Storm Forecast
Valid: Sat 30 Jun 2007 06:00 to Sun 01 Jul 2007 06:00 UTC
Issued: Fri 29 Jun 2007 14:31
Forecaster: DAHL

SYNOPSIS

Striking feature this period will be an intense Atlantic upper trough, which is characterized by several vorticity maxima, the first of which will affect western Europe late in the period.
A strong surface cyclone is attendant to this upper feature, and will boost the low-level warm advection across the western parts of Europe. The cold front trailing from the SFC low is expected to stretch from the NW Iberian Peninsula across the central Biscay and central France into the eastern British Isles by Sunday morning. An upper trough expected over the North Sea southern Scandinavia at the beginning of the period will move into the Baltic States, thereby attaining a strong negative tilt.

DISCUSSION

... France ... Benelux ...

It appears that at least weak CAPE will develop over France in the warm-sector air mass during the early evening hours. Weak DCVA-related ascent is expected over France, and at least scattered thunderstorms should form in the early evening. Given 20 m/s 0-6 km shear, some threat for well-organized multicells and also some supercells exists, with an attendant threat for large hail and damaging wind gusts. GFS 06Z advertises a small overlap of 7 m/s LLS with the region where convective precip is forecasted, so that the chance of a tornado or two is also increased in the evening hours. CAPE should remain quite weak due to stratiform cloudiness/precip over the area early in the day, so that allover severe weather threat may be somewhat limited. Late in the evening/night however, convection may develop into increasingly unstable air towards the south, so that the severe weather threat will be maintained through, or even increase during the night.

... Balkan States ...

Scattered thunderstorms will likely develop over the Balkan States in the afternoon hours in weakly capped environment. Given about 15 m/s deep shear, storms may evolve into multicellular storms capable of marginally severe hail and wind gusts. Storms should gradually dominish after sundown.