Storm Forecast
Valid: Mon 23 Jul 2007 06:00 to Tue 24 Jul 2007 06:00 UTC
Issued: Sun 22 Jul 2007 22:04
Forecaster: GROENEMEIJER

SYNOPSIS

Monday at 06 UTC... south of low pressure over N Europe flow over the European continent is WSW in the mid- troposphere.
An intense mid-/upper-level trough west of Brittany moves eastward reaching the Benelux on Tueday morning. Downstream over eastern Europe only very weak vorticity perturbations are forecast in the flow and the forecast where convective storms will form is challenging.

DISCUSSION

Central Russian Upland, Central and SW Ukraine, N Romania, N Moldova...

Remnants of Sunday's convective activity over Poland, Belarus, Ukraine and Slovakia may be ongoing on Monday morning. This convection was tied to a cold front, whose weak remants will be undergoing further frontolysis on Monday. On the warm side of the remnant baroclinic zone over the northern Carpates, storms are most likely to form. New development is also likely ahead near the outflow boundary of the MCS that affected Belarus on Sunday. Given that deep-layer shear should be moderate with about 15 m/s 0-6 km bulk shear and up to around 1000 J/kg MLCAPE should be available, large hail will be possible with the storms. Additionally, a few severe gusts are possible.

W-Central and Central France...

Cold air behind the cold front of a surface cyclone forming over N France, becomes rather unstable over much of W and central France. Convective lines are likely as low-level shear should be rather strong with 12.5 m/s 0-1 km shear forecast. Short-lived rotation in updrafts cannot be excluded, but low amounts of helicity should limit the threat of supercells and attendant tornadoes, although they cannot be fully ruled out. A few gusts approaching severe levels and some hail up to around 2 cm are quite possible however.