Storm Forecast
Valid: Thu 23 Aug 2007 06:00 to Fri 24 Aug 2007 06:00 UTC
Issued: Wed 22 Aug 2007 21:29
Forecaster: GATZEN

SYNOPSIS

Weakening cut-off low will affect most parts of Europe on Thursday. A strong upper jet streak spreads northward from northern Italy to southern Baltic Sea during the period. At lower levels, warm and moist air mass is present over east Europe and central Mediterranean, while cool air mass affects western Europe. A strong frontal boundary stretches from western Mediterranean Sea to eastern Alps, and northern Baltic States.

DISCUSSION

Poland, Czech, Slovakia, eastern Austria, Hungary

Frontal boundary will be present near the east Germany boarder, and easterly surface winds are forecast over the region. Given quite rich boundary layer moisture, instability will likely remain during the day. Some QG forcing will likely occur at the eastern flank of strong upper jet streak moving across the frontal boundary. Additionally, low-level forcing is likely along old outflow boundaries. Thunderstorms are forecast to develop. Given strong (30 m/s) DLS as well as favorable veering profiles, thunderstorms will likely become supercells, capable of producing large hail and severe wind gusts. Especially in the range of a southerly low-level jet that forms from eastern Austria to southern Poland in the evening hours, tornadoes are not ruled out given 10-15 m/s LLS as well as 100 J/kg 0-1 km SRH. Thunderstorms may merge into a MCS that moves northeastward during the night.

Adriatic, Balkans

The frontal boundary is expected to move eastward into Balkans and Adriatic as surface low pressure spreads northward in the range of the upper jet streak. As a consequence, CAA is forecast that will limit QG forcing during the day. However, given high moisture as well as numerous outflow-boundaries, expect that thunderstorms will go on during the day. Given strong DLS and locally veering profiles, a few supercells are forecast to develop, capable of producing large hail, severe wind gsust and possible a few tornadoes. Thunderstorms will likely weaken in the evening hours.