Storm Forecast
Valid: Tue 11 Aug 2009 06:00 to Wed 12 Aug 2009 06:00 UTC
Issued: Mon 10 Aug 2009 21:28
Forecaster: TUSCHY

A level 1 was issued for E-Spain, the Balearic Islands and surrounding areas mainly for large hail and severe wind gusts.

SYNOPSIS

A combination of a weakening upper trough over SW-Europe, an eastward moving upper trough over N-Europe and a belt of low geopotential heights in-between results in unsettled conditions over most parts of Europe.

DISCUSSION

... SW-Mediterranean ...

The upper trough over the Iberian Peninsula remains in place but already ongoing weakening trend continues during the period. Nevertheless, numerous short-waves along its eastern fringe affect the extreme western Mediterranean.

Surface dewpoints in the lower twenties beneath a northward spreading EML assist in moderate MLCAPE of 1000-2000 J/kg. The temperature profile below 700hPa remains unchanged with 850hPa temperatures in excess of 20°C south of the Balearic Island and marginal lower values along the east coast of Spain. Although soundings from this area indicate that thunderstorms tend to be more elevated, surface based convection can't be ruled out offshore above the warm Mediterranean. Initiation will be bound to the aforementioned short-waves but will probably take place along the thermal boundary east of Spain and next to the Balearic Islands.

Strong DLS and CAPE release support organized thunderstorms with large hail and severe wind gusts the primary risk. More widespread initiation will take place over the highlighted areas of Spain beneath cold mid-/upper-levels. Shear is quite weak, but still strong enough for large hail.

The rest of the highlighted regions over N and SE-Europe will see scattered to widespread thunderstorms. Shear remains weak, but instability over the Balkans is high enough for strong updrafts with isolated large hail.

N-Finland will be monitored for an isolated tornado risk with a moist and warm surface layer and some LL CAPE in place. In addition, surface wind field backs as a weak depression forms to the west. However, discrepancies in global models preclude a level area.