Model Output Discussion - 5th December - 11th December

[A.J]

A quick question for the learned, FAX & GFS show an old occluded front and trough associated with tuesdays system which runs west to east across the country at around T72..What type of occlusion would this be? ie CF running up over the back of a warm front, or a classic wintry CF undercut type occlusion?...I'm presuming it's the latter as the post frontal air mass is cooler than pre-frontal (although seemingly not by much, if I'm reading the run correctly)....Cheers

[NickR]

ECM out... and it just disappears entirely! From 72 to 96 hrs it just goes... weird evolution. Thoughts?

[Beasterly]

Where did the storm go on the ECM?

http://images.meteociel.fr/im/5425/ECM1-96_eqk0.GIF

[SMU]

yes no storm on the ecm- it splits the system into 2 small shortwaves

interesting that the models are beginning to fracture the jet around day 9 & 10

s

Edited December 11, 2011 by Steve Murr

[January Snowstorm]

Has the ECM been on the brandy

The differnce between it and all other models is astonishing

[Harps]

Second storm not even developing on the ECMWF..odd

[ukpaul]

yes no storm on the ecm- it splits the system into 2 small shortwaves

s

I think two of the GFS ensembles did something similar.

[wimblettben]

ECM out... and it just disappears entirely! From 72 to 96 hrs it just goes... weird evolution. Thoughts?

Well for one it looks like one of the models are allready taking away the storm unless it is a massive outlier!

I would wait and see if other models dramatically downgrade it before we can say that it will turn out to be nothing of note.

[Chris D]

Well, we didn't see that coming!

http://www.wetterzen...ics/Recm962.gif

But you can clearly see the strong jet. Just doesn't develop it at all. The ECM has gone off on one me thinks...

Edited December 11, 2011 by chris93

[Harsh Climate]

Where did the storm go on the ECM?

http://images.meteoc...CM1-96_eqk0.GIF

Bet it's an outliar! Certainly in regards to that storm.

I just can't see the gfs backing away from it within a 120 hour time frame.

Edited December 11, 2011 by Harsh Climate

[Optimus Prime]

Lmao either something is technically wrong with the ECM model or the people jumping on the bandwagon far too early have just had wagon wheels thrown in their face.

[nick sussex]

Well the ECM comes as a relief and even at 120hrs low pressure still looks weaker.

On a different note the UKMO at 144hrs looks rather interesting in terms of where the pattern might go, I wouldn't be too surprised to see some more potential shown on the ECM.

Anyway lets hope we continue to get downgrades with this low.

[jpwild]

If that latest model does come off, what does it mean regarding chances of cold and snow

[Harsh Climate]

If that latest model does come off, what does it mean regarding chances of cold and snow

It means that the gulf stream is dying and were about to be plunged into the next ice age!

Edited December 11, 2011 by Harsh Climate

[A Winter's Tale]

If that latest model does come off, what does it mean regarding chances of cold and snow

Don't know.

But what the models are showing is a cold snap for next weekend under a Northerly/North Westerly. This should bring snow showers to much of Scotland, NI, NW England, N Wales and parts of W England and the Midlands.

[OldMetMan]

Here is a sequence of forecast charts from the NOGAPS model which shows an interesting take on the predicted Friday storm.

NOGAPS depicts it as a much faster moving system and takes it eastwards rather than NE. Note the extreme gradients on the southern side, plus the addition of a secondary low to the west of the main centre that effectively prolongs the period of maximum pressure gradient.

If this scenario plays out, then the south of the UK would be worst hit.

I know that NOGAPS tends to be dismissed here as not much of a model, yet I have seen it perform pretty well sometimes in the 5+ days timeframe. I just hope on this occasion it lives up to its unreliable reputation, for all our sakes!

[Optimus Prime]

I just can't see the gfs backing away from it within a 120 hour time frame.

It's not about whether the GFS is going to 'back away' or not it's about whether the hype over Fridays storm is actually going to come off. As a few of us mentioned yesterday, storms like these are notoriously difficult to forecast at range and most of the time they never actually happen.

It was hyped beyond reasoning this time. It may still happen but the odds have now been slashed below <25% after the ECM puts some reasoning into the matter.

[Harsh Climate]

It's not about whether the GFS is going to 'back away' or not it's about whether the hype over Fridays storm is actually going to come off. As a few of us mentioned yesterday, storms like these are notoriously difficult to forecast at range and most of the time they never actually happen.

It was hyped beyond reasoning this time. It may still happen but the odds have now been slashed below <25% after the ECM puts some reasoning into the matter.

lol, we don't know that until we see where this ECM run sits in it's esembles. It could be a complete outliar for all we know.

[wimblettben]

It's not about whether the GFS is going to 'back away' or not it's about whether the hype over Fridays storm is actually going to come off. As a few of us mentioned yesterday, storms like these are notoriously difficult to forecast at range and most of the time they never actually happen.

It was hyped beyond reasoning this time. It may still happen but the odds have now been slashed below <25% after the ECM puts some reasoning into the matter.

It was the consistancy though of it being shown over so many runs and with cross model agreement that got me worried as it never does that normally.

[jonnybradley]

Do the ECM ensembles update at 12z? Anybody got a link for the ECM ensembles, would be intresting to see what they think

[ukpaul]

It was hyped beyond reasoning this time.

It's on all of the models, it still is on all apart from one (post noted for potential future hubristic response anyway).

[nick sussex]

Do the ECM ensembles update at 12z? Anybody got a link for the ECM ensembles, would be intresting to see what they think

This is the link for the ECM ensemble maps upto 168hrs:

http://www.ecmwf.int...t!2009112700!!/

Generally though at this timeframe it's better to follow the operational runs because of their higher resolution.

That should update around 8.30pm .

Edited December 11, 2011 by nick sussex

[VillagePlank]

We'll know, by the 6z tomorrow how good GFS is behaving. It all relies on a ridge extending and forming a LP over cooling seas that eventually gets tied up to the jet-stream. Overview, here Certainly possible that ECM is throwing a wobbly as the evolution looks OK, and reasonable at the moment from GFS.

One should read yellow warnings as "Yes, we've seen it, we're looking into it, perhaps more to follow"

Edited December 11, 2011 by Boar Wrinklestorm

[kold weather]

ECM goes from having a 944mbs low at 120hrs to a 972mbs low...

Thats a huge difference from the previous runs and smacks of a outlier to me...of course it may well have a new trend but we'll have to wait and see...but to have a 30mbs difference from one run to another run doesn't inspire ANY confidence in the ECM solution tonight.

[jonnybradley]

This is the link for the ECM ensemble maps upto 168hrs:

http://www.ecmwf.int...t!2009112700!!/

Generally though at this timeframe it's better to follow the operational runs because of their higher resolution.

That should update around 8.30pm .

Thanks Nick, will be checking those out later. Of course if you get the chance your self... have found your analysis of these very helpful over the past couple of weeks