Storm Forecast
Valid: Tue 05 May 2009 06:00 to Wed 06 May 2009 06:00 UTC
Issued: Tue 05 May 2009 02:29
Forecaster: VAN DER VELDE
A level 1 was issued for northern Russia mainly for severe wind gusts / tornado.
A level 1 was issued for northeastern Ukraine mainly for hail.
SYNOPSIS
Western flow has recommenced over the northwestern half of Europe, and the large region of weak low pressure filled with unstable airmass are now found from Italy, the Balkan, and northward all the way to northern Russia. Thunderstorms can pop up easily in southeastern Europe, in particular over elevated grounds and in range of the sea breeze. Wind shear is weak, with a few exceptions.
DISCUSSION
...northern Russia...
During late morning/early afternoon a shortwave trough passes over the northern end of a plume of higher theta-e advecting northward. CAPE values (few hundred J/kg) are low, but convective initiation does seem likely with the strong available forcing, and is placed well within the area of shear. The kinematical parameters are strong: 25-30 m/s DLS, 250-400 mē/sē 0-3 km SREH, enhancing the chances for storm rotation, while also LLS (0-1 km) of 10-20 m/s range is already beyond sufficient for tornadogenesis and bowing line segments. Corfidi vectors suggest forward-building MCS, with shear vectors under a large angle to the cold front enhancing bow echo potential with severe gusts, which appear the primary threat, but a tornado is quite possible too.
...northeastern Ukraine...
Around a lobe of an upper low, large scale ascent will be present. At the same time, decent vertical DLS (>10 m/s) and 3 km SREH (100-200 mē/sē) along a north-south predicted convergence zone can produce a few organized multicell storms with large hail.
