Storm Forecast
Valid: Mon 25 Aug 2008 06:00 to Tue 26 Aug 2008 06:00 UTC
Issued: Sun 24 Aug 2008 20:10
Forecaster: GROENEMEIJER

SYNOPSIS

On Monday at 06 UTC... the mid and upper level flow across Europe is predominantly not very strong and zonal. Over the waters between Scotland and Iceland, a broad and intense cyclonic vortex is present, that moves slowly eastward. A sharp, intense trough stretches from Lithuania to the Krimean peninsula and translates east northeastward during the day.

DISCUSSION

NE Ukraine, Belgorod, Voronezh, Kursk...

Ahead of the intense trough, a cold front is initially located along the Belorussian/Russian border across Ukraine to just east of Odesa. A 15 m/s southerly low level jet is expected ahead of the front, yielding relatively strong low-level shear. Deep-layer shear of about 20 m/s should be present also. A number of storms, likely linearly organized is expected to develop during the moring and/or early afternoon. Low storm-relatively helicity will inhibit updraft rotation to some extent, but one or two tornadoes are not ruled out. Additionally localized severe gusts are possible. The relatively weak CAPE should limit the large hail threat, but some 2-3 cm hail is possible. The line should cross the Ukrainian/Russian border during the afternoon and proceed east northeastward before moving out of the forecast area during the late evening.

Eastern Spain...

Although forcing for upward motion from the mid and upper atmosphere should be virtually absent, numerical models do produce some isolated to scattered storms across teh eastern Spanish highlands and possible even across the adjacent Mediterranean waters. To surface-based storms developing across the mountains, on the order of 1500 J/kg MLCAPE should be available per GFS. Deep-layer shear around 15 m/s suggests some storms could develop into well-developed multicell clusters. These may produce a few severe gusts and isolated large hail with diameters up to 3 or 4 cm.