Uk Convective General Discussion & Forecasts, 5th July 2012>

[Gorky]

more thunder here, albeit more distant. gorky are you in scarboro? (mobile netweather doesnt show locations)

Yeah.. Not gonna be walking to work today. I'll take my chances with traffic chaos instead I think

[peterf]

thunder and lightning here and minor flooding already.not looking good for the rest of the day.

[Cheese Rice]

Thunder here!

Didn't see any lightning although I wasn't looking, sky is milky white, probably won't show up as much.

[Bellingen Weather]

Strikes detected so far today, the action seems to be from a line north of the Humber straight across.

Very havy ppn moving westwards across N England.

Looks like some rotation on the radar to the NE of East Anglia?

Been watching this with interest from Australia - looks like one of the systems we get here in summer and autumn. Agree about the rotation off the coast - when we get broader systems moving in we tend to see smaller vortices running with the main flow. Looks like that is what is responsible for that larger area of rain off the coast to the N of East Anglia.

Loved watching that line of storms develop and move onshore right along the coast. You guys are having an amazing summer!

[Alex95]

Thunder here at 6am. Didn't expect that ride awakening!

[Keraunic]

Dull gun metal grey here in Ipswich. Drizzly rain but warm/ish. Ah well, no T&L for us again. *shrugs philosophically*

[stormchaser1]

Oh well i made it home!, A19 North was passable, but alot of surface water , fog as well, thunder and lightning, oh well im off too bed im knackered, not long finished my 12 hr shift

[NW Leeds Russ]

Lightning just seen in Leeds city centre.

So dark the street lights are on.... more like mid November...

[Coast]

Dull gun metal grey here in Ipswich.

Owww very descriptive!!! How many shades of grey do you get - 50?!!!!!

Morning all, here's a quick round up of what clever people are saying:

Storm Forecast

Valid: Fri 06 Jul 2012 06:00 to Sat 07 Jul 2012 06:00 UTC

Issued: Thu 05 Jul 2012 21:24

Forecaster: SCHLENCZEK

A level 2 was issued for E Germany, W Poland and Czech Republic mainly for widespread large and isolated very large hail, severe wind gusts and excessive precipitation.

A level 1 surrounds the level 2 for large hail, severe wind gusts and excessive precipitation.

SYNOPSIS

An upper cut-off low over France will slowly translate to the north. Between this low and a high pressure area extending from the N Maghreb States towards SE Europe and Finland, a plume of hot and very moist air is advected into portions of central and SE Europe. This leads to high instability (> 2 kJ/kg CAPE) over most places of central, SE and E Europe. Due to the fact that the vertical gradient of Theta-E is steep, almost every storm in this environment may produce large hail and severe wind gusts. The regions with the highest probability of widespread severe events are covered with a LVL2.

DISCUSSION

...France...

In the vicinity of the upper cold core, some 15 - 20 m/s deep layer shear are in place combined with a few hundred J/kg CAPE. As the cloud base is expected to be fairly low, an isolated funnel/ brief tornado event is not ruled out. Some marginal hail and gusty winds are possible as well but the expected severity does not justify a threat level.

Storm Forecast

Slight

Forecaster: Dan

Last Updated: 2012-07-06 06:41:00

Valid: 2012-07-06 00:00:00 - 2012-07-06 23:59:00

Synopsis:

A developing wave on the cold front will eventually form a new surface low as a large area of rain moves from BeNeLux across central Britain, leading to local flooding in places given advection of high ThetaE. To the south, surface-based convection is expected in response to diurnal heating.

Discussion:

... SE SCOTLAND, NE ENGLAND, YORKSHIRE ...

A line of thunderstorms has developed along the ThetaE ridge well to the north of the main frontal wave. Although elevated, with PWAT values of ~33m, local flooding is possible from prolonged torrential downpours, accompanied by initially frequent lightning. As the line moves inland it is expected to weaken and start to lose sferic activity over the next few hours.

... NORFOLK, SUFFOLK, LINCS AND N CAMBS ...

Along/ahead of a significant wave on the cold front, a plume of high ThetaE is advected westwards during the morning hours. It is possible given a few hundred J/kg MLCAPE that some embedded elevated convection may produce some sporadic lightning over the highlighted areas, but general thinking is that incredibly saturated profiles will inhibit this chance somewhat, especially as the mass of rain associated with the wave moves inland and further west. Main threat from this event is significant flooding given several hours of torrential rain since PWAT values will be near 38mm locally on eastern upslopes. The chance of lightning is considered on the low-end of the SLGT threat level.

It is possible given small pockets of instability for some embedded convection and a few sferics elsewhere along this wave during the day, but the spot probability is currently considered <5%, and thus does not satisfy our SLGT criteria. However, with relatively low LCLs and a backed surface flow, there could be the chance for a funnel or weak tornado, especially along the southern edge of the main area of rain.

... SW, CS & SE ENG, WEST COUNTRY, HOME COUNTIES ...

To the south of the cold front and under the influence of an upper cut-off low over the Channel Islands, cold mid-levels (~-19C at 500mb) will steepen lapse rates as diurnal heating generates a few hundred J/kg CAPE. Depending on how far north (or south) the main frontal wave tracks, there is scope for scattered showers and a few thunderstorms to form, especially where there is better insolation and low-level convergence.

Rather weak speed and directional shear will result in poorly organised convection, with a series of pulse-type showers/storms anticipated with sporadic lightning. Nevertheless, the main risk due to slow storm motion and PWAT of ~28mm, is local flooding possible from prolonged heavy downpours.

... W IRELAND ...

A rather low risk, but 500-600 J/kg CAPE may allow a few showers/isolated thunderstorms to develop ahead of the main frontal wave, which will spread cloud and eventually rain into eastern portions of Ireland through the afternoon, inhibiting the convection chances further west by the end of the day.

... ARGYLL AND BUTE ...

Another low risk, but weak CAPE and low-level convergence may result in a few showers forming during the midday hours. Instability looks too weak for lightning activity, but there may be the potential for an isolated thunderstorm for a time. For now, confidence is not high enough to warrant a SLGT area.

SKYWARN UK SEVERE THUNDERSTORM WARNING #036

ISSUED: 0600UTC FRIDAY 6TH JULY 2012 (GJ/SM/DH)

SKYWARN UK HAS ISSUED A SEVERE THUNDERSTORM WARNING FOR THE FOLLOWING REGIONS: NORTHERN ENGLAND

IN EFFECT UNTIL 2100UTC FRIDAY 6TH JULY 2012

REFER TO WATCH #035 FOR SYNOPTIC DETAILS

SEVERE THUNDERSTORMS ARE EXPECTED IMMINENTLY, OR OCCURRING, SOMEWHERE WITHIN THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO: HEAVY RAIN...FLASH FLOODING...RIVER FLOODING...LIGHTNING...STRONG GUSTS

DISCUSSION:

MODEL OUTPUT AND RADAR OBSERVATIONS ARE PROVIDING CONFIDENCE IN THE GREATEST WEATHER RISK IMPLIED BY WATCH #035 OCCURRING ACROSS NORTHERN ENGLAND IN THE NEXT FEW HOURS. IN ADDITION TO MCS DEVELOPMENT OFF THE DUTCH COAST MOVING TOWARD THE EASTERN COAST OF THE UK, FURTHER CONVECTION HAS INITIATED NORTH ALONG THE COAST MOVING INTO PARTS OF SCOTLAND AND NORTHERN ENGLAND AND WILL GENERATE ATTENDANT SEVERE THREATS FOR A BRIEF TIME OVER THESE AREAS AHEAD OF DYNAMIC FRONTAL PRECIPITATION LATER TODAY. THIS WARNING MAY BE UPDATED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

I'll go find some charts to try and illustrate the thinking for today

[Liam J]

Been watching this with interest from Australia - looks like one of the systems we get here in summer and autumn. Agree about the rotation off the coast - when we get broader systems moving in we tend to see smaller vortices running with the main flow. Looks like that is what is responsible for that larger area of rain off the coast to the N of East Anglia.

Loved watching that line of storms develop and move onshore right along the coast. You guys are having an amazing summer!

Welcome to the forum, all the way from Australia!

I was quite impressed with the storm formation which moved into NE England and also affecting Southern Scotland, certainly been a very active few days. Got my eye on that line of showers currently heading westwards towards my location and the larger area of rainfall with the vortices as it makes landfall. Interesting weather day

[Lewis]

Torrential rain here in the East of Hull, started around 7am.

Luckily and thankfully, there is a respite soon, as the second wave in the north sea should go North of here.

Lewis

Edited July 6, 2012 by Lewis

[Cheese Rice]

A few lightning strikes here, rain is getting heavier!

[Lewis]

http://www.null the forum for all convective weather, we have tonnes of members, come and take a look!

[Darren Bown]

Just started raining here this morning, still feels humid but has cooled off a bit recently.

[Cheese Rice]

343 ------> 8

[Lewis]

Blimey, thats some heavy rain.

Edited July 6, 2012 by Lewis

[Liam J]

Rainfall heading into Eastern Cumbria now but it's losing all the sferics damn it!! Still gonna chuck it down with rain pretty soon.

[WeatherGuru2012]

lightning and thunder and torrential rain for 15 mins, just woke me up! very loud. Can we expect any more thunder and lightning from this system. It is truly very wet outside and i am beginning to worry.

[sunny scunny]

It looks as though the rain will clear away from here much quicker than expected.18.4mm so far today.

[gottolovethisweather]

Am I right in thinking the very high rainfall totals being predicted are unlikely to come off now?

The storm system seems to be moving through quite quickly and is not stalling yet!

Well done to those that have got thunder already and my eyes are drawn to the area of showery activity down in the English Channel which could go boom as it comes ashore.

Game on for a few active days ahead.

gottolovethisweather

[Hodr]

Extreme downpour here, frequent CG lightning deep booming thunder. Very nice wake up call but I'm worried for the folks down in the valley.

[paul m]

• Shotgun thunder woke me up Yessssss.
  

[richardc1983]

Hammering it down here in Leeds

[Norfolk Sheep]

Rain easing off now, nothing particularly biblical as the worst went up the coast and then inland over the NE. Don't think we warranted an amber warning!

[Darren Bown]

Rain getting heavier, my location, M45, should be hit by some very heavy rain, and hopefully the same thunderyness as is being witnessed in Leeds at the moment.