17 July 2011 - Storm/convective Forecast, Discussion And Reports

[Jane Louise]

Please discuss here for today's potential.

Nick F has issued a UK Severe Convective and Storm Forecast ,thanks Nick and good luck all.

http://www.netweather.tv/index.cgi?action=convective;sess=

[Andy Bown]

There is a narrow area around the Bristol Channel that has had nearing 20mm of rain overnight from frequent showers/downpours!

With the LOW situated as it is I can see these continuing throughout the day and tonight.

[Stuart]

Good Morning all

Last Updated: 23:18 Saturday, 16th July 2011

Valid: 00:00 Sunday, 17th July 2011 - 23:59 Sunday, 17th July 2011

Areas Affected:

Much of Britain, especially E England and S Scotland.

Synopsis:

A deep, vertically stacked area of low pressure will be centred across NE Britain bringing a broad area of cyclonic flow and associated large scale ascent through the day

Discussion:

Multiple bands of vorticity spinning around an area of low pressure will be the focal point for enhanced uplift through the day. This combined with SBCAPE forecast in the region of 600-700kg across parts of S Scotland, N England and East Anglia during the afternoon will bring the threat of scattered thundery showers. 500mb temps are modest in the region of -20C and very weak DLS is forecast therefore thunderstorms will likely be of the pulse variety with short lived updraft/downdraft life-cycles. There does look to be a significant amount of LLS with 0-1km values in excess of 20-25kts across western parts of Britain, but this does not tie in with the instability and PVA regions. As usual with upper lows, convergent boundaries, particularly closer to the surface low in N England along with terrain could provide the risk of a few funnels around the strongest updrafts.

Heavy showers may also be slow moving in N England and S Scotland and could produce flash flooding - heavy rain may also fall near occluded fronts in NW England, N Wales and N Ireland providing the risk of flash flooding.

Main risk: Flash flooding, Iso Thunder

http://www.ukasf.co....rm-forecasts/42

[Coast]

Following on from the NW and UKASF forecasts, here's ESOTFEX's take on it:

Storm Forecast

Valid: Sun 17 Jul 2011 06:00 to Mon 18 Jul 2011 06:00 UTC

Issued: Sun 17 Jul 2011 05:43

Forecaster: SCHLENCZEK

SYNOPSIS

A strong low pressure system over the British Isles will move very slowly towards Scandinavia. At the southern tip of this system, a 45 m/s upper jet streak stretches from S France towards N Italy. The cold front of this low stretches from N Spain via SE France and extreme N Italy towards E Germany and especially in N Italy, some instability is predicted in place with strong to very strong vertical shear.

Further east, moderate to high instability is found in a tongue of very warm and unstable air which stretches from Bulgaria towards W Russia. Even though vertical shear is rather weak, isolated severe hail is possible.

DISCUSSION

...France and British Isles...

Showers and thunderstorms are likely to occur in the vicinity of the upper cold core. Rather weak vertical shear and low instability should preclude severe weather, but as often seen in such cases, an isolated funnel / brief tornado cannot be ruled out.

and SkyWarn:

SKYWARN UK SEVERE WEATHER WATCH #038

ISSUED: 1200UTC SATURDAY 16TH JULY 2011 (SM/GJ)

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

ALL AREAS SCOTLAND

NORTHERN IRELAND

NORTHERN ENGLAND

NORTH WALES

EAST MIDLANDS

COASTAL AREAS OF WEST SCOTLAND, WALES AND ENGLAND.

IN EFFECT FROM 1200UTC SAT 16TH UNTIL 2359UTC SUNDAY 17TH JULY 2011

STALLED LOW PRESSURE SYSTEM INTENSIFYING OVER SCOTLAND WITH ASSOC OCCLUDED FRONTS

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...GALES...STRONG GUSTS...FLOODING...THUNDERSTORMS

DISCUSSION:

DUE TO THE COMPLEXITY OF THE CURRENT LOW SYSTEM OVER THE UK, A BROAD WATCH IS ISSUED AS THERE IS GOOD CONFIDENCE OF POTENTIAL THREATS WITHIN SPECIFIC AREAS OF THE UK. AS THE INITIAL OCCLUSION MOVES EAST TODAY, HEAVY AND THUNDERY SHOWERS WILL MOVE SLOWLY THROUGH NORTHERN IRELAND, SCOTLAND, NORTHEAST ENGLAND AND THE EAST MIDLANDS. THESE SHOWERS ARE EXPECTED TO PERSIST THROUGH THE NIGHT OVER SCOTLAND, ADDING TO SATURATING PRECIPITATION AMOUNTS AND GENERATING A SUSTAINED FLOOD RISK. SIMILARLY, STORMS MAY COVER SCOTLAND AND NORTHEAST ENGLAND AGAIN THROUGH SUNDAY WITH AN ATTENDANT HEAVY RAIN RISK. ALSO THROUGH SUNDAY, THE WRAP AROUND OCCLUSION BRINGS POTENTIALLY GALE FORCE WINDS WITH DRIVEN HEAVY RAIN INTO NORTHERN IRELAND AND NORTH WALES, WITH DRIER BUT VERY GUSTY CONDITIONS FOR COASTAL AND EXPOSED AREAS OF WESTERN, SOUTHERN AND SOUTHEASTERN UK.

Not huge amounts of CAPE around:

Going to get windy again!

Look at the area over Wales and surrounding + in Scotland!

More rain, especially in Scotland where it seems it is not welcome!

Yet again this one caught my attention. Red area of Ireland in the middle of the day but that patch around Wales looks potent too:

Moving East and getting going as the afternoon progresses

Another interesting day in store!

[Stuart]

thanks Coast hope i dont miss out today

Issued at - 17 Jul 2011, 09:35

Valid from - 16 Jul 2011, 15:00

Valid to - 17 Jul 2011, 21:00

Showers, heavy and thundery at times, will develop during Sunday. Further rainfall accumulations of 10-15mm in any one hour period are likely with 20-30mm expected over a 3 hour period. There is a risk of as much as, 40mm very locally.

http://www.metoffice...t_warnings.html

[P-M]

This from UKWW. Usually very good with forecasts.

9.40am Sun

Moderate Risk of Scattered Thundery Showers 09Z-21Z Northern and Eastern Regions of UK

Quasi stationary low remains in place close to Scotland. Occluded front continues to develop heavy rain for many parts during the morning. Later in the day we can expect scattered convective showers to initiate as lapse rates increase. Some of which are likely to turn thundery. Relatively weak upper supporting winds and lack of convergence looks to minimise any real organisations within developing convection. Instability looks to become strongest north of Yorkshire by mid afternoon.

The risk map can bve viewed here: http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=44008&posts=1

[NUT]

Very heavy shower coming through us now (Saw it nicely on NW radar) All over now but some of the heaviest rain I seen in quite a while

[UKVoodoo]

Cant see anything happening today in my area thanks to the rain thats hitting making today a rather damp squib...however im very thankful for the rain thats hitting our area so no grumbles (or rumbles lol) from me

[Cloud 10]

This from UKWW. Usually very good with forecasts.

9.40am Sun

Moderate Risk of Scattered Thundery Showers 09Z-21Z Northern and Eastern Regions of UK

Quasi stationary low remains in place close to Scotland. Occluded front continues to develop heavy rain for many parts during the morning. Later in the day we can expect scattered convective showers to initiate as lapse rates increase. Some of which are likely to turn thundery. Relatively weak upper supporting winds and lack of convergence looks to minimise any real organisations within developing convection. Instability looks to become strongest north of Yorkshire by mid afternoon.

The risk map can bve viewed here: http://www.ukweather...d=44008&posts=1

Looks like newcastle could be in the sweetspot yet again! :lol:

[P-M]

Another Update From UKWW:

Moderate risk of Showers and Thunderstorms across Scotland and N/E Parts of the UK Sunday.

Main Risk is in the inherintly unstable air across Scotland and extending into NE England where forecast ascents are deeply unstable air and where this is more conditional instability to be released. HIRLAM Convergence zones are picked up as across Central Grampian , the Highlands and into NE England this afternoon and forecast ascents indicate CB readily acheivable with slow moving heavy showers and Thunderstorms developing in the slack flow.

Other Showers, isolated Sferics likely across Eastern England into East Anglia. Wrap around across Wales, NW England and N England contains frontal debris and is not true convection.

Activity across Southern Areas this morning could be heavy for a time as it moves east.

[Cloud 10]

Another Update From UKWW:

Moderate risk of Showers and Thunderstorms across Scotland and N/E Parts of the UK Sunday.

Main Risk is in the inherintly unstable air across Scotland and extending into NE England where forecast ascents are deeply unstable air and where this is more conditional instability to be released. HIRLAM Convergence zones are picked up as across Central Grampian , the Highlands and into NE England this afternoon and forecast ascents indicate CB readily acheivable with slow moving heavy showers and Thunderstorms developing in the slack flow.

Other Showers, isolated Sferics likely across Eastern England into East Anglia. Wrap around across Wales, NW England and N England contains frontal debris and is not true convection.

Activity across Southern Areas this morning could be heavy for a time as it moves east.

Already a few strikes showing up.:unsure:

[Staffordshire]

Sorry but this just has to be said by me, this summer has been an absolute p**s take! Scotland and NE have had all the glory and have had numerous days of storms, oh look they get it today aswell... I wouldn't really mind it but they are the sweet spot for winter aswell, so they get the good stuff in winter and summer! It's so frustarting, rant over.

[TonyH]

It would seem the wrap around and associated cloud and moderate rain, sitting over NW England and north Wales, is restricting convection possibilities over mid and south Wales and the MIdlands today.

[Alex95]

Its looking rather threatening to my NW now

[Staffordshire]

It would seem the wrap around and associated cloud and moderate rain, sitting over NW England and north Wales, is restricting convection possibilities over mid and south Wales and the MIdlands today.

What a suprise!

Anyway just to note the met office claims 100mm of rain could fall over NW Wales, and just look how that PPN has pepper up in the last 45mins!

[Ross B]

A thunderstorm is just brushing past here (Hamilton), I could hear faint rumbles of thunder when I went out to the car. Sky looks very dark as well to the west.

[Harry]

What a suprise!

Anyway just to note the met office claims 100mm of rain could fall over NW Wales, and just look how that PPN has pepper up in the last 45mins!

Oh have a look - much of Kent and the Thames Estuary have a warning too for bands of heavy thundery showers

[P-M]

Sorry but this just has to be said by me, this summer has been an absolute p**s take! Scotland and NE have had all the glory and have had numerous days of storms, oh look they get it today aswell... I wouldn't really mind it but they are the sweet spot for winter aswell, so they get the good stuff in winter and summer! It's so frustarting, rant over.

lol

[NUT]

A thunderstorm is just brushing past here (Hamilton), I could hear faint rumbles of thunder when I went out to the car. Sky looks very dark as well to the west.

Might be what came over cumbernauld at 11 this morning. Was really seriously heavy but not thundery

[Staffordshire]

Oh have a look - much of Kent and the Thames Estuary have a warning too for bands of heavy thundery showers

Yea but no upto 100mm!

lol

It's alright for you isn't it?

[todd1970]

A thunderstorm is just brushing past here (Hamilton), I could hear faint rumbles of thunder when I went out to the car. Sky looks very dark as well to the west.

Just had that one here Ross...although not a direct hit it was close enough..got 4 rumbles and 3 good flashes of lightning from it..one directly above my house with the explosion of thunder straight after it.

Moved away now though.

[P-M]

Yea but no upto 100mm!

It's alright for you isn't it?

Sorry maybe that was a tad flippant but nohing meant by it other than that it's usually us up here with the frustration and I understand how you feel thats all I meant by it Staffordshire.

[Harry]

Yea but no upto 100mm!

Indeed that's why I don't live near any significant mountains

Looking increasingly convective here now - some showers organising nicely and developing increasingly thundery looking bases. In a small blue gap I can see some quite robust anvils within the mess.....

Eyes up, Lauren (and fingers crossed naturally)

[P-M]

This just reported from a member off another site so looking good so far for the NE and other areas of the UK going by reports:

Newcastle Airport Area - Picking up Sferics, and just had a massive torrential downpour. But even better, there was very strong rotation, and there was definately a funnel trying to form less than a mile away. Was amazing to watch.

If you go to raintoday.co.uk and look at the radar at 11am and then again at 12.45 you can see the line that has developed between Bamburgh and Stockton looks good!

Showers also really picking up in the SE.

[Staffordshire]

Sorry maybe that was a tad flippant but nohing meant by it other than that it's usually us up here with the frustration and I understand how you feel thats all I meant by it Staffordshire.

Damn right it is! and don't worry it's fine..