Storm Forecast Valid: Wed 07 Aug 2013 06:00 to Thu 08 Aug 2013 06:00 UTC Issued: Tue 06 Aug 2013 23:55 Forecaster: GROENEMEIJER
A level 2 was issued across north and northwest Germany for tornadoes, large hail, severe wind gusts and excessive precipitation.
A level 2 was issued across south Germany and east Germany mainly for large hail, severe wind gusts and excessive precipitation.
A level 2 was issued across southeast France and northeast Spain mainly for large hail, severe wind gusts and excessive precipitation.
A level 1 was issued for an area surrounding the level 2 areas including east Spain, south and east France, the Benelux countries, much of the Alps and much of north and west Poland for a lower risk of large hail, severe wind gusts, excessive precipitation and tornadoes.
At 06 UTC on Wednesday, a frontal zone stretches from eastern Spain across southeast France and northeast Germany to northern Poland. It separates a warm air mass with relatively steep lapse rates to its east from cooler air to its west.
A mid/upper-level trough is initially located near 8 W and forecast to move eastward during Wednesday.
A wave is in the front is expected to evolve with an area of low pressure developing over France and moving northward into the Benelux countries. A major driver behind the pressure falls is likely the latent heat release in abundant convection across France.
On the eastern fringe of the low pressure system, a mid-level jet is expected to strengthen, reaching wind speeds of 20-25 m/s at 700 hPa.