Convective / Storm Risk Discussion - 23rd July 2013 onwards

[topbanana]

Got dark here in Slough and thunder rumbling away

just popping out with camera

[NOAJOA]

Hope one of the cells in the channel hits me

me too...

[imriecm]

I just want some sustained rain here, at least something to clear the air, I guess it's a case of keeping an eye on the radar.

[Supacell]

Just had a massive flash of lightning and instant boom of thunder that shook the house. That must have been close!

[Rainy]

Did anyone detail the lightning hit at Piccadilly Sta Manchester.

See Mancunian Matters.  Pic and info.

 

Wakeup call around the north west.

[snowrye]

Rain rader not working on my mob,any other sites would love to see those cells in the channel

[topbanana]

looks like it is coming from the south and now starting to rain.

nothing worth taking a call of yet.

 

correction... tipping down now as I wright

[BrickFielder]

More surface based convergence as pointed out by Estofex is likely to be a focus over the UK during the afternoon with storms developing tend to move northwards toward north eastern coasts.  Eumetsat images suggest some marked vorticity approaching from the west. The Cambourne sounding from last night shows some drier air coming in at Mid levels with a bit of a Cap above that. My view having looked at the other soundings from the UK is that higher temperatures will be required for storm development in the south and west.  Mid level lapse rates begin to dwindle from the west into the evening meaning storms will begin to be limited to the east as the evening goes on.  Mid level winds look to be unidirectional (no veering as you go up), but there is some speed shear. Most importantly is the speed shear between the surface and 925hpa in the north east and perhaps to a lesser extent the high level winds over central areas in the afternoon.  Forecast SkewT contrasts between London and Middlesborough show saturated air in the north whilst somewhat less so further south. Don't forget the Cambourne sounding Cap which is not showing up on the forecast SkewT's when assessing these.  Some key things to watch for might be how messy the convection is in the north and whether it affects the ability of storms to be surface based or their intensity (don't think it matters much). Another might be whether temperatures in the south reach high enough for storm initiation.  Beyond that and you are better off watching the radar.

 

Edited July 23, 2013 by BrickFielder

[Convective]

UPDATE: Confidence just isn't great enough to warrant a 'SEVERE' level on the following forecast map. Bear in mind that there is an extremely slight risk of a 'SEVERE' thunderstorm just about anywhere within the red highlighted areas mainly down to the possibility of large hail and very strong wind gusts.

 

[PMPhotography]

Nothing here all night, just 0.2mm of rain which fell 30 minutes ago. The onshore breeze killed everything that approached. What a massive dissapointment!

I thought the sea breeze would ruin our chances but we had a terrific storm this morning. From my inexperienced interpretation of the forecast the sea breezes may work in our favour as it will set up convergence zones through this afternoon.Exciting stuff!

[jonoclouds]

 

Forked lightning over Nottingham, 22/7/13 21:44 BST. Panasonic Lumix DMC-LX2, set to manual focus.

This discharge was one of at least three that fired in very rapid succession.

Edited July 23, 2013 by jonoclouds

[Kiwi]

same here, south central, no rain, no thunder...everythings missing us

Heard a rumble of thunder here about 9.30am, and that's been the highlight!!

Nice sunshine now here in north hampshire. Bone dry, not one drop of rain all night!

I'm looking to the SSW on the radar and can't see any hint of storms developing  for the central south. I'll patiently wait to see what brews up later this afternoon.

[scud]

Thunder and hailstones here now

[Coast]

From IOW http://www.isleofwightweather.co.uk/live_storm_data.htm

 

 

** NexStorm TRAC Report generated 23/07/2013 11:09:49

 

Tracking 9 thunderstorms

 

------------------------------------------------------- 

Thunderstorm ID N-304 detected 10:45              

 

Storm location bearing 38.0 dgr distance 86 mi              

 

Last recorded activity      11:09              

Intensity class             Weak              

Intensity trend             Weakening              

 

Current strikerate          3/minute              

Peak strikerate             10/minute              

 

Total recorded strikes      70              

Cloud-Ground strikes        42 - 60.00%              

Intracloud strikes          28 - 40.00%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 0 - 0.00%              

Negative Cloud-Ground [-CG] 42 - 60.00%              

Positive Intracloud   [+IC] 19 - 27.14%              

Negative Intracloud   [-IC] 9 - 12.86% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID Q-3571 detected 09:52              

 

Storm location bearing 105.1 dgr distance 128 mi              

 

Last recorded activity      11:08              

Intensity class             Weak              

Intensity trend             Intensifying              

 

Current strikerate          6/minute              

Peak strikerate             10/minute              

 

Total recorded strikes      130              

Cloud-Ground strikes        55 - 42.31%              

Intracloud strikes          75 - 57.69%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 14 - 10.77%              

Negative Cloud-Ground [-CG] 41 - 31.54%              

Positive Intracloud   [+IC] 48 - 36.92%              

Negative Intracloud   [-IC] 27 - 20.77% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID D-3194 detected 06:13              

 

Storm location bearing 359.1 dgr distance 87 mi              

 

Last recorded activity      11:07              

Intensity class             Weak              

Intensity trend             Weakening              

 

Current strikerate          6/minute              

Peak strikerate             28/minute              

 

Total recorded strikes      3004              

Cloud-Ground strikes        1500 - 49.93%              

Intracloud strikes          1504 - 50.07%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 275 - 9.15%              

Negative Cloud-Ground [-CG] 1225 - 40.78%              

Positive Intracloud   [+IC] 728 - 24.23%              

Negative Intracloud   [-IC] 776 - 25.83% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID H-5340 detected 10:21              

 

Storm location bearing 126.6 dgr distance 164 mi              

 

Last recorded activity      11:09              

Intensity class             Weak              

Intensity trend             Intensifying              

 

Current strikerate          4/minute              

Peak strikerate             7/minute              

 

Total recorded strikes      70              

Cloud-Ground strikes        38 - 54.29%              

Intracloud strikes          32 - 45.71%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 12 - 17.14%              

Negative Cloud-Ground [-CG] 26 - 37.14%              

Positive Intracloud   [+IC] 21 - 30.00%              

Negative Intracloud   [-IC] 11 - 15.71% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID Q-1513 detected 11:04              

 

Storm location bearing 72.6 dgr distance 164 mi              

 

Last recorded activity      11:09              

Intensity class             Moderate              

Intensity trend             No change              

 

Current strikerate          10/minute              

Peak strikerate             10/minute              

 

Total recorded strikes      25              

Cloud-Ground strikes        13 - 52.00%              

Intracloud strikes          12 - 48.00%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 0 - 0.00%              

Negative Cloud-Ground [-CG] 13 - 52.00%              

Positive Intracloud   [+IC] 11 - 44.00%              

Negative Intracloud   [-IC] 1 - 4.00% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID T-470 detected 10:47              

 

Storm location bearing 175.4 dgr distance 247 mi              

 

Last recorded activity      11:09              

Intensity class             Weak              

Intensity trend             No change              

 

Current strikerate          4/minute              

Peak strikerate             4/minute              

 

Total recorded strikes      23              

Cloud-Ground strikes        10 - 43.48%              

Intracloud strikes          13 - 56.52%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 1 - 4.35%              

Negative Cloud-Ground [-CG] 9 - 39.13%              

Positive Intracloud   [+IC] 10 - 43.48%              

Negative Intracloud   [-IC] 3 - 13.04% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID A-1178 detected 10:59              

 

Storm location bearing 149.8 dgr distance 214 mi              

 

Last recorded activity      11:07              

Intensity class             Weak              

Intensity trend             No change              

 

Current strikerate          2/minute              

Peak strikerate             4/minute              

 

Total recorded strikes      25              

Cloud-Ground strikes        11 - 44.00%              

Intracloud strikes          14 - 56.00%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 3 - 12.00%              

Negative Cloud-Ground [-CG] 8 - 32.00%              

Positive Intracloud   [+IC] 5 - 20.00%              

Negative Intracloud   [-IC] 9 - 36.00% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID S-295 detected 10:44              

 

Storm location bearing 86.3 dgr distance 154 mi              

 

Last recorded activity      11:09              

Intensity class             Weak              

Intensity trend             Intensifying              

 

Current strikerate          5/minute              

Peak strikerate             12/minute              

 

Total recorded strikes      93              

Cloud-Ground strikes        51 - 54.84%              

Intracloud strikes          42 - 45.16%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 5 - 5.38%              

Negative Cloud-Ground [-CG] 46 - 49.46%              

Positive Intracloud   [+IC] 35 - 37.63%              

Negative Intracloud   [-IC] 7 - 7.53% 

-------------------------------------------------------

 

------------------------------------------------------- 

Thunderstorm ID N-1545 detected 11:05              

 

Storm location bearing 13.3 dgr distance 129 mi              

 

Last recorded activity      11:08              

Intensity class             Weak              

Intensity trend             No change              

 

Current strikerate          5/minute              

Peak strikerate             7/minute              

 

Total recorded strikes      14              

Cloud-Ground strikes        9 - 64.29%              

Intracloud strikes          5 - 35.71%              

 

-- Strike type distribution --              

Positive Cloud-Ground [+CG] 3 - 21.43%              

Negative Cloud-Ground [-CG] 6 - 42.86%              

Positive Intracloud   [+IC] 4 - 28.57%              

Negative Intracloud   [-IC] 1 - 7.14% 

-------------------------------------------------------

 

*** TRAC Report end - NexStorm V1.9.1.8120:ST-PCI

 

 

[Supercell 89]

Well the storm that popped up to our SSE moved NE'wards so still no proper direct storm here in Reading although did catch a couple of CG strikes in the distance. Already 23.7c and the sun is out so hoping we may get some heat to fuel some storms later on 

[anvilcrawler]

Had an active cell come over with about 6 or 7 loud crashes of thunder and fair bit of lightning,still going off to my east

[carlyb]

Storm to the SW of Hinckley now active again, Lots of thunder not much in the way of fork lightning 

[sparky1972]

still cloudy here, but quite bright, not sure if this will hinder storm chances here later

[JRMcLeod]

It is sooooo typical.  Here in Aberdeen, i have been watching the line of storms moving up the East coast.  As it approaches me, the rain fizzles out and the lightning stops. 

 

Reading the TORRO and ESTOFEX warnings, i was hopeful for some storms this afternoon and evening but it is looking less and less likely as the day goes on.  I cant see that there will be enough energy to develop more down south for us to be in with a chance.

 

Looks like i will need to wait another year to witness lightning here in Aberdeen.

 

I think thats going on nearly 2 years now!!!

 

Just as well i travel to Nigeria and Cameroon annually for my Thunder fix...

[Stuart]

Last Update: 1000UTC Tuesday 23rd July 2013
 

SKYWARN UK SEVERE THUNDERSTORM WATCH #022
ISSUED: 1000UTC TUESDAY 23RD JULY 2013

SKYWARN UK FORECASTS THE POTENTIAL FOR SEVERE THUNDERSTORM CONDITIONS AS FOLLOWS:
STRONG, POTENTIALLY DAMAGING WIND GUSTS - SOUTHEAST ENGLAND, MIDLANDS, EAST ANGLIA, NORTHERN ENGLAND & SCOTLAND
LARGE, POTENTIALLY DAMAGING HAIL - SOUTHEAST ENGLAND, EAST ANGLIA, EAST MIDLANDS NORTHERN ENGLAND & SOUTHEAST SCOTLAND
BRIEF, POTENTIALLY DAMAGING TORNADOES - EAST MIDLANDS, EAST ANGLIA, NORTHEAST ENGLAND & SOUTHEAST SCOTLAND

IN EFFECT FROM 1000UTC TUESDAY 23RD UNTIL 0400UTC WEDNESDAY 24TH JULY 2013

REINTENSIFICATION OF CONVERGENCE FOCUSSING THUNDERSTORM DEVELOPMENT, WITH INCREASING LOW TO MID LEVEL SHEAR

DISCUSSION:
THERE IS STRONG MODEL AND PARTNER AGENCY CONFIDENCE IN THE POSSIBILITY OF SEVERE THUNDERSTORM RISK ACROSS A WIDE WATCH AREA THROUGH TODAY AND OVERNIGHT. THE APPROACHING UPPER TROUGH AND JETSTREAM WILL REINTENSIFY THE SURFACE CONVERGENCE ZONE UP THE EASTERN SIDE OF THE COUNTRY. DESPITE OVERNIGHT AND ONGOING CONVECTION, TEMPERATURES ARE LIKELY TO RESPOND AND FOSTER SURFACE-BASED STORM DEVELOPMENT FROM EARLY AFTERNOON AND PERHAPS EARLIER FURTHER SOUTH. STRONG OVERSPREADING LAPSE RATES AND THE REMAINS OF THE HIGH THETA-E PLUME WILL ALLOW FOR HIGH INSTABILITY AND STRONG UPDRAFTS. INCREASING MID LEVEL WINDSPEEDS MAY ALSO ALLOW FOR MORE ORGANISED AND SUSTAINED STORMS. AS SUCH, MODERATE HAIL SIZES AND STRONG GUSTS ARE A POSSIBILITY FOR ALL AREAS, ESPECIALLY LATE AFTERNOON AND EVENING ACROSS EASTERN AND NORTHERN AREAS. ALONG AND EAST OF THE SURFACE CONVERGENCE ZONE, STORMS MAY BENEFIT FROM AN INCREASING EASTERLY FLOW AND INLAND SEA BREEZE CONVERGENCE WHERE THERE MAY BE SUFFICIENT DIRECTIONAL AND SPEED SHEAR FOR SUPERCELL DEVELOPMENT AND POSSIBLE TORNADOES. THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

SPOTTER ACTIVATION IS REQUESTED AND SPOTTERS ARE REQUESTED TO REPORT ALL FACTORS EXCEEDING ACTIVATION CRITERIA.

 

http://www.skywarn.org.uk/current.html

[JRMcLeod]

INCREASING MID LEVEL WINDSPEEDS MAY ALSO ALLOW FOR MORE ORGANISED AND SUSTAINED STORMS. AS SUCH, MODERATE HAIL SIZES AND STRONG GUSTS ARE A POSSIBILITY FOR ALL AREAS, ESPECIALLY LATE AFTERNOON AND EVENING ACROSS EASTERN AND NORTHERN AREAS.

 

I can but hope.....

[Summer Sun]

MDT

 

Last Updated: 2013-07-23 05:46:00

 

Valid: 2013-07-23 00:00:00 - 2013-07-23 23:59:00

 

Synopsis:

 

Moisture plume will continue to destabilise as a sharp upper trough migrates northeastwards, accompanied by cooling aloft. This will result in a large area of potential thunderstorm activity, with greater than normal uncertainty in the forecast evolution given the notorious difficulties in modelling plume breakdowns.

Discussion:

 

** Map updated at 05:46BST **

Models have struggled to simulate convection over parts of the country already this evening, so no great confidence is given to any NWP output during this forecast period. A shortwave trough drifting slowly NNEwards has already developed a mixture of elevated and surface-based thunderstorms, particularly over the north Midlands at the time of writing. This zone will continue to track northeastwards across Yorkshire and Lincolnshire, with continued development possible in places, albeit increasingly elevated as a low-level nocturnal inversion develops. Given some uncertainty and poor modelling of this shortwave, isolated development further west across NW England and S/SW Scotland through the remainder of the night cannot be ruled out, but is deemed less likely.

... ENGLAND, SCOTLAND, WALES ...

The next bout of thunderstorms is expected to arrive along southern coastal counties, particularly Dorset, Isle of Wight and Hampshire (possibly also East Devon) from 00-03z onwards, transferring and expanding northeastwards towards London, the Home Counties and south Midlands during the remainder of the early hours of Tuesday morning as a second shortwave trough destabilises the moisture plume. This area of primarily elevated thunderstorms is expected to continue to track NNEwards across western portions of East Anglia and the East Midlands during Tuesday morning, although probably weakening/fragmenting with time later in the morning.

Thereafter it becomes a very messy setup, with a mixture of elevated and surface-based thunderstorms expected. It is possible a second round of initially scattered thunderstorms will develop during the early to mid afternoon hours in response to forcing aloft and diurnal heating, particularly in a zone from SE England northwards through the Home Counties, western East Anglia and the East Midlands. DLS is marginally better, so if cells can remain fairly discrete then they have the opportunity to become reasonably well-organised. Most models simulate a gradual merging of initially scattered thunderstorms into a more defined QLCS towards the end of the afternoon and into the evening, as this line continues to slowly drift eastwards. This QLCS is likely to extend from S/SE Scotland down the Pennines/E England towards the Home Counties, capable of producing strong, gusty winds and perhaps an isolated tornado given slightly backed surface winds ahead of this line. 

The slow motion of these thunderstorms and subsequent QLCS coupled with PWAT values of 30-40mm suggests local flash flooding may occur, especially given how dry and hard the ground is currently. Hail between 2.0-3.0cm in diameter is possible from any stronger cells, particularly in the afternoon where any cells can remain discrete.

Please note given the complex and (to a certain extent) unpredictable nature of his setup, a few isolated thunderstorms cannot be ruled out elsewhere across the British Isles.

... IRELAND, NORTHERN IRELAND ...

Cooling mid-levels, falling heights and the approach of an upper low will steepen lapse rates through the day, as diurnal heating raises CAPE values to 600-700 J/kg. Scattered showers and a few thunderstorms are therefore expected during the daytime, although may tend to merge into a larger area of showery rain across western parts for a time during the afternoon and evening. Here, hail between 1.5-2.0cm in diameter and a funnel or weak tornado cannot be ruled out.

 

http://ukasf.co.uk/storm-forecasts/257

 

 

[Darren Bown]

I hope the convergence in Cheshire provides something for more western and northern areas of NW England for this afternoon. Was so tantalisingly close this morning!

[NO LONGER POSTING]

Epic storm just gone through here.. Flats behind my nans house got hit by lightning will upload video later

[Weather-history]

I hope the convergence in Cheshire provides something for more western and northern areas of NW England for this afternoon. Was so tantalisingly close this morning!

Can see blue skies to my SW. Hopefully the high cloud clag will clear.