Model Output Discussion

[NorthantsSnow]

P2 would be my pick of the ensembles tonight. Proper greenie high with belting E'ly and plenty of snow for all:

http://91.121.94.83/modeles/gens/run/gens-2-1-300.png?18

[Bobby]

ECM ensembles, op was sizeable mild outlier from 1st - 4th of Feb.

[NorthantsSnow]

Did anyone else spot tonight's ECM operational masquerading as a GFS ensemble in the 18z output? The little rascal, stuck out like a sore thumb. No flies on me!

http://91.121.94.83/modeles/gens/run/gens-7-1-240.png?18

http://www.wzkarten3.de/pics/Recm2401.gif

[NorthNorfolkWeather]

The best chart ever in HISTORY

Ensembles are actually EPIC-

Reverse / Negative Zonalilty at it finest-

http://91.121.94.83/modeles/gens/run/gens-8-1-216.png?18

S

That must be a 5,000 mile run of easterlies, from the Black sea (possibly further) across to Labrador.

Maybe winter isn't (quite) finished.

[TEITS]

Rather late looking at the GFS tonight.

I have read some of the comments and I have to be honest I can't help but feel bemused at times. We have comments such as "fax chart is poor" when to be honest the potential E,ly isn't going to develop at this timeframe.

A few things to consider before I pop to bed. During yesterdays runs the models suggested the N,ly would then turn into an E,ly maintaining the cold spell. However as some of us suggested this morning the models yesterday were too progressive in bringing the E,ly. At the moment what is likely to happen is after the N,ly we may see a short spell of W,lys i.e 24/48hrs. However around the +168 timeframe the block to the NE may start influencing our weather. At the moment we still don't know if this will be surface cold via HP centred over the UK or bitter E,lys.

Rather than looking at the operationals have a look at the SLP ensembles for various locations.

http://charts.netweather.tv/ensimages/ens.20100127/18/prmslReyjavic.png

http://charts.netweather.tv/ensimages/ens.20100127/18/prmslOslo.png

http://charts.netweather.tv/ensimages/ens.20100127/18/prmslCambridgeshire.png

Clearly see from these ensembles that blocking is the dominant trend. What is also clear from the Iceland ensembles is the 18Z has very little support. Now I haven't looked at each ensemble member but im guessing the drop in pressure for Cambs towards the latter half of F.I is due to LP systems tracking to the S of the UK.

So now we have cleared up the SLP ensembles what about the temps?

http://charts.netweather.tv/ensimages/ens.20100127/18/t850Cambridgeshire.png

Well with a mean at -8C with a cluster of -10Cs is encouraging with regards to the positioning of the block. However like I said earlier a small shift in the positioning of the blocking can make a huge difference to the upper temps. So whilst HP is looking fairly solid the positioning of this remains uncertain and will continue to do so for many more runs yet.

Overall another excellent day of model watching.

[Duane S.]

Strange but expected comments regarding the latest output. Bigger picture people, bigger picture.

24 hours after posting about that incredible ECM 12z run and the fact I thought it was too progressive about it bringing in the Easterly, nothing has changed. The GFS 18z has gone the other way giving far too much energy and sustainability to the Northern arm, the Iceland SLP ensembles show up the 18z Op for what it really is! And today's ECM 12z had little support from its other members.

Anyone noticed at the moment that even when we have a mild(er) Operational run, despite it doing its damdest to put the brakes on it all, often the cold gets in via another route? That's a good sign.

Outrageous, stupifying chart posted by Steve Murr earlier on. There are good reasons why these charts, FI or not, don't come up very often. Not because its impossible (although, yes, it would still be unlikely) but because right now we have the ingredients in the computer models to allow preturbations like that to occur. 99.9% of the time you could have 50, 100, 1000! members per run and none would ever get close to that evolution.

Further good pressure anomaly forecast ensembles today. Uniform agrement for the AO to go into 'tank mode' from tomorrow before there is then spread opinion on where it goes from the start of next week, but - its pretty much negative all the way. The NAO is unlikey to go to the sort of levels the AO has hit this winter (and may again soon), it doesn't need to though. I think we are looking at it bumbling around Neutral for about a week before starting to drop down to around the -2 mark which would be plenty low enough with a -AO to deliver

Again the MJO forecasts look excellent for us..

Of course things can go wrong as we head towards a potentially very cold spell but I have seen little over the past 24 hours to indicate that it will though.

Good night all and maybe the 00zs will have us back in dreamland come the morning!

[Eugene]

Very dangerous to get excited over easterlies developing after 5 days out, looks a very risky evolution to get to the easterly on GFS 00Z and it could easily go JMA's way which was a stinker.

Personally i`m going for HP to dominate our weather in February though so hopefully some severe frosts and not these stupid mild useless toppler northerlies

[Eugene]

GFS 00Z ensembles you have to say look promising for cold weather fans.

http://www.wzkarten3.de/pics/MT8_London_ens.png

[Iceberg]

A very solid trend to cold this morning on the 00Z suite.

Good agreement for cold on the 12Z ECM ensembles overnight.

A quick word re the ECM, with such strong ensemble support it would be rare to not see the ops come into line a bit. The ECM ops still isn't fully in line I feel but is cetainty alot closer and follows the ensemble trend of no warm up between the northerly and the the continental flow.

The GFS 00Z Ensemble mean for Dorset has temps struggling to get above 0C and average 850's of -7 or -8, all fantastic indications of the still solid agreement post 168 of the cold weather continuing and backed up by the teleconnection signals.

Far to early to got hung up on detail but the trend is as good as it has been.

Going to the Northerly, is is largely a coastal affair, very little easterly component to it so the east coast is really going to be restricted to the showers and the west coast, although the west could see them coming in a bit further inland.

[Polar Continental]

The 0z GFS evolution to the easterly is much the same as yesterday. After the northerly this weekend, pressure begins to build from the south at T120 making for a few fair less cold days. By Wednesday next week (T150) low pressure in the Atlantic begins to edge towards the UK, at the same time the high slowly transfers east and begins its joining with the big Russian high which has been so prominent this winter.

At first we get a pull of southerly winds as the isobars tighten, although at this stage the air won’t be particularly mild. The GFS begins to open the easterly floodgates at T204.

The 0z ECM is better than yesterdays 12z, and starts to look very promising at T192, then seems to change its mind and holds a stale mate.

ECM at T192

So still some way to go with this.

Edited January 28, 2010 by Polar Continental

[Weather-history]

Remarkable Manchester 2m temps, hardly any get above 5C

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

[LomondSnowstorm]

Not too unhappy with the output this morning, as there appears to be reasonable agreement about the development of the easterly. http://charts.netweather.tv/ecmimages/20100128/00/ecm500.240.png Note the yellows over Greenland).

http://www.meteociel.fr/ukmo/run/UN144-21.GIF?28-06 Not entirely sure which way the UKMO would go in FI.

http://91.121.94.83/modeles/gfs/run/gfs-0-216.png?0

http://charts.netweather.tv/ensimages/ens.20100128/00/t850Fife.png Nice ensembles also, with the mean for eastern Scotland only getting briefly above -5.

http://charts.netweather.tv/ensimages/ens.20100128/00/prmslReyjavic.png The tendency for the high to ridge west towards Greenlandd is supported well by the ensembles.

Encouraging signs.

LS

[Nick F]

Very good trends for colder weather this morning, a solid set of ensembles and ECM continues the theme and minor changes would see a spectacular set-up. It looks a case at the moment of just where the block sets up.

Indeed, though a look at the models this morning suggests some patience needed for everything to fall into place to bring cold and snow prospects in the longer term. But good agreement GFS v ECM wrt the upper pattern looking at the 00z 8-10 day mean H500 comparisons - with a large +ve height anomaly centred roughly over the Barents Sea and also hints that energy may start to undercut this block towards SW Europe longer-term:

As some others have mentioned over last few days, the models (particularly GFS) may have been a bit too hasty to bring in the easterly that was modelled in some of the good runs over last few days, so it's a case of hanging on in there.

Eventually the polar vortex looks to be displaced to lower latitudes and fragment, as indicated by growing support for a -ve AO and blocking to our N and NE developing, but it may be a slow process

[TEITS]

It looks a case at the moment of just where the block sets up.

Yes and we still don't know where this will be. Unlikely to find out for a while yet which is frustrating.

Having said this in these situations I do look for model consistency and the most consistent has to be the GEFS mean.

Here is the GEFS mean at +168/192/240.

http://91.121.94.83/modeles/gens/run/gens-21-1-168.png?0

http://91.121.94.83/modeles/gens/run/gens-21-1-192.png?0

http://91.121.94.83/modeles/gens/run/gens-21-1-240.png?0

The GEFS has been very consistent in bringing us E,lys starting around +168. What we see in F.I is pressure rising over Greenland. What this means is we start seeing a long train of E,lys but we also see LP to our S. This is consistent with the slight drop in pressure in Cambs during the latter half of the run and was also seen on the 18Z ensembles.

Overall another excellent set of models this morning but still too early to get excited.

Edited January 28, 2010 by THE EYE IN THE SKY

[Frosty.]

I'm not surprised that many on here are ignoring the Northerly and looking longingly further ahead to possible Easterlies because the N'ly will deliver very little to inland areas with the wishbone effect in operation, northeast scotland looks the best place to be for heavy, frequent snow showers and drifting in the strong N'ly winds although there will also be some snow showers down eastern coasts of england as well and some on western coasts bordering the irish sea but sunny inland.

[TEITS]

I'm not surprised that many on here are ignoring the Northerly and looking longingly further ahead to possible Easterlies because the N'ly will deliver very little to inland areas with the wishbone effect in operation, northeast scotland looks the best place to be for heavy, frequent snow showers and drifting in the strong N'ly winds although there will also be some snow showers down eastern coasts of england as well and some on western coasts bordering the irish sea but sunny inland.

Yep looking very dry for my location. Still I shall look forward to the clean, crisp air of a N,ly with the abundance of sunshine and frost at night.

The main locations that look favorites is NE Scotland as you say and also NE Norfolk.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/01/28/basis00/ukuk/prty/10013000_2800.gif

[Snowyowl9]

I'm not surprised that many on here are ignoring the Northerly and looking longingly further ahead to possible Easterlies because the N'ly will deliver very little to inland areas with the wishbone effect in operation.

Could be a little backedge snow tomorrow,as the cold air finally makes it,today is just a halfwayhouse NW-ly.

http://www2.wetter3.de/Animation_00_UTC/36_30.gif

Sunday looks the best day for snow showers as it`s a more NW-ly.

http://www2.wetter3.de/Animation_00_UTC/90_30.gif

[snowmadchrisuk]

Yes and we still don't know where this will be. Unlikely to find out for a while yet which is frustrating.

Having said this in these situations I do look for model consistency and the most consistent has to be the GEFS mean.

Here is the GEFS mean at +168/192/240.

http://91.121.94.83/modeles/gens/run/gens-21-1-168.png?0

http://91.121.94.83/modeles/gens/run/gens-21-1-192.png?0

http://91.121.94.83/modeles/gens/run/gens-21-1-240.png?0

The GEFS has been very consistent in bringing us E,lys starting around +168. What we see in F.I is pressure rising over Greenland. What this means is we start seeing a long train of E,lys but we also see LP to our S. This is consistent with the slight drop in pressure in Cambs during the latter half of the run and was also seen on the 18Z ensembles.

Overall another excellent set of models this morning but still too early to get excited.

Have just used my whole tea break looking through all the models, and on the GFS,UKMO,ECM,GEM and NOGAPS we at some point see blocking from Scandinavia to Greenland , the MJO looks like it might stall in mid phase 7 and that in it's self is exciting me .

[mushymanrob]

urgh.... what a horrible outlook with that massive anticyclone drifting out of siberia and introducing possible easterlies. dunno why this is popular here as they will be quite dry, especially under high pressure. i understand why people like snow, but cold for colds sake?...

[Matt12]

urgh.... what a horrible outlook with that massive anticyclone drifting out of siberia and introducing possible easterlies. dunno why this is popular here as they will be quite dry, especially under high pressure. i understand why people like snow, but cold for colds sake?...

Because if it is cold for 2 works or more, it is bound to snow at some point (even if the models don't forecast it way out in FI). It just sets the right conditions which are needed for snow, and then usually the rest follows (but not always).

[TEITS]

urgh.... what a horrible outlook with that massive anticyclone drifting out of siberia and introducing possible easterlies. dunno why this is popular here as they will be quite dry, especially under high pressure. i understand why people like snow, but cold for colds sake?...

Only dry Mushy if the HP sits over us or we do not pull in colder upper temps.

I feel Nick F made a very good point this morning with regarding requiring patience with this possible E,ly. Obviously ideally I would prefer this ASAP along with the cold upper temps. However we might have to wait until +192/+240 before this happens. Even then there isn't a guarantee a pool of colder upper temps will be under the block. Some of the GFS runs have shown this and its taken a while before we have pulled in very cold air. Having said this if you do have the block in the ideal position then its only a matter of time before the cold pools are advected W.

Have to say Mushy I do feel sorry for you. What with a combination of rubbish recent summers and now this cold winter, our recent weather patterns certainly haven't been favourable for you.

[Nick F]

Wrt the northerly this weekend GFS does suggest some back edge snow on the rain band edging south tomorrow morning - though 00z NAE keeps it rain all through.

Looks like some convergence zones may set-up in the west over the weekend, which may bring snow showers inland across N Ireland/Ern ROI, Wales, SW England and perhaps Cheshire and the Midlands - zone will be where winds from the N and NW converge and force air upwards, these convergence zones are shown by the 'tree' like diagrams on the faxes (below), in case anyone wondered what they are. Eastern coastal fringes and Ern Scotland look like benefiting from snow showers too.

I feel Nick F made a very good point this morning with regarding requiring patience with this possible E,ly. Obviously ideally I would prefer this ASAP along with the cold upper temps. However we might have to wait until +192/+240 before this happens. Even then there isn't a guarantee a pool of colder upper temps will be under the block. Some of the GFS runs have shown this and its taken a while before we have pulled in very cold air. Having said this if you do have the block in the ideal position then its only a matter of time before the cold pools are advected W.

Yes, getting an easterly is one thing, but getting cold enough uppers and low enough pressure for snow is another piece of the jigsaw to attain. Could be a cold dry easterly or southeasterly to begin with then the real fun later on into first half of Feb if the block can hold to allow lows to undercut.

[aspire27]

I presume we are seeing the trends to colder weather now in the essemblies etc. But people have seem to forgotten that this weeks easterly died a death and the

Northerly now seems pretty poor too. Anything any good is in FI and seems to be pushed out on the models.

But as people say, look for the cooling trend.

[stewfox]

Only dry Mushy if the HP sits over us or we do not pull in colder upper temps.

I feel Nick F made a very good point this morning with regarding requiring patience with this possible E,ly. Obviously ideally I would prefer this ASAP along with the cold upper temps. However we might have to wait until +192/+240 before this happens. Even then there isn't a guarantee a pool of colder upper temps will be under the block. Some of the GFS runs have shown this and its taken a while before we have pulled in very cold air. Having said this if you do have the block in the ideal position then its only a matter of time before the cold pools are advected W.

Have to say Mushy I do feel sorry for you. What with a combination of rubbish recent summers and now this cold winter, our recent weather patterns certainly haven't been favourable for you.

It's interesting how a few days ago we get the best charts since 1947 etc the mother of all cold spell coming up all getting pushed back and back.

Testis I do hope you do get your beloved easterly before the summer but T240 its all back in F1.

I always find it interesting few people talk about things within T96, we have seen on recent runs nothing is 'nailed' within that time frame.

Cold air can arrive over night with the right synoptics, waiting 10 days for everything to be in place I'm afraid is wishful thing and hope casting.

For the next week the temps are going to be slightly below average with a few cold nights (cira -4c CET zone).

Edited January 28, 2010 by stewfox

[penicuikblizz]

It's interesting how a few days ago we get the best charts since 1947 etc the mother of all cold spell coming up all getting pushed back and back.

Testis I do hope you do get your beloved easterly before the summer but T240 its all back in F1.

I always find it interesting few people talk about things within T96, we have seen on recent runs nothing is 'nailed' within that time frame.

Cold air can arrive over night with the right synoptics, waiting 10 days for everything to be in place I'm afraid is wishful thing and hope casting.

For the next week the temps are going to be slightly below average with a few cold nights (cira -4c CET zone).

Yeah but GFS has been and still is consistant in bringing the easterly in next weekend. No its not going to be 1947 all over again people on here and on two website were getting a bit carried away. I can see a 3 or 4day event with snow in the east biggest threat east and south england