Valid: Sun 22 Apr 2012 06:00 to Mon 23 Apr 2012 06:00 UTC
Issued: Sat 21 Apr 2012 23:25
A level 1 was issued for N Algeria and Tunisia mainly for large hail.
SYNOPSIS / DISCUSSION
An upper trough is centered over the western, central and northern parts of Europe. In the vicinity of this system, diurnal heating of the boundary layer and upper level cooling lead to some hundred J/kg CAPE. Except for N Italy, deep layer shear is not worth to mention which will limit the severe weather threat. An isolated large hail / heavy precipitation event may occur but as none of the models show a clear focus for an enhanced hail chance, no threat level is issued.
It is still questionable whether thunderstorms are likely to form over N Italy or not. Deep layer shear is very strong (30 - 40 m/s) but the CAPE signal is very weak. Therefore, no threat level was introduced but an update might be possible.
Another small region with instability is found over N Algeria and N Tunisia. Some 15 - 20 m/s of deep layer shear and 150 - 200 mē/sē SRH3 may allow a few supercells with a large hail threat.