General Model Output Discussion

[West is Best]

I think we should acknowledge that this is the end of the really cold spell for now. It is going to turn progressively milder, and here in the south-west peninsular next weekend looks positively spring-like. Colder elsewhere though, with some overnight frosts still and for a few days yet not particularly 'mild' in central Britain.

Although the jet pattern is meridional we're perilously close to Bartlett territory on some of these outputs (e.g. the ECM). One to watch I think. However, perhaps there will be a cold reload. We really need a north-west block to re-emerge as per Christmas time otherwise the irrepressible Atlantic express will come steaming back through.

As for today: the GFS has had this as a rain event for Devon and Cornwall. I have struggled to see how it could be much of a snow event given the upper air temps. Further east where the edge of the ppn rests could be a very different story.

[Frosty.]

The 00z models still show atlantic low pressure pushing east across the uk by this weekend bringing wet & windy weather at times and temps slowly rising but still below average at around 4-6c but lower on hills with sleet and snow still likely on northern hills. The main interest is whether or not the very cold continental winds will return next week and having looked at the latest gfs, ecm and ukmo I would say it's probably 50/50 at this stage, very finely balanced although there is nobody on here who wants the bitterly cold air back more than me.

[ANYWEATHER]

Evolution looks interesting to me with riding building up from the east and lows developing on it's SE'rn flank. Many classic cold spells develop this way.

To sum up staying very cold (particularly by day) upto Saturday then much uncertainty after a brief 'possible' less cold day Sunday. I would go for ridging to take place and lows developing under it's southern flank dragging back an easterly for next week.

Massive uncertainty at that range as always in these situations. One thing I think we can guarantee - no raging Atlantic for the foreseeable future.

If I was to go for a guess for the end of the month, with the AO and NAO situation developing I'd go for more unsettled finish.

Could not agree more! Even 24hrs ago much milder conditions were shown by the gfs and now Im not sure its going to warm up much at all. The "big player! is not the Atlantic but that huge cold block to our east and indeed the models ecm and gfs are now showing that!

Edited January 12, 2010 by ANYWEATHER

[pureasthedriven]

My eye is still firmly on that huge Scandi/W Russian block retrogressing westwards around 18th-20th timeframe, as it has done for run after run on the GFS. Long way out but definitely a trend in this model.

[Frosty.]

The GEM 00z begins to look interesting @ T+240 hours with Scandi/W.Russian block advancing westwards but until then looks fairly atlantic driven for a time from the weekend into early next week before the ridge builds in from the west, the ukmo 00z doesn't show any sign of returning E'lies unless i'm reading the T+144 chart incorrectly.

[Yozzer]

The GFS has taken an awful lot of stick from many members on here recently for its tendency to be too progressive, but it was the first to pick up on the breakdown when all other models showed the block holding firm over the UK, and despite the straw clutching of many in terms of reloads/beast from the east, there is no evidence that this will happen in the reliable, or even at all.

[snowingtequila]

The GEM 00z begins to look interesting @ T+240 hours with Scandi/W.Russian block advancing westwards but until then looks fairly atlantic driven for a time from the weekend into early next week before the ridge builds in from the west, the ukmo 00z doesn't show any sign of returning E'lies unless i'm reading the T+144 chart incorrectly.

maybe I am missing something but I see less of the block returning in every run. All I can see is an incresing chance of a high pressure to the south, icelandic lows and Sw winds.

[Weather-history]

I'd be inclined to dissagree with the above as looking through all models I think the trend is definately for the Atlantic to win out mid to long term.

I don't agree. I don't think it will be Atlantic dominated at least not what I see from the models, I think we will be caught between two stalls or in no man's land with neither having domination.

If you look at the GFS SLP ensembles, hardly any ensemble dips below 1000mb for Manchester through the entire run, the mean is around 1020mb for Manchester. If it was to be Atlantic dominated I would expect it to be nearer 1000mb.

http://www.wzkarten3.de/pics/MT2_Manchester_ens.png

Edited January 12, 2010 by Mr_Data

[drgl]

The GFS has taken an awful lot of stick from many members on here recently for its tendency to be too progressive, but it was the first to pick up on the breakdown when all other models showed the block holding firm over the UK, and despite the straw clutching of many in terms of reloads/beast from the east, there is no evidence that this will happen in the reliable, or even at all.

If you stick to the same outlook sooner or later it will come true. I think the fact that it may have got it right is simply down to this!

[johnholmes]

Below is the main apart of what I posted last evening concerning the longer term

One of the major differences in the next week as compared to the week past is the position of the two main troughs-west of and east of the North American continent.

Both are about 30 degrees further east on the predicted NOAA 500mb anomaly charts. This, in turn, means the upper ridge is that much further east; its over the far NE of Norway or north Russia as opposed to being over the UK, or a touch NW of the UK. The pattern, of each of those wavelengths is fairly slow moving. However, the one now and the past week means the UK on the cold side, the predicted pattern suggests on the warm side (warm being a very relative term), thus no deep cold and a more unsettled spell of weather, or perhaps more accurately a more Atlantic type pattern. Mainly Pm or rPm but not true Pm or even less Am (Arctic).

Just how the Pacific jet will react in all this is unclear but it seems to be defaulting, as NOAA comment, to the position in late November. This MAY mean a return is on the cards, as per the post in the Technical thread by GP, or it may not. On a differing time scale the AO has today shown a signal for falling again. Perhaps this is linked to the teleconnections which GP refers to as a 'reload' for the third week in January.

What I would add having time to sleep on it and seeing further output across the Atlantic is this.

There is less and less sign of any immediate return to any cold weather. The Pacific jet is driving things east. Just how this almost ‘split’ flow coming into the States will affect downstream is unclear. In the 7-10 day period it simply has the effect of pushing any ‘real’ cold further east as the major Atlantic trough becomes the main player. There are signs on the various circumpolar charts of the whole wave train beginning to move east, only slowly, and at the same time POSSIBLY showing some sign of buckling way west(USA area) but its not yet clear. The 500mb does show signs of building pressure over the east of the states. IF this happened and it’s a big IF it would be a similar evolution to what occurred in mid December. However, then most other links also supported a block establishing itself. From the 30mb Stratosphere temperatures through the Tropics feedbacks to the AO and NAO. Today there is little sign of this, the 30mb temperature(I agree its only a quick snapshot but not a bad indicator of events above the Tropopause in my view), Tropics, AO and NAO are nowhere near as supportive of this developing into a major block. Having said that the upper ridge and its surface high continue to build way east of the UK.

Currently I would favour mild into February against cold into February at about 60-40.

I think if there is going to be some kind of ‘link’ up of the various factors for another cold spell then its beyond the start of February for it to begin to start taking effect. As to whether this will be from the NE or NW I honestly have no idea.

[FENDER.]

Nobody deleted your post, they moved it, besides, there is nothing and models showing NO mild February. If you wish to mention mild or anything, please show me a chart where it's going to be mild.

I think GP was suggesting a very mild Feb, due to the upstream signs, thats what I was refering to, perhaps that has now changed?

[DEYS(Kent)]

http://www.knmi.nl/exp/pluim/vijftiendaagse/

HP to the east ridging west. Good ECM ENS.

[chionomaniac]

http://www.knmi.nl/exp/pluim/vijftiendaagse/

HP to the east ridging west. Good ECM ENS.

I think it is important to remember with the de Bilt ensembles that they may show a lot colder temperatures than we are likely to have here, especially if we are caught in a no mans land as Mr Data has suggested. The de Bilt ensembles would be cold, the east of the UK average and Ireland possibly above.

of the UK.

Currently I would favour mild into February against cold into February at about 60-40.

I think if there is going to be some kind of ‘link’ up of the various factors for another cold spell then its beyond the start of February for it to begin to start taking effect. As to whether this will be from the NE or NW I honestly have no idea.

It certainly looks like we are walking along a synoptic Striding Edge and could fall off either way!

[snowingtequila]

I think it is important to remember with the de Bilt ensembles that they may show a lot colder temperatures than we are likely to have here, especially if we are caught in a no mans land as Mr Data has suggested. The de Bilt ensembles would be cold, the east of the UK average and Ireland possibly above.

It certainly looks like we are walking along a synoptic Striding Edge and could fall off either way!

No model really suggests the cold coming back, the only hope really is a hopecast in the sense that things can change in a week if signals are picked up. The block is just too far south though and I can see no sign of the cold marching back on any model not even the lesser looked at ones

[ANYWEATHER]

No model really suggests the cold coming back, the only hope really is a hopecast in the sense that things can change in a week if signals are picked up. The block is just too far south though and I can see no sign of the cold marching back on any model not even the lesser looked at ones

What do you mean by the "Block is too far south"? The block of high pressure is to the east and northeast of the uk! How much that influences us in the days ahead is still open to question?

Edited January 12, 2010 by ANYWEATHER

[Eugene]

despite the straw clutching of many in terms of reloads/beast from the east, there is no evidence that this will happen in the reliable, or even at all.

LOL, you probably made the same comments before the reload in early Jan, i find it strange people dismiss or forget the cold charts from last night but suddenly believe the runs this morning, more flips to come me thinks

[Methuselah]

When a model 'sees' a cold-spell in FI, it's being a trendsetter; but, when the very same model 'sees' anything milder coming, it's being over progressive...Still, with the Metman on Five Live talking of a possible return to cold next week, nothing's cut-and-dried, IMO?? :unsure:

Plenty of interest over the next few days...

[arnott]

Ths weather has been brilliant but not special like old winters gone by and sadly the models show very very mild weather on the way and that sadly looks like continuing! We are just too far west of tht block. so close but so far. Hope eveyone enjoyed wht we had.

[len]

The GFS has taken an awful lot of stick from many members on here recently for its tendency to be too progressive, but it was the first to pick up on the breakdown when all other models showed the block holding firm over the UK, and despite the straw clutching of many in terms of reloads/beast from the east, there is no evidence that this will happen in the reliable, or even at all.

Yes indeed. The ECM has completely flipped to follow the GFS suit this morning;..... just as it did last week when the GFS was the first to show the Atlantic spoiling things.

Len

[chionomaniac]

No model really suggests the cold coming back, the only hope really is a hopecast in the sense that things can change in a week if signals are picked up. The block is just too far south though and I can see no sign of the cold marching back on any model not even the lesser looked at ones

Sometimes it is worth looking a bit further than the models.

10- 14 day blocking forecasts:

[derrylynne]

When a model 'sees' a cold-spell in FI, it's being a trendsetter; but, when the very same models 'sees' anything milder coming, it's being over progressive...Still, with the Metman on Five Live talking of a possible return to cold next week, nothing's cut-and-dried, IMO?? :unsure:

Plenty of interest over the next few days...

Could not agree more re your comments as regards model output as regards trends. I am sure many that visit this thread only want to see cold and then if it does not show start throwing the toys out the pram. lol

However, to my untrained eye looking at the models it is clear the jet will remain far to our south, leaving us on the cold side the jet, so temperature are not likely to be that mild, giving a chance for much more snow than we have become used to - even if it is snow then a thaw rota. However, with the AO looking to stay on the negative side, and the solar conditons I would give a high chance that February will be very cold. Don't forget that synoptics can change at very short notice, almost out the blue, and so a reload could be possible at short notice. Personally though I will be glad of a thaw, even if temporary to clear the roads and to see a bit of green for a change; many folk have on the high ground been trapped in their homes for more than a week. And peeps like me that suffer from chest problems are forced to in the main stay indoors. In the short term it does look at though the far SW may reach double digits by the weekend, hopefully us here on the high ground will at least reach high single figures....I expect the cold will return next week though.

[Weather-history]

Yes indeed. The ECM has completely flipped to follow the GFS suit this morning;..... just as it did last week when the GFS was the first to show the Atlantic spoiling things.

Len

Having said that, GFS didn't really go for the recent easterly flow but ECM did and it was GFS that backed down that time. I think its a case of "6 of one" and "a half a dozen of another"

Edited January 12, 2010 by Mr_Data

[TEITS]

Yes indeed. The ECM has completely flipped to follow the GFS suit this morning;..... just as it did last week when the GFS was the first to show the Atlantic spoiling things.

Len

Sorry but I strongly disagree.

Look at the +168 06Z and thats hardly the Atlantic dominating.

http://www.wetterzentrale.de/pics/Rtavn1681.png

So is this an outlier?

Answer no because I just said in another thread that a trend may emerge in the ensembles. Look around the 20th on the link below and note how the 0Z control/OP both show colder upper temps.

http://charts.netweather.tv/ensimages/ens.20100112/00/t850Cambridgeshire.png

Keep an eye on that mean around the 20th to see if a dip occurs as other members follow suit.

[Eugene]

Actually after having a closer look they aren't that different from last night really, still air frosts saturday and monday night, by the sounds of some posts i thought we were in for a mega warm up or something.

Not a bad outlook at all really with HP building again over us early next week, who knows what might transpire from there at this range

And with perturbations like these which shows what could transpire i am astonished hardly anybody is positive today, this has support from some other members too including control and the ECM ensembles.

http://www.meteociel...&mode=0&runpara=

Edited January 12, 2010 by Eugene

[Weather-history]

Look at the size of that high pressure coming out of Siberia, its huge, reminds me of January 1933

http://www.wetterzentrale.de/pics/Rtavn1741.png