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Jane Louise

Uk Convective General Discussion & Forecasts, 17th July 2012>

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I am without car tomorrow until around teatime and so will be hoping something comes here rather than me having to go to it. A very quick look through the charts makes me think the best time for here could be early morning.

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Darn, that shower is just going to miss me by the looks of things! :(

41.png

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GFS model doesn't give my area much tomorrow, but the Meto are a tad more bullish. The following is from Ian Fergusson:

W COUNTRY: New Met Office analysis suggests rain/showers tomoro AM could prove heavier than previously indicated; thunder poss in N/NW areas

and also, Chris K, the Thunderstorm symbol has returned again! clapping.gifrofl.giftease.gif

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GFS model doesn't give my area much tomorrow, but the Meto are a tad more bullish. The following is from Ian Fergusson:

W COUNTRY: New Met Office analysis suggests rain/showers tomoro AM could prove heavier than previously indicated; thunder poss in N/NW areas

and also, Chris K, the Thunderstorm symbol has returned again! clapping.gifrofl.giftease.gif

Interesting blum.gif I watched Ian's forecast late this evening and he did say rainfall would now likely be heavier than the graphics show, with possible thundery downpours in the morning before it starts clearing away to the East.

We shall see soon enough anyway on how it pans out! Even if it doesn't...it has to be our turn eventually laugh.png

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Interesting blum.gif I watched Ian's forecast late this evening and he did say rainfall would now likely be heavier than the graphics show, with possible thundery downpours in the morning before it starts clearing away to the East.

We shall see soon enough anyway on how it pans out! Even if it doesn't...it has to be our turn eventually laugh.png

MO must have the instability pushed more South than GFS. I for one hope GFS is right as my BBC local forecast shows hardly anything.

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Well quite an upgrade on the 00z for here, CAPE and LI look good and also last for a long time, from about 09z to 19z. Liverpool airport also going for +TSRA,

heavy thunderstorm rain,

for the same time. I think as long as the winds at the higher levels stay south of west then I think we could get something from north Wales.

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Edit, forgot to say that those times are in UTC not BST hense the Z, just add an hour.

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ESTOFEX not forecasting anything in Europe today but UK based storm sites going with:

UKASF

Forecaster: Chris

Last Updated: 2012-07-17 23:01:00

Valid: 2012-07-18 00:00:00 - 2012-07-18 23:59:00

Areas Affected: Wales, Ireland and much of England.

Synopsis:

An area of low pressure will move across northern Britain pushing a cold front from west to east across southern Britain during the day. An occluded front will stall and bring heavier rain to much of Scotland through the day. An upper trough will follow the cold front across Ireland and into southern Britain during the afternoon.

Discussion:

After the passage of the cold front, mid-levels will cool and allow for destabilisation, and with the passing of a short wave upper trough showers and a few thunderstorms will develop across the slight risk area. CAPE values will range from 300-800j/kg with the highest CAPE developing where mid-levels cool for the longest (across eastern Ireland). A corridor of higher CAPE will also spill across central parts of England as well, likely near a Birmingham to Peterborough line during the afternoon. Sufficient CAPE combined with DLS in the range for 40kts and LLS values in the range of 25kts could be enough to trigger some "low-topped" supercells with sustained updrafts capable of producing hail to 1-2cm. An few funnels and even a weak tornado cannot be ruled out, particularly into parts of East Anglia during the mid-to-late afternoon.

This may be updated mid-morning on Wednesday to provide more focus for highest convective potential.

SKYWARN UK SEVERE THUNDERSTORM WATCH #042

ISSUED: 1930UTC TUESDAY 17TH JULY 2012 (GJ/SG)

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

NORTHERN IRELAND NORTHERN ENGLAND SOUTHERN SCOTLAND WALES MIDLANDS EAST ANGLIA

IN EFFECT FROM 2100UTC TUESDAY 17TH UNTIL 2100UTC WEDNESDAY 18TH JULY 2012

ONCOMING JET GENERATING CYCLOGENESIS AND DESTABILISATION OF SLIM PRE-FRONTAL PLUME, FOLLOWED BY AN UNSTABLE AND SHEARED 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...PERSISTENT RAIN FLASH FLOODING STRONG GUSTS HAIL LIGHTNING

DISCUSSION:

THERE IS GOOD MODEL CONFIDENCE OF THE POSSIBILITY OF A SEVERE CONVECTIVE WEATHER RISK THROUGH TONIGHT AND WEDNESDAY. A SHALLOW LOW PRESSURE TO THE WEST IS ENGAGED BY THE ONCOMING JET WITH A PLUME OF HIGH THETA-E AND PRECIPITABLE WATER VALUES ENCOURAGED AHEAD. OVERNIGHT AND INTO LATE MORNING, FRONTAL FORMATION AND ELEVATED INSTABILITY MAY COMBINE TO PRODUCE HEAVY SHOWERS AND POSSIBLE THUNDERSTORMS THROUGH THE WATCH AREAS. HIGH RESOLUTION MODELS AND PARTNER AGENCY FORECASTS SUGGEST 50MM MAY BE POSSIBLE ACROSS EASTERN NORTHERN IRELAND TO THE ISLE OF MAN AND WESTERN PARTS OF SOUTHERN SCOTLAND AND NORTHERN ENGLAND, ALONG WITH HIGH GROUND IN THE WATCH AREAS. EXCESSIVE SURFACE WATER AND RAPID RUN-OFF MAY CONTRIBUTE TO FLASH FLOODING AS A RESULT.

DURING WEDNESDAY, AREAS WITHOUT TOTAL CLOUD COVER MAY SEE UPWARDS OF 700J/KG CAPE GENERATED IN AN UNCAPPED ENVIRONMENT. THE MIDLANDS, EAST ANGLIA AND PARTS OF NORTHERN ENGLAND ALONG THE EDGE OF THE JET MAY SEE SUFFICIENT INSTABILITY AND VERTICAL SPEED SHEAR FOR ISOLATED STRONG CONVECTION. DRIER AIR OVERSPREADING ALOFT MAY SEE ENHANCED POSSIBILITIES FOR HAIL AND LIGHTNING, WHILE AMPLE LOW LEVEL SHEAR MAY PROVIDE FOR SOME STRONG GUSTS FROM ANY ORGANISED STORMS. THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

Nothing yet from TORRO so here are the usual indicators for discussion:

21st OWS have pretty much the whole of the middle of the UK highlighted:

051848Z_21OWS_ATLANTIC-EUROPE_FITL_THUNDERSTORM-STANDARD_12071809.GIF

Lightning ensembles going with that too:

002643Z_21OWS_AFWA-GEPS-PRODUCTS_MODEL-DATA_ENSEMBLE_PROB-OF-LTG-STRIKE_ENSEMBLE_24_12Z.png

Congested areas of convective activity over the UK according to aviation chart for the day:

PGNE14_CL.gif

Big band of CAPE forecast by GFS:

gfs_cape_eur15.png

SBCAPE looking good through that middle section, moving West to East through the day and highlighted later in NW Scotland particularly:

gfs_spout_eur15.png

Plenty of shear aloft:

gfs_icape_eur15.png

and again lots going on from the West in the morning through to the East as the afternoon wears on:

gfs_layer_eur15.png

More rain in Scotland and around the NE:

gfs_prec_eur15.png

gfs_lfc_eur15.png

Lapse rates again defining the area of interest for me today:

gfs_lapse_eur15.png

gfs_lapse2_eur15.png

HiRLAM pretty much in agreement with GFS for that area of potential stretching West to East through the day and ending up Around EA and the Humber:

hir_cape_eur15.png

hir_layer_eur15.png

Simple format GFS traces it well for me today:

06_20.gif

12_20.gif

18_20.gif

24_20.gif

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Looking great for Englands Tornado Alley again today, area from Mid Wales across the Central Plains Parts and into Kansas Lincolnshire looking good for some possible Severe Storms. Surprised there is not much more buzz about this tbh!

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and into Kansas Lincolnshire looking good for some possible Severe Storms.

OhShutUpTotokKansasSucked-copy.jpg

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Some heavy rain in South Wales currently. No sferics yet though.

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Estofex now have a Level 1 issued for central England, marginally large hail and tornadoes.... Central England ...

00 UTC Camborne and Herstmonceux soundings suggest moderate to strong, mostly unidirectional DLS with steep lapse rates at mid-levels and stable low levels of troposphere. Further destabilisation might be expected during the day with approaching short-wave trough and decreasing mid-level temperatures / height falls. Albeit degree of the instability will likely be a limiting factor with only few hundreds J/kg of MLCAPE expected, strong DLS might promote some well organised DMC, including possiblity of supercells. With enhanced LLS and rather low LCLs an isolated tornado is not ruled out besides some marginally large hail with better organised and more persistent storms.

http://www.estofex.org/

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The guys in the Midlands must be sick of the risk of Supercells, Large Hail and Tornadoes for 2012 but will put the following in for them.

Good Luck

http://www.ukweatherworld.co.uk/forum/index.php?/topic/92601-convective-outlook-weds-18th-july-2012/page__view__findpost__p__813046

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HAHAHAHAHahahahahahhahAHHAHAHAHAHAHahahahahahahHAHAHAHAHAHAHAHAHahhhaahahhaha AH AHAHAHHAhaahahah

Guise! Guys! Guise! hahaha.

You will never,, hahahahaha guess, hahaah whats ive seen..

Hahahah

Apparently..

Get this..

Apparently, Theres.

Hahahahha

Apparently theres this warning out..

AHhahaahhaah

So funny..

Aparently , Theres warnings out for .. ahhahahaha Tornadoes! and hail, and thunder and stuff..

AHahahhaha

Guise!#

GUYS!!!

Hahahahahah

:falls over and dies:

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Hmmm....another day where my property is safe from hailstone damage...shock horror!!!

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The guys in the Midlands must be sick of the risk of Supercells, Large Hail and Tornadoes for 2012 but will put the following in for them.

Good Luck

http://www.ukweather...post__p__813046

East Midlands, old boy, East Midlands..lol....Us in the West Midlands have been stormed starved, having only had one elevated MCS monster, which whilst pretty intense, was also pretty crap visually due to it being in broad daylight.....Anyhoos, I'm driving down to Northampton in an hour or so, see a few customers and then take a slow drive back home up the A45 this afternoon...Should be a decent route for catching something

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Estofex now have a Level 1 issued for central England, marginally large hail and tornadoes.... Central England ...

00 UTC Camborne and Herstmonceux soundings suggest moderate to strong, mostly unidirectional DLS with steep lapse rates at mid-levels and stable low levels of troposphere.

Yet strangely I would have thought that both Camborne and Herstmonceux are too far South of the potential action for today?

sounding3.curr.1300lst.d2.png

I'd certainly go with those steep lapse rates but more so in the middle of the country?

gfs_lapse_eur12.png

gfs_lapse2_eur12.png

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East Midlands, old boy, East Midlands..lol....Us in the West Midlands have been stormed starved, having only had one elevated MCS monster, which whilst pretty intense, was also pretty crap visually due to it being in broad daylight.....Anyhoos, I'm driving down to Northampton in an hour or so, see a few customers and then take a slow drive back home up the A45 this afternoon...Should be a decent route for catching something

Aw bless....only one you say? One more than some of us old boy.....GRRRRRRRR! mad.gifblum.gif

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Aw bless....only one you say? One more than some of us old boy.....GRRRRRRRR! mad.gifblum.gif

yes, just the one......and guess what Carl?.....It's one more than you'll ever see!..mwahahahaha!!,.bomb.gifw00t.gif

joking aside, I guess today is as good a day as any for you to break your 'storm duck' with the current setup in place...good luck!

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Nice line of shower popping up. Good for 10 am..

Shame its all gonna miss here as usual.

ALWAYS! north.

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ALWAYS! north.

Not always, but today seems like the favoured areas are through the middle band of the country just to the North of your lcoation and then across to the East.

It's only the weather though, it doesn't have SatNav programmed for your postcode!!! laugh.png

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Tricky forecasting today as on the one hand there appears to be plenty of potential yet there are signs that thunderstorms might be rather isolated. First up we have increasing mid level lapse rates which should help development.

The humidity story rather complicates things though. Dry air moving in at mid levels does not overlap exactly dry air moving in at upper levels.

The import here as you can see from the following forecast skewT for birmingham is that you might get some high level cloud keeping surface temperatures down.

Vertical velocity at lower levels is not that impressive either which suggests to me updraft strengths may not be that strong which I think would be consistent with surface temperatures not really getting that high.

Cloud tops although moderately high are a little limited and tend to improve further east as the day goes on which I think combined with the updraft potential in the lower layers could limit hail and lightning potential.

Looking at wind shear then for me it looks fairly unidirectional although quite strong through the mid levels. Being unidirectional does not make much of a difference to super cell formation but helps at lower levels. Speed shear on the northern eadge of the mid level jet could help with super cell formation. Surface winds are a little high somewhat limiting horizontal vorticity and lifting of this vorticity could be limited unless you get some sun to provide daytime heating.

Overall its a bit of mixed bag, with plenty of instability through the mid to upper levels, low cloud bases, limited surface temepratures. My guess is that there is some potential for a severe storm probably towards east anglia and lincolnshire later in the afternoon. Possibly not a classic storm day for me at the moment, but things are still developing with some encouraging bright cells over Ireland on the satelite pictures. On a positive note thee are probably some of the steepestlapse rates we have seen this year.

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Anything for Merseyside? O no, I forgot, storms self distruct when they come near here. Hope today's my day though.'

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