Storm Forecast
Valid: Mon 12 Apr 2010 06:00 to Tue 13 Apr 2010 06:00 UTC
Issued: Sun 11 Apr 2010 21:10
Forecaster: DAHL

A level 1 was issued across extreme N Algeria and extreme N Tunesia mainly for marginally severe wind gusts and large hail.

SYNOPSIS

Dominating feature on the upper air maps remais the large-scale upper low that is anchored over the Alpine regions. A vorticity maximum at its southern periphery will cause weak SFC cyclogenesis over the central Mediterranean late in the period. Another upper low is located off the Iberian west coast, supporting weak WAA over SW Europe. At the SFC, high pressure persists over much of the continent.

DISCUSSION

... central Mediterranean ...

Some convective potential will exist ahead of the Mediterranean vort max / area of SFC cyclogenesis, where marginally unstable air mass should be present.
Late in the night, shear will become supportive of severe evolution, but model guidance suggests diminishing CAPE toware the evening. However, QG forcing for ascent will also increase towads Monday evening/night ... will thus introduce 50 per cent lightning probabilities but refrain from a LVL1 given too weak model support.

... extreme N Tunesia and extreme N Algeria ...

Convection over extreme N Algeria and extreme N Tunesia will be reasonably strongly sheared (20 m/s DLS). Expect isolated severe straight-line winds and marginally severe hail with the strongest cells.

... southern Iberia ...

Scattered thunderstorms may occur over southern Iberia in a region of frontogenetic forcing in the afternoon and evening hours. Severe potential should remain quite low given weak thermodynamic and kinematic fields.