Forecast Update
Valid: Sun 27 Apr 2008 16:00 to Mon 28 Apr 2008 06:00 UTC
Issued: Sun 27 Apr 2008 15:58
Forecaster: GROENEMEIJER

SYNOPSIS

Refer to convective forecast...

DISCUSSION

British Midlands...

An upgrade seems to be in order for parts of Britain as convection is developing in the left exit of a mesoscale jet streak working its way northeastward into Britain. The area of upward forcing currently centered over the western Midlands will likely translate northeastward. 2 m temperatures have been able to climb to values of 18 C with dew points near 10 C, suggesting that on the order of 500 J/kg MLCAPE should be available. Unidirectional, but rather strong southerly shear of about 25 m/s up to the 6 km level suggest that storms may become well-organized and radar indicates that some cells indeed exhibit supercell characteristics. This suggests that locally some large hail range will be possible, as well as strong wind gusts. The threat of tornadoes should remain limited given that low-level shear is only moderate and helicity is low, too.

France...

Surface-based storms have initiated in central parts of France. It is expected that a few more will do so in the next few hours. These storms will develop in a moderately-sheared environment and some could evolve into well-organized multicell systems, capable of producing some large hail -especially since mid-level lapse rates are rather steep. Some local gusty winds are possible as well, although this threat will gradually diminish during the evening as the boundary layer cools. Clusters of storms that likely become elevated rather soon, will probably move into the SE Benelux and western parts of Germany overnight.
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