winter model output Winter Model Output Discussion -12Z 07/02/13 onwards

[Coast]

Please continue the fascinating current winter model output discussion here.

Please keep you posts relevant to the topic title, polite and respectful to all other posters and try to include some data or charts to help people understand your point or analysis.

Roll on the 12z runs!

[MR EXTREMES]

two views hardly warrants a measured view of them Ian, how about you spend 12 months checking them every day as I did then give your views

anyway below is the link to the pdf I promised part 1

http://forum.netweat...11#entry2590411

id also like to add to this its clear to see the anomly charts have been very good tool and with have been so close to a really dominant cold winter its been by far a better winter than 2011 2012 and we have seen continued knife edge stuff which goes in favour of the anomly charts just because it didnt get into the freezer everytime its certainly been accurate of developing situations with our weather.

its never been a above average winter and it certinly is not heading towards this even through out the rest of this month and indications are that alantic blow torch tm air is still not in the mix.

if alantic does dominate then id expect a cool cold west nw northerly flow.

as all models suggest to at the moment but i expect these to change over the next few days possibly a continued blocked a cold theme.

Edited February 7, 2013 by model rollercoaster

[Severe Siberian icy blast]

I think we are now seeing the evidence in the models , showing what the anomaly charts have been showing recently ,( and by that I mean what they have actually been reading ) yes the anomaly charts are showing heights over Greenland to increase over the next 14 days , and I think the models are beginning to get a grip and feel we will see this now move forward and approach a more reliable time frame, but big hints from gfs now of heights building toward Greenland , with a trough south/southeast of uk , a southerly tracking jet , (more or less non existent )

Also notice the vortex removing itself from Greenland and pushing over the pole , with more energy keeping north of Greenland toward the pole and then down into Siberia also

Also I strongly advise ones to take A look at the 500 anomaly chart provided by John h earlier with his excellent summary of what we can expect the upper air flow to look like during this period , notice the areas east of Iceland , John eluded to in his post and the potential for disturbances (short waves ) to develop in these areas .

So all in all I think we can agree that we can expect to see height rises toward Greenland of some sorts .

Edited February 7, 2013 by Severe Siberian icy blast

[Tim Bland]

GFS (06Z) Ensembles Shows that the OP was a colder solution for the north and a milder solution for the south with the mean for London below average throughout. Could mean that any slider lows could be further south?

You can see from the ensembles that the Operational uppers on Sunday are at the mild side of the ensembles. the mean for London is -5C when the percipitation spikes. I expect a southward shift on the 12Z

Edited February 7, 2013 by Tim Bland

[Interitus]

The weather looks like exploding into life during saturday night and sunday with potentially large snowfalls across the uk and colder air being sucked into the lows circulation from the east, it's like a cold bomb and it's big and it could bring the heaviest most disruptive and prolonged snowfalls of this winter so far

There are some similarities between this system and December 8th 1990 (locally for the UK not the wider North Atlantic/Europe) which gave a foot of snow widely across the Midlands after starting as rain -

Temperatures may have been a touch colder then though

[bobbydog]

GFS (06Z) Ensembles Shows that the OP was a colder solution for the north and a milder solution for the south with the mean for London below average throughout. Could mean that any slider lows could be further south?

probably, the Meto warnings suggest they are going with an ECM type scenario. the 06z GFS wouldn't warrant such a widespread warning

[Gael_Force]

Snowking wrote this in last thread -

Well it would be very interesting for you to point me in the direction of an NMM output that current stretches as far as Sunday at the moment, as I have been unable to locate such an output?

There is WRF NMM output available up to +120 hours but I've no idea about the accuracy.

http://www.meteocenter.eu/

[MR EXTREMES]

sleepy sun is a sign of things to come its certainly getting drowsey and its certainly been intresting model watching i really think the continued theme of sliders could well spring a fair few suprises im still on the fence and awaiting the outcome of the next couple of days model outputs could be some exciting runs as we are or the boundry of a possible below average feb.

[Backtrack]

Snowking wrote this in last thread -

Well it would be very interesting for you to point me in the direction of an NMM output that current stretches as far as Sunday at the moment, as I have been unable to locate such an output?

There is WRF NMM output available up to +120 hours but I've no idea about the accuracy.

http://www.meteocenter.eu/

Considering the NMM is ran in house at Net Weather, I fail to see how another site would have an extended NMM model that Net Weather themselves don't run?

[weather eater]

It’s interesting that the 06z run ends up similar to last night’s 18z obviously a mighty long way to go and it’s a shame that this evolution has come from the two poorest GFS runs in terms of verification, nevertheless they are not the first two GFS runs to trend that way in the last two or three days.

[Paul]

Considering the NMM is ran in house at Net Weather, I fail to see how another site would have an extended NMM model that Net Weather themselves don't run?

Because there are various versions of the NMM, ours is a high res version which we run, generally extended versions will be at a lower res or different physics etc.

[Coast]

Considering the NMM is ran in house at Net Weather, I fail to see how another site would have an extended NMM model that Net Weather themselves don't run?

Ermmmmm:

The "Nonhydrostatic Mesoscale Model" or NMM is designed for forecasting operations. Versions of the NMM are run at various National Weather Service offices, colleges, and universities in the United States over relatively small regions, usually with the higher 4 km grid spacing.

http://en.wikipedia.org/wiki/Weather_Research_and_Forecasting_model

[weather eater]

Considering the NMM is ran in house at Net Weather, I fail to see how another site would have an extended NMM model that Net Weather themselves don't run?

No idea, but it would depend on whether it’s a piece of bespoke software for NW only or an off the shelf product available to anyone

Seen coasts post, the latter then.

Edited February 7, 2013 by weather eater

[Nick F]

Quite a spread in the ens with the T850s come Sunday-Monday for London, showing the uncertainty over the position of the developing low across southern Britain.

As we saw on the 06z, GFS has the low centred over E Anglia at 00z Monday (11th), with the -5C 850mb isotherm over Sern Scotland. 00z ECM on the other hand, has the low centred over the English Channel with the -5C line along/near M4 corridor with a snow signal as far south as the south coast.

[Paul]

No idea, but it would depend on whether it’s a piece of bespoke software for NW only or an off the shelf product available to anyone

Seen coasts post, the latter then.

It's not really either, as there are many different flavours to the NMM in that it can be run at just about any resolution and with a mix of different physics options, ours is currently 8km with physics tailored to the UK, so other versions are likely to be quite different.

[mulzy]

GME indicating a predominantly rain event on Sunday.

[shaky]

GME indicating a predominantly rain event on Sunday.

Well the gem did this yesterday aswell and ukmo and ecmwf followed so i fully expect to see the ukmo amd ecmwf to backdown from the 850hpa temps it was showing this morning for satirday and sunday!!a push east!!

[Barry12]

Well the gem did this yesterday aswell and ukmo and ecmwf followed so i fully expect to see the ukmo amd ecmwf to backdown from the 850hpa temps it was showing this morning for satirday and sunday!!a push east!!

Wrong.

The GFS will upgrade them, along with the UKMO/ECM.

Mark my word.

[Summer Sun]

Looking like a backtrack from GFS with rain and sleet quickly following on from the leading edge snow

Edited February 7, 2013 by Gavin.

[MR EXTREMES]

alot futher west at t72

Edited February 7, 2013 by model rollercoaster

[Barry12]

Looking like a backtrack from GFS with rain quickly following on from the leading edge snow

That's Sunday afternoon, sunday night-monday will be an upgrade for snow.

Edited February 7, 2013 by Barry95

[Stu_London]

Wrong.

The GFS will upgrade them, along with the UKMO/ECM.

Mark my word.

Given the the GFS has only the tip of east Anglia with -5C uppers at midnight on Sunday, it's very difficult to see where a snow event will come from on Sunday based on that particular model.

Perhaps some back edge snow but not even sure about that to be honest. Colder uppers wrap around on Monday but I suspect it will just be a raw dry day.

Not suprising really as: -

1) All models have been edging away from a snow scenerio for Sunday in the last couple of days.

2) With snow in the UK, generally anything that can go wrong, will go wrong

[Paul]

Latest from Michael Fish - significant snow possible later this weekend and early next week..

[MR EXTREMES]

Given the the GFS has only the tip of east Anglia with -5C uppers at midnight on Sunday, it's very difficult to see where a snow event will come from on Sunday based on that particular model.

Perhaps some back edge snow but not even sure about that to be honest. Colder uppers wrap around on Monday but I suspect it will just be a raw dry day.

Not suprising really as: -

1) All models have been edging away from a snow scenerio for Sunday in the last couple of days.

2) With snow in the UK, generally anything that can go wrong, will go wrong

but better for midterm.

[Summer Sun]

Later Sunday and into Monday looks wintry for the south

Edited February 7, 2013 by Gavin.