Storm Forecast
Valid: Sat 25 Jul 2009 06:00 to Sun 26 Jul 2009 06:00 UTC
Issued: Fri 24 Jul 2009 22:41
Forecaster: DAHL
A level 2 was issued across the western Ukraine for large hail, severe wind gusts, excessive rainfall, and tornadoes.
A level 1, surroundings the level 2, was issued across the western Ukraine, Moldova, and Romania mainly for large hail, ssevere wind gusts, and excessive rainfall.
A level 1 was issued across NW Germany and the Benelux countries mainly for tornadoes.
SYNOPSIS
Broad meandering upper westerlies are present over the Atlantic and across Europe. An upper trough will affect E Europe on Saturday, with warm/unstable air being present to its east. The next trough will reach the British Isles late in the period, with some upper ridging present downstream, spreading into central Europe during Saturday night.
DISCUSSION
... W Ukraine ... Romania ... Moldova ...
Convection will likely develop ahead of the central/east European upper trough. CAPE in the warm/moist plume ahead of the trough should be on the order of 1500 J/kg, with DLS around 20 m/s, locally in excess of 25 m/s, which will be sufficient for well-organized thunderstorms. However, models seem to put bulk of precip in the WAA regime west of the frontal boundary, with little development in the SFC-based unstable air. However, it does seem that strong DCVA forcing will overspread Romania and the W Ukraine during the day/evening, and confidence is rather high that thunderstorms will initiate.
Main storm modes should be linear segments and supercells, both capable of large hail and severe wind gusts. Over the western Ukraine, LLS is simulated to increase in the early evening hours so that an additional threat for tornadoes seems to exist. Given anticipated large size of the storms, excessive amounts of rain may occur.
... mainly NW Germany ... Benelux countries ...
Farther west in the thermal-trough region, diurnally-driven showers and thunderstorms are anticipated. As is typical of modified maritime polar air, little capping and a rather moist BL will be present, so that a few funnel clouds / tornadoes may occur. Best chance of this to happen may exist over NW Germany and the Benelux countries where 10 m/s LLS are predicted.
