General Model Output Discussion

[danm]

LOL- Well so far this morning the GFS has handed the biggest can of xmas whoop ass ever to the UKMO & every other model.....

Patiently awaiting the end of the week....

Do you think the fact that the GFS is sticking to its guns in the short term means that it may be correct in its modelling of the low pushing further north? Shouldnt the fact that all the other models are going against the GFS mean that its being far too progressive with how far north it is projecting the low to go?

[SMU]

Do you think the fact that the GFS is sticking to its guns in the short term means that it may be correct in its modelling of the low pushing further north? Shouldnt the fact that all the other models are going against the GFS mean that its being far too progressive with how far north it is projecting the low to go?

Have a look at the UKMO 00z.............

Overall though whatever people say about the overnight runs is barring the short term risk - that actually has only elimated the snow for the central belt remains VERY GOOD- especially for the East & North east & poss the SE

Signs are deleloping more & more that pressure will develop & ridge NW out of Iberia as well as the undercut from thw shortwave moving the East-

thats where the proper cold comes from & thats where we should concentrate on,.....

S

Edited December 28, 2009 by Steve Murr

[danm]

Have a look at the UKMO 00z.............

S

If im looking at the most recent update, it seems to show the low getting up to north wales by t96, then rapidly moving south east, drawing in the colder air. Am i right?

EDIT: I was looking at the 00z link thats on this website, i think that might be yesterdays 00z. Not sure if im looking at the correct charts

Edited December 28, 2009 by danm

[Duane S.]

Oh my word. Looking like maybe the GFS was right all along??

Edited December 28, 2009 by s4lancia

[KTtom]

Well, the Fax's don't take the front further north than the M4, GFS and UK much further north, one consolation is BBC seem to be going with the Fax's and have snow covering Wales/Central England for nearly 48 hrs!

Long term the GFS is much better with no breakdown though the entire run.

[KTtom]

Just to add to that excellant post above , ECM is going with the Fax's, I think i'll go with them and the man from the TV against the GFS!

All models do look better mid to long term compared to yesterday.

[Duane S.]

Just to add to that excellant post above , ECM is going with the Fax's, I think i'll go with them and the man from the TV against the GFS!

All models do look better mid to long term compared to yesterday.

I agree that the GFS has perked up mid-long term. The ECM carries on driving the LP on past the Meridian without so much as a second thought.

[03jtrickey]

http://www.wetterzentrale.de/pics/Recm721.gif

EC sticking to its guns. GFS does the same.

Such a big disagreement in such a short timeframe. Very worrying and confusing.

[Iceberg]

Both GFS and METO take the peak snow area upto Carlisle now. (NW England could get lots and lots of lots of snow from this come Tuesday night/wed morning) accumulated precip shows anything upto 40-50cm.

However it does tend to turn the snow to rain below say Manchester except for very high ground.

An absolute forecasting nightmare as determine where the band will stall. The temp gradient on the wrap around is pretty intense as well 0 to -5 in about 60-80 miles. But the rain back to snow looks like taking palce on new year eve night.

Beyond that and the easterly is definately on with much better model agreement over the northern hemisphere than yesterdays 0Z suite.

[Iceberg]

Just to add a quick look at the ensembles shows that the ops from GFS was the furthest north the heavy precip went, the chances are that it will be 50 miles or so further south.

ECM ends up with a potent northerly.....

[Frosty.]

The most exciting aspect of the 00z runs is the duration of the cold spell is increasing, the gfs and ecm keep it very cold throughout with no sign of milder air to be found, of course this could change easily but it's a good sign that the cold could become entrenched again and there is the potential for this upcoming cold spell to be more severe than the last one. The GFS & ECM 00z both go for a more N'ly flow in their respective extended range thanks to hp retrogression, even the GEM attemps it too, hopefully this trend will continue. As for who gets most snow this week, parts of wales and the midlands currently look like becoming snowy by tomorrow and this risk could extend further north before pulling southeast after midweek, snow flurries also look like affecting coastal areas in the north & east and overnight frosts will be severe, in fact, the frosts will probably stay in the ground with no thawing.

[West is Best]

Just to add a quick look at the ensembles shows that the ops from GFS was the furthest north the heavy precip went, the chances are that it will be 50 miles or so further south.

Or 500 miles further south?! That's the difference between the GFS and ECM. Incredible short range variation.

However, the GFS operational is once again the furthest north. There is massive medium and long term scatter on the GFS, with the operational's cold scenario having very little support.

Fantastic GEM overnight which actually has the easterly winning the battle so that the centre of the low never makes it across our shores. There's a hint of that with GFS, and the FAX charts certainly prog a stalling front. This seems to me to be the likeliest scenario: the front will stall, and the easterly will set in with a vengeance. The area just to the north of the front could see a severe snow event.

[Duane S.]

I'm not sure how many times this sentence gets posted at times such as these but... the faxes will be interesting later on!

[nick sussex]

Still no agreement this morning with the early track of the low however the gfs has improved slightly in the early timeframe, the ukmo now wants to be the Xmas Scrooge!

In terms of the early track of the low and general orientation the models line up in two camps, the ecm, gem and two cannon fodder models the gme and no gaps keep the low further south, the gfs and ukmo have the whole system further north.

The ukmo fax charts have been modified at T 84hrs which is very unusual and these obviously take the ecm into account here, further on general model agreement for a good chance of the next low undercutting the block.

Edited December 28, 2009 by nick sussex

[Snowaddict]

Overnight ECMWF @ T+48... Keeping the low to the south...

T+48

[MKN]

The best thing will be to see what the metoffice do with there warnings today, because if theres disagreement between the models they usually no which one to go with.

[azores92]

remarkable scenario this morning. the gfs has not let up with its northerly prediction, and it now looks as if ukmo is following in its footsteps! looking like a messy week of weather ahead, and tomorrow it is most likely to be transient snowfall for central parts with rain eitherside of the main event i would have thought. later on in the week things look more promising/interesting though.

[nick sussex]

The best thing will be to see what the metoffice do with there warnings today, because if theres disagreement between the models they usually no which one to go with.

The met office have a new 48 hr ensemble system called the MOGREPS so i'm sure they will be seeing what it says, but one thing is evident from their fax charts is that they're dumping their own raw output quite early and modifying this towards the ecm and it's ensembles.I think this says all we need to know about what they think of their main model at the moment!

This morning people might assume that the gfs 12hrs and 18hrs were onto the right trend but if anything after the initial early disagreement the gfs has caved in to the ecm once again! I really hope people don't jump on the ukmo as proof the gfs was right as thats looking suspect as well,the only model that has been consistent and also the first one to show the next low undercutting the block was the ECM, there is absolutely no argument on this, the gfs is still performing poorly!

Edited December 28, 2009 by nick sussex

[MKN]

For me personally i think my location may end up being the southern most area for any settling snow with the band from here northwards rather than from the m4 northwards, although the bbc at 7am still go for snow m4 northwards which is far different to the gfs. some sort of middleground between the gfs and ecm is what im expecting.

[Archie_Lewis]

Alex deakin on breakfast this morning going for snow north of the M4!

With the snow line reaching north midlands

[TEITS]

Morning everyone.

This morning I viewed the UKMO first and then the GFS so you can imagine my reaction. However after viewing the rest of the model runs/fax charts my glum face changed to a smile.

You may find this rather strange but I actually think the models in some respects are better than last night. The reason I say this is because in the medium term the GFS is backtracking towards the ECM and the chances of an E,ly are increasing. The general trend seems to be an E,ly followed by a N,ly as the PV drops into Scandi.

Back to this LP system and to be honest when you have such disagreement between the GFS/ECM the reality tends to be something inbetween. I feel this will be the case this time and the +84 fax chart suggests this.

[MKN]

Can some1 just clear up, if central areas do get snow tuesday, why do eastern areas seem less likely to get snow? temps etc seem about the same as to the west, and if anything ground temps are colder because the precip and warmer air heads up from the ssw? Just noticed it seems to be the case on the bbc forecasts

[nick sussex]

Alex deakin on breakfast this morning going for snow north of the M4!

With the snow line reaching north midlands

That sounds about right before the low pulls away, in these situations with a fine balancing act between strengthening Greenland high and low coming in from the sw its incredibly difficult to accurately call where snow will fall. We often see resident blocks with attacks from the sw but this set up is even more complicated hence even at this stage there is likely to be further movement in the models.

[bluearmy]

the UKMO at T144 offers enough questions as to where this pattern evolves. the GEFS at longer range are less supportive of extended cold than the 18z were last night. given that they were previously not supportive, that would set the 18z apart from the GEFS trend.

that ECM T48 op still has the low further north than it did yesterday. we were thinking that this occlusion would be difficult to place at 36/48 hours. looking impossible to place its direction of movement, never mind its likely place of situ!!

we are very observant of de bilt temps from the ecm ens. i note from the GEFS this morning that de bilt is at mean temps below zero from the 3rd to the 8th. to the north of london is at mean temps 3c for the same period. we must remember that the temps in holland are only indicative of the general pattern for us (ie cold/average/mild). we are unlikely to see those frigid means on our island climate.

so monday morning, when most expecteds resolution brings more confusion. just as it should be!!

[tinybill]

morning all i can see the whole of the UK coming to a halt by Friday if you if the gfs is right!!!