Storm Forecast
Valid: Sat 29 Jan 2011 06:00 to Sun 30 Jan 2011 06:00 UTC
Issued: Sat 29 Jan 2011 06:27
Forecaster: VAN DER VELDE
SYNOPSIS
High pressure is present in a band over British islands to Romania. North and south of it, low pressure areas are present over Scandinavia, the western Mediterranean Sea, and the eastern Mediterranean Sea. The latter are associated with unstable airmasses and vigorous quasi-geostrophic forcing, resulting in abundant thunderstorm activity.
DISCUSSION
...W Mediterranean...
During the night before the period started, several long-lived storms formed over the western Mediterranean near Spain. The region of strong low-level convergence in which they formed remains today between the French-Spanish border and Corsica, curving back to the Algerian side of the sea. Maps of 700-500 hPa theta-e show a mid level cold front and significant cold air advection at those levels will destabilize the area further, and a mid level PV maximum enters the region around 15Z which will likely activate storms. In the north, storm-relative helicity soars over 300 mē/sē and 0-6 km shear over 20 m/s, but at the limit of CAPE availability. Multicell/MCS and possibly a few rotating cells (supercells) are the likely mode. Marginally large hail, gusts and perhaps a tornado or waterspout could occur, but are unlikely to make much impact over sea.
...E Mediterranean...
Storm-relative helicity over 300 mē/sē along the southern Turkey coast and Cyprus and moderate instability could yield multicells, MCS with some supercells as well, which can bring large hail and perhaps even a tornado, given 0-1 km low level shear in a quite large area (not only due to friction over land) above 10 m/s. A level 1 would be appropriate (off the map).
