Forecast Update
Valid: Mon 29 May 2006 13:00 to Tue 30 May 2006 06:00 UTC
Issued: Mon 29 May 2006 13:45
Forecaster: GROENEMEIJER

(corrected grammar at 17:04 UTC)

SYNOPSIS

Refer to Storm Forecast...

DISCUSSION

northern Italy

A pool of cold air fills much of the eastern Po-Valley, precluding surface-based convection to initiate there. Across the western Po-Valley a moister and warmer low-level air-mass is present. The 12:00 UTC Cuneo sounding shows steep lapse rates in the 800 to 700 hPa layer, and a capping inversion that should be overcome soon as the trough approaches from the northwest.
Together with observed values of 25/19 sfc T/Td about substantial SBCAPE should be present locally. Convective initiation is expected in the coming hours over northwestern Italy, most likely along the western edge of the cold air south of Milano, where towering cumulus is apperent. The strong shear profiles sampled by the aforementioned soundings are more than sufficient for the formation of supercells. These will likely bring large or very large hail in places as well as a few damaging gusts. Tornadoes may form as low-level shear is sufficient and the storms may favourably interact with the aformentioned boundary.

northern Adriatic/northwestern Balkans

Surface-based convective development is likely later this afternoon and evening. Storm modes may include a couple of supercells with an attendant risk of large hail, strong winds and a small risk of tornadoes.

southeastern France

Steep low-level lapse rates and strong shear were detected by the 12:00 UTC Lyon sounding. Bows and perhaps a couple of rotating storms are expected over the area until about 18:00 UTC. These may bring strong to severe winds in places as well as large hail, and -given the strong low-level shear- perhaps a tornado as well.