Storm Forecast
Valid: Fri 29 Jul 2011 06:00 to Sat 30 Jul 2011 06:00 UTC
Issued: Thu 28 Jul 2011 17:35
Forecaster: TUSCHY
A level 1 was issued for E-Spain mainly for an isolated large hail and strong wind gust event.
A level 1 was issued for Albania all the way to central Romania mainly for isolated large hail and strong wind gusts.
SYNOPSIS
No major changes occur in the European streamline pattern. A broad upper trough remains in place over central Europe. Beneath this feature, scattered showers / thunderstorms will probably occur. A weak upper wave enters W-Europe during the forecast period and assists in some convection over the extreme W-Mediterranean. The rest of the Mediterranean region remains hot and stable
DISCUSSION
...Italy, Romania, W-Ukraine and the Balkans...
Flat upper trough is still in place. Cool mid-levels and weak BL moisture recovery from the Black Sea assist in widespread modest MLCAPE over Romania and Bulgaria. Further west, mid-levels cool down with scarce moisture just above the planetary boundary layer (may keep surface dewpoints down as daytime driven mixing occurs), so widespread 200-500 J/kg MLCAPE are expected with up to 800 J/kg along the coast of the Adriatic Sea and over Italy. Shear (deep layer and BL ) is weak with somewhat augmented values along the S/E fringes of the highlighted area. Therefore, a marginal level 1 was added to account for an isolated large hail event next to strong wind gusts. Otherwise, strong wind gusts and marginal hail will be the main hazard.
... E-Spain ...
Flow becomes more cyclonically curved during the day, as a short wave approaches Spain from the NW. Along the E-coast of Spain, a pronounced zone with convergence flow becomes established with increasing CAPE, as mid-level temperature profiles cool down during the forecast. 500-800 J/kg MLCAPE, weak forcing and up to 15 m/s DLS allow for a few better organized thunderstorms to form with isolated large hail and strong wind gusts. Isolated thunderstorms keep going during the night and probably increase in coverage, as better forcing gradually approaches from the NW....mainly offshore. We highlighted the coast with a level 1 to cover the region with best CAPE, but right now only a few thunderstorms are expected. Hence this will be a marginal level 1 situation.
... Parts of Norway/Sweden all the way to extreme W-Russia ...
A quasi-stationary low pressure area over the Baltic Sea deepens somewhat and hence some modest strengthening of the LLJ is expected...up to 15 m/s from the east. Hence, a warm and moist air mass advects far to the west with CAPE increasing from west to east...from roughly 400 J/kg to more than 1kJ/kg. Shear at mid/upper levels remains weak. The main risk will be marginal hail and strong wind gusts.
Of more concern will be the trend for numerous slow moving thunderstorm clusters over far W-Russia, where locally excessive rainfall may occur. However, no concentrated LLJ maximum is expected, so confidence in a more robust heavy rainfall event remains too marginal to go with a level 1.
