Convective Weather UK

[Coast]

ESTOFEX have a small area on the East Coast under a watch. Their forecast for today says:

Storm Forecast

Valid: Tue 27 Jul 2010 06:00 to Wed 28 Jul 2010 06:00 UTC

Issued: Tue 27 Jul 2010 06:14

Forecaster: KOROSEC

... British Isles...

British Isles will be afftected by the short-wave trough crossing during the daytime hours. Weak signals for instability are found just ahead of the moving cold front. With some deep-layer shear in place, convection could envolve into a multicells with mainly some strong wind gusts locally. However, both high uncertainities and only marginal severe threat preclude a level 1, so only 15% probability thunderline was placed where convection could occur.

UKASF have the same:

Storm Forecast Issued: 2010-07-27 00:38:00

Valid: 2010-07-27 00:00:00 - 2010-07-27 23:59:00

Regions Affected

(East Anglia and SE England are included in the WATCH)

Synopsis

Low pressure "Silke", located over Iceland, and an extension of the Azores High which will nudge into southern Britain during the day, will dominate the weather across the country on Tuesday.

As a rather weak cold front drifts southeastwards across England and Wales during daylight hours, a wave is forecast to develop along the front, providing an intensification of the precipitation, with the pulse running eastwards along the front.

It is possible that instability may increase ahead of the front with prolonged insolation in the warm and humid airmass. This may develop scattered heavy showers and possible thunderstorms, though this risk is somewhat limited by cloud heights, and as a result confidence is considered currently to be 30%.

Nevertheless, there is a chance for scattered sharp showers and local thunderstorms to develop ahead of the front during the afternoon hours across East Anglia and SE England, before the cold front clears through during the latter hours of the evening. The cold front itself may exhibit embedded thunderstorms as it exits into the North Sea at the end of this forecast period.

Here's all the pictures for you to guess!

Worth remembering the low probabilities highlighted today and not get too carried away!

[Harry]

Worth the watch though - we haven't had any luck really this year, so what are the odds our first proper storm will come from a 15-30% risk??? You know where I'm going with this Wouldn't it just be total irony!

[Nick F]

Convective / Storm forecast - Issued 27/07/2010 09:00

Forecast Summary Map:

Valid: 27/07/2010 09:00 - 28/07/2010 06:00

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

Synopsis

Upper trough will move SE across England and Wales today, waving cold front currently stretching from S Ireland - NW Wales - NE England will move SE during forecast period clearing Kent by midnight.

... SE ENGLAND, SE/E MIDLANDS and E ANGLIA ...

A warm/moist airmass in place, with dew points currently 17-18C across SE/S England, is suggested by models to show some modest destabilisation this afternoon and evening, as upper trough and cold front approaches from the NW and creates lift. Convection is likely, perhaps with a few isolated weak thunderstorms. Given approach of westerly jet streak aloft, cells may organise into multicells with an isolated strong wind gust threat, but main risk will be torrential downpours with a risk of localised flooding. Cold front and isolated storm risk should clear far SE corner of England in early hours of Wedsnesday morning.

[Coast]

ESTOFEX have the closest action in France today but UKASF going along with the NW risk as follows:

Storm Forecast Issued: 2010-07-27 22:55:00

Valid: 2010-07-28 00:00:00 - 2010-07-28 23:59:00

Regions Affected

E Scotland (Scotland, Northern Ireland, N + E England are included in the WATCH)

Synopsis

Shallow area of Low pressure "Silke", located to the north of Scotland, will dominate the weather across the country on Wednesday.

Scattered showers are forecast to develop in the rPm airmass as a result of daytime heating across Scotland and eastern England in particular. Cloud heights appear quite limited, so thunder and lightning is likely to be quite isolated, with the best chance over eastern Scotland where orographic lift may increase cloud heights. Small hail is possible in some showers given the airmass.

The showers are forecast to decrease in coverage slowly during the evening hours.

[NL]

Overcast skies here on the NE coast and temps pegged back at only 16.8°C so without much dinurnal heating i think a few heavy showers are on the menu today and thunderstorms will be at a premium. The visible satellite images dosen't show much in the way of breaks in the cloud either. Feels quite fresh out today not thundery at all, still early days so hoping something develops later.

Some heavy showers in the thunderstorm risk area (UKASF) in Scotland around Aberdeen, so orographic lift aiding these showers i would think

.

NW 5min radar

Edited July 28, 2010 by NL

[Coast]

UKASF slightly optimistic for today

Storm Forecast Issued: 2010-07-30 00:58:00

Valid: 2010-07-30 00:00:00 - 2010-07-30 23:59:00

Regions Affected (Northern Ireland, Wales and the majority of Scotland and England are included in the WATCH)

Synopsis An area of Low pressure situated to the northwest of Scotland will dominate the weather across the United Kingdom on Friday. As a set of weather fronts cross the country during this forecast period, there appears to be a chance of embedded convection along the cold front, and close to the triple point. The chance of thunder and lightning occuring is quite low, hence only a WATCH level has been issued, despite cloud heights looking reasonably favourable. A weak funnel or tornado is also possible.

ESTOFEX are getting up late and don't have a forecast yet (must be the school holidays!)

Maybe a very, very slight risk off the NI coast, but don't hold your breath.....

[Stuart]

Thanks coast

but i saying no for storms today

Edited July 30, 2010 by Stuart

[Stuart]

And Today from UKASF

Storm Forecast Issued: 2010-07-31 00:48:00

Valid: 2010-07-31 00:00:00 - 2010-07-31 23:59:00

Regions Affected

NE/E/SE Scotland (Scotland, Northern Ireland, N Wales and N England are included in the WATCH)

Synopsis

Low pressure "Uschi" (FU Berlin) located over northern Scotland will dominate the weather across the United Kingdom on Saturday.

As the cold front clears East Anglia into the North Sea from 03z onwards, there is a chance of embedded convection developing out to sea, with a risk of isolated thunder and lightning. This is particularly likely to occur over E Holland/NW Germany during the evening hours.

In the following rPm airmass, scattered showers and isolated thunderstorms are expected to develop across northern Britain. Best potential for thunder and lightning exists across many eastern portions of Scotland, aided by orographic lift. Any storms that do occur in the afternoon/evening hours are likely to continue on a path across the North Sea towards Scandinavia during the late evening/overnight period. Given the airmass, small-to-moderate hail is likely in many of the showers, with a chance of local flooding in any prolonged torrential downpours.

i will see

http://www.ukasf.co....orecast/id-321/

Edited July 31, 2010 by Stuart

[Stuart]

and for Toay

Storm Forecast Issued: 2010-08-01 00:47:00

Valid: 2010-08-01 00:00:00 - 2010-08-01 23:59:00

Regions Affected

(SE Scotland, NE England, Yorkshire, Midlands, East Anglia, E Wales and Northern Ireland are included in the WATCH)

Synopsis

The United Kingdom is sandwiched between two Low pressure systems on Sunday, one to the southwest and one to the northeast, providing a dominant northwesterly airflow.

In the rPm airmass, scattered showers are expected to develop across eastern Britain. Best potential for thunder and lightning, albeit low, exists across the SE Scottish Borders and NE England during the late afternoon and early evening where the best cloud heights are likely to be.

Elesewhere any thunder and/or lightning is likely to be very isolated. Given the airmass, small hail is possible in some of the showers, with a chance of local flooding in any prolonged torrential downpours.

http://www.ukasf.co....orecast/id-322/

[Nick F]

Valid: 04/08/2010 06:00 - 05/08/2010 06:00

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

Synopsis

Upper low to the N of Scotland will drive a cyclonic W to NW upper flow across UK with embedded shortwave crossing UK on Wednesday. At the surface, frontal wave moving into Ireland at 00z Weds will continue to move E across Sern England during the day, clearing SE England by late afternoon. While shallow low moves south over N Sea and low with wrap around occlusion moves SE towards Scotland.

… S ENGLAND …

Shortwave trough indicated by dry air slot on WV imagery to west of Ireland this evening will drive frontal wave east across Sern England during Weds. Warm sector will contain fairly warm moist low-level airmass overlaid by steep lapse rates as upper trough arrives aloft with colder air ... GFS generates a small area in the warm sector of several 100 j/kg of CAPE across S England in the afternoon. Enhancement of potential instability of low-level airmass by over-running dry mid-level air along with forced ascent by approaching upper trough and cold front moving through may lead to a few thunderstorms across southern counties of England, more particularly invof cold front. Fairly strong upper flow and 20-30 knots of deep layer shear may lead to multicell/line segment development of convection, with a risk of strong winds gusts and hail. Given dry mid-level air modelled above warm sector, LCL heights below 1000m and some low-level shear possible near triple point - buoyant updrafts could rotate and lead to a tornado. Also convection may produce excessive rainfall with risk of localised flooding. Therefore issued a SLIGHT risk for this area.

... E SCOTLAND, N and E ENGLAND ...

Broad upper trough extending south across UK will create steep lapse rates across Scotland, N and E England by the afternoon - as surface heating increases. As a result, scattered heavy showers and isolated t-storms are likely over these areas. Fairly weak upper flow and weak vertical wind shear will mean no severe weather is likely, though potential for gusty winds and low risk of localised flooding with any storms. Possible wind convergence towards N Sea coasts suggests a weak tornado/spout cannot be ruled out. Any storms should die out after dark.

[Stuart]

Storm Forecast Issued: 2010-08-03 21:43:00

Valid: 2010-08-04 00:00:00 - 2010-08-04 23:59:00

Regions Affected

E + SE Scotland, Yorkshire and NE, SW, CS + SE England,

Synopsis

A complicated forecast on Wednesday, not helped by subtle inter-model disagreements.

Low pressure "Viola" (FU Berlin) located to the north of Scotland will dominate the weather across the country.

A waving cold front moves eastwards across England and Wales, providing showery bursts of locally heavy rain during the morning. Particular attention is given to the triple point (though in this respect the associated occlusion is not present) where convection is expected to occur. The triple point is forecast to move in an ESE direction from south Wales, along the M4 corridor, to SE England (give or take 40 miles or so to the north or south of this track). Embedded thunderstorms are forecast to develop at the triple point and perhaps along the cold front. Given the conditions, moderate-sized hail is possible and perhaps a tornado, especially at the triple point where a shallow Low is forecast to develop. Should a tornado develop, it may be sustained for some time over CS England in particular given the setup. Any thunderstorms that do develop should clear the SE onto the nearby continent during the evenings hours. Locally high rainfall totals are possible, with over 30mm possible in places.

Behind the cold front, scattered showers and thunderstorms are forecast to develop over Scotland and northern England, with the best environment on the eastern side of both countries. Small hail and local torrential downpours are possible with these showers/storms, whcih should decrease in coverage after sunset.

http://www.ukasf.co....orecast/id-323/

[Coast]

SO NW and UKASF have a forecast so what are the others saying?

Storm Forecast

Valid: Wed 04 Aug 2010 06:00 to Thu 05 Aug 2010 06:00 UTC

Issued: Tue 03 Aug 2010 22:55

Forecaster: PUCIK

SYNOPSIS

Main macro-synoptic feature at mid-levels will be a complex trough with one axis stretching over Western Europe and another one stretching from Central Europe to the Southeastern Mediterranean. An embedded short-wave is expected to develop on its forward flank over Baltic States during the day and will quickly progress northward in 20-25 m/s 500 hPa flow. A 30 m/s jet-streak at 300 hPa will be observed on the fringes of this short-wave. To the east, a high pressure system will stall over Russia.

Closer to the surface, cyclogenesis over Baltic States, related to the short-wave trough, is forecast. Surface cyclone and its attendant frontal system will quickly move northward towards Scandinavia. A cold front, stretching from this low southwards, will separate unseasonably hot airmass over Eastern Europe from cooler, polar airmass over Western and Central Europe.

Now that looks a little better....

[Stuart]

sure do coast let see how it plan out later today

[Neilsouth]

Tony Gilbert ( UKWEATHERWORLD)

8.35am Weds

Moderate Risk Thunderstorms Central East UK and Southern Counties 09Z-21Z

Slight Risk Tornado Development Central South and SE UK

Outlook remains visually potent as per most recent model update. In addition synopsis develops post frontal trough in the lee of the cold front.

A good combination of conducive indices are likely to overlay through this convective outlook with the potential for a strong isolated severe storm. Further to this the given instability with workable shear could promote supercell characteristics for the southern most box. Prime threat prolific CG's and moderate hail showers. Vertical shear increases numerically with height with strong CAPE values overlaid to dynamic lift. A high instability low shear set up! A dry punch eventually overruns the cold front by the SE sector. Leading up to this point we can expect a secondary feature at surface to develop in the wake of the cold front. Triple point looks to run from Bristol Channel and along Thames Valley and could well develop the strongest isolated feature today. Though for the prospect of tornadoes I see the best low level shear closer to the southern counties where 45 deg shear and an increase of 16 kts below cloud base should become apparent.

UKWEATHERWORLD

http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=38223&posts=8&start=1

Edited August 4, 2010 by neilsouth

[Coast]

Some new ones from me:

The vertical change in wind through the BL, specifically the magnitude of the vector wind difference between the top and bottom of the BL. Note that this represents vertical wind shear and does not indicate so-called 'shear lines' (which are horizontal changes of wind speed/direction).

Convective Available Potential Energy indicates the atmospheric stability affecting deep convective cloud formation above the BL. A higher value indicates greater potential instability, larger updraft velocities within deep convective clouds, and greater potential for thunderstorm development (since a trigger is needed to release that potential). Note that thunderstorms may develop in regions of high CAPE and then get transported downwind to regions of lower CAPE. Also, locations where both convergence and CAPE values are high can be subject to explosive thunderstorm development.

This height estimates the cloudbase for small, non-extensive 'puffy' clouds in the BL, if such exist i.e. if the Cumulus Potential parameter is positive or greater than the threshold Cumulus Potential empirically determined for your site. The surface LCL (Lifting Condensation Level) is the level to which humid air must ascend before it cools enough to reach a dew point temperature based on the surface mixing ratio and is therefore relevant only to small clouds - unlike the below BL-based CL which uses a BL-averaged humidity. However, this parameter has a theoretical difficulty and quite possibly that the actual cloudbase will be higher than given here - so perhaps this should be considered a minimum possible cloudbase.

[Neilsouth]

Haven't seen those before , thanks coast

[Stuart]

Like them coast

[Costa Del Fal]

Saturday looks showery but right now i doubt they will be thundery. Lapse rates are poor, Cape/LI is poor too.

[Stuart]

Valid: 2010-08-05 00:00:00 - 2010-08-05 23:59:00

Regions Affected

(E + SE Scotland, NE England, Yorkshire, E Midlands and East Anglia are included in the WATCH)

Synopsis

Low pressure "Viola" drifts slowly northeastwards away from the United Kingdom and towards Scandinavia during Thursday. Low pressure "Wilhelmina" approaches from the northwest, dominating the weather for Friday across the country. In between these two systems, a ridge of High pressure extends in, with a rather slack northwesterly airflow.

Scattered showers are expected to develop in the rPm airmass across eastern Scotland and eastern England in response to daytime heating. Hail is possible in some showers given the airmass, and a low risk of thunder and lightning, most likely over E/SE Scotland where best cloud heights aided by orographic lift seem likely. Showers will decrease in covereage during the evening hours.

There is also a low risk (about 20%) of showers developing in the warm sector of the approaching weather fronts at the very end of this forecast period over SW Ireland, drifting southeastwards which may be convective in nature - however, this is uncertain.

http://www.ukasf.co.uk/module-Storm/mode-forecast/id-325/

[Coast]

ESTOFEX show an area over the lowlands of Benelux and Germany as the closest to us for today but the UKASF have the following:

Storm Forecast Issued: 2010-08-05 01:04:00

Valid: 2010-08-05 00:00:00 - 2010-08-05 23:59:00

Regions Affected

(E + SE Scotland, NE England, Yorkshire, E Midlands and East Anglia are included in the WATCH)

Synopsis

Low pressure "Viola" drifts slowly northeastwards away from the United Kingdom and towards Scandinavia during Thursday. Low pressure "Wilhelmina" approaches from the northwest, dominating the weather for Friday across the country. In between these two systems, a ridge of High pressure extends in, with a rather slack northwesterly airflow.

Scattered showers are expected to develop in the rPm airmass across eastern Scotland and eastern England in response to daytime heating. Hail is possible in some showers given the airmass, and a low risk of thunder and lightning, most likely over E/SE Scotland where best cloud heights aided by orographic lift seem likely. Showers will decrease in covereage during the evening hours.

There is also a low risk (about 20%) of showers developing in the warm sector of the approaching weather fronts at the very end of this forecast period over SW Ireland, drifting southeastwards which may be convective in nature - however, this is uncertain.

EDIT - Sorry Stuart, Snap!

[Stuart]

well looking at the Models this morning i say there no storms in the uk for Today so am away to

[Nick F]

48 mm was reported by a rain gauge in the West Sussex town of Haywards Heath, just north of Brighton early yesterday afternoon, most of this apparently falling within an hour. Looking at the radar returns between 13.50 and 14.40 there was continuous very heavy rainfall for almost an hour from a train of multicell thunderstorms ... so certainly possible this big total that caused the flash flooding in the town and further east in Uckfield, even though the site is not an 'official' one:

[ZONE 51]

i like the new? charts up there , cu-cloud base/wind shear.

Monday looks like a widespread storm outbreak.

Edited August 5, 2010 by nimbilus

[Coast]

ESTOFEX highlighting that NE corner today with a watch:

Storm Forecast

Valid: Mon 09 Aug 2010 06:00 to Tue 10 Aug 2010 06:00 UTC

Issued: Sun 08 Aug 2010 20:59

Forecaster: DAHL

SYNOPSIS

A broad large-scale upper trough is located over the central parts of Europe, with a rather complex upper-flow structure in its interior. Several upper-low centers are present over E Germany and the Baltic Sea region. These features will lift east-/northeastwards during the period, affecting the eastern parts of Europe. Another, rather intense Atlantic upper low will reach the British Isles late on Monday. The S and E periphery of the large-scale trough will stretch from northern Iberia across the northern Mediterranean, and then curving northwards towards eastern Scandinavia/western Russia. S and E

of this upper frontal zone, warm and unstable air is present with quiescent synoptic SFC conditions.

UKASF have it more to the Western side of Scotland (that will please Stuart!):

Storm Forecast Issued: 2010-08-08 21:52:00

Valid: 2010-08-09 00:00:00 - 2010-08-09 23:59:00

Regions Affected

NE/E/SE Scotland (Scotland, N England and Northern Ireland are included in the WATCH)

Synopsis

Low pressure "Xenia" (FU Berlin) located to the NW of Scotland will dominate the weather across the United Kingdom on Monday.

Behind an eastward-moving cold front, an rPm airmass covers much of northern Britain. Scattered showers and isolated thunderstorms are expected to develop here, as instability increases particularly as a result of daytime heating. Any showers that do become thundery are expected to be 'pulse type' storms, with the best potential for thunder and lightning over eastern Scotland, aided by orographic lift and longer land track.

Given the airmass, hail is likely in many of the showers, which may be locally moderate in size over western Scotland later in the day. There is also a chance for a weak funnel or tornado.

Showers are expected to continue through the night in western portions of Scotland in particular overnight, with a continued (low) risk of thunder and lightning in places.

[Stuart]

sure is coast but no good today i am going up to my sister and comeing on tue but i back down here on tue afternoon just in times for the late afternoon storms :blush: