Storm Forecast
Valid: Mon 02 Jul 2007 06:00 to Tue 03 Jul 2007 06:00 UTC
Issued: Sun 01 Jul 2007 23:12
Forecaster: GROENEMEIJER

SYNOPSIS

Monday at 06:00 UTC... a strong southerly flow is present over the Central Russian Plain advecting warm air northward. To the west, a compact mid/upper closed low is located over Belarus and moving eastward. Further upstream... a ridge stretches along a line from southern Sweden to the Adriatic Sea.
Farther to the west, a NW-SE-oriented trough stretching from Scotland to the Western Mediterranean moves eastward. It is followed by a strengthening WNW-ly jet that moves into western Europe.

DISCUSSION

North Russian Plain...

A small vort max located over the upper northern Dvina region moves northward and should produce very strong lift over the northern Plains. In association with about 1000 J/kg MLCAPE forecast by GFS, and strong deep-layer and low-level shera, this may cause a marginally severe bow-echo storm to develop moving northward along and to the east of the Dvina River. This activity should be capable of producing some winds exceeding the severe threshold of 25 m/s locally. Low shear and low LCL heights suggest some potential for tornadoes will be present, too. Isolated large hail will be possible as well.

Central Russian Upland...

Upward vertical motion is expected ahead of the approaching upper low over Belarus. 0-6 km shear of around 20 m/s is the south and high ambient vertical vorticity in combination with low lcl heights suggests that the potential for a few, relatively weak, tornadoes exists with low-topped supercell storms over the southern half of the area and with more poorly organized storms further north. Some marginally severe large hail cannot be excluded either in the southern half of the level 1.

Germany, Czech republic, Poland, Austria...

Remaining widespread cloudiness from convective activity over west Germany and the western Alps are expected to pose a rather major problem for convective initiation further east. Increasing instability over western and central Poland, the Czech republic and northeastern Austria should however occur, albeit quite late. There, shear and CAPE should be and remain relatively weak so that a significant threat of either hail, tornadoes or winds is currently not anticipated.