Storm Forecast
Valid: Sat 18 Dec 2010 06:00 to Sun 19 Dec 2010 06:00 UTC
Issued: Sat 18 Dec 2010 05:50
Forecaster: VAN DER VELDE
A level 1 was issued for southern Spain and northern Morocco mainly for excessive convective rainfall.
SYNOPSIS
A large mid level low pressure area dominates much of Europe and cold airmass prevails about half way into the Mediterranean. Unstable air is present around the British Isles, with several low pressure centers present. Warm unstable air is found within a stationary low in the southwestern corner of the map. Another low moves from Italy eastward into Romania and the Black Sea.
DISCUSSION
...southern Spain and northern Morocco...
In the warm and relatively moist airmass (9 g/kg 0-1 km mixing ratio) more than 500 J/kg MLCAPE is present, and continuous storm development is possible in the coastal convergence zone and larger region with QG lift from warm air advection. The persistence may lead to excessive rain amounts. Vertical wind shear on the east side of the unstable airmass, with some overlap, is veering with altitude (SREH of 300 mē/sē) and may induce mesocyclogenesis, with a tornado not ruled out. Also severe gusts can occur given strong flow of more than 20 m/s in the lower levels.
...Adriatic area...
Weak CAPE here, but under more than 30 m/s 0-6 km shear and 200 mē/sē SREH is possible with good looking (round) GFS hodographs. Slight chance exists for tornadogenesis and severe wind gusts but instability seems really marginal and confidence for level 1 insufficient. Forcing, though, is very strong during the beginning hours of the forecast and has already created a lightning-active line over southern Italy.
