Model Output Discussion:

[cyclonic happiness]

Dunno why all the doom and gloom still, all the signals are pointing in the right direction I think it's just the lack of any model agreement proper over the last few days.

We always think the worst when it comes to these things but it doesn't feel this winter like we will get a substantial southwesterly spell.

I think also that there will be a major league backtrack of models over the next 2-3 days, in the mean time, at least we can get prepared for what may be to come.

[johnholmes]

don't worry if the 18z shows a cold set up, be it northerly or easterly, there will be lots of relief and no doubt some rather incorrect back slapping.

[bluearmy]

noaa cpc have 100% confidence in their 6/10 day chart

http://www.cpc.ncep.noaa.gov/products/predictions/610day/610day.03.gif

the pattern isnt far off being very good for us with a tweak of the trough extension to our se a few hundred miles or supression south of the pattern the same distance. not exactly knife edge, but as the last few ecm op runs show, a similar evolution with the emphasis on cold being moved around. i guess the meto's take this morning was that we were tilting the dice in favour of cold for us. as ian says, tomorrow morning, they may drift the other way.

[January Snowstorm]

don't worry if the 18z shows a cold set up, be it northerly or easterly, there will be lots of relief and no doubt some rather incorrect back slapping.

Yes and back stabbing too

18z is on the base!

[nick sussex]

Before the next dream killer comes out! oh sorry I mean't the GFS 18hrs run I think we're at that point where if there is to be yet another model change it has to come by tomorrow morning, because of the timeframes involved, however we have to be realistic in what can happen, a plausible model backtrack would be for them to take a little less energy eastwards from the main upper trough which would allow perhaps a little more colder air to move up from the se.

The problem we have is the ejection of energy out of the USA, even though the upper trough eventually weakens this energy wants to shunt the low ne'wards, unless theres a strong block in place this cannot force disruption of the trough so the low heads ne and then the low train starts up to the nw.

Theres also the problem of that Norwegian shortwave so there are quite a few hurdles to overcome,a decent sign from the GFS 18hrs run would be to see it keep the energy further west that comes off the main trough.

Edited February 2, 2010 by nick sussex

[snowfish]

Before the next dream killer comes out! oh sorry I mean't the GFS 18hrs run I think we're at that point where if there is to be yet another model change it has to come by tomorrow morning, because of the timeframes involved, however we have to be realistic in what can happen, a plausible model backtrack would be for them to take a little less energy eastwards from the main upper trough which would allow perhaps a little more colder air to move up from the se.

The problem we have is the ejection of energy out of the USA, even though the upper trough weakens this energy wants to shunt the low ne'wards, unless theres a strong block in place this cannot force disruption of the trough so the low heads ne and then the low train starts up to the nw.

Theres also the problem of that Norwegian shortwave so there are quite a few hurdles to overcome,a decent sign from the GFS 18hrs run would be to see it keep the energy further west that comes off the main trough.

Evening Nick

Yes, I know what you mean! What surprised me was how the BBC on tonight's regional bulletin were insisting on a mild few days but at the weekend turning and I quote: "Much, much colder" (!) OK......?

[SP1986]

I think although there is much confusion or so it seems despite the models all pretty agreeing in the outlook, even if the 18z goes for a cold outlook, this doesn't mean it is so, it could well be that it is just reacted to mixed signals.

People need to be aware of this because no doubt if it does come cold, some people will no doubt claim a cold spell is assured when it isn't, just like mild isn't assured to last.

At the end of the day you can only go on what you can see, anything else is just hope, expectation and guesswork.

[andymusic]

I vote we add a new model (as the others are performing so badly) - the ground hog day model to our list - and the result today was - 6 MORE WEEKS OF WINTER!!!!!!!!!!!!!!!!!!!!!!

[Frosty.]

What surprised me was how the BBC on tonight's regional bulletin were insisting on a mild few days but at the weekend turning and I quote: "Much, much colder" (!) OK......?

Yes they must be looking at their secret model again because there is nothing to suggest that happening on any of the operational runs today.

[LomondSnowstorm]

don't worry if the 18z shows a cold set up, be it northerly or easterly, there will be lots of relief and no doubt some rather incorrect back slapping.

http://91.121.94.83/modeles/gfs/run/gfs-0-12.png?18

What is this I see? A northwesterly? Potential there for some breakdown snow in Scotland! Well done to all those who progged this!

Had to be done!

Anyway, I second what both JH and NS say: this run is unlikely to change too much, even if there is cold in FI.

LS

[Buxton Codge]

Latest 18z http://www.wetterzentrale.de/pics/Rtavn601.png

[igloo]

Yes they must be looking at their secret model again because there is nothing to suggest that happening on any of the operational runs today.

heard about this secret model before but i find it hard to believe they actually have one reason being us tax payers which help to pay for the MET would be by right able to view it

[Buxton Codge]

A cold weekend ahead

http://www.wetterzentrale.de/pics/Rtavn782.png

[cyclonic happiness]

Out to +78 now and it's showing a major low pressure off the US eastern seaboard, but where are these lows getting all of their energy from? it cannot be the sea as it's alot cooler than it should be?

http://www.meteociel.fr/modeles/gfse_cartes.php

[Glacier Point]

Well between GP's comments on the other thread and Ian's above, good news afoot

Perhaps the mother of all model backtracks is looming

Yes, starting to get just a little encouraged and events over the tropics and now extratropics are getting my attention.

Forward momentum has been building over the tropics in the last week - 10 days. We are now starting to see the extra-tropical circulation respond with momentum transport across 30N likely to result in high latitude ridge development and circumglobal troughs.

If, I state again, if, Asian mountain torques join in, we could well see a mighty impressive jump in angular momentum (tendency in relative angular momentum is already close to being off the scale) which would increase the probability of colder air being brought back south and westwards across the UK. The northern half of the UK is already in a good position and we're dealing with a potential stark gradient between the cold and warm airmasses.

With the core of any ridge likely to be over western Greenland / Canada, low pressure will likely be centred to our south-west. Encouragingly, tonight's CPC 8-14 dayer minimises ridge devlopment over Iberia. That could in the best case scenario lead to either a channel low or low getting stuck as it attempts to work in from the south-west. The difference between a mega snow event and damp mild squib would be 200 miles. At this range, that's nothing.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

[Nick L]

A cold weekend ahead

http://www.wetterzen...cs/Rtavn782.png

If you think mild muck is cold, yes.

[Ben_Cambs]

Out to +78 now and it's showing a major low pressure off the US eastern seaboard, but where are these lows getting all of their energy from? it cannot be the sea as it's alot cooler than it should be?

http://www.meteociel...gfse_cartes.php

Seems like another case of the GFS overcooking the lows!

[Geordiesnow]

Yes they must be looking at their secret model again because there is nothing to suggest that happening on any of the operational runs today.

Thing is though the UKMO and ECM shows a brief easterly and in there eyes, temps of 3-6C are described as "very cold" by some "soft"(no disrespect) forecasters.

GFS 18Z is having none of it mind and goes for milder SW'lies. I think we are on a verge of a milder and wet spell which no doubt will please most BBC forecasters.

We shall see by tomorrow morning though what the models are saying but again, no matter how hard some models try, any significant easterly seems unlikely.

[LomondSnowstorm]

If you think mild muck is cold, yes.

Looks distinctly, what's the word, average http://charts.netwea...0/ukmaxtemp.png

Not that different a run so far, but it is the GFS pub run, so although it may be plausible, it won't influence my mind too much!

Edited February 2, 2010 by LomondSnowstorm

[remymartin]

The gfs low production line continues, Why does the gfs nearly always overcook LP systems in the atlantic?

[cold snap]

On tonights model viewing with ten being a brilliant eastlerly heres how i rate the models this includes 18Z

ECM 2/10

GFS 4/10

UKMO 3/10

Just seen the Met office fax for Sunday and its terrible.

Only one way down now.Met office have to change there words now.Dont there?

[Cloud 10]

fax charts

The latest 96 and 120 hrs fax charts are out a little early.

[johnholmes]

Yes, starting to get just a little encouraged and events over the tropics and now extratropics are getting my attention.

Forward momentum has been building over the tropics in the last week - 10 days. We are now starting to see the extra-tropical circulation respond with momentum transport across 30N likely to result in high latitude ridge development and circumglobal troughs.

If, I state again, if, Asian mountain torques join in, we could well see a mighty impressive jump in angular momentum (tendency in relative angular momentum is already close to being off the scale) which would increase the probability of colder air being brought back south and westwards across the UK. The northern half of the UK is already in a good position and we're dealing with a potential stark gradient between the cold and warm airmasses.

With the core of any ridge likely to be over western Greenland / Canada, low pressure will likely be centred to our south-west. Encouragingly, tonight's CPC 8-14 dayer minimises ridge devlopment over Iberia. That could in the best case scenario lead to either a channel low or low getting stuck as it attempts to work in from the south-west. The difference between a mega snow event and damp mild squib would be 200 miles. At this range, that's nothing.

http://www.cpc.ncep....y/814day.03.gif

yes I would recommend that some with a jaundiced view on weather forecasting variability actually read the NOAA 6-14 day explanation from them of how the models are coping. The most likely set up over the northern hemisphere-largely geared to their area of course, but often with ramifications in a similar time scale for the Euro area.

For instance this evening they comment with marks of 5/5 that the pattern Stewart has given the link to is considered correct.

Note the wave length of the main troughs-its very long, which suggests only slow movements and a tendency to edge west does happen sometimes. The UK is shown to be under a 'weak' upper ridge which has the effect of weakening and slowing the apparently active Atlantic.

By no means is the pattern settled beyond the end of this week, be it for mild or cold.

If you can accept that and watch the developments then you should not suffer too much trauma for what actually occurs!

[SP1986]

The gfs low production line continues, Why does the gfs nearly always overcook LP systems in the atlantic?

How do we know it's overcooking the lows though? Especially when the balanced forum poster will admit that they don't know whats going on, as much as everyone may disagree with this for obvious reasons, at the time frames suggested as deep low has as much chance as a returning easterly.

[MP-R]

How do we know it's overcooking the lows though? Especially when the balanced forum poster will admit that they don't know whats going on, as much as everyone may disagree with this for obvious reasons, at the time frames suggested as deep low has as much chance as a returning easterly.

One does have to question where the lows are getting all their umph from though. As has been already said, the sea temperatures are below average. I would also like to know what is causing the Atlantic to be so active in general as isn't February supposed to be quite quiet?

Edited February 2, 2010 by Michael Prys-Roberts