Storm Forecast
Valid: Tue 13 Mar 2007 06:00 to Wed 14 Mar 2007 06:00 UTC
Issued: Tue 13 Mar 2007 01:55
Forecaster: VAN DER VELDE

SYNOPSIS

Calm weather persists under a blocking high pressure area over the European mainland, while active depressions affect Scotland and Scandinavia. A shallow low with an unstable airmass lingers over the southern Mediterranean Sea. Upper cut-off lows cause somewhat unstable conditions around Portugal and the southern Black Sea/Turkey region, into the eastern Mediterranean Sea later in the period.
This latter system is associated with moderate deep layer shear here and there, but low boundary layer mixing ratios could inhibit somewhat the development of storms and the chance of marginally large hail. An isolated waterspout is not ruled out over the Mediterranean Sea.

Some thunder may be possible west of Norway where equilibrium level temperatures reach -30C, with actually not that low mixing ratios (higher than Turkey), with surface convergence (GFS) providing lift, as well a mid level vorticity maximum (SW-Norway, afternoon). An isolated strong gust could occur.

A small area is indicated in the upper trough over N-Portugal/Spain where GFS indicates very steep 2000-4000 m temperature lapse rates, with also sufficiently cold EL temperatures (-30C), while surface convergence may trigger convection during the afternoon. As of 00Z, La Coruna sounding has a cap that could be overcome if the temperature manages to reach 21 degrees.