Storm Forecast
Valid: Thu 01 May 2008 06:00 to Fri 02 May 2008 06:00 UTC
Issued: Wed 30 Apr 2008 19:08
Forecaster: TUSCHY
SYNOPSIS

Large mid - / upper - level cyclone over the NE Atlantic slowly develops SW- ward as a huge cut - off complex and this retrograde movement continues during the next 24 hours. Downstream of this feature, very weak pressure gradients at all levels prevail with about 5 hPa pressure difference from SW Europe to Belarus.
As a result, an extensive forecast area will see mainly diurnal driven thunderstorm activity. Cold mid-levels and more or less favorable diabatic warming result in steep lapse rates both at low / mid - levels with widespread low -end instability release. Only pulsating thunderstorms are expected with small hail / strong wind gusts as the main risk. Locally, higher coverage of thunderstorms could lead to an upscale growth into small clusters of thunderstorms but environment does not support any enhanced severe weather threat. Weak background flow could support an localized flash flood risk with those clusters.

There are a few spots where stronger instability release / at least somewhat stronger DLS could support an isolated large hail risk, which includes N-France ( DLS up to 20m/s ) and N / NE Germany / N -Algeria ( better instability release ). We decided not to include those regions in a marginal level - 1 area, as expected coverage of reports and seesaw changes of best instability fields from run to run yield too many uncertainties. A level area was issued for the Ukraine / Slovenia / parts of Croatia , where confidence is higher that hail could locally reach our criterion. The other regions could see a conditional upgrade later on if data continues to hint at an isolated large hail threat.
In all those areas we talk about a potential large hail size between 2 and 3cm and therefore a marginal level - 1 situation.

Thunderstorm coverage should rapidly decrease over NW / central Euopre after sunset, but should keep going until 06Z over parts of E / SE Europe. No severe thunderstorms expected during the night hours.

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Storm Forecast Issued: Wed 30 Apr 2008 at 22:46
Valid: 01 May 08 at 00:00:00 - 02 May 08 at 00:00:00

Regions Effected
East Midlands, South Midlands, Southwest England, East Anglia, and parts of Lincolnshire, West Midlands, southeast Wales, Northern Ireland, (Ireland)

Synopsis
A Low pressure system will slowly pull away to the northwest of Scotland, with trailing fronts bringing some patchy rain to Northern Ireland and parts of Scotland. These will ease off during the day, but heavy showers will develop across much of central and southern England and Wales, and central parts of Scotland. These showers could be thundery with some hail during the afternoon, and slow moving. Some showers, perhaps thundery, are expected over Northern Ireland, more especially merging together over southern parts of the Republic of Ireland with thunder possible. The greatest risk of thudnery activity in the UK, based on current information, is thought to be in the THUNDERSTORM region over England and Wales, although some sharp thundery showers are possible over central Scotland. Northern England and north Wales are likely to heave a predominately drier day, and Kent & Sussex may escape most of the showers. The showers will die away quickly after sunset, losing any thundery potential.

All times are GMT+1
View this forecast here

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Looks like you got your wish Dolly ! ..... Large storm over East Anglia and down your way !! (Blitzortung 12.17pm !)

lol Mitch

I had a look at Blitzortung between 11.50-12.10 and it showed storms over Essex and Kent (density) - right over us! However, it was lovely and sunny at the time and no thunder was heard.

Torrential hail shower from 9.20 to 9.35am, a very good soaking from that. Another shower around 10.30, apart from that a lovely sunny afternoon with a few puffy clouds around. A heavy shower with a visible anvil to the NW of me atm, towards London? Any reports of thunder around there?

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Told you the other day that I thought that they were right off track !!.....

Hailstorm here now about 1-2mm size stones !! ......and as I speak a huge flash of lightening and crack of Thunder almost immediately. Must have been Close !!!!!!!!!

bit late, but better than never

TORRO CONVECTIVE DISCUSSION - issued at 08:50 GMT on Thurs 1st May 2008
Valid from/until: 08:50 - 19:00GMT on Thursday 1st May 2008 for the following regions of the United Kingdom & Eire:

Much of Scotland
Eire
Wales
Much of England

SYNOPSIS

Heavy showers/thunderstorms are already developing across parts of S England, with recent reports of marble sized hail. These will become more numerous through the day, with further hail, gusty winds, and heavy rain. An isolated tornado is possible given steep low-level lapse rates, although the lack of strong low-level convergence should limit this threat. However, mesoscale models hint at a couple of low-level convergence zones across portions of Highland Scotland, and perhaps N Ireland/NW Eire.

The overall risk is deemed too low for a WATCH.

TORRO: http://www.torro.org.uk/torro/forecast/index.php

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Storm Forecast
Valid: Fri 02 May 2008 06:00 to Sat 03 May 2008 06:00 UTC
Issued: Thu 01 May 2008 20:06
Forecaster: TUSCHY
SYNOPSIS

Really not many changes to talk about as weak pressure gradients prevail over most parts of Europe. Retrograde southwestward shifting cyclone over the far NE Atlantic induces an intense surface depression on its SE quadrant which again strengthens WAA on the downstream periphery of the broad cyclonic vortex. The system is far west of Europe and so is the strongest axis of WAA but nevertheless, mid-levels warm up somewhat over western Europe ( e.g. France / S - UK ) so modifications to yesterday's broad and far westward extending general thunderstorm area become necessary.
Otherwise no changes for the rest of Europe with diurnal driven and sub-severe pulsating thunderstorm activity.
The focus for most intense initiation will be an eastward moving frontal boundary, slowly degenerating over Romania / Bulgaria into a loosely structured occlusion. Still, convergence along this boundary will serve as a focus for scattered to widespread thunderstorm development.

DISCUSSION

.... Bulgaria ...

Latest surface observations show dewpoints ranging from 10°C over W - Bulgaria to near 13°C over central / E - Bulgaria. Latest sounding reports from Bulgaria and SE Romania reveal a well mixed boundary layer with a strong T - Td spread and very steep LL lapse rates. Mid-levels show somewhat weaker lapse rates but this column should cool down 1 or 2 °C during the forecast period. Those parameters combined with a forecast increase of the BL moisture should yield moderate instability release of 500 - 1000 J/kg MLCAPE . DLS increases from the north ( 10 m/s ) to the south ( near 20 m/s ) and combined with locally intense updrafts, large hail will be a threat with hail stones of locally up to 4cm being a possibility. Coverage of storms should be quite high as both surface front and a weak UL impulse cross the area during maximized diurnal heating when atmosphere is only weakly capped.
Thunderstorms will cluster while moving eastwards and they will go on until 06Z over far eastern Bulgaria and offshore.

... Romania and Moldova ...

The same like described above but DLS is very weak with mostly sub - 10 m/s shear values forecast. BL is also not that humid with dewpoints just below 10°C but still 400 - 800 J/kg MLCAPE will be possible. Storm mode will be pulsating and upscale growth into one or more clusters is likely. Despite an isolated large hail / severe wind gust report during the mature phase of an intense thunderstorm, no real severe thunderstorm risk can be expected.
LL CAPE values are enhanced with very strong signals over Moldova as BL is well mixed and an isolated funnel report can't be excluded. We therefore decided to include those regions in a marginal level - 1 area as isolated large hail / funnel reports could justify one. However weak shear makes this a low-end level - 1 situation.
Thunderstorms will continue over E - Romania / Moldova and offshore until 06 Z.

The same for NE Poland, W - Belarus and S - Lithuania ( an isolated large hail risk ) but also for SW Finland ( impressive LL CAPE and therefore an augmented funnel / tornado threat ).

W - Romania, N - Serbia, S - Hungary, N / NW Austria, the Czech Republic and E - Germany are all placed along the cyclonic side of a strong UL jet with modest instability release and 10 - 20 m/s DLS. Shear could support some local storm organisation but overall environment does not support a level area as the main risk will be sub-severe hail / wind gusts. An isolated large hail report can't be excluded but confidence is too low to increase the probabilities.

N - Ireland / Scotland and parts of UK will see some low - end instability release combined with stronger DLS but warming from the south should help to decrease thunderstorm probabilities over S - UK during the day. The same story for the EL temperature which indicates an increasingly more hostile environment for deep convection. A few stronger thunderstorms could still develop over the area of interest but nothing severe expected.

... N / NE Algeria ...

Don't see a reason why to agree to the very optimistic instability forecast of latest GFS 12Z run, indicating more than 1 kJ/kg SBCAPE over NE Algeria. Temperatures at 500 hPa don't change a lot and LL get only warmer ( e.g. 850hPa temperatures warm up by ~ 5°C ). Impressive mid-level lapse rates, 15-20 m/s DLS would be favorable for large hail but at the moment we only expect a very isolated and short-lived thunderstorm in the highlighted area.



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Storm Forecast Issued: Thu 01 May 2008 at 22:25
Valid: 02 May 08 at 00:00:00 - 03 May 08 at 00:00:00

Regions Effected
Central, Eastern and parts of Northern Scotland

Synopsis
A generally southerly flow will dominate the weather in the UK on Friday. A few showers are likely to form mid-late morning almost anywhere across the UK, but are expected to be well scattered. Some of the showers may be heavy, but are less likely to be thundery in the south compared to recent days. Some rather heavy and possibly thundery showers are possible across Scotland, with hail also possible. Well scattered, perhaps thundery showers, may develop elsewhere in the WATCH region. The showers will decay during the evening, ahead of a warm front moving up from the southwest which may bring some patchy rain to the extreme west of Wales and southwest England, and perhaps southern parts of Northern Ireland, close to the end of this forecast period.

All times are GMT+1
You can view this forecast here

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