Forecast Update
Valid: Mon 21 May 2007 06:00 to Tue 22 May 2007 06:00 UTC
Issued: Mon 21 May 2007 13:48
Forecaster: GROENEMEIJER

SYNOPSIS

Refer to convective forecast...

DISCUSSION

Balkans...

North of a stationary front stretching from Montenegro to eastern Bulgaria, warm air is advected eastward in the lower troposphere. However near the surface in vicinity of the front, winds are north to northwesterly creating strong directional shear and about 20 m/s 0-6 km bulk shear. Abundant moisture with surface dew points of 17-20C in the lower Danube Valley and eastern Serbia suggests that about 2000-2500 J/kg SBCAPE should be available there. Relatively high buoyancy can be expected below 700 hPa, too. This altogether suggests that supercells are likely with a few tornadoes possible. Additionally, large or very large hail and some strong to severe gusts are expected. Weaker buoyancy and shear are expected further north, but risk of large hail will be present there as well.
The storms will likely consolidate into a large MCS moving into Bosnia and/or Montenegro in the evening.

Benelux, NW Germany...

12Z soundings show that a warm layer is capping a cool layer of air from the North Sea that is not likely to be broken far enough to the northwest to profit from the higher shear available there.