Model Output Discussion 23/11/2012 18Z onwards

[chionomaniac]

Good evening all,

Here is a new thread for the pub run.

Please, please wait on commenting on a run if you are not sure how it is likely to pan out.

We are trying to be a little more flexible this year with the posting on model threads, but still keep relevant.

If any one has any nerves left after the long drawn out wait for that ECM 144 chart then please post away!

[bradymk]

Another very cold set of extended ECM ensembles tonight and they show that the OP is still a bit all over the place after around day 6. Encouraging post by Nick earlier about the upstream pattern and that NWS are with the ensembles tonight rather than the ops. Also, I have heard that the ECM 32 Day was cold throughout the whole run, can anyone confirm this?

Regards,

Matthew

[phil nw.]

The 12z NAEF`s ht.anomls show the Atlantic ridge/Svalbard high link up cemented by T156hrs and keeps the pattern through the rest of the run.

some reassurance that inspite of any operational differences around T96-144hrs it looks likely that a colder north easterly flow will emerge.

GFS/ECM T240hrs ht anomls also confirm this picture.

As TEITS alluded to earlier a deep cold easterly is not yet suggested with the low ht anoml around the UK we are likely to be under the influence of the trough for a while.

We need that to ease a little further south to allow a colder flow to develop but let`s get the change in and then see how the pattern evolves.

[bobbydog]

Good evening all,

Here is a new thread for the pub run.

Please, please wait on commenting on a run if you are not sure how it is likely to pan out.

We are trying to be a little more flexible this year with the posting on model threads, but still keep relevant.

If any one has any nerves left after the long drawn out wait for that ECM 144 chart then please post away!

should be quiet in here for the next hour and a half then......

[Bobby]

The 18z GFS has deepened tomorrows low and thus increased the rainfall totals quite a bit from the 12z run, more in line with what the MetO and BBC (and other models) has been suggesting, Susan Powell on the BBC mentioned 60mm in places, not good on already saturated ground.

12z:

18z:

Strong winds too on the southern flank of the low with 60-70mph gusts along the south coast.

So at last some agreement it seems on this tricky depression.

Edited November 23, 2012 by Barb-

[bluearmy]

i noted nicks comments from noaa re the operationals. however, noaa cpc used the gfs/ecm ops in their blend as they said they showed good continuity with their ens means !! i recall this a bit from previous years chit chats. looking at the consistent naefs anomolys, dont rule out a cold snowless trough (away from high ground and perhaps scotland/the north) followed by another more successful attempt second week dec. i really hope i'm wrong and we can get snowcover next weekend as that gives the chance of at least a couple of weeks of freezing conditions and maybe longer.

[MrSunshine]

should be quiet in here for the next hour and a half then......

Then the wrist slashing will begin!

[crimsonp]

we are on the 18Z aren't we?

[pyrotech]

Okay sorry mods slightly off topic but just to clear things up about meto as mentioned in last forum

The forecasters are well aware of a likely cold spell, they (individual forecasters) have hinted on their blogs

Remember they are guided on what to say by their senior forecaster

There are important issues with rainfall at the moment, not only warning the public, but also trying to prewarn the emergency services, some rivers like the Severn can take days to peak and with extra rainfall, you will have rainfall from catchment areas which can be estimated as takes days, but with local streams and rivers having extra rainfall as well as the catchment areas the situation could become critical, so the emphasis will be quite rightly put on the definite issues not maybes for later next week. Plus starting talking about any possible snow on TV and the public would miss the warnings about the severe weather and be distracted by thoughts of wintry stuff.

I think its very sensible of them to keep the emphasis on whats highest priority and to feed the info about cold as the situation eases and cold starts to move in.

[Cloud 10]

Looking at the 12z mean height comparisons between ECM and GFS, the ECM looks

rather odd with its "boomerang" shape high pressure.

What will the 18z gfs bring i wonder? No doubt some more shortwave drama!

[Cheshire Freeze]

Looking at the 12z mean height comparisons between ECM and GFS, the ECM looks

rather odd with its "boomerang" shape high pressure.

What will the 18z gfs bring i wonder? No doubt some more shortwave drama!

Yeah looks like a high pressure handlebar moustache to finish off Movember.

Edited November 23, 2012 by CreweCold

[weather_it_will]

The 18z GFS has deepened tomorrows low and thus increased the rainfall totals quite a bit from the 12z run, more in line with what the MetO and BBC (and other models) has been suggesting, Susan Powell on the BBC mentioned 60mm in places, not good on already saturated ground.

Not sure where you got your charts from, but GFS 18Z looks dry over the midlands Sunday afternoon, which is same as ITV forecast

http://www.wetterzentrale.de/pics/Rtavn424.png

http://www.wetterzentrale.de/pics/Rtavn484.png

[Ice BIast]

The 18Z looks similar to the UKMO regarding the trough sinking into Europe.

[Bobby]

Not sure where you got your charts from, but GFS 18Z looks dry over the midlands Sunday afternoon, which is same as ITV forecast

http://www.wetterzen...cs/Rtavn424.png

http://www.wetterzen...cs/Rtavn484.png

I posted the rainfall accumulations by Sunday afternoon not the rainfall charts for Sunday afternoon.

More heavy rain arriving into the SW by the end of the day

Edited November 23, 2012 by Barb-

[Jason T]

Funny really,Its as almost the PV feels guilty for leaving us out last year.

[Geordiesnow]

I don't think the forecasters will menturn the S word too much in the coming days as its the wet stuff that will dominate upto Tuesday potentially. In terms of Tuesday forecast, its not all that far away from a chilly bright day with convective showers piling in off the North Sea, we can see into Scotland this is already the case and for some higher ground in Scotland, these are bound to fall as snow.

The GFS however wants Tuesday to be wet and miserable across some parts of Eastern England though but as I say, a small shift eastwards and it will be sunshine and showers instead!

[weather_it_will]

I posted the rainfall accumulations by Sunday afternoon not the rainfall charts for Sunday afternoon.

Ok, Thanks for clarifying.

[EML Network]

If that LP system stalls on Monday as per the 18z then the midlands could see ridiculous amounts of rainfall on Monday and Tuesday !..what with the rainfall for the South West, the Rainfall in Scotland, 1/2 of the country could be under water by the middle of next week (slightly over the top, but my god that's a LOT of rainfall for parts of the Mid North of England on tonight's run !!

[LomondSnowstorm]

Apologies for the lack of charts because I'm on my phone, but the pub run looks somewhat less likely to repeat the antics of the 12Z.

[snowking]

The 18Z looks similar to the UKMO regarding the trough sinking into Europe.

Yep, its a case of spot the difference at +90 (+96 on UKMO)

SK

[bobbydog]

Okay sorry mods slightly off topic but just to clear things up about meto as mentioned in last forum

The forecasters are well aware of a likely cold spell, they (individual forecasters) have hinted on their blogs

Remember they are guided on what to say by their senior forecaster

There are important issues with rainfall at the moment, not only warning the public, but also trying to prewarn the emergency services, some rivers like the Severn can take days to peak and with extra rainfall, you will have rainfall from catchment areas which can be estimated as takes days, but with local streams and rivers having extra rainfall as well as the catchment areas the situation could become critical, so the emphasis will be quite rightly put on the definite issues not maybes for later next week. Plus starting talking about any possible snow on TV and the public would miss the warnings about the severe weather and be distracted by thoughts of wintry stuff.

I think its very sensible of them to keep the emphasis on whats highest priority and to feed the info about cold as the situation eases and cold starts to move in.

not too off topic really, funnily enough, i was just about to comment that the GFS increases the wind speeds for the LP system coming in on saturday night. we've got some dodgy weather to get through before we get to the good stuff....

[cold snap]

So Far so good that low(spoiler ) not showing up

Spoke to soon it's firing up at 120 , lets hope it gets pushed back

Edited November 23, 2012 by cold snap

[If Wishes made Weather]

Already quite different modeling from the 18z compared to the 12z. In particular at T108 the shortwave to the south of Greenland is far less wound up, and there is a far slacker set of pressure gradients shown over northern Canada/Arctic area.

[NickR]

My eye has been taken off the potential cold and onto the rain. This really is a serious situation - a disastrous amount over the weekend for parts of the S (SW esp), added to what they already have, and then 36-48 hrs of heavy rain for NMids (18z) or N Eng (12z). Worrying.

[ukpaul]

Pushing 15cm of rain by next Wednesday for a swathe of the north midlands on this run.