Increases the chance of snow on Tuesday. ECM doesn't have it's first chart until Wednesday so we only have GFS to go on for the next 48 hours.

[BarnetBlizzard]

I just can't see much snow coming from this, the models are showing sign of reallly cold uppers, say over -10. You may say -5 is cold enough, yes but not cold enough for real convection from this easterly which shortlived enough anyway. Also, a few other members have also commented which i agree with is these different sections of the spell keep downgrading. Say a week ago we were looking at the easterly which was meant to arrive to day, but all i recieved today was rain.

But to look on a more positive side we are normally looking at raging south-westerlies at this time of year.

[Buzzit]

Seriously : If anyone mentions the term "rollercoaster" one more time I might blow a fuse

Its not a rollercoaster, Im not sure why some on here are expecting agreement from all the models all of the time

and for that to be then set in stone. If it was the case then we would only need check the forecast every couple

of weeks to know what was going to happen - pretty boring !

As mentioned previously the ECM seems to have gotten over its previous blip and from what I can tell it is the most

likely output at the moment. I dont think anyone can say for sure that there is any model agreement +72 the

synoptics are highly unusual as compared to recent years and we have yet to see any proof in relation to the UK

that any of the models can deal with the UK accurately (above 85%) on an ongoing basis during winter months.

The UK is an island and not a big one, as such under the current conditions any new model run is going to change

the evolution, I expect this to happen every day for the next week at least.

It is safe to say we are in for a cold spell, which is unusual for this time of year in consideration of recent years.

There is just as much enjoyment to be had on focusing on +48 to plus +96 let alone going way out in FI. I dont

believe any of the current models have aced this period and it is all up in the air.

I for one am very thankful of the excellent considered posts from the members on here that take the time to care

and explain themselves in ways that make sense to the rest of us. Man cant place all trust in machines just yet

[J10]

Generally I think that the models have dealt with this cold spell quite well, since the initial evolution this has been a downgrade, but not a huge one, apart form maybe some of the wilder runs.

When you consider some of the downgrades in recent times, most people must surely be happy with current charts.

If anything the forecast for this week seems a little better than was the case yesterday, with some snow for many, and heavy snow in some places especially in Eastern areas. Even places who miss out on the snow are likely to plenty of cold sunny weather.

[SMU]

Updated 12z ECM on the IMO site-

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_84.png Weds midnight-

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_90.png thurs 06am

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_96.png thurs 12pm

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_102.png thurs 18pm

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_108.png Friday midnight

24 hours of convective flow- especially in the East & SE-

All that is different is the energy into Southern arm by the UKMO holding up the trough from the North & generating a harder easterly flow-

its much of a muchness- sure the UKMO is better & the ECM is not quite as good as the 00z, but remember the models are still not quite alligned at even 72 so we have to roll with the punches-

Theres going to be ups & downs- but the aggregate is still stunning-

If anything the 192 ECM is to good for a shortwave intrusion from the south as the jet is over spain-

216 & 240 could be a total classic, just need a bit more of a surface high over scandi- but lets not pick hols because if we go back 7/8 days day 10 has actually turned out to be 13/14 because the models have been to progressive in the mid term- they are more than likely being to progressive again...

Chill out- its a good day--

S

Edited December 13, 2009 by Steve Murr

[West is Best]

& for those keen eyed- see the wedge of higher pressure on the western tip of ireland- so the 192 should show undercutting-

S

Agreed Steve. Massive unndercut potential from the ECM. A lot of younger people on here may not be aware that for consistent widespread snowfall across the UK the end of the ECM run may prove significant. Getting snowfall on these shores from an undercut will always be a dicey affair, and judging by the way some of you are reacting even now you're going to need to calm down. But that potential off an advancing south-westerly system is considerable.

Anyway, these 12z outputs remain brilliant runs for cold lovers. And how wonderfully seasonal it's getting.

[Tim Bland]

Updated 12z ECM on the IMO site-

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_84.png Weds midnight-

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_90.png thurs 06am

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_96.png thurs 12pm

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_102.png thurs 18pm

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_108.png Friday midnight

24 hours of convective flow- especially in the East & SE-

All that is different is the energy into Southern arm by the UKMO holding up the trough from the North & generating a harder easterly flow-

its much of a muchness- sure the UKMO is better & the ECM is not quite as good as the 00z, but remember the models are still not quite alligned at even 72 so we have to roll with the punches-

Theres going to be ups & downs- but the aggregate is still stunning-

If anything the 192 ECM is to good for a shortwave intrusion from the south as the jet is over spain-

216 & 240 could be a total classic, just need a bit more of a surface high over scandi- but lets not pick hols because if we go back 7/8 days day 10 has actually turned out to be 13/14 because the models have been to progressive in the mid term- they are more than likely being to progressive again...

Chill out- its a good day--

S

Does anyone remember the M11 fiasco where drivers where stranded, I think it was around 2003. Does anyone know if the synoptics on Thurs / Fri are similar. If this 24hr Easterly occoured What sort of acumulations could be expected in the East?

[SMU]

Does anyone remember the M11 fiasco where drivers where stranded, I think it was around 2003. Does anyone know if the synoptics on Thurs / Fri are similar. If this 24hr Easterly occoured What sort of acumulations could be expected in the East?

THe M11 fiasco was a Northerly toppler with a lot more dominence from the low pressure to the East-

It will probably be more like the ECM 144 chart-

Thats a potent Northerly coming in that hasnt got to mix out mild surface air....

Best case scenario tonight would be the UKMO run of aroun 30 hours of convective snowfall for the ESE-

S

Edited December 13, 2009 by Steve Murr

[Alex95]

Does anyone remember the M11 fiasco where drivers where stranded, I think it was around 2003. Does anyone know if the synoptics on Thurs / Fri are similar. If this 24hr Easterly occoured What sort of acumulations could be expected in the East?

I think that was a northerly, but the 850s were unusually low for a northerly, widely below -10. There wasn't actually that much snow (widely 5-10cm) but the road wasn't gritted or something. I know the North East did well, I remember it.

[andy_leics22]

The 12z is a massive upgrade for Tuesday in the Midlands, Net weather forecasts have a max of 0 , heavy ppn 525 dam and the little icons actually forecast snow. Wednesday is showing as an ice day with temps below freezing all day . Very impressed with the short term potential .

Chris

Agreed, A lot can chop and change in terms of PPN position even within 36 hours so we must be cautious with what the models are showing at this moment in time. It does look promising though, we'll see what they show in terms of PPN placement on Tuesday evening and then decide whether it's time to get excited or time to have a moan in the whiners thread

[weather eater]

Updated 12z ECM on the IMO site-

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_84.png Weds midnight-

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_90.png thurs 06am

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_96.png thurs 12pm

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_102.png thurs 18pm

http://en.vedur.is/photos/atlant_evr_hitaspa/091213_1200_108.png Friday midnight

24 hours of convective flow- especially in the East & SE-

All that is different is the energy into Southern arm by the UKMO holding up the trough from the North & generating a harder easterly flow-

its much of a muchness- sure the UKMO is better & the ECM is not quite as good as the 00z, but remember the models are still not quite alligned at even 72 so we have to roll with the punches-

Theres going to be ups & downs- but the aggregate is still stunning-

If anything the 192 ECM is to good for a shortwave intrusion from the south as the jet is over spain-

216 & 240 could be a total classic, just need a bit more of a surface high over scandi- but lets not pick hols because if we go back 7/8 days day 10 has actually turned out to be 13/14 because the models have been to progressive in the mid term- they are more than likely being to progressive again...

Chill out- its a good day--

S

Excellent post as ever Steve, To be honest I'm happy that this evenings ECM is not quite as good as this mornings, in my book FI wonder synoptics will fall over sooner or later, much better sooner, then we have time to see what evolves and who knows maybe it will be something much better. I have no doubts that this will develop into an excellent start to winter even if it never hits the heights that some models have projected over the last few days.

[Whether Idle]

The 72 hour fax from Bracknell follows the 12z Met O for same date, which is encouraging as it leads to best potential later for convective snowfall.

[Terminal Moraine]

I like to look into the deepest reaches of F.I for trend spotting, sometimes it works, sometimes not.

The general synoptics of the forthcoming cold spell were well forecast by GFS around 260 hours out and there are a few relevant points to flag up if we look a similar distance ahead now.

Even though ECM has now leaned towards the GFS scenario of milder weather making inroads over Christmas it's worth bearing in mind that there is very little energy in the northern arm of the jet and the high pressure may not give way without a considerable fight, and perhaps not at all in the north.

If christmas does see something of a milder interlude all is not lost as the synoptics beyond, plus the weak northern arm of the jet, give all the indications of cold air flooding south again towards the new year or shortly afterwards.

Something worth keeping an eye on during the excitement of the coming week.

[LomondSnowstorm]

A rather curious and strange looking T+72hrs fax chart, a real dogs breakfast in fact.

It is a bit, but if those two cold fronts pick up precip and the 528 line moves across a bit quicker, northeastern areas might see some decent snowfall on Wednesday night. Too early to tell what will happen but the potential for snowfall is still there.

[Thundery wintry showers]

I like to look into the deepest reaches of F.I for trend spotting, sometimes it works, sometimes not.

The general synoptics of the forthcoming cold spell were well forecast by GFS around 260 hours out and there are a few relevant points to flag up if we look a similar distance ahead now.

Even though ECM has now leaned towards the GFS scenario of milder weather making inroads over Christmas it's worth bearing in mind that there is very little energy in the northern arm of the jet and the high pressure may not give way without a considerable fight, and perhaps not at all in the north.

If christmas does see something of a milder interlude all is not lost as the synoptics beyond, plus the weak northern arm of the jet, give all the indications of cold air flooding south again towards the new year or shortly afterwards.

Something worth keeping an eye on during the excitement of the coming week.

Yes, the breakdowns from the SW being progged by the models is very similar-looking to the breakdown that occurred near the end of December 1981, and by the 6th January 1982 we were back in a very cold easterly flow. Also the northerly around 20 December 1995 broke down temporarily from the SW in similar fashion, yet by the 24th, it was back again with avengeance.

I also think the models are often too progressive in these breakdown situations- especially at T+200 onwards!

[PB22]

Fantastic output again tonight. The cold spell is now upon us and we can start looking for snow opportunities. These can crop up more or less un-noticed and out of the blue, so expect the unexpected would be my message for the coming days.

Its interesting to note there is still divergence amongst the GFS and its ensembles for as soon as tomorrow, especially the further south you are, so expect further changes:

http://www.wzkarten.de/pics/MT8_London_ens.png

http://www.wzkarten.de/pics/MT8_Manchester_ens.png

http://www.wzkarten.de/pics/MT8_Aberdeen_ens.png

[johnholmes]

A rather curious and strange looking T+72hrs fax chart, a real dogs breakfast in fact.

I have to ask W why is it curious and strange

Is it not consistent from the previous one?

Care to explain why its as you describe it-to me it seems to sum up the probability of what is to be expected at that time quite well.

[chrisbell-nottheweatherman]

Fantastic output again tonight. The cold spell is now upon us and we can start looking for snow opportunities. These can crop up more or less un-noticed and out of the blue, so expect the unexpected would be my message for the coming days.

Its interesting to note there is still divergence amongst the GFS and its ensembles for as soon as tomorrow, especially the further south you are, so expect further changes:

http://www.wzkarten.de/pics/MT8_London_ens.png

http://www.wzkarten.de/pics/MT8_Manchester_ens.png

http://www.wzkarten.de/pics/MT8_Aberdeen_ens.png

Yes, we are now at the point where minor variables within a few hours can greatly change each areas' experience of this spell. I'm also of the opinion that, with cold air ell-established by the start of the week leading-up to Christmas, the progressive outlook suggested by GFS could well see decent snowfall. Less scientifically, it seems likely to me that cold would re-establish itself later into the New Year as the continent and North Sea would be pretty cold.

[Snowstorm1]

I have to ask W why is it curious and strange

Is it not consistent from the previous one?

Care to explain why its as you describe it-to me it seems to sum up the probability of what is to be expected at that time quite well.

John when you writing your blog because some who have lost hope because of some pathetic posters may be surprised when reading your blog.

[Cecil Hogmanay Melchett]

Its all about that trough dropping through Scandy at 72hrs.

UKMO has it dropping south but ecm has it moving South east dragging the REALLY cold uppers into Europe.

FAX charts are the ones to watch guys.

We have reached the timeframe where Pro forecasters experience should decipher whats going on.

The truth is ecm is a good run,imo its better for those further North but it could be barking up the wrong tree for

all we know.

It does look a win win though because even if the Eastrly is short there is a monster northerly coming hot on

its heels.

The outlook is

[Mondy]

Fantastic output again tonight. The cold spell is now upon us and we can start looking for snow opportunities. These can crop up more or less un-noticed and out of the blue, so expect the unexpected would be my message for the coming days.

But PB, we are already in a cold spell up here. It's bitter feeling in freezing fog, for four days in a row now, not particularly enjoying it if honest. Prior to this fog nonsense, it's been cold and frost in what can only be described as every second day.

I really wish some of you lived in more rural areas and appreciated the fact the forthcoming "cold spell" is not "exclusive" and has actually been cool/cold here for, an average, weeks on end since mid-November.

[pyrotech]

Hi John,

any chance you could do a quick update on the models as its all getting a bit mad on here.

Your input would be welcomed by the users who like Teits, Jackone, steve, nick and the others who post regular informative posts, and the people like myself who respect them.

Sorry just noticed johns blog link below

http://forum.netweather.tv/topic/57953-the-predicted-pattern-change/page__pid__1632173__st__34entry1632173

Edited December 13, 2009 by pyrotech

[Iceni]

Does anyone remember the M11 fiasco where drivers where stranded, I think it was around 2003. Does anyone know if the synoptics on Thurs / Fri are similar. If this 24hr Easterly occoured What sort of acumulations could be expected in the East?

Remember it well — 31st January 2003. I was working in London and had to wait a couple of hours for a train which reached its destination without incident (station about a mile off M11) the car had easily about 12" snow on it and when I got out onto the M11 heading north east it was strangely deserted. Road ungritted — only when I'd struggled the 25 miles home an hour and a half later did I realize there was a massive gridlock which started about a couple of miles down the M11 and that was why it was so quiet — made driving through it a lot easier.

I think we got about 14" snow in my location but it drifted into a couple of feet in NE/E exposed places.

[Birkhill saints]

Models look ok to me,

Remember these islands are a big place.

Some may win some may loose,lets look at the bigger picture if you can?

[LomondSnowstorm]

Madness has decended on the forum once again in light of ONE chart showing a SLIGHTLY less potent easterly, which apparently means that the entire situation has been DOWNGRADED, leading to the people who actually know what they are talking about having to reassure everyone that one chart means very little in the overall outlook. It's getting so bad that I'm having to ignore all posts not posted by those I know will actually make a valid input into this thread. The ECM outlook is still very good for snowlovers, as is just about every other model output at the moment. We won't know the specifics until very close to the time so can we just stop the upgrade/downgrade nonsense unless it is actually fairly significant?