Storm Forecast
Valid: Fri 23 Mar 2007 06:00 to Sat 24 Mar 2007 06:00 UTC
Issued: Fri 23 Mar 2007 11:24
Forecaster: VAN DER VELDE

SYNOPSIS

Two low pressure centers circle around in a large, cold upper cut-off low, one from Germany to France, the more important other over the Balkan. A tongue of high theta-e air moves out of the area of Turkey and albeit associated with strong shear and helicity, has not proven to be active convectively due to lack of instability, apparent in 00Z profiles. Widespread convection is continuing over the Mediterranean Sea area, with more isolated thunder possible over the southern Balkan. A few isolated waterspouts are expected. The western Mediterranean stabilizes, with cloud top heights decreasing. A new impulse comes during the night when convergence near the Balearic Islands can trigger some convection with fairly good low-level instability (GFS and MM5 precip signals).

DISCUSSION

Over the eastern Aegean Sea, Crete and the S/W coast of Turkey a jetstream is present, creating strong deep layer shear over 35 m/s (0-6 km). Decent low level (0-1 km) shear >10 m/s is also progged to be present over Turkey due to friction over land. GFS keeps somewhat enhanced (up to 150 m2/s2) 0-3 km SREH over Turkey as well in the late afternoon and evening in co-existence with postfrontal instability of up to 300 J/kg MLCAPE. Additionally, potential instability is present (boundary layer WBPT of 8C and 700 hPa WBPT of 4 indicated in GFS) that could enhance CAPE by layer lifting.
This combination of parameters is thought to result in strong, long-lived storms, mostly along the Turkish southwest coast and further inland (low level convergence and near PV intrusion) , with a chance of rotating updrafts and hence a threat of large hail and perhaps a tornado.