Forecast Update
Valid: Thu 25 Mar 2010 12:00 to Fri 26 Mar 2010 06:00 UTC
Issued: Thu 25 Mar 2010 11:35
Forecaster: TUSCHY

A level 1 was issued for N-Portugal and NW-Spain mainly for large hail, severe wind gusts and an isolated tornado.

A level 1 was issued for SW-France mainly for large hail and and isolated tornado event.

A level 1 was issued for SW-Turkey mainly for an isolated tornado event.

SYNOPSIS

Please refer to the main outlook, issued at Wed 24 Mar 2010 23:42 UTC.

DISCUSSION

No major changes were performed for most areas, despite N-Italy, parts of Slovenia, Croatia and Bosnia and Herzegovina, where the 15%-thunderstorm area was expanded. Latest HVIS loop showes most places along the NE Adriatic coast covered by a thick stratus/cumuls cloud shield due to southerly onshore flow. However, first better organized Cu fields evolve over NE Italy and given modest lapse rates and missing mid-/high-level clouds, showers/isolated thunderstorms are possible south/southeast of the Alps. Nothing severe is forecast and thunderstorm activity remains quite sporadic with diminishing activity after sunset.

A small area over E-France has to be discussed, too. Latest satellite loop places a weak vorticity lobe over NE-France and this forcing will affect the level area during the following hours. First Cu-hum fields are present north and east of this vorticity lobe, already inidcating more surface based convection with 10Z temperatures ranging from 16-21°C over W-Germany with dewpoints between 6-8°C. Modified soundings point to potential initiation during the afternoon hours with a dry (inverted-V type) subcloud layer and augmented 0-3km mid-level directional shear. This may assist in an isolated large-hail risk over E-France and extreme W-Germany during peak time heating, when EL temperatures drop to below -40°C. Overall thunderstorm coverage, limited time-frame, weak shear and modest forcing don't support a level-1.