Storm Forecast
Valid: Wed 16 Apr 2008 06:00 to Thu 17 Apr 2008 06:00 UTC
Issued: Tue 15 Apr 2008 22:13
Forecaster: GATZEN

SYNOPSIS

Cold situation goes on over Europe, with a blocking high over northern Europe and a polar trough situated over central and eastern Europe. Given another amplified polar trough over northern Atlantic, a southern polar jet stream is present that spreads across northern Africa, and east Mediterranean. A northern branch of the polar jet can be found along the periphery of the European trough from Alpine region to Aegean, where it merges to the southern jet. A low levels cold air mass has spread across all of the forecast region. This air mass destabilizes due to diurnal heating in the range of the upper trough. Some deep layer vertical wind shear will overlap with these instability underneath the polar jet.

DISCUSSION

South-west Germany

In the range of an upper trough axis, cold and rather moist low-level air mass will likely destabilize in response to diurnal heating. Showers are forecast given weak CIN and some forcing in the range of the trough axis and underneath the cyclonic flank of the upper jet axis. Showers and thunderstorms are forecast during the day. Vertical wind shear is not expected to be favorable for severe convection, but given at least 20 m/s DLS in the range of the upper jet streak, some thunderstorms may be strong. Given steep low-level lapse rates and rather cold mid-level air mass, marginally severe hail reaching around 2cm in diameter seems the be the most significant threat.

Balkans

The situation over western Balkans seems to be comparable to southern Germany. Cold air mass will destabilize during noon and showers and thunderstorms will likely develop given QG forcing underneath the upper jet streak. Given some DLS, isolated severe hail seems to be possible. Thunderstorms will likely weaken during the day as the upper trough moves north-eastward.

Turkey

A cold front has crossed most of Turkey on WED morning, and weak westerly winds are forecast. During the day, strong diurnal heating over the altiplano as well as QG forcing in the range of a strong upper jet streak will lead to deepening low pressure over Turkey. As a consequence, northerly winds are forecast over northern Turkey, advecting rather moist air mass southward. Given upslope flow and QG forcing, initiation seems to be likely. Thunderstorms that form my profit from moderate deep layer vertical wind shear, and a few strong cells may have rotating updrafts, capable of producing isolated large hail.