Atlantic Storms - 12th December 2011 Onwards

[Coast]

OK, I'll start the day with a round up of what the storm websites are saying:

ESTOFEX not really highlighting where I was expecting TBH:

Valid: Mon 12 Dec 2011 06:00 to Tue 13 Dec 2011 06:00 UTC

Issued: Sun 11 Dec 2011 17:19

Forecaster: TUSCHY

SYNOPSIS and DISCUSSION

Before another major branch of the polar vortex becomes established over far NW Europe, numerous weaker upper troughs/waves affect major parts of Europe.

The most active one will be a diffuse wave, crossing the central Mediterranean during the forecast from west to east while weakening. At the surface, pressure fall overspreads Italy and the Adritatic Sea with a broad LL depression in progress....again weakening during the night hours as another upper low drops to the south over the central Mediterranean and as CAA over SE-France weakens (a more zonal flow becomes established to the north/over France).

This set-up assists in scattered thunderstorms with heavy rain mainly along the westward facing coasts of Italy, Croatia, (Bosnia and Herzegovina), Montenegro, Albania and Greece. Shear remains too weak for substantial organization of the convection, although 2 more or less conditional severe risks exist: - an isolated waterspout risk along any convergence zone along the coast with enhanced LL CAPE - an augmented training shower/thunderstorm risk with messy alignement of mesoscale convergence zones and up to 15 m/s LL flow (locally aligned parallel to convergence zones). No level 1 was issued for that event due to the conditional nature of coverage and intensity of any DMC.

Isolated thunderstorms are also forecast beneath numerous upper troughs over the N-North Sea/S-Norwegian Sea, far NE Atlantic, parts of Ireland and Scotland. Of note is a potential warm seclusion process with significant core temperature anomalies forecast by globel model data NW of Ireland (00Z onwards). Latest data indicates a successive slower approach to Ireland, so no impact by damaging wind gusts is expected during this forecast period. However the cold front passage has to be monitored for better postfrontal CAPE availability mainly over S/SE-UK. Right now, forecast soundings only indicate shallow convection and there is no reason to go with a lightning area. However, strong to severe wind gusts may mix down even without deeper updrafts with briskly 25 m/s at 850 hPa.

Surprised UKASF haven't put anything up

SkyWarn have a severe thunderstorm watch:

Last Update: 0000UTC Monday 12th December 2011

SKYWARN UK SEVERE THUNDERSTORM WATCH #068

ISSUED: 0000UTC MONDAY 12TH DECEMBER 2011 (GJ/SM/RB)

SKYWARN UK HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR THE FOLLOWING REGIONS:

ALL AREAS UK

IN EFFECT FROM 1800UTC MONDAY 12TH UNTIL 1200UTC THURSDAY 15TH DECEMBER 2011

STRONG JET ADVANCE INSPIRING DEEP LOW CENTRES TO THE NORTH, AN ACTIVE COLD FRONT AND UNSTABLE POST-FRONTAL ENVIRONMENT THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...STRONG GUSTS...FUNNELS/WEAK TORNADOES...HAIL...LOCALISED FLOODING

DISCUSSION:

THERE IS GOOD MODEL CONFIDENCE IN THE GENERATION OF A NUMBER OF SEVERE WEATHER THREATS IN THE FIRST HALF OF THIS WEEK. A STRONG JETSTREAM ADVANCES EAST DEVELOPING A RAPIDLY DEEPENING LOW TO THE WEST, CROSSING SCOTLAND INTO TUESDAY WITH FURTHER CENTRES THROUGH WEDNESDAY INSPIRED BY A BROAD UPPER TROUGH FOLLOWING ON FROM THE INITIAL LOW. THE COLD FRONT TRANSITS LATE MONDAY OVERNIGHT, WITH A PRONOUNCED SHEAR AND INSTABILITY OVERLAP. THE NORTHERN PORTION OF THE FRONT, NORTH OF BIRMINGHAM, SURGES EAST UNDER THE DIVERGENT LEFT EXIT REGION OF THE JET GENERATING LINE CONVECTION WHICH FRAGMENTS OVER NORTHERN ENGLAND. STRONG FOCUSSING OF WINDS WITH PRONOUNCED HELICITY DUE TO WIND VEER COULD SEE ORGANISED DEEP CONVECTION AND A RISK OF STRONG GUSTS AND VORTICES. FURTHER SOUTH, THE STRONG UPPER WIND FLOW MAY WELL KEEP CONVECTION LOW, BUT STILL PROVIDES FOR A RISK OF STRONG DOWNDRAFT GUSTS WITHIN THE FRONTAL ZONE ALREADY GUSTING TO AROUND 60MPH, POSSIBLY HIGHER FOR THE SOUTHEAST. RAINFALL ACCUMULATIONS OF 3OMM CAN BE EXPECTED OVER WESTERN AND SOUTHERN REGIONS, POSSIBLY 50MM OVER HIGH GROUND, EXPOSED AREAS AND REGIONS CLOSE TO THE CHANNEL. FOLLOWING ON FROM THE FRONT THROUGH TUESDAY AND WEDNESDAY, AN UNSTABLE POST-FRONTAL ENVIRONMENT UNDER THE SUSTAINED JET MAINTAINS THE RISK OF STRONGER ISOLATED CONVECTION, ESPECIALLY FOR SOUTHWEST ENGLAND AND SOUTH WALES. ALTHOUGH STORMS WILL BE FAST-MOVING, STRONG GUSTS AND LOCALISED FLOODING COULD OCCUR AS ACTIVITY CONTINUES FOR SUCCESSIVE DAYS. FURTHER UPDATES AND ALERTS ARE POSSIBLE.

I expect TORRO will issue a forecast by mid morning.

[Terminal Moraine]

We now have GFS, ECM and the Met' Office takng the low on a more southerly track, particularly the GFS which has it going across the southern part of northern England and taking the strongest winds across southern England.

The new kid on the block is the small secondary which develops during Wednesday and runs south east, that could also be one to watch.

Obviously still a great deal of uncertainty as to the track and depth of this low and it's going to be Wednesday before there's any clear resolution.

[BleakMidwinter]

Thanks, Coast, for starting the day with a summary of the current model charts - and Terminal Moraine for a verbal summary. Saves me trying to work backwards before I've hit full caffeine!

the MetO Warning is a bit eye-opening, but sensible, I suppose, given the uncertainty of the track this far ahead. Kind of "it's coming, but we're not quite sure of the angle".

Will spend the day finding more boulders to put on top of various outdoor things...

[NO LONGER POSTING]

Hope everybody keeps safe..Looks pretty rough for the southern half of the UK, then all the attention will turn to the North Tuesday.. Northern Ireland and Northern Scotland, as blizzards above I heard about 200m..

I depth discussion has lots more info on tonights events..With a high risk of tornado/hail and thunder events..

[cyclonic happiness]

Very unusual for a low to be stil developing as it crosses the southern UK, it doesn't reach full intesity until it is in the North Sea.

At the rate it's going, it will be tracking futher south still and will probably leave the Midlands within the centre of the low and therefore, without any winds!

I'm a bit jaded this morning

[Coast]

Thanks, Coast, for starting the day with a summary of the current model charts - and Terminal Moraine for a verbal summary. Saves me trying to work backwards before I've hit full caffeine!

No probs, just remember I only see words, pictures, patterns and colours, I'm not one of the clever people on here who can tell you why it may be going to do what it's going to do!!! :lol:

For instance, I haven't looked too far into the rest of the week so far, but this brief overview of London on Friday shows what GFS think is going to happen in the atmosphere. Look at the peak for tonight and then compare it to the peak for Friday and see how it is even bigger then. So far GFS (and most of the other models) have been pretty consistent on this weeks potential:

[geoffw]

Disapointed about friday storm vanishing on the models ... will it appear again?

[cyclonic happiness]

Disapointed about friday storm vanishing on the models ... will it appear again?

It is still on the models?

What makes you think it's vanished?

[Coast]

Disapointed about friday storm vanishing on the models ... will it appear again?

Erm,, not sure what you mean? This one shows it even stronger than tonight, actually this would be a real worry if it came off:

153 km/hr of the East coast around the Humber facing the North sea

[NO LONGER POSTING]

Has anyone check SAT24? Is that mass of cloud in the Atlantic approaching tonight's strom? If it is...To me it looks like it's tracking further south..Or am I being stupid..

[bobbydog]

Erm,, not sure what you mean? This one shows it even stronger than tonight, actually this would be a real worry if it came off:

153 km/hr of the East coast around the Humber facing the North sea

it certainly would, between F10 and F12 for much of the east of the country!

[NO LONGER POSTING]

it certainly would, between F10 and F12 for much of the east of the country!

Not only that..But once again highly populated areas like London..Will have force 10/11!!!!!

[geoffw]

It is still on the models?

What makes you think it's vanished?

would you like to tell me where the 90mph winds for NI are because they were shown on previous models but not now?

[bobbydog]

Has anyone check SAT24? Is that mass of cloud in the Atlantic approaching tonight's strom? If it is...To me it looks like it's tracking further south..Or am I being stupid..

no, its about where it should be at the moment, compare the GFS charts with the satellite pics. the swirling cloud running north west from the top of ireland is the elongated 'centre' of the low. the bigger mass of cloud to the south of that is the rain we're getting later

[Coast]

would you like to tell me where the 90mph winds for NI are because they were shown on previous models but not now?

Long way to go until the specifics are known, but the Friday storm still shows, it's just moving around a bit on the model runs.

Back to today and MetO have yellow warnings out all over the place:

Here's what my local one highlights:

Issued at - 11 Dec 2011, 14:25

Valid from - 12 Dec 2011, 18:00

Valid to - 13 Dec 2011, 23:59

Heavy rain accompanied by strong winds is expected during Monday evening and into the early hours of Tuesday across many parts of southwest England, south and west Wales. Although the main rain area and strongest winds will clear away early on Tuesday, further heavy showers are expected through the day.

The public is advised that the rainfall has the potential to cause localised flooding from rivers and surface water.

http://www.metoffice...t_warnings.html

[Crimson_Sprite]

hmmmm....?????? I have just looked at the 0z GFS this morning and my friday storm of 70mph wind gusts for the majority of the day has vanished to wind gusts of 43mph and down to the upper 30mph range for most of the day. Where has my storm gone? Nottingham is indeed in a weatherless zone. I hate this city. And before everyone jumps down my throat at once and crashes netweather's server, saying the storm is still there (of course it is I know that ) I have found that when my local forecast says winds of 45mph, and I go outside in that, it literally is more like 25 mph gusts not 45 mph gusts. When my forcast says Im going to get gusts like that, I have not even seen a single wheelie bin move, fall over or budge. There were no branches broken or twigs on the ground, or small puppies flying through the air. Last weeks storm that hit Scotland said I would have gusts of winds in the 40mph-50mph range for the majority of the day, and I went outside in that and the trees were just swaying a little bit like in a strong breeze. So i figured that I need to have the GFS say Im gonna get 75mph gusts in order to see some wheelie bin chaos. As far as my forceast goes, i will not be getting a storm on Friday. Just lots of rain and a strong breeze... I reckon I love live in some kind of weatherless pit..

I mean LIVE in some kind of weatherless pit :lol:

Edited December 12, 2011 by Crimson_Sprite

[NickR]

would you like to tell me where the 90mph winds for NI are because they were shown on previous models but not now?

The fact it's not hitting a particular location as much doesn't mean the system has vanished. What a bizarre post.

I get the feeling several people in here don't bother looking at the charts, they just type in their location to the forecast generator and that's that.

Edited December 12, 2011 by NickR

[Crimson_Sprite]

Long way to go until the specifics are known, but the Friday storm still shows, it's just moving around a bit on the model runs.

Back to today and MetO have yellow warnings out all over the place:

Here's what my local one highlights:

http://www.metoffice...t_warnings.html

LOL! Once again Nottingham is out of the warning +sigh+

[Coast]

As far as my forceast goes, i will not be getting a storm on Friday. Just lots of rain and a strong breeze... I reckon I love in some kind of weatherless pit..

As posted above, it's days away yet and we all should have learnt years ago that the models swing backward and forward right up until something happens (or not!) :lol:

Actually I'm rather hoping that some of what the models have been showing doesn't come off, as those possible gusts could be quite a handful.

[NickR]

LOL! Once again Nottingham is out of the warning +sigh+

That's Tuesday's chart.

Friday's covers the whole country.

[Coast]

LOL! Once again Nottingham is out of the warning +sigh+

I think you will get a windy wake up in the night (unless you stay up of course). As for model runs, this latest one for tornado and shear is an 'upgrade' if you like (I'm not a fan of that word TBH)

[NO LONGER POSTING]

In regards to The storm that has vanished Friday??? It is still 4 days away...Lots to play for...

[Crimson_Sprite]

That's Tuesday's chart.

Friday's covers the whole country.

OHHH!!!! My bad....

don't get me wrong folks, I dont want to have total annihilation to the country with some of the forecast winds! my only gripe is that my gust chart seems to be on some kind of happy pills when it forecasts my wind gusts for storms, so I know that I need it to say like 80mph gusts for it to start strewing trash all over the street. But I know in reality, if I had TRUE 50mpg wind gusts, that would be just fine. LOL!! Its just my gust forcast thingy-ma-dingy saying 50 when its more like 25....

I think you will get a windy wake up in the night (unless you stay up of course). As for model runs, this latest one for tornado and shear is an 'upgrade' if you like (I'm not a fan of that word TBH)

lol! that would be ironic.... talk about localised wind!!! Tornado hitting my house.....

here ya go Crimson!!!! all the wind ya want!!!

ok,, too much..... :lol:

[weatherobsuk]

I'll give it until tomorrow myself before worrying about uncertainties (short-term wise.) If this beast still hasn't been nailed down 48 hours BEFORE the event then i'd start to worry.

[gottolovethisweather]

The model projections and charts etc. shown are NOT INFALLIBLE.

Of more concern for some as shown by the MetO warnings is later today and tomorrow.

Climate is in a permanent state of chaos, therefore, making asumptions about future events such as what is likely to happen at t2600 minutes from now is ludicrous. Only the trend can be established and thats for a gale day for some or potential storm day for a lucky/unlucky few.

My intention is not to be a killjoy here but more appropriately to make sure folks get some kind of perspective of weather related matters and the complexities of the models.

Please listen to the more well informed longer term members in here as its precisely those folk that have taught me the ropes by simply learning from what they have to say.

Back to the topic of the thread, every day of this week is worth WATCHING CLOSELY IMHO. Round 1 tonight and tomorrow, Round 2 Wednesday, a brief lull then Round 3 late Thursday into Friday. Rain, Wind, Sleet & Snow, Flooding, Tornadoes being all in the mix.

Entertaining weather for sure.

Cheers

gottolovethisweather

Edited December 12, 2011 by gottolovethisweather