Storm Forecast
Valid: Sat 07 May 2016 06:00 to Sun 08 May 2016 06:00 UTC
Issued: Sat 07 May 2016 05:35
Forecaster: TASZAREK

No threat levels are issued.

SYNOPSIS and DISCUSSION

Thunderstorm activity on Saturday is divided into two main features. A first one concerns W Europe where a well defined warm sector with southerly advection of rich low-level moisture presses up to British Isles. Within this moisture and rather moderate lapse rates, a CAPE up to 800-1000 J/kg will develop in the line from SW France up to CNTRL Great Britain. A passage of the poorly marked shortwave trough in the afternoon hours will initiate northerly moving scattered thunderstorms. Due to weakly sheared environment (DLS < 10 m/s), no severe weather phenomena are expected in this area.

Second area where DMC and thus thunderstorms are likely concerns SE Europe where a broad mid-level low with weakly defined cold and warm section is located. Due to cold mid-levels over an area that at this time of the year receives considerable diurnal heating, a steep lapse rates (~ 7.5 K/km) will develop, especially in the weakly defined warm section on the S and W flank of the trough. Although a boundary layer's moisture will be not impressive, a CAPE up to 400-800 J/kg will develop on the large area stretching between Austria Greece and Ukraine. Thanks to orographic lift along Alps, E Adriatic coast and Carpathians, and patches of potential vorticity advection within the trough circulation, a scattered thunderstorms with 50% lightning probability are expected over broad area in SE Europe. Low elevation of 0C isotherm and steep lapse rates may be supportive for the hail occurrence, however due to rather low CAPE mainly a small hail is expected. Since majority of these thunderstorms will originate in a weakly sheared environment, no severe convetive weather phenomena are expected, and thus no level threats are issued.

According to NWP models, W Iberian Peninsula may receive a large amount of stratiform precipitation within a trough approaching from Atlantic. In our current understanding, only a marginal instability (limiting a DMC occurrence) is available on this area. However, if the convective precipitation will get involved, a local flash flooding cannot be ruled out.