Storm Forecast
Valid: Wed 04 Jul 2007 06:00 to Thu 05 Jul 2007 06:00 UTC
Issued: Tue 03 Jul 2007 20:46
Forecaster: DAHL
SYNOPSIS
Unseasonably intense upper zonal flow is present over the Atlantic, curving around a large-scale upper low which is centered over the North Sea region. Several short-wave troughs are embedded in the upper jet, which are expected to induce rather intense cyclogeneses over Poland late in the period as well as over the eastern Atlantic. The large-scale upper low is expected to slowly spread southeastwards during the period. At low levels ... a large low-pressure system is accompanying the upper system being augmented/merging with the developing cyclones associated with the short-wave troughs. Main frontal boundary is expected to curve from northern Spain across the N mediterranean and N Italy into the Baltic States.
DISCUSSION
... E France ... Alpine Region ... S Germany ... Czech Republic ...
In the postfrontal environment, numerous showers and thunderstorms should form in uncapped and deep polar air mass. LLS seems to be rather large especially from E France across the Alpine Region, S Germany, and the Czech Republic, so that at least briefly organized storms capable of marginally severe hail and possibly also a tornado or two may occur.
... Extreme NE Italy ... N Balkan States ... E Poland ... S Baltic States ... W Belarus ... W Ukraine ...
It seems that very strong forcing for upward motion, as well as strong deep-layer shear will overspread the frontal boundary from the northern Mediterranean into the eastern half of Europe during the period. CAPE will likely be rather weak but sufficient for deep convection. Given the strong forcing and strong shear, evolution of a linear MCS/line segments/bow echoes and isolated supercells seem likely. Main threats should be severe wind gusts as well as large hail, though an isolated tornado or two cannot be exluded either. Bulk of convection and attendant severe weather activity may well occur in the late evening to early Thursday morning time frame.
