Model Output Discussion

[TEITS]

BBC follows the UKMO output for it forecasts hence why Darren Bett said a few days ago it will turn milder with SW'lies when the UKMO produced that one off run on it's 144 hour chart. I think they use the ECM output for it's long range forecasts for the website but i don't think they have ever used the ECM output for the TV forecasts. And they certainly do not use the GFS!

Let me clear this confusion up.

The Met O fax charts are not just based on the UKMO model because they also take into account the ECM ensembles. Now the BBC will use the Met O fax charts as will ITV, not sure about Sky. I also think im right in saying that the Met O brief the BBC forecasters on a daily basis.

[andy_leics22]

Anyone agree with me that East Anglia and the South East could see some sleet/snow tomorrow afternoon/evening? Temps a tad high at 5-6c maximums but under PPN I would expect it to fall and with -5 uppers I would say there is certainly a half decent shout for some wintry stuff in those areas I just mentioned.

I'm surprised no ones making more of it.

[Met4Cast]

Anyone agree with me that East Anglia and the South East could see some sleet/snow tomorrow afternoon/evening? Temps a tad high at 5-6c maximums but under PPN I would expect it to fall and with -5 uppers I would say there is certainly a half decent shout for some wintry stuff in those areas I just mentioned.

I'm surprised no ones making more of it.

I was looking at the risk for tomorrow too - But dewpoints are above freezing so I think anything other than some sleet in the heavier bursts is unlikely. We could see wet snow over the Downs I guess, but certainly no snow to lower levels. Monday though, if any showers develop they'll almost certainly fall as snow.

[Neilsouth]

http://91.121.94.83/modeles/gfs/run/gfsnh-0-72.png?18

^ North Easterly / Easterly coming in now , will it follow the ecm or downgrade to the ukmo

[TEITS]

This is certainly an upgrade compared to the 12Z although the GFS remains far more progressive than the ECM.

http://www.wetterzentrale.de/pics/Rtavn781.png

[Snowstorm1]

This is certainly an upgrade compared to the 12Z although the GFS remains far more progressive than the ECM.

http://www.wetterzen...cs/Rtavn781.png

Teits i fully agree mate and the main thing was this not to trend towards the met o and it hasnt so now i can sleep slightly easier tonight

[multi cellular thunderstorm]

To me it looks like we could get a stronger flow and more ppn on this run, and it looks a little more advanced too.

I'm fairly happy with it so far, to my untrained eye it looks like an upgrade up to T+81.

[Lewis]

To me it looks like we could get a stronger flow and more ppn on this run, and it looks a little more advanced too.

I'm fairly happy with it so far, to my untrained eye it looks like an upgrade up to T+81.

Took the words right out of my mouth.

Slightly more progressive, but certainly looking good, at first i though everything was heading More S than it was pushing East.

But looking good up to now.

Lewis

[Neilsouth]

http://www.wzkarten.de/pics/Rtavn841.png

http://91.121.94.83/modeles/gfs/run/gfs-1-90.png?18

Could get snow as early as wednesday now from the north sea , good so far!

[johnholmes]

re the two posts below

BBC follows the UKMO output for it forecasts hence why Darren Bett said a few days ago it will turn milder with SW'lies when the UKMO produced that one off run on it's 144 hour chart. I think they use the ECM output for it's long range forecasts for the website but i don't think they have ever used the ECM output for the TV forecasts. And they certainly do not use the GFS!

Let me clear this confusion up.

The Met O fax charts are not just based on the UKMO model because they also take into account the ECM ensembles. Now the BBC will use the Met O fax charts as will ITV, not sure about Sky. I also think im right in saying that the Met O brief the BBC forecasters on a daily basis.

I have explained before just what they use but to repeat for those who are not long on this site.

UK met do brief the BBC and ITV media presenters(such as Ian Fergusson) and obviously their own forecasters, usually on BBC TV, are part of this briefing. Indeed they may add their own view if they feel strong enough that the technical discussion sent out by the senior forecaster at Exeter needs a tweak here and there. They are rarely if ever allowed more than a tweak!

As to what they use-they have access to every model in the world and will use whatever the senior forecaster decides is going to give the more accurate idea over day 1 out to day 16, so not always the same model for any issue. ECM is used just as any other model is used. They have their own large scale (world model), more localised and their Fine Mesh with a grid-I think-Ian Fergusson may have the most up to date idea-of about 10km, an output from MOS (Model Output Statistics) and others whose names escape me at the moment.

So they have a huge amount to assimilate every 6-12 hours for their updates, usually twice a day, sometimes 4x daily.

Hope that helps.

Ian if I've missed anything out or said something not now correct please feel free to correct it.

Edited December 12, 2009 by johnholmes

[Yeti]

Nice to see the shortwave pulling away to the SW on the 18z - it pulls in the ENE'ly feed much better afterwards than the 12z.

http://www.wetterzentrale.de/pics/Rtavn961.png

The cold air is a fair bit closer - watch the gates open...

http://www.wetterzentrale.de/pics/Rtavn962.png

[PB22]

Anyone agree with me that East Anglia and the South East could see some sleet/snow tomorrow afternoon/evening? Temps a tad high at 5-6c maximums but under PPN I would expect it to fall and with -5 uppers I would say there is certainly a half decent shout for some wintry stuff in those areas I just mentioned.

I'm surprised no ones making more of it.

Yes, I think there is a chance.

It was just mentioned on the BBC weather that showers in East Anglia, Kent and Sussex could be heavy and have thunder and wintriness in them tomorrow....the uppers will certainly be cooling:

http://www.wzkarten.de/pics/Rmgfs242.html

[winter watcher]

Let me clear this confusion up.

The Met O fax charts are not just based on the UKMO model because they also take into account the ECM ensembles. Now the BBC will use the Met O fax charts as will ITV, not sure about Sky. I also think im right in saying that the Met O brief the BBC forecasters on a daily basis.

Just to add i am extremely happy and encouraged by the meto forecast and here is my reason. I have a friend who works for the met office and i also work on the trains and the met usually send faxes over to us if they believe any severe weather is on the way. I mentioned the other day on here that i was doing the early shift Thursday and about 11am we received a fax from the met office about a very high chance that severe cold was on the way they stated the cold spell would more than likely begin the Friday just gone and they did say in the latter part off next week it will get even more colder and with that brings the increasing risk off snowfall. They said we would advise you to notice off this fax and make sure you are well equipped to deal with adverse weather conditions i,e salt and kill frost. Now the other pleasing aspect is my friend who works for the met said to me last winter before the February snow occurred that the met will always play the situation down to the public as long as possible different with public sector jobs like the rail but the met forecast that was released today said wintry showers over and over again and talked about it getting colder as the week progressed now to me they know that something severe is on the cards. I am going to get on the blower to me mate and ask him what is being hyped up down there and will get back to you all either in around a hour or tomorrow. Very cold times ahead by the looks though

Edited December 12, 2009 by winter watcher

[Harsh Climate]

http://www.wetterzentrale.de/pics/Rtavn1081.png

In terms of wed/thu easterly this run is rubbish, not what i wnated to see.

[LomondSnowstorm]

Lovely 18Z, showing a stream of snow showers packing into Fife and Dundee overnight Wednesday into Thursday, with perhaps similar accumulations to the 2nd February here, which gave 2-3 inches

LS

[Sawel]

Lovely 18Z, showing a stream of snow showers packing into Fife and Dundee overnight Wednesday into Thursday, with perhaps similar accumulations to the 2nd February here, which gave 2-3 inches

LS

I think the GFS 18z is worse than the 12z and is nowhere near as good as what the ECM showed earlier at 96 hrs.

[Harsh Climate]

Lovely 18Z, showing a stream of snow showers packing into Fife and Dundee overnight Wednesday into Thursday, with perhaps similar accumulations to the 2nd February here, which gave 2-3 inches

LS

sorry mate but it just wont be cold enough. No real deep cold has filtered through yet and coming off warm sst's, confined to above 1000ft i would have thought.

[Neilsouth]

From two , about this run

Rob, the differences are subtle but important - the GFS doesn't develop the low in NE France but instead develops a new high pressure cell in the ridge east of the Iceland/Greenland high. The effect is to drive the cold south instead of south-west.

[Geordiesnow]

I'm glad to see the 18Z has not trended towards the UKMO, i think that is the important thing imo.

I think what the ECM is showing is probably the most "extreme" we will get from any easterly with the UKMO being the "least extreme". I somehow think the GFS will be closer to the mark.

I also hope the GFS is being over progressive in sinking the easterly.

[morfius]

Is this not northern blocking to the max?! I've never seen such a continuous ridge of high pressure cells stretching from canada to siberia!

*Ignore the one to the west of Greenland as it is a low.

Edited December 12, 2009 by morfius

[winterof79]

-10 isotherm making land around yorkshire and the north east thursday ,with precipitation,and people still are not satisfied.I am quite frankly asstounded

[Alex95]

Easterly all too short imo, 2-3 inches max from this run. However, I wouldn't be bothered if it was followed by a northerly before the snow melted, that could top the coving up.

[snowking]

Yet another scenario thrown up by the 18z - a toppler-like situation followed by the LP responsible for the toppler giving us a northerly. The best sign from that is that we still end up in cold despite a different scenario

What I feel makes this run unlikely is the fact the high still topples despite the pressure across greenland - however i suppose it depends what feeds that LP which fills out near svalbard

SK

[I remember Atlantic 252]

sorry mate but it just wont be cold enough. No real deep cold has filtered through yet and coming off warm sst's, confined to above 1000ft i would have thought.

mighty cold to me -10 uppers but easterly topples too quickly, dry by midday thursday

[Neilsouth]

-10 isotherm making land around yorkshire and the north east thursday ,with precipitation,and people still are not satisfied.I am quite frankly asstounded

Because if you had read every run so far the timescale of the easterly is getting shorter and shorter , the depth of the cold taking longer to get here and sometimes not at all. People are concerned that it's going to be a blink and you'll miss it affair or be pushed into the med!.

See?