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Severe T-Storm Risk UK & IRL June 29th-July 7th

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Author Topic: Severe T-Storm Risk UK & IRL June 29th-July 7th  (Read 6679 times)
Martin Mc Kenna
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Maghera, N. Ireland

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« Reply #30 on: June 30, 2009, 11:15:47 pm »

Hey John, I don't trust the TV forecast that much as you know but it should be interesting to see what they go for. Here's Wed's outlook from ESTOFEX. There might be a low risk of thunder for Ireland also, but it's low.

Storm Forecast
Valid: Wed 01 Jul 2009 06:00 to Thu 02 Jul 2009 06:00 UTC
Issued: Tue 30 Jun 2009 21:57
Forecaster: GATZEN

A level 1 was issued for the north-eastern British Isles for excessive rainfall.


Large-scale weather pattern has not changed significantly across most of Europe. To the east of low geopotential over the northern Atlantic, the airmass is unstable over a large area in the range of weak geopotential gradients. A weak upper ridge stretches from the Iberian Peninsula to Scandinavia, while mid-level heights remain lower over the Balkan. A frontal system belonging to an Atlantic low will affect Ireland and Great Britain.

For most of Europe, weak vertical wind shear is forecast, and storms will tend to move very slowly, contributing to pulse type storms with local flash floods, to possibly more excessive convective rain events near persistent convergence zones. Isolated landspouts are also not ruled out.

Across north-western Russia, rather strong vertical wind shear is expected in the range of an amplifying short-wave trough moving eastward, and vertical wind shear will likely overlap with instability. Mid-level winds will also increase compared to yesterday over extremely western Europe as the Atlantic trough slowly moves eastward, but low-level cold air advection is expected to limit convective potential there.


A nearly saturated airmass with large precipitable water content is advected from the south and CAPE is predicted to develop especially over the central portions. Storm motion will be relatively slow and oriented along the source of lift. Regenerating convection may therefore keep training along a line for extended periods, leading to local flash floods. In Ireland the same moist airmass passes but with almost no instability due to rather cool low-level air masses.

The UKASF forecast has a wider area in the watch box.
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