CONVECTIVE FORECAST - UPDATE
VALID 23Z SUN 22/06 - 06Z MON 23/06 2003
ISSUED: 22/06 23:11Z
FORECASTER: GROENEMEIJER

There is a slight risk of severe thunderstorms forecast across the eastern UK, western France, the western Benelux

General thunderstorms are forecast across northern Spain, much of France, the western Alps, the Benelux countries and much of the UK as well as a part of th Ukraine

SYNOPSIS

Refer to previous update

DISCUSSION

...The slight risk area...
Storm coverage is increasing over southern England, The Channel region southward over Western France as forcing for upward vertical motion increases ahead of the upper trough approaching the area. Most convective activity over northern France and the UK is likely elevated. The convection is clustered into three main areas, being an MCS along the English south coast, an MCS forming over extreme northwestern France and a large MCS over Bretagne. These MCS's are expected to persist during the next few hours as upper forcing increases and differential theta-e advection will aid in destabilisation. Activity may spread northward over eastern England, over parts of the western Benelux and the southern North Sea. Also, additional convection may initiate over the Bay of Biscay. Some storms will likely be accompanied by large hail. Main threat, however will be strong wind gusts as nearly adiabatic low-level lapse rates will allow for strong downdrafts and increasing low-level shear will allow for strong vertical exchange of horizontal momentum. This might lead to MCSs becoming increasingly linearly organised with a chance of bowing segments associated with damaging winds.

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