Uk Convective General Discussion & Forecasts, 7th July 2012>

[Coast]

A brand new thread for all that convective storm based discussion

[Harry]

A brand new thread for all that convective storm based discussion

Well, tbh it's becoming a bit of a joke...that estofex chart is on another level!!

That said, over the past few weeks thy given us everything and we've had nothing!!!! This in some ways is a good omen!

[Coast]

Good chance of storms Saturday Night into sunday morning .

Lets hope for once they pass this way please! Morning peeps, lets have a look at what's going on up there today and into the night then:

Well ESTOFEX say there's a lot of possibilities!!

Storm Forecast

Valid: Sat 07 Jul 2012 06:00 to Sun 08 Jul 2012 06:00 UTC

Issued: Sat 07 Jul 2012 07:44

Forecaster: VAN DER VELDE

A level 2 was issued for Poland mainly for large hail. Severe wind gusts and tornadoes (northern Poland) are also possible.

A level 1 was issued for eastern Germany, Czech Republic, western and northern Poland mainly for chances of excessive convective rainfall and large hail.

A level 2 was issued for southwestern to eastern France mainly for severe convective wind gusts and large hail.

A level 1 was issued for central/northern France and Belgium mainly for chances of marginally large hail and tornadoes.

A level 1 was issued for parts of England for land/waterspouts.

SYNOPSIS

A complex situation today on the map. A low pressure area stationary over western Europe with its center at the south coast of England has destabilized the airmass over France and Germany behind a cold front that stretches from Austria into northern Poland, southern Sweden and Baltic states. The warm side of this front still contains large MLCAPE (1500-2000 J/kg) whereas the cooler airmass over western Europe reaches only a few hundred J/kg MLCAPE and is quite weakly capped. Large areas of moderate CAPE are also found over southeastern Europe, but without dynamics initiation wil depend on orographic factors, and vertical wind shear for organization is weak. PV maps reveal the dynamic features well, with afternoon lifting to be expected over the W Poland area but also further east and south. Lots of forcing also around the swirling low in the English Channel. Strong dynamics arrive after 18Z from the Atlantic as a fast-moving PV maximum (500/300 hPa shortwave trough) digs into southwestern France, reaching the Alps early Sunday morning. It is associated with a 300 hPa jetstreak over 40 m/s.

DISCUSSION

...N France...

Quite low LCL heights and somewhat enhanced signals of 0-1 km shear >10 m/s, in addition to an island of deep layer shear >20 m/s and SREH >200 m2/s2, suggest that besides isolated marginally large hail, tornado chances are somewhat elevated as well.

...UK...

An area of slight CAPE, decent low-level buoyancy and weak wind profiles north of the low can be suitable for funnel clouds and perhaps an isolated land- or waterspout. The same might be true in the high vorticity area in the center of the low.

UKASF:

Forecaster: Dan

Last Updated: 2012-07-06 22:24:00

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

Synopsis:

Upper low becomes located over South West England with a slack surface flow across England and Wales. Daytime convection is expected in response to diurnal heating.

Discussion:

... NW & NE ENG, MIDLANDS, WALES, EAST ANGLIA, WEST COUNTRY ...

Scattered showers and a few thunderstorms are forecast during the day in response to diurnal heating generating ~700J/kg CAPE. Very weak shear will result in disorganised cells, although general inter-model consensus is for a line of cells to form during the afternoon in an W-E orientation from Cambs/Lincs to the north Midlands, with perhaps a greater focus here to more widespread sferic activity.

Low LCLs and slight veering of surface winds increases the risk of a funnel or weak tornado, especially where any low-level convergence can develop in the slack flow. Given increasingly dry air aloft, hail up to 1.0cm in diameter is possible in stronger cores. However, slow storm motion coupled with PWAT values of ~24mm suggests the risk of localised flooding from prolonged downpours.

Showers decay during the evening as diurnal heating subsides, while more general showery rain is forecast over the South East from residual occlusions.

SkyWarn have a warning of a 'Particularly dangerous situation' for the rain in the SW:

SKYWARN UK SEVERE WEATHER WARNING - PDS #038

**PARTICULARLY DANGEROUS SITUATION**

ISSUED: 2300UTC FRIDAY 6TH JULY 2012 (RB/SM)

SKYWARN UK HAS ISSUED A SEVERE WEATHER WARNING - PDS FOR THE FOLLOWING REGIONS: SOUTH-WEST ENGLAND

IN EFFECT UNTIL 1800UTC SATURDAY 7TH JULY 2012

SEE SEVERE WEATHER WATCH #037 FOR FURTHER DETAIL

THIS IS A PARTICULARLY DANGEROUS SITUATION; EXTREMELY SEVERE WEATHER IS EXPECTED IMMINENTLY, OR OCCURRING, SOMEWHERE WITHIN THE REGIONS INDICATED. THREATS WITHIN THIS WARNING INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...FLOODING...LANDSLIPS

DISCUSSION:

FURTHER REVIEW OF FORECAST MODELS FOCUSING ON THE SOUTH-WEST OF ENGLAND CONTINUES TO PROMOTE HEAVY AND SUSTAINED RAINFALL ONTO ALREADY SATURATED GROUND WHICH WILL FURTHER HEIGHTEN THE RISK FOR FLOODING TO OCCUR IN THE REGION. THE ENVIRONMENT AGENCY AND MET-OFFICE CONTINUE ALSO TO HIGHLIGHT FLOODING POTENTIAL. GIVEN THE SATURATION OF GROUND, COUPLED WITH FURTHER HEAVY AND SUSTAINED PERIODS OF RAINFALL THROUGH THE WATCH PERIOD, LANDSLIPS ARE NOTED AS AN ADDITIONAL RISK. THIS PDS MAY BE UPDATED. PLEASE MONITOR WEATHER AND TRAVEL INFORMATION AS NECESSARY.

Nothing from TORRO yet, but here's some other indicators for us to asses:

21st OWS is down today, aviation weather shows:

GFS based Lightning Wizard shows the CAPE towards the East this afternoon:

But look at the SBCAPE areas in the SW too!

If I was getting around the swear filter I would list a whole load of OMG's etc at this lot in the SW:

With a lot of rain to come

The rain scooting South and East, hopefully into The Channel:

and maybe the odd funnel of even a tornado?

In simple format, here's where GFS shows any T Storms later today:

HiRLAM not much different:

Maybe they have the rain progressing more along the coast to my area?

Going to be a messy and wet day out there folks!

[Supacell]

Should be okay around my area today, although some of the charts there show the best risk of thunderstorms being a little south - maybe Manchester to Sheffield areas? (I am talking individual thunderstorm risk, clearly the highest risk of severe weather is in SW and Southern Central areas today).

[Nick F]

Valid: 07/07/2012 10:00 - 08/07/2012 06:00

Headline: ... THERE IS A RISK OF THUNDERSTORMS FORECAST...

Synopsis

Upper and collocated surface low are slow-moving across S/SW England during Saturday, occluded front wrapping around low across the SW brings general heavy rain across SW and S England through the day, to the N and NE - an unstable E to SE flow across central UK.

... CENTRAL, NERN and ERN ENGLAND, N WALES ...

Cloud and general non convective rain across SW England, some of which is heavy and creating a flood risk, will spread further east across S England through the day - tending to limit convective potential here. Though a few thundery showers with isolated sferics are possible across the SE this morning.

The main focus for convection today will be further north across central, northern and eastern England and perhaps N Wales - where dew points of 13-14C and insolation will generate an unstable airmass with 300-600 j/kg CAPE indicated by GFS. Surface heating, large scale ascent near low and more local forced ascent along wind convergence zones will help heavy showers and thunderstorms to develop. Vertical shear will be rather weak, so storms will tend to be dis-organised and pulse-type, though some organisation of cells along wind convergence zones (indicated across N England and N Wales this afternoon) with a threat of large spot rainfall totals exacerbating the flooding problems here. Funnels or perhaps even brief weak tornadoes/waterspouts can't be ruled out over N England and N Wales with more buoyant updrafts along wind convergence. Showers and storms will tend to fade after dark.

[East_England_Stormchaser91]

Morning all . Well as I speak, I can see some awesome looking cb's already, they've absolutely exploded up in the past half hour on my way back from work !

[Harry]

Some great looking Cb's going up around here....sadly though not for my pleasure

[viking_smb]

talking of tornado's nick, I saw one on thursday eve whilst sailing in cardiff bay, it was seen just above the barrage on the other side of channel

[Nick L]

Blimey, it hasn't taken long for stuff to kick off! Nothing electrical though...yet...

[Buzzard]

Quite a heavy shower here - which im sure will be on their way to the central / NE sector like storm homeing pidgeons !! Well at least a little heavy rain - being quite boring here and in London the last week.

Regards the rain in the SW - Looking at the radar, some of the heaviest and persistant rain seemed to be in Dorset, however, only Devon seems to be mentioned on the TV/radio?

[syncmaster]

I now reside in N. lincs but these were sent from my hometown area of the south hams in s. devon by my sister this morning,,

This is the main rd to plymouth from the south hams

this is just outside my hometown of kingsbridge (where i would walk my dogs)

[Lynxus]

Looks like gloucester is no mans land today.

DOh

[Convective]

Where do I need to be today then? I am currently at Little Eccleston (near Preston, Lancashire) so I suppose here will be okay after? The breeze should blow something over from the Pennines maybe?

Edited July 7, 2012 by Convective

[Cloud 10]

Blimey, it hasn't taken long for stuff to kick off! Nothing electrical though...yet...

First strikes of the day just north of Norwich.

I'm going to wash the car now,this should enhance any chances of showers/storms at my location.

[Nick L]

First strikes of the day just north of Norwich.

I'm going to wash the car now,this should enhance any chances of showers/storms at my location.

I might light up the BBQ

[I Cumbria Marra I]

Lincolnshire getting there daily storm

[Darren Bown]

Red warning has been removed from the metoffice site, the main rain is east of that location today.

[Aaron]

Lincoln, England must have the same amount of thunderstorms as Lincoln, Nebraska

[Nick L]

Lincoln, England must have the same amount of thunderstorms as Lincoln, Nebraska

Lincolnshire always seems to get in the news every winter for snow as well!

[Supacell]

Where do I need to be today then? I am currently at Little Eccleston (near Preston, Lancashire) so I suppose here will be okay after? The breeze should blow something over from the Pennines maybe?

Hi Convective

It is a really difficult one today as pulse storms are hard to chase and you kind of have to be in the right place at the right time. My advice, if you have radar with you, is to pick out convergence zones, look which way shower motion is and get near to one of them.

I don't want to give poor advice as I can be unlucky sometimes when I am out chasing, but I would guess a little further south of your location. Not a lot of sferics so far though and I am not sure there will be that many this afternoon. Personally, i am staying around Bradford/Halifax today - staying local.

Good luck mate.

EDIT: Actually Preston isn't too bad a location for later on. Get yourself near to a road that lets you go north to south so you can intercept should anything move across from the SE later.

Edited July 7, 2012 by Supacell

[Harry]

Lincolnshire getting there daily storm

You know that Norwich is in Norfolk dont you??? Teehee

Agree though, the are lucky so and so's although not as far up the merit table for snow I think you'll find

[Supacell]

I think my area has to be up there for snow. Since moving from Derby i have been very impressed with the ferocity of some of the blizzards here in the winter. April 4th this year was one to remember here with around a foot of snow in about 5 hours!! Although in the centre of Bradford there were just some slushy deposits.

Sorry that off topic.... However, for storms its not great - although there has been a couple of weak ones the last 2 days (weak in terms of sferic activity not rain). Maybe something today also - who knows? Netweather have a 51% chance here at 4pm and 7pm and we look to be under one of the wind convergence lines so i have my fingers crossed.

[mattyk1985]

I can assure you that this part of Lincolnshire doesnt get that many thunderstorms or that much in the way of snow. Southern Lincolnshire on the other hand...

[Chris.R]

Had no snow here at all last winter and no storms here yet this year but that's not unusual. Having said that, when we do get snow we often sometimes get batterd, e.g: 30 CM snow on 17th dec 2010. This is not really true for storms though.

Very sunny this morning and looking good for this afternoon. Just heard a huge genralisation on Talk Sport, "if you look out your window you'll se it's not a nice day!" Well that's sertainly not the case here.

[Harry]

I can assure you that this part of Lincolnshire doesnt get that many thunderstorms or that much in the way of snow. Southern Lincolnshire on the other hand...

Indeed, very good point!!!! Once upon a time a major variation between between East and West Kent for storms...now we both get naff all lol