Model Output Discussion

[Tom D]

The ensemble mean remains on good form for an Scandinavian AND a Greenland block by 8th February.

http://91.121.94.83/modeles/gens/run/gens-21-1-276.png?12

P6 is particularly mouth-watering with the vast majority of ensembles similar to the mean.

http://91.121.94.83/modeles/gens/run/gens-6-1-300.png?12

Edited January 28, 2010 by Tommyd1258

[Cecil Hogmanay Melchett]

Well i guess its a forum and everyone is entitled to an opinion.

I dont share the optimism from the ukmo run.Still far too much oomph in the atlantic and plenty of energy spinning westwards at 144h.

The high is patently struggling to get far enough north and west to allow the bitter stuff to come west,i really hope

we dont just miss out .

[SP1986]

Some fantastic Ensemble agreement from the GFS 12Z today at 168T for the Easterly to develop. You would have to be very brave/foolish to go against this. Particularly with the ECM agreement.

How about a pint for the first person that posts up a chart showing -20 850's somewhere in the BI. ?

Having just looked at the stamps, I wouldn't say it's fantastic agreement as there are a few southwesterly ensembles there, however there is agreement which is more prevelant in the easterly suggestion.

[Geordiesnow]

12z downgrades the Northerly, it lasts 30 hours now. It's slowly vanishing....

Seems too last longer than that too me Lewis, what charts are you looking at? Admittedly, the high topples from the SW but it takes a little while longer before the Northerly to topple completely in North Eastern areas. I can't see the Northerly vanishing now and it looks like it will topple completely by Monday. I think its because it does not show much PPN for most of us, the northerly does not class highly amongst people when infact, its not that bad of an attempt of a cold shot imo.

I'm not sure where the UKMO would lead to after 144 hours but it looks fairly similar to the GFS. Problem at this moment in time is that any real cold shot is well out into FI and does not appear to be getting closer but there is alot of potential out there with impressive blocking to our NE. As we know though, this does not automatically mean a cold spell and we could always still end up on the mild side of any blocking.

[Bobby]

Decent ensembles, better than the 06z ones I think but not as good as last night. Some great runs in there.

Be a while before anything is firmed up on though.

[Frosty.]

plenty of energy spinning westwards at 144h.

Surely that's a good sign, if it was spinning eastwards I would be more concerned. All things considered, we have taken a step in the right direction since the 6z gfs and ecm 00z. As for the impending Northerly, the duration is exactly the same, 72 hours for most of the uk but 96 hours for northeast scotland.

[Cecil Hogmanay Melchett]

Surely that's a good sign, if it was spinning eastwards I would be more concerned. All things considered, we have taken a step in the right direction since the 6z gfs and ecm 00z. As for the impending Northerly, the duration is exactly the same, 72 hours for most of the uk but 96 hours for northeast scotland.

sorry frosty i meant spinning eastwards.It looks very similar to ecm 0z run to me.

[The PIT]

One thing I remember about panel maps. GFS was predicting a big storm the panel maps in FI all agreed with the low bar one. The next run the low had gone and the GFS had fastened correctly onto the quiet weather pattern instead. So after several runs it dumped the storm suddenly. So although many panels may show cold it's no guarantee that it will come off.

I notice the 00 oz ECM has backed away from the milder run from yesterday.

Easterly still up in the air at the moment the northerly should arrive bringing n ice clear crisp days for us.

[LomondSnowstorm]

GEM just brought in the easterly at +144 hours http://91.121.94.83/modeles/gem/run/gem-0-144.png Similar to the UKMO just a bit further west.

LS

[Frosty.]

sorry frosty i meant spinning eastwards.It looks very similar to ecm 0z run to me.

It looks good to me, cold pool covering most of the uk with the siberian high sending a ridge towards us. I would say it's an improvement on recent ukmo output.

[Snowyowl9]

These temps will change at this timeframe,like today for instance but not mild today.

But if this is all the mild we get then this winter will be very known for it lack of mild days since this cold period began.

http://91.121.93.17/pics/Rtavn12617.png

http://91.121.93.17/pics/Rtavn15017.png

Edited January 28, 2010 by Snowyowl9

[Glacier Point]

Models are going bonkers for a huge blocking structure over the eastern side of the Arctic which is totally related to upper atmosphere profile at 100 hPa and 200 hPa layers - ahead of the dowwelling zonal wind anomalies associated with the MMW.

For example, see 00z ensemble mean GEM and GFS mean heights for day 10, yes day 10 projecting a 380m+ height anomaly:

http://raleighwx.eas...nomalyNH240.gif

http://raleighwx.eas...nomalyNH240.gif

The trend has been to draw those heights towards Greenland which makes sense if there is a significant reversal or weakening in polar westerlies associated with propagating effects of the MMW - movement of winds from areas of high to low pressure.

The timescales for this are still uncertain (anywhere between 14-28 days) so low confidence in any projections on this basis.

What I like about the 12z runs so far is that the models are starting to put up a realistic solution to the longwave trough to our east. With the Global Wind Oscillation in low orbit phases 5-6-7-8 we have to look at troughing to our east as a player (slowly filling) and ridge development initially south-west and then towards the UK. Phase 6 of the GWO also favours height rises further north and trough dispruption in the Atlantic, again, starting to show up in the 12z model runs.

With the general concensus for the height anomaly over Siberia to transfer westwards, there is the prospect of the trough to our east becoming cut off helping to advect the cold upper pool westwards until we end up with a solution like the operational GFS 12z with the ridge to our west.

I stress again though the timings on this are uncertain and we may well end up with the initial ridge centred over the UK for longer than currently projected but the overall direction of travel looks good.

Edited January 28, 2010 by Glacier Point

[Harsh Climate]

As will almost everyone else if this easterly doesn't occur or isn't as severe as perhaps someone would be led to believe if they were naive enough to believe everyone had a balanced view on the weather

I think certain people are right, although it does look like like an easterly is favoured, it wil never be even 80% certain until 2 days before the actual event starts. I do think the nature of the GFS does create a suggestion of a long easterly spell but that's to do with the 3 hourly/6 hourly time segments, depending on which models/part of the model you look at.

I don't believe myself that this certain yet, even if other members are getting excited. I do believe there will be come form of easterly, but a notable one I'm sceptical of yet.

Yes, when an easterly is being predicted at 7/10 days out, 9/10 it wont be severe or properly materialise at all. I think what is looking almost certain though, is all the signs are there for a cool to cold (possibly very cold) start-mid februrary..... :lol: With the AO expected to plummet and the NAO heading negative I cant see any lengthy mild weather in this perriod. So I think its safe to say a mild februrary is now looking very unlikly, something close or colder than the 1971-2000 average is more likely.

I agree, its far too early to jump on the 'Beast From The East' wagon as I think as we get nearer to the event it will be watered down with wintry showers/outbreaks of sleet/snow rather than blizzards and sub zero maximums (although that is a POSSIBILITY.) But certainly some interesting model watching lies ahead, with more seasonal weather on the way :lol:

[TEITS]

Crikey only just seen the GFS 12Z and my word what a run. Funny thing is the ensembles show much colder runs than the OP!

Superb UKMO/GEM tonight.

http://charts.netweather.tv/ensimages/ens.20100128/12/t850Cambridgeshire.png

[Frosty.]

Great update as usual GP

Nice to be looking NE or E for our weather instead of SW, GFS 12z is a really good run for cold fans like me, there are some really bitter uppers hopefully heading our way later next week onwards. As for the imminent N'ly, sunny inland with snow showers around the coasts and potential blizzard conditions for northeast scotland on sunday.

[TEITS]

Models are going bonkers for a huge blocking structure over the eastern side of the Arctic which is totally related to upper atmosphere profile at 100 hPa and 200 hPa layers - ahead of the dowwelling zonal wind anomalies associated with the MMW.

You don't often see a mean of +1040mb over Oslo & a mean of 1030mb in Iceland at the same time!

http://charts.netweather.tv/ensimages/ens.20100128/12/prmslOslo.png

http://charts.netweather.tv/ensimages/ens.20100128/12/prmslReyjavic.png

The ensembles continue to be very keen in rising heights over Greenland beyond the intial E,ly.

[nick sussex]

Nice ECM upto 120hrs this could be a great run, pressure stronger to the north.At 144hrs the Siberian high is ridging over the top towards Greenland, this looks nerve shredding as the 168hrs could deliver a chart of epic proportions!Me and my big mouth! so close to a great chart but that shortwave at 144hrs to the ne is a real nuisance as the Atlantic low comes in too far north.

Edited January 28, 2010 by nick sussex

[D KARLSON]

I think its nailed on that next week, this pool of intense cold air will spill westwards ,but i suppose the big questions are orientation of the high and whether there is any undercutting of the jet to the south.

At this point its impossible to say, but you can have an educated guess and to my eyes this looks to be perhaps a unique set up with p[ressure up to 1060 mbs thats rare in itself and the intensity of the cold advected would be something weve not seen since the 80s so surprises are in store and the cold could well set up some small troughs or lows as cold hits the north sea or channel for that matter .

[nick sussex]

The ECM this evening is very frustrating as its output earlier on suggests something very good, but that shortwave to the NE at 144hrs stops the high ridging westwards, this then becomes absorbed by the Atlantic low but because of this the low ends up further north, its quite simple here, if the shortwave doesn't appear then the ridge backs west forcing the Atlantic low further south and with it some very cold upper air backs west, its earlier set up is much better upto 120hrs than the other models.

[cooling climate]

To my eyes the ECM is still having trouble with the troughing to the east and over complicates things

as it not sure what to do. The trend continues though with the heights coming west.

[Bobby]

ECM looks messy... but it looks like easterly is roaring in by 216.

[TEITS]

its earlier set up is much better upto 120hrs than the other models.

Yes I thought exactly the same mate.

Have to say if you was going to base a forecast on consistency it certainly wouldn't go to the ECM. The past 4 runs have been different, whereas the GFS has been far more consistent. Obviously this doesn't mean the ECM is wrong but the model is hardly filling me with much confidence due to its inconsistency.

[Cecil Hogmanay Melchett]

ecm again refusing to buy it.

Looks quite similar to meto at 144h as well.

That god damn atlantic is determined to stop us getting the cold stuff to the east.Virtually all of europe in the

freezer at 168h,apart from the uk.

EDIT we get there at 216h but its so delayed its very annoying.

Edited January 28, 2010 by happy days

[bluearmy]

The ECM this evening is very frustrating as its output earlier on suggests something very good, but that shortwave to the NE at 144hrs stops the high ridging westwards, this then becomes absorbed by the Atlantic low but because of this the low ends up further north, its quite simple here, if the shortwave doesn't appear then the ridge backs west forcing the Atlantic low further south and with it some very cold upper air backs west, its earlier set up is much better upto 120hrs than the other models.

i recall that norwegian shortwave screwed up yesterdays 12z aswell. given GP's consistent mutterings that the trough will hold longer to our east than the models are showing, maybe we should begin to factor this in as a probable delay to the e - w flow getting started. this repeating shortwave situation may not get picked up by the ens. hmmmmmm

[nick sussex]

To my eyes the ECM is still having trouble with the troughing to the east and over complicates things

as it not sure what to do. The trend continues though with the heights coming west.

Yes it certainly wants to drag the drama out by sticking that pesky shortwave in the worst possible position at 144hrs, i suspect around the 144hrs to 192hrs timeframe this will show as a mild outlier on the ensembles for the Netherlands, its amazing how one small feature can make such a huge difference. However given thats at 144hrs theres plenty of time for changes and for the timebeing theres still a very good chance of an easterly.