Storm Forecast
Valid: Mon 31 Oct 2016 06:00 to Tue 01 Nov 2016 06:00 UTC
Issued: Mon 31 Oct 2016 01:53
Forecaster: VAN DER VELDE

A level 2 was issued for S Greece and Crete mainly for excessive convective precipitation and waterspouts.

A level 1 was issued for S Greece and Cyprus mainly for excessive convective precipitation and waterspouts.

SYNOPSIS / DISCUSSION

Between a mid-level ridge over SW Europe and a trough extending from Russia to Turkey, cold air advection destabilizes the Black Sea and the eastern Mediterranean Sea. A surface level low formed over the Ionean Sea and will track eastward along a stationary frontal boundary near southern Greece and Crete. Some 500 J/kg MLCAPE or 1000-1500 J/kg SBCAPE can be released during thunderstorms which shall focus along the frontal boundary and produce mainly excessive rainfall, at 06Z in the west of the marked area, during the afternoon across Crete. A level 2 was selected because of the strong low level convergence combined with upper level divergence signals (GFS model) suggesting that dynamics supports persistent, focused convection as the system moves eastward, raising the chance of rain sums over 50 mm within 40 km of any point over 15%. This will cause flash flooding. Also, strong surface level vorticity helps waterspout type tornadoes to form. Additionally, large SREH north of Crete at the boundary aids chances of mesocyclones in thunderstorms, associated with phenomena as large hail, although it is not sure whether the CAPE is available so far north (it may be a few tens of kilometers displaced). At night the activity should reach Cyprus, but not as focused as near Crete.