Convective Weather UK

[Stuart]

Storm Forecast Issued: 2010-08-22 22:36:00

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

Regions Affected

N + S Scotland, Northern Ireland, N England, N Wales, Yorkshire, Midlands + East Anglia (all of the United Kingdom is included in the WATCH)

Synopsis

An unseasonably deep area of Low pressure, Beate (FU Berlin), moves northeastwards across England during the morning hours, deepening all the while.

In the warm sector, convection is possible leading to isolated thunderstorms developing during the early hours perhaps across parts of CS/SE England into East Anglia. Conditions will be favourable for the development of a tornado, perhaps strong in nature, this risk greatest at the Triple Point. Any storms that do develop in the warm sector will continue to move NE/ENE across the North Sea during daylight hours towards Scandinavia by evening.

As "Beate" continues to deepen in the morning, wind gusts of up to 50mph are possible along some eastern and southeastern coastlines for a few hours during the morning, before moderating.

In the following rPm airmass, widespread showers and thunderstorms are expected to develop across many parts of central and northern Britain. With lighter winds here, showers will be prolonged and may merge into longer spells of rain, increasing the threat of flash flooding. Given the airmass, hail is likely in many showers, locally moderate in size.

Showers will decrease in coverage during the evening hours, though will persist quite widely across Scotland and the North Sea overnight.

http://www.ukasf.co.uk/module-Storm/mode-forecast/id-335/

[Coast]

More interesting stuff then.....

Storm Forecast

Valid: Mon 23 Aug 2010 06:00 to Tue 24 Aug 2010 06:00 UTC

Issued: Sun 22 Aug 2010 22:23

Forecaster: DAHL

A level 2 was issued for NE Germany, the N Czech Republic, and much of Poland for damaging winds, large hail, tornadoes, and excessive rainfall.

A level 2 was issued across east-central France and SW Germany mainly for damaging winds, large hail, and tornaodes.

A level 1 was issued across a region stretching from France across central Europe into NW Russia. See text for individual severe weather elements.

A level 2 was issued across the southern UK, mainly for marginally severe winds/hail and a few tornadoes.

SYNOPSIS

South of a rather extensive upper-low complex over the northern Atlantic, a belt of intense and broad westerlies extends from the Atlantic across central Europe into Russia. Several waves are imbedded in this flow, the strongest of which is associated with unseasonably strong cyclogenesis over the North Sea, Benelux, and N Germay on Monday. The main low-level frontal zone will initially stretch from N France across N Germany into the Baltics, but will leap eastwards in response to the cyclogenesis. The air mass south of the baroclinic zone should remain rather moist and unstable.

DISCUSSION

.. S UK ...

Some line segments and/or mesocyclines could develop in rather shallow but strongly sheared airmass over the S UK. Expect isolated wind gusts/hail briefly exceeding severe levels and maybe also a brief funnel/tornado or two

.

This one just going out of the time-scale from TORRO:

TORNADO WATCH 2010/007

A TORRO TORNADO WATCH has been issued at 19:00GMT on Sunday 22nd August 2010

Valid from/until: 19:00 - 08:00GMT on Sunday 22nd/Monday 23rd August 2010 for the following regions

Parts of (see map)

SW England Central S England SE England S Midlands E Anglia Channel Is

THREATS

Tornadoes; wind gusts to 60mph; hail 10-15mm diameter; CG lightning; heavy rain

DISCUSSION

Developing depression will move NE across the region overnight. Very moist Tm airmass will be in place within the warm sector. Instability is indicated within the warm sector and close to the fronts. Convection may develop, especially close to the cold front and triple point. With most of the instability located within the lower parts of the troposphere, and the strongest shear also located here, there is the risk of tornadoes, given the strong directional shear in the lowest layers. A conditional risk for an isolated strong tornado exists, should robust convection develop - indeed, any deep convection which can become rooted close to the triple point could take on a quasi-supercell type structure, perhaps with hail. In addition, strong gusts are possible, although these may also be augmented by the tightening pressure gradient, especially in the east. Finally, torrential rain is possible in places, perhaps leading to local flash flooding.

Forecaster: RPK.

[Stuart]

Thanks Coast

[Neilsouth]

Torro's forecasting has been pretty awful lately

[Lynxus]

TY coast, I dont know why i even look anymore.

Signals show ... Yeha possibly maybe.. But it never happens.

Good luck with the storms. Ill certainly be looking but i feel my nerves are now shot from all this yes/no/maybe/no this year...

[Harry]

Torro's forecasting has been pretty awful lately

To be fair, many forecasts this year have been pretty off the mark, particularly regarding anything convective.

I think it's reasonable to say the weather has been throwing many curve balls this year, with setups being largely complex and lastminute.com, as opposed to the traditional setups which you can track days in advance. I.e, it wasn't that long ago you could see a weather setup, watch it develop, watch the event, and discuss the aftermath...you simply haven't been able to do this of late.

Even the storm last night tracked slightly further S and E than was projected...

Incidentally, MetO invent suggesting the risk of thunderstorms running East north of the M4 corridor towards EA through this afternoon. This would tie in very well with the Estofex level 1 marker....could be worth a gander through the afternoon!

Edited August 23, 2010 by Harry

[Coast]

To be fair, many forecasts this year have been pretty off the mark, particularly regarding anything convective.

Well here's another one to contemplate then!!!

Storm Forecast

Valid: Tue 24 Aug 2010 06:00 to Wed 25 Aug 2010 06:00 UTC

Issued: Mon 23 Aug 2010 21:19

Forecaster: KOROSEC

SYNOPSYS

A broad upper trough amplifies over north-central Europe. Embedded in this trough, a robust vort-max is located over southern Scandinavia. One short-wave trough crosses the alps, while another wave moves from Belarus into western Russia. The main surface cold front extends from the surface low centered over southern Scandinavia SW-wards across Poland towards the Alps while slowly moving SE-wards towards northern Balkans by Wednesday. A large ridge with stable conditions persists over southern Europe.

I'm not holding my breath today But if I was, I'd be holding it in Humberside and Lincolnshire.......

[Coast]

So near but......

Extended Forecast

Valid: Thu 26 Aug 2010 06:00 to Fri 27 Aug 2010 06:00 UTC

Issued: Tue 24 Aug 2010 19:42

Forecaster: TUSCHY

A level 1 was issued for parts of France/Germany, Luxembourg, Belgium and the Netherlands mainly for severe wind gusts, tornadoes and a few large hail events.

SYNOPSIS

Progessive upper-level wave train affects most parts of Europe with a strong wave crossing the English Channel, S-North Sea and Denmark during the forecast. A gradually developing depression at lower levels and its broad warm sector result in a chance for organized convection over parts of western Europe. The hot and stable weather prevails over the Mediterranean with unsettled conditions over E-Europe.

DISCUSSION

... Belgium, the Netherlands, Luxembourg, parts of France and Germany ...

Overall predictability of this event increased in the past, but model discrepancies still exist, especially with ECMWF, which takes this depression into the North Sea a tad later. Nevertheless, the structure of this depression reveals striking similarities, with an SW-NE elongated depression. There remains a chance that this vortex degenerates into an open wave-like structure, but this would have only marginal effects on the final kinematic environment. NCEP ensemble also support that scenario with strong clustered members regarding different geopotential height fields. Favorable phasing between the eastward shifting upper-level short-wave over the English Channel/S-North Sea and a NE-ward surging ridge over the central Mediterranean cause a markedly increase of the isohypse gradient over the area of interest, pushing shear parameters to a nievau for organized deep moist convection.

Future model runs will still cause considerable fluctuations regarding the final wind field strength (especially if weaker/slower ECMWF solution asserts itself), but for now we use GFS/WRF, which did a good performance (assesing the kinematic environment) in past events. 0-6 km bulk shear of 20-30 m/s and 0-3 km shear of 20-25 m/s are already favorable for organized updraft structures. However, the main concern arises when studying the BL wind field, which reveals strong shear of roughly 15 m/s and 200 m^2/s^2 SRH-1, so well organized LL mesocyclones will be possible.

Main uncertainty will be the thermodynamic profile of the lower troposphere for that day. This will be another event, where a well mixed maritime air mass and an EML from Spain start o mix over France/S-Germany. In addition, this depression taps into a pool of partly modified subtropical air over the E-Atlantic, so BL moisture will be more than adequate. A broad warm sector with 300 - roughly 800 J/kg MLCAPE evolves with values decreasing from Benelux eastwards. Also, EL temperature forecasts reveal quite warm cloud top temperatures, which could further limit electrified convection. Hence, a broad level 1 was issued, to cover a severe wind gust risk with downward mixing (20-25 m/s in lowest 1-3 km AGL), an augmented tornado risk and isolated large hail. Later model data will be used to discern potential concentrated swaths with enhanced severe and a possible subsequent upgrade.

Thunderstorms are also forecast over extreme W-Russia, but right now, either shear or CAPE or both parameters won't support organized convection.

Storm Forecast Issued: 2010-08-24 21:48:00

Valid: 2010-08-25 00:00:00 - 2010-08-25 23:59:00

Regions Affected ( Scotland, S Midlands, Home Counties, S Wales and SW/CS/SE England are included in the WATCH )

Synopsis Low pressure "Cathleen" (FU Berlin) approaches the United Kingdom from the southwest, dominating the weather across the country on Wednesday. Scattered showers are expected to develop over Scotland in response to daytime heating. There is a low risk (around 20%) of these exhibiting thunder/lightning. These showers will largely decay during the evening. Attention then turns to the approaching area of Low pressure (Cathleen) from the southwest. Outbreaks of heavy rain will spread northeastwards across England and Wales during the day, with local torrential downpours. The warm sector of this system moves over CS + SE England during the evening hours. There is a chance of convection developing in the warm sector, which may produce isolated thunder/lightning. There is also a risk of embedded convection along the cold front, with a risk of isolated thunder/lightning. There also exists a risk of a tornado should any convection occur, particularly so along the cold front. However, given rather poor cloud heights, the risk is currently deemed to low for a Thunderstorm Threat Level at this stage. SE England seems best favoured for any thunder/lightning after midnight.

and here's the interesting one......

[Neilsouth]

^ Touch n go , thanks Coast

[NL]

The ESTOFEX forecast is for Thursday into Friday coast. Todays forecast has a small risk out into the Atlantic about 100 mile SW off the cornish coast.

http://www.estofex.org/

[Coast]

The ESTOFEX forecast is for Thursday into Friday coast.

Yep, it was their update, here is what everyone has for today:

Storm Forecast

Valid: Thu 26 Aug 2010 06:00 to Fri 27 Aug 2010 06:00 UTC

Issued: Wed 25 Aug 2010 19:34

Forecaster: GATZEN

A level 2 was issued for North-eastern France mainly for tornadoes.

A level 1 was issued for most of France, the Benelux countries, western/central Germany mainly for tornadoes, large hail, excessive rain and severe wind gusts.

SYNOPSIS

A strong westerly flow affects most of Europe to the south of low geopotential from Iceland to northern Europe and to the north of a high present over Iberia and the Mediterranean. Several jet streaks travel eastward during the period ahead of a short-wave trough that will cross the Bay of Biscay and France during the period. At low levels, a quasi-stationary frontal boundary is expected from the Channel region to central Germany and southern Poland. A tongue of rich low-level moisture originating from the Bay of Biscay is forecast to spread eastwards to the south of this boundary, while steep lapse rates over Iberia will likely spread north-eastwards ahead of the approaching short-wave trough.

DISCUSSION

France

A broad low pressure zone is present along the frontal boundary over the Channel region that will expand eastwards during the next hours. With the westerly flow to the south of this front, latest models expect a rapid moisture return over northern France. Latest soundings confirm that rich low-level moisture is present over the Bay of Biscay exceeding 10 g/kg in the lowest 1500 metres. At the surface latest observations also show dewpoints around 20°C spreading into France.

On Thursday, hot and well-mixed air will spread into southern France ahead of the approaching short-wave trough. Over central France, the moist low-level air is expected the warm underneath the capping inversion and weak instability will likely develop given the steep lapse rates spreading northward. Latest model runs predict a surface low that travels eastwards in the range of the warm air nose ahead of the trough in the evening hours. It seems that QG forcing and low-level moisture pooling will result in increasing instability, and initiation becomes more likely in the range of low-level convergence to the east of the low.

Current thinking is that storms will develop over central France in the late afternoon and evening hours. The vertical wind shear will be around 20 m/s in the lowest 3km and 25 m/s in the lowest 6km, supporting rapid storm organization. Depending on the degree of backing surface winds, favourably veering profiles may support supercells. GFS already indicates 100 m²/s² low-level SRH and circular hodographs over north-eastern France. Given the large overlap of strong low-level vertical wind shear and instability, supercells are expected to be capable of producing strong tornadoes in the afternoon and evening hours. Large hail and severe wind gusts will be another threat. Storms will likely cluster in the range of the frontal boundary given the strong forcing, what reduces the tornado threat, and severe winds and excessive rain will be more likely.

Storms will spread eastwards during the night and are expected to decay over the southern portions where low-level moisture is expected to weak. Over the northern regions, convection is expected to continue along the cold front spreading southward from the Channel. The strong vertical wind shear supports a slight chance of brief tornadoes.

The Benelux countries, Germany and Alps

The main uncertainty over this region will be the moisture advection from the west on Thursday. The best moisture is indicated near the frontal wave that is expected over the Netherlands in the afternoon hours. A mixing ratio of 12 g/kg in the lowest 500 m is forecast by latest GFS. The lapse rates may improve in the range of the nose of warm air and models agree about instability spreading eastward along the warm front that will be supported by QG forcing. Storms that develop in the warm air advection regime and root to the moist boundary layer are expected to produce tornadoes as the low-level shear is strong. The degree of instability is unclear at this time, and stratiform precipitation will also be likely in place, reducing low-level temperatures.

Over southern Germany and the Alpine region, low-level moisture will be quite poor initially referring to latest GFS and ECMWF. Although some moisture increase is expected, the warm air advecting into the Alpine region will likely suppress initiation. The best potential seems to exist over the mountains, and the strong shear supports a large hail threat, but current thinking is that storms will not fire given the weak QG forcing and low-level moisture.

In the evening hours convection over France will likely spread into south-western Germany. While the low-level buoyancy decreases gradually, storms may become elevated. However, large hail and severe wind gusts are not ruled out given the strong vertical wind shear. Storms that root to the boundary-layer will profit from 15 m/s 0-1km vertical wind shear and may produce (strong) tornadoes, though. During the night, excessive rain may become the most significant threat across Germany.

UKASF and TORRO has expired, not expecting one later necessarily.

Another close call for us on the South Coast later today, gut feeling is it will stay in France but dew points are really high here - already 17.7 DgC!

[Harry]

Certainly mother nature is being a spiteful cow to us in the SE - it's all either glided past us to the North or, on this occasion, to the South!

[Stuart]

and i dont see much happing next week

[Gray-Wolf]

and i dont see much happing next week

I think al ot may hang on the 'remnants from our 'Canes' and whether the ridge keeps them at bay 'till they've lost some more of their energy?

[Coast]

Yup!!! get the weekend out of the way and we are back into a very quiet period:

Perhaps the sunshine is on its way at last?

[staplehurst]

I think al ot may hang on the 'remnants from our 'Canes' and whether the ridge keeps them at bay 'till they've lost some more of their energy?

The trajectories of both storms (Danielle and Earl) based on the 18z GFS last night show them steering clear of the UK, and that seems to be a trend for Danielle, with her being caught up in a large Low over the northern Atlantic and rotating anticlockwise around the Low's southern, then eastern flank.

[Stuart]

Not much going on with Storm Wise at the mo

Storm Forecast Issued: 2010-09-04 01:13:00

Valid: 2010-09-04 00:00:00 - 2010-09-04 23:59:00

Regions Affected

W, SW + NW Ireland ( Northern Ireland and Ireland are included in the WATCH )

Synopsis

With High pressure "Helmut" (FU Berlin) situated over Scandinavia, and a very slow eastward-moving cold front over Ireland, sourtherly winds will dominate the weather on Saturday.

Scattered thunderstorms associated with an occlusion are expected to decay over SW Ireland during the early hours. Attention then turns to the cold front, where scattered showers and thunderstorms are forecast to develop over some western and central parts of Ireland during the morning and afternoon hours, moving NNE. These are forecast to decrease in coverage during the evening hours.

http://www.ukasf.co....orecast/id-344/

[Stuart]

Storm Forecast Issued: 2010-09-05 00:48:00

Valid: 2010-09-05 00:00:00 - 2010-09-05 23:59:00

Regions Affected

W, SW, S + C Ireland ( Ireland, Northern Ireland, Wales and SW England are included in the WATCH )

Synopsis

With High pressure "Helmut" (FU Berlin) situated over Scandinavia, and a complex, reasonably deep area of Low pressure just to the west of the United Kingdom, a brisk southerly flow dominates the weather on Sunday.

A developing trough towards dawn will bring scattered showers to parts of SW/CS England and later in the morning into the Midlands and Wales, before the trough, and associated showers, die during the afternoon hours. There is a low risk (around 20%) of thunder/lightning associated with these scattered, locally sharp showers.

Attention then turns to the approaching set of weather fronts from the Atlantic during the evening hours. Scattered showers and thunderstorms are expected to develop in the warm sector, and potentially along the warm and cold fronts during the evening and first part of the night. These are forecast to push into the southwestern quadrant of Ireland, before decaying after midnight. Back-building may occur given favourable wind fields, which may result in locally high rainfall totals.

Conditions also appear favourable for a marginal severe thunderstorm, exhibiting a risk of a tornado possibly of moderate intensity and hail up to 3cm in diameter, particularly so close to the triple point.

http://www.ukasf.co.uk/module-Storm/mode-forecast/id-345/

[Stuart]

and for Today

Storm Forecast Issued: 2010-09-05 21:02:00

Valid: 2010-09-06 00:00:00 - 2010-09-06 23:59:00

Regions Affected

S Wales, SW England, SW Northern Ireland and Ireland ( England, Wales, Northern Ireland and W Scotland are included in the WATCH )

Synopsis

A large area of Low pressure to the south of Iceland dominates the weather across the United Kingdom on Monday.

Behind a cold front moving erratically northeastwards across the country, an rPm airmass is in place. Steep lapse rates are expected to enable widespread showers and thunderstorms to develop over a good portion of the north Atlantic, and also parts of central and southern Ireland, given enough insolation and cloud clearance from the straddling front.

In any of the showers, given the airmass, hail seems very likely, perhaps up to 3cm in diameter.

Showers should become to confined to coastal parts, and over the north Atlantic, during the evening and night hours, though brisk winds may enable them to travel further inland. The risk of thunderstorms continues into the night.

http://www.ukasf.co....orecast/id-346/

[BrickFielder]

Chance of a few storms tommorrow in the south west.

[Coast]

ESTOFEX have this to say about today:

Storm Forecast

Valid: Mon 06 Sep 2010 06:00 to Tue 07 Sep 2010 06:00 UTC

Issued: Mon 06 Sep 2010 05:17

Forecaster: SCHLENCZEK

A level 1 was issued for NE Spain and S France mainly for excessive precipitation and to a lesser extent for large hail and severe wind gusts.

SYNOPSIS

The Omega pattern over the NE Atlantic tends to weaken during the following days as an upper trough over the Irish Sea will shift eastwards. Unstable air remains near the center of this upper trough and also over SE Poland / Slovak Rep. Subtropical air with weak to moderate instability should be located over S France, NE Tunisia and the E Mediterranean.

DISCUSSION

...Ireland and SW England...

In the wake of the cold front, upper level cooling and diurnal heating should provide some hundred J/kg SBCAPE in an environment with weak LL shear and locally 10 - 15 m/s deep layer shear. As the cloud base should be very low (only a few hundred meters AGL), an isolated funnel / brief tornado cannot be ruled out.

Not sure about today, but later tonight into tomorrow maybe look west?

[Stuart]

Regions Affected

Wales, Northern Ireland, S Scotland and England (excluding East Anglia and SE England - all parts of the UK south of the Moray Firth are included in the WATCH)

Synopsis

Behind a cold front moving erratically northwards across northern Britain, an rPm airmass is advected across Ireland, England and Wales. Steep lapse rates are expected to enable widespread showers and thunderstorms to develop over a good portion of the country, including overseas, given enough insolation and cloud clearance from the straddling front.

In any of the showers, given the airmass, hail seems very likely, perhaps up to 3cm in diameter. Thunder and lightning is expected to be quite widespread, but rather more isolated in the east due to less favourable cloud heights.

Showers should become to confined to coastal parts, and over the north Atlantic, during the evening and night hours, though brisk winds may enable them to travel further inland. The risk of thunder/lightning continues into the night.

http://www.ukasf.co....orecast/id-347/

Edited September 7, 2010 by Stuart

[Coast]

No storm forecasts issued by ESTOFEX today........

Is this significant? (or are they just short staffed?). Well UKASF have a great chunk of the UK circled (see above post by Stuart), TORRO have nothing so far and the charts look like this:

I'd say Devon today, maybe even over the top of the MetO HQ!!!

[Harry]

As I've just said on my status, we have very impressive convection here in C London at the moment!

Not looking particularly organised, but the rate the Cu are going up is something I've not seen in a long time...and the SE is supposed to get the least of any action today (according to some sources).

I'd be quite surprised if there aren't some storms today, if not here, elsewhere!!

Edited September 7, 2010 by Harry

[Stuart]

my last post for the night

here wed one

Storm Forecast Issued: 2010-09-07 21:36:00

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

Regions Affected

Northern Ireland, Ireland East Anglia, S Wales and SE, CS + SW England ( all of the United Kingdom, excluding the far north of Scotland, is included in the WATCH )

Synopsis

A slack area of Low pressure situated across the United Kingdom will dominate the weather on Wednesday.

A finger of heavy rain will extend into CS England through the early hours, with a rather low risk of embedded lightning/thunder. This band is then expected to move very slowly eastwards during Wednesday daytime, but will break up into scattered heavy showers, with a chance for a thunderstorm or two as well.

Numerous showers and thunderstorms are forecast over Ireland and Northern Ireland, and these may be carried across parts of the North Atlantic into SW England and S Wales at times.

Showers are forecast to shrink rapidly to coastlines during the evening hours, lingering close to the south coast through the first part of the night where they may still emit thunder/lightning. Small hail, to 1cm in diameter, may accompany many of the showers over Ireland/Northern Ireland, Wales and SW England given the rPm airmass.

http://www.ukasf.co....orecast/id-348/