Storm Forecast
Valid: Sun 01 Feb 2009 06:00 to Mon 02 Feb 2009 06:00 UTC
Issued: Sun 01 Feb 2009 00:04
Forecaster: SCHLENCZEK
SYNOPSIS
A strong low pressure complex over western Iberia will move eastward during the period. Other upper-level disturbances are present over the western Mediterranean and Germany. The upper trough over Iberia is surrounded by an 80 m/s upper jet streak that is forecast to weaken while the trough digs southward. The most important feature on Sunday with respect to organized convection is a small upper shortwave trough over the central Mediterranean. Near the trough axis / left exit region, slight to moderate instability is forecast in an environment with enhanced deep layer shear.
High pressure will persist over Scandinavia and a dry arctic airmass is advected into western / central Europe. Stable conditions are expected to continue some more days over the northern parts of Europe.
DISCUSSION
...SW Iberia, Strait of Gibraltar, NW Morocco...
The cold front of the low pressure system west of Iberia will cross southern Portugal on early Sunday morning. A small region with more than 30 m/s deep layer shear and some low-end CAPE exists over southern Portugal / southern Spain. Ahead of the trough, strong QG forcing is expected with the upper vort-max. Current thinking is that some organized multicells may develop along the cold front, capable of producing isolated severe gusts and perhaps a tornado. The threat of severe weather should diminish in the afternoon as the cold front weakens. A level-1 threat should be warranted for the first half of the forecast period.
... C Mediterranean, Sicily, S Italy, SW Ionian Sea...
Ahead of an upper shortwave trough, moderately warm and moist air is advected towards southern Italy. MLCAPE in order of 500 J/kg should be available and about 20 m/s deep layer shear and 200 J/kg SRH3 may allow organized multicells and perhaps a few supercells, capable of producing isolated large hail and severe gusts. Locally enhanced LLS as well as low LCL heights may pose a risk of isolated tornadoes. Although the region with an overlap of moderate CAPE and strong DLS is rather small, a level-1 threat is warranted for the region.
