Storm Forecast
Valid: Sat 08 May 2010 06:00 to Sun 09 May 2010 06:00 UTC
Issued: Fri 07 May 2010 17:36
Forecaster: TUSCHY

A level 1 was issued for parts of E-Latvia/Estonia and extreme W-Russia mainly for an isolated tornado event, large hail and severe wind gusts.

A level 1 was issued for W-Portugal mainly for an isolated tornado event.

SYNOPSIS

Extensive cyclonic vortex remains established over most parts of Europe with numerous disturbances mainly along its southern part. High pressure is present over parts of SW-Russia.

DISCUSSION

... E-Latvia/Estonia , most parts of Belarus and parts of W-Russia ...

Hot/dry continental air mass circles a strong high pressure area and mixes with somewhat better moisture, advected northwards from the E-Mediterranean. Hence, quality of that air mass is modest with ongoing evapotranspiration and diabatic heating. BL dewpoints may stall at or above 10°C, which is substantially lower compared to what GFS forecasts. However, moisture pooling along the cold front over E-Latvia/Estonia but also along the warm front further to the northeast may yield enough BL moisture for up to 1 KJ/kg SBCAPE. Kinematic parameters are maximized along the warm front, with good speed/directional shear below 3km. All kind of severe, including tornadoes, severe wind gusts and large hail, may accompany thunderstorms, which move along the warm front with a better hail risk along the cold side of the warm front (elevated CAPE) and an enhanced tornado/wind hazard along the south side of the warm front, where storms become surface based.

Shear remains modest at best along the cold front with a large hail and strong wind gust threat. Diurnal thunderstorm activity wil be widespread over parts of W-Russia with mainly pulsating storms (marginal hail/strong wind gusts).

... W-coast of Portugal after 15 Z ...

A strengthening depression approaches W-Portugal during the late afternoon hours, with a warm and very moist warm sector due to a good connection to a tropical air mass. Lapse rates remain weak, but LL shear increases with strong speed/directional shear. An isolated tornado event is forecast in the level 1 area although thunderstorm coverage may be quite limited.

A training shower/thunderstorm situation may evolve over S-Portugal during the late night hours, but model discrepancies preclude a level 1 for excessive rain for now.

...Rest of the highlighted area...

Modest CAPE/weak shear preclude anything severe with mainly daytime driven thunderstorm activity.