Storm Forecast
Valid: Sat 23 Aug 2008 06:00 to Sun 24 Aug 2008 06:00 UTC
Issued: Fri 22 Aug 2008 22:40
Forecaster: SCHLENCZEK

SYNOPSIS

Two upper troughs over the western parts of Europe will be the focus for convective storms on Saturday. The first one, initially located over the Netherlands, is forecast to travel eastward while digging to the south. On both flanks of the trough, a 40 m/s jet streak at 300 hPa is present, leading to strong speed shear in the vicinity of the cold front and the trough axis. The other trough with its axis from extreme SW France towards SW Portugal around 06 UTC on Saturday will also move eastward towards the Balearic Islands on Sunday morning. A well-defined frontal boundary stretches from Belarus via eastern Germany / Czech Republic, Austria, northwestern Italy and Gibraltar towards northwestern Morocco. It separates hot and moist air over the Mediterranean region and eastern Europe from cool air over the east Atlantic and western Europe. At lower levels, pressure gradients should be rather weak except for the surface low over Poland and the frontal wave west of Ireland. Hot and dry conditions will continue over the southeastern parts of Europe.

DISCUSSION

...British Isles...

A frontal wave will cross the British Isles during the second half of the forecast period. GFS suggests that some low-end instability will develop in the small warm sector over Ireland in the evening. Wind speeds in order of 20 m/s at 850hPa are present near the cold front and a convective line with isolated severe gusts may evolve. Even though SRH around 200 J/kg is expected, tornadoes should be rather unlikely as most of the vertical shear is in the lowest 2 km which does not favour organized multicells or supercells. A threat level is not issued.

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