Valid: Fri 20 Apr 2012 06:00 to Sat 21 Apr 2012 06:00 UTC
Issued: Thu 19 Apr 2012 22:06
A level 1 was issued for parts of Serbia mainly for an isolated large hail and strong wind gust event.
A level 1 was issued for parts of W-Greece mainly for an isolated large hail and strong wind gust event.
A level 1 was issued for parts of the NE Aegean Sea and W/NW-Turkey mainly for an isolated large hail and strong wind gust event.
SYNOPSIS and DISCUSSION
Low geopotential heights with cold mid-level temperature cover most parts of Europe. Yesterday's soundings show good mid-level lapse rates and well mixed low-levels. BL moisture is scarce but still adequate for scattered to widespread showers and thunderstorms. Better moisture availability on the mesoscale may assist in a localized enhanced thunderstorm coverage. Despite weak shear, a lowered WBZ with a dry and deep subcloud layer provide a somewhat more supportive environmental set-up for isolated large hail and strong wind gusts, mainly in the 50-% thunderstorm area. There a model signs that storms over Austria and parts of Serbia/SW-Romania tend to cluster during the evening hours with a localized heavy rainfall risk.
Model QPF agree well with diversity in CAPE magnitude (EZ lower, GFS more aggressive). Confidence in widespread initiation is high so we issued a very large general thunderstorm area.
Three small level 1 areas were added, where some CAPE/shear overlap exists. The one over SW/W-Greece and Serbia cover a marginal large hail risk (a few strong pulsating storms over Serbia with locally more than 500 J/kg MLCAPE and an isolated better organized multicell over SW-Greece with 25-30 m/s DLS). Both areas see a peak activity during the afternoon/evening hours with a gradual decrease thereafter.
The third level 1 was issued for far NE- Aegean Sea /W-coast of Turkey. Favorable directional shear with elongated LL hodographs are forecast but marginal LL moisture may keep thunderstorm coverage very limited. If an isolated thunderstorm manages to evolve, storm rotation is likely with an isolated tornado risk. After sunset, the isolated tornado risk decreases onshore but remains present just along the W-coast of Turkey.