Storm Forecast
Valid: Wed 20 Mar 2013 08:00 to Thu 21 Mar 2013 06:00 UTC
Issued: Wed 20 Mar 2013 08:08
Forecaster: PUCIK

A level 1 was issued for Northwestern Algeria and Tunisia mainly for marginally large hail and severe wind gusts.

SYNOPSIS

With low geopotentials over Northern Europe, fresh westerly flow persists over much of the continent, especially over the southern half. A broad but rather low amplitude trough should cross France and the Western Mediterranean during the day, continuing towards east. Another trough will move over Ukraine and the northern Black Sea. Closer to the surface, high pressure system dominates over Scandinavia with shallow lows over the Mediterranean and Western Europe. Most of Europe will be under too dry conditions to support any notable DMC risk, though few areas might experience isolated to scattered tstms.

DISCUSSION

... France ...

Steepening of the mid-level lapse rates can be expected with the passage of the trough associated with the cooling of mid and upper tropospheric temperatures. However, low-level moisture will be rather meager, mixing ratios persisting in the range of 4-5 g/kg. Moreover, forcing should be confined to the region ahead of the unstable airmass, so that no significant contribution can be expected. This prevents us from going for Lvl 1 as especially southern part of the area will be under rather strong DLS with values around 20 m/s.

... Northeastern Algeria, Tunisia ...

Some hundreds J/kg of CAPE should be available thanks to the steep mid-level lapse rates over the region. Together with at least some forcing on the forward flank of the trough along with the strong vertical wind shear should provide some slight chance for well organised DMC, despite weak CAPE. Marginally severe large hail or wind gusts should be the primary threat accompanying well organised multicells and/or supercells.