Storm Forecast
Valid: Thu 08 Apr 2010 06:00 to Fri 09 Apr 2010 06:00 UTC
Issued: Wed 07 Apr 2010 22:03
Forecaster: GATZEN

A level 1 was issued for portions of western Russia, eastern Belarus, western Ukraine, and western Romania mainly for severe wind gusts.

SYNOPSIS

To the east of a subtropical high ridging into the Bay of Biscay and Ireland, numerous cut-off lows spread across Europe within rather weak geopotential. At the surface, high pressure stretches from the Bay of Biscay across Central Europe eastward, while low pressure systems are situated over southern Europe. Weak frontal boundaries are present within the high pressure area.

DISCUSSION

Western Russia to Romania

A weak convergence zone has build across eastern Europe associated with slightly increasing boundary-layer moisture. Latest soundings and observation indicate that steep lapse rates / inverted-v profiles have developed up to the 750 hPa level. Given rather cold mid-levels, most unstable parcels may rise to the 500 hPa level or higher and first thunderstorms have already formed across Belarus. On Thursday, the chance of isolated thunderstorms seems to increase along the convergence zone given some additional forcing due to a north-easterly mid-level jet streak that will also provide 15 to 20 m/s deep layer vertical wind shear. Given weak winds in the lowest few kilometres, storm rotation is not favoured, but the strong deep layer vertical wind shear may lead to some storm organization and increasing updraft strength. Combined with the dry boundary-layer, the chance of stormy wind gusts and downbursts as well as hail is expected to be large enough for a level 1. Storms will likely spread southward during the afternoon and evening hours and will likely produce rather widespread cold pools, leading to clusters of storms that will likely disappear soon after sunset.