237 replies to this topic

[THE EYE IN THE SKY]

Just seen the ensembles and blimey is the first word that comes to mind. When I mentioned the uncertainity last night in the 18Z ensembles I have to be honest I thought I might be straw clutching. Now i've finally looked at the 06Z ensembles and the answer is no I wasn't.

What some of the ensembles do is similiar to the OP with the trough moving SE. However quiet a few other members keep this to the W and then we see trough disruption with the energy going SE and at the same time pressure building over Scandi.

The upper temp mean has taken quiet a drop around the 25th and thats a full 5C colder than the ensembles were suggesting yesterday.

http://cdn.nwstatic....bridgeshire.png

[bluearmy]

the parallel gefs remaining interesting. given that they are running at a decent resolution to t192, this theme of raising heights to our north a little and diverting the trough to our sw is certainly something thats been hinted at over the past few days but never become the dominant trend. need to be cautious though. only one run. want to see the 12z 'pick up the baton

[No balls like Snow Balls]

THE EYE IN THE SKY, on 19 January 2012 - 13:11 , said:

Just seen the ensembles and blimey is the first word that comes to mind. When I mentioned the uncertainity last night in the 18Z ensembles I have to be honest I thought I might be straw clutching. Now i've finally looked at the 06Z ensembles and the answer is no I wasn't.

What some of the ensembles do is similiar to the OP with the trough moving SE. However quiet a few other members keep this to the W and then we see trough disruption with the energy going SE and at the same time pressure building over Scandi.

The upper temp mean has taken quiet a drop around the 25th and thats a full 5C colder than the ensembles were suggesting yesterday.

http://cdn.nwstatic....bridgeshire.png

And they could well be 5c warmer by the end of the 12z such is the chaos in the models at the moment. I am just being pessamistic hopefully lol. Probably the best thing to do is to take the mean of the mean ensembles over the course of a week lol.

Edited by No balls like Snow Balls, 19 January 2012 - 13:26 .

[Sinth]

Blimey someone has re-booted the GFS computer, even at T60 looks colder.
http://www.meteociel...?&ech=60&mode=0

[MisfitDog3]

The shift is astonishing...yes I know it's only one run but even looking at a like with like, I've rarely seen such a shift in such a short time, particualarly from GFS. It's a worry though because it just screams 'instability' in any reliable output to take forward, especially when it starts moving phantom Low Pressures around (see current English Channel solution!!). I've seen that before and it's not a vote of confidence.... The next 24 hours are going to be the most important of the last two weeks to decide where we go in the next fortnight.

[waz20000]

MisfitDog3, on 19 January 2012 - 13:20 , said:

The shift is astonishing...yes I know it's only one run but even looking at a like with like, I've rarely seen such a shift in such a short time, particualarly from GFS. It's a worry though because it just screams 'instability' in any reliable output to take forward, especially when it starts moving phantom Low Pressures around (see current English Channel solution!!). I've seen that before and it's not a vote of confidence.... The next 24 hours are going to be the most important of the last two weeks to decide where we go in the next fortnight.

[jethro]

THE EYE IN THE SKY, on 19 January 2012 - 10:31 , said:

Don't know if I want to laugh or cry but the 06Z is predicting widespread snow!

http://cdn.nwstatic....ctypeuktopo.png

Ditto. I live smack bang in the middle of that grey hole.

[nick sussex]

Who needs model output, just come in here and see how many pages the thread has extended to, I left to go out at page 8 and came back to see its upto page 13!

I sort of knew then it wasn't just 5 pages of toys out of prams posts! I think these models should be sued for cruelty to cold lovers, the GFS 06hrs run picks up on a trend hinted at by both the ECM and UKMO, typically they've now dropped this!

This is really the only quick way to cold as the other option is that slow moving trough over the UK and waiting for that to eject some energy south eastwards under the block, I'd advise people to not get too excited yet as we've been here before countless times over the last few weeks.

If the others go with this tonight then there may finally be light at the end of the tunnel but thats still a big IF!

[feb1991blizzard]

The most important run of the winter is going to be the ECM 32 dayer and the subsequent MO update tommorow, though of course any favourable OP or ens output in the meantime is always a welcome boost and maybe a pointer.

[THE EYE IN THE SKY]

Delighted to see the Oslo SLP mean increase.


http://cdn.nwstatic....6/prmslOslo.png

Whilst some of the ensembles do take us on a quick route to cold E,lys the underlying trend is for pressure to increase over Scandi. I think im right in saying that this is an increase of 15mb compared to a few days ago.

When you have a 50/50 forecast from the Met O its this rise in the SLP mean that you want to see. Using the SLP mean for Iceland/Scandi proved a valuable tool for me during Dec 2009/10.

[Jayces]

There was a post recently (From Nick I think) about someone in the States (NOA?) wanting to send out an aircraft to get atmospheric pressure readings as they weren't convinced with what the models were showing.

I also think somewhere along the line I read about how different data is fed into the model runs at the start so is it possible they have done the plane thing and fed that data into the GFS 06 run which is why the output is now so different?

It does seem like a radical change from 6 hours ago and if it's going to kep doing that then FI would seem to be 4 days away on Mon / Tue at the moment which sounds crazy.

[feb1991blizzard]

Good to see pressure dropping off in Europe on the GEFS as well, not massively but a trend, indicating the AH could be staying out of harms way and hopefully ultimately troughing digging south.

[Radiating Dendrite]

So what do we want to see on the 12z?

The most crucial time period is post +96, out to around +160.

It was this period which saw the greatest difference between the 00z and 06z.

On the 00z run the low that dropped off the PV still remaining around Greenland deepened and travelled in a NE direction. As can be seen on the image below, this is not good for our cold chances in the medium term.



We need to see the 12z pick up the development that the 6z had. The 6z did not deepen the low as much as the 00z did and had it moving in a SE direction, over the British Isles and not to the north of us. This lead to a pressure rise to the west of the low and allowed winds from the N/NE to develop over the UK as it cleared away, undercutting high pressure to the NE. This can be seen on the image below:



We therefore need to see this development continue on the 12z if we are to see colder weather in the next 7 days.

Edited by Radiating Dendrite, 19 January 2012 - 14:15 .

[Timmytour]

The way things are going, I wouldn't be surprised to find out that GFS modelled sunday at T384 a whole lot closer than it did in a lot of runs closer to the day!

[phil n.warks.]

The 00z and 06z operationals still show quite Zonal conditions in the early to mid term.
A slight tilt to the North west at times with some incursions of PM air but any wintry stuff seems destined for higher ground further north at the moment.

The 3 main runs show this well at T120(114 fro GFS06z)
http://www.wetterzen...s/Rtavn1141.png
http://www.wetterzen...cs/Rukm1201.gif
http://www.wetterzen...cs/Recm1201.gif

Still a colder outlook shown on both Ens graphs though


The GFS graph is now showing a good clustering of cold members beyond day 6-just as the OP run goes milder.
Certainly details on which way this will go are still to be resolved beyond around T120hrs.

[stewfox]

nick sussex, on 19 January 2012 - 13:30 , said:

Who needs model output, just come in here and see how many pages the thread has extended to, I left to go out at page 8 and came back to see its upto page 13!

There is of course an amazing correlation between models showing colder solutions , particular ones that take you by surprise and number of pages posted within a certain time frame.

I'll come back after the 18z and expect 13 new pages, then i know its good before I start reading. if its 5 pages it will be bad.

[legritter]

looking at all of todays output so far i think that low pressure will move s/e across the uk at about 120/144 hrs from now ,. tonights 192 hrs ecm i am HOPING will be the start of the change , its also worth using the gfs 144hrs / 192hrs for trend setting ,been on a GFS HUNT IN NORTHERN HEMISPHERE ,and its been pretty good last couple of days predicting local ised weather events .i am sure that all professional met office personal have some very good model scenarios at the moment but are sworn to secrecy ,im going to give these postage stamp things a go soon , best of luck all ,

[Osbourne One-Nil]

New thread available - if anyone's interested.