Convective Outlook

[Karen Ann]

Heard a few distant rumbles late this afternoon. All I can say is. Il pleut!!!! Again.

[Neilsouth]

Pouring down again

[West Sussex Kate]

Woke up to thunder at 7am this morning.

Lots of rain today huge amounts of water on the roads.

[Harry]

No thunder or lightning yesterday for me

A LOT of rain though, some if very heavy at times - big puddles/flash flooding in areas around here too.

[Coast]

Here we go then, only those in the extreme East look to be in with any chance today according to ESTOFEX:

Storm Forecast

Valid: Thu 03 Dec 2009 06:00 to Fri 04 Dec 2009 06:00 UTC

Issued: Wed 02 Dec 2009 19:44

Forecaster: GATZEN

A level 1 has been issued for the Aegean mainly for waterspouts.

SYNOPSIS

Rather low geopotential is present over Europe and the polar jet stretches from the western British Isles to the Iberian Peninsula and further across the southern Mediterranean. Rather stable conditions are forecast across most of the continent due to cold and dry low-level air masses.

DISCUSSION

Western Europe

Strong mid-level jet streaks will affect western Europe in the wake of two short-wave troughs propagating south-eastwards, while cold air advection of rather dry low-level air is expected to limit instability sufficiently to suppress deep moist convection over most places. Best potential seems to exist across the Bay of Biscay, where some instability may be present in the range of the trough axis in the morning hours given rather moist low-level air masses and moist-neutral lapse rates, but increasing mid-level warm air advection in the wake of the trough axis will likely lead to stabilization during the day.

TORRO and UKASF have nothing, I tend to go with that (although what's that out to the West of Cornwall later?)

Here's some stuff to help you decide:

Red and yellow and pink and green, orange and purple and blueeeeeeeee......

[Coast]

ESTOFEX going for it again today, but I'm more cautious about the daytime (possibly a remote chance in the evening):

Storm Forecast

Valid: Fri 04 Dec 2009 06:00 to Sat 05 Dec 2009 06:00 UTC

Issued: Thu 03 Dec 2009 18:32

Forecaster: TUSCHY

SYNOPSIS

A huge vortex over Europe gradually decays and features various vortices. Ridging builds in from the west over W-/NW-Europe. CAA over NE-Europe causes rising pressure and stable conditions.

DISCUSSION

.. Extreme SW/W-UK ...

A weakening cold front affects UK during the night hours. Compared to the past events, prefrontal moisture advection is more conditional, so CAPE will be weak at best. Shear increases and any convective element will be able to produce strong to isolated severe wind gusts, but currently forecast conditions don't warrant a TSTM area.

Nobody else offering a forecast so far today, here are some pictures, please join the dots to make a representation of a famous weather forecaster.....

[Jane Louise]

TORRO have issued a warning for tonight.

TORRO CONVECTIVE DISCUSSION 2009/045

A TORRO CONVECTIVE DISCUSSION has been issued at 17:40GMT on Friday 4th December 2009

Valid from/until: 17:40- 12:00GMT on Friday 4th/Saturday 5th December 2009 for the following regions of the United Kingdom & Eire:

S England

Cent & S Wales

Midlands

E Anglia

Channel Islands

THREATS

Wind gusts to up to 55mph; isolated tornadoes; isolated CG lightning.

SYNOPSIS

An upper trough moving in from the west will become negatively tilted overnight as it overspreads a cold front. This will provide strong lift along the front, and could allow convection to develop along and close to the front. Low-level shear may be locally favourable for low-level rotation, bringing the risk of marginally severe wind gusts and isolated tornadoes. Showers and isolated thunderstorms are likely to follow the front, especially close to the west and south coasts. Marginally severe winds will be the main threats from these, although isolated tornadoes cannot be ruled out.

Forecaster: RPK.

http://www.torro.org.uk/site/forecast.php

[Snowyowl9]

Seen 2 flashes of quite bright lightning in the last hour,caught me by surprise as there was no thunder and only low cloud with a light shower which just passed,and the 2nd flash could see where it came from in the west,no high cloud and the stars were seen.

[TonyH]

One loud crack of thunder at 1730 just as I was setting off home from Aberystwyth, the radar shows this cell crossing the coast just north of Aber, although the sferics were not picked up.

[Coast]

The extreme South Coast coming on for a level 1 from ESTOFEX this morning:

Storm Forecast

Valid: Mon 07 Dec 2009 06:00 to Tue 08 Dec 2009 06:00 UTC

Issued: Mon 07 Dec 2009 04:47

Forecaster: GATZEN

A level 1 was issued to the south of the British Isles mainly for severe wind gusts.

SYNOPSIS

A broad delta flow is present across Europe, blocking the westerly jet to the west. On Monday, an intense short-wave trough travelling around the main north-eastern Atlantic long-wave trough cuts off over the Benelux countries and France. In the range of the trough axis, a convectively mixed air mass will spread across western Europe. To the south, a tongue of moist and warm air advects into south-western Europe, but weak QG forcing and rather stable low-levels will likely suppress deep moist convection. Further east, northerly winds and cold air advection are expected over the east Mediterranean. Stable conditions are likely in the range of weak winds over most of Europe.

DISCUSSION

British Isles, northern France, Benelux

Ahead of the approaching trough axis, a tongue of rather moist maritime air mass spreads into France, the British Isles and the Benelux countries. As the trough cuts off over France, a cold front will spread rapidly south-eastward into France. Along the front, a narrow convective line has developed west of Ireland that is expected to spread south-eastward today. Along The Channel and the surroundings, this line may be still active given some low-level convergence and strong QG forcing in the range of a jet streak curving around the cut-off trough. As low-level vertical wind shear is strong (10-15 m/s in the lowest kilometre) and low-level winds will reach more than 25 m/s at the 850 hPa level, isolated severe wind gusts are not ruled out, especially when bowing segments may form along the leading gust front. Limiting factor is rather weak instability and weak low-level buoyancy that also leads to a quite low chance of tornadoes. Further south, low-level convergence and QG forcing will be quite weak as well, and deep moist convection is not expected along the cold front.

In the wake of the cold front, a convectively mixed air mass will spread across the British Isles and France. However, latest models indicate that the low levels will be quite dry, and deep moist convection seems to be not very likely. However, some showers and isolated thunderstorms are not completely ruled out.

TORRO and UKASF not picking up on this yet and the charts say:

Well, I'll be keeping an eye on the radar later!

[A.J]

some very heavy rain at the moment, associated with a showery band crossing west to east, nothing electrical, but worth mentioning due to the intensity, an absolute downpour here!

[Coast]

Well with all the excitement over the potential for snow, I forgot to look a the convective aspects of todays weather!

ESTOFEX show action in the Channel:

Storm Forecast

Valid: Fri 18 Dec 2009 06:00 to Sat 19 Dec 2009 06:00 UTC

Issued: Thu 17 Dec 2009 11:14

Forecaster: TUSCHY

SYNOPSIS

An active branch of the disturbed polar vortex has established over most parts of Europe. A strong arctic front along its southern edge pushes southwards and affects the Mediterranean during the forecast. North of this front, the main convective focus is bound to isolated, electrified convection over the North Sea and the English Channel. However for onshore regions, very scarce moisture content (locally less than 1-2 g/kg 500m mean-layer mixed) precludes deep convection. There will be one exception, as thunderstorm probabilities over the north-central Mediterranean and central Italy increase again during the night, as another disturbance approaches from the west. For the rest, thunderstorms occur along and south of the arctic front.

Charts say:

and later

Thundersnow at Manston tonight then?????

[Jane Louise]

Thanks Coast! Good luck with the thunder and Snow!! Awww, wish it was me :-( lol

[Coast]

Still worth keeping an eye on the convective possibilities at the moment. ESTOFEX have the whole of the UK in a watch area today:

Storm Forecast

Valid: Mon 21 Dec 2009 06:00 to Tue 22 Dec 2009 06:00 UTC

Issued: Sun 20 Dec 2009 23:58

Forecaster: DAHL

A level 1 was issued across SW Iberia mainly for excessive rainfall.

SYNOPSIS

A deep layer frontal zone is stretching from the western Atlantic into SW Europe. Cyclogenesis is underway off the Iberian W coast, which will boost the warm advection over SW Europe and the central Mediterranean on Monday. By Tuesday morning, subtropical air will have reached central Europe per latest model guidance. Continental polar/arctic air masses prevail over northern and eastern parts of Europe.

DISCUSSION

... North Sea ... British Isles ...

Comparatively shallow polar-air convection will exist over the North Sea, the eastern Atlantic, and the British Isles. Though most of the clouds will likely not be electrified, the strongest cells may produce a lightning flash or two

UKASF have it too:

Storm Forecast Issued: 2009-12-20 23:24:00

Valid: 2009-12-20 23:00:00 - 2009-12-21 22:59:00

Regions Affected

Northern Ireland, Scotland, northwest Wales, northern England and western Ireland (the whole of the United Kingdom is included in the WATCH)

Synopsis

A complex area of LOW pressure situated over the United Kingdom will dominate the weather during Monday. A cold and unstable Arctic airmass is present over the whole of the British Isles for the entire duration of this forecast period, with the exception of the extreme southeast where some slightly milder air may move in later in the forecast period due to a developing area of LOW pressure there.

Showers will develop, due to the large temperature differences between the upper atmosphere and the sea surface - these mainly affecting those areas exposed to the gusty northwesterly winds (thus northern and western areas). The showers will be frequent, forming into bands (or troughs) at times, and providing significant snowfall in places due to the cold airmass. Electrical activity seems possible, and hence thundersnow is a strong possibility.

There is a chance for a weak funnel or waterspout to develop. During the evening a warm front approaches the far southeast, introducing some slightly milder air. There is a good deal of uncertainty between the models even at this short timeframe as to the exact path of the warm front. Nevertheless, showers will continue to affect western and northern coastal areas well into the night, though decreasing significantly in coverage.

Interesting times for weather watchers!

[Coast]

Thundersnow reported yesterday so a couple of site on the money there!

ESTOFEX forecasting the extreme NW of Ireland and Scotland today:

Storm Forecast

Valid: Tue 22 Dec 2009 06:00 to Wed 23 Dec 2009 06:00 UTC

Issued: Tue 22 Dec 2009 06:46

Forecaster: VAN DER VELDE

A level 1 was issued for Corsica, NW Italy and Slovenia/Croatia for a combined chance of convective gusts, excessive precipitation and tornadoes.

A level 1 was issued for southern Spain mainly for a chance of convective wind gusts and tornadoes.

SYNOPSIS

A large depression with its main center over the western North Sea <976 hPa is filled with a cold unstable airmass. Its warm sector moves over France, Benelux, Germany and Denmark with the potential of causing freezing rain.

Another low and upper shortwave trough moves over Spain into the northern Mediterranean.

Bit of an outsider I think as no support from the other websites and with charts looking like this:

I guess most people's interest will be elsewhere today!

[Coast]

Wow!!! Crazy weather here in Sussex. Left work at 6.10 pm in -2 DgC, 4 miles South along the A23 it was + 4 Dgc and out in The Channel, somewhere off Worthing LIGHTNING!!!!!!!

6 flashes of what looked like IC out to sea between 6.15 & 6.45 as it rattled along, what a ruddy funny thing The English Channel is and totally unexpected today!!

[Lightningboy]

Just in the car on my way back from bowls, and saw 2 flashes of lightning out too sea was quite suprised

[Coast]

OK, so interesting convective times at the moment. What have ESTOFEX got for us today?

Storm Forecast

Valid: Wed 23 Dec 2009 06:00 to Thu 24 Dec 2009 06:00 UTC

Issued: Wed 23 Dec 2009 00:52

Forecaster: PUCIK

A level 2 was issued for SW Iberia mainly for severe wind gusts, tornadoes and excessive precipitation.

A level 1 was issued for the area surrounding the level 2 mainly for severe wind gusts, tornadoes and to the lesser extent for excessive precipitation.

SYNOPSIS

A deep trough, filled with very cold airmass is forecast over Western Europe with significant mid and upper level flow surrounding it with windspeeds locally over 40 m/s at 500 hPa level. Several impulses are forecast to rotate around the trough in strong westerly to southwesterly flow. To the east, a ridge will stretch from Southeastern Mediterranean to Russia.

At the surface, a complex pattern of low pressure systems will cover most of Western / Southwestern and Central Europe. Main frontal zone will lie across Iberia, then curving northeastwards from Northern Italy to Central Europe and a warm front will cross Belarus by the end of forecast period. A high is expected to stretch across continental Russia

.

TORRO and UKASF not reporting anything so here's the charts:

South Cornwall and Devon today showing possibilities, but maybe I'll get lucky again later on?

[Harry]

Just in the car on my way back from bowls, and saw 2 flashes of lightning out too sea was quite suprised

I could have sworn I saw lightning last night too towards the SSE!

If so, not been a bad year for storms/lightning at all!! :lol:

[Coast]

I could have sworn I saw lightning last night too towards the SSE!

Right direction Harry, but a long way off as I saw it out over the sea. Could be bright enough I guess

Bit sporadic this year, but my enduring memory will be sharing a seafront shelter with a load of drunk 16/17 years olds, trying to take photos with them falling around and jumping about every time it thundered!

[Karen Ann]

I saw a massive flash of lightening here at about 10.30pm last. Just the one but by heck did it light up the whole sky.

[Karen Ann]

Hail, thunder and lightening here. Bizzare!

[butler_son]

Hail, thunder and lightening here. Bizzare!

Just had the same up here - I just walked back from the supermarket in it all. Nature hates me...

[keithm]

Hail, thunder and lightening here. Bizzare!

here too.

[Coast]

South Cornwall and Devon today showing possibilities, but maybe I'll get lucky again later on?

OK, so it was a bit further East and a bit later on, but the charts seem to have got it right today then!