Storm Forecast
Valid: Sun 18 Jun 2006 06:00 to Mon 19 Jun 2006 06:00 UTC
Issued: Sat 17 Jun 2006 17:25
Forecaster: GATZEN/DAHL

SYNOPSIS

Broad subtropical ridge present over Mediterranean ... with a short-wave trough to the west over Iberian Peninsula ... yielding a deep southwesterly flow over western Mediterranean, and southern France. To the north ... small cut-off low over Poland digs eastward into western Belarus ... while northern Atlantic trough affects northwestern Europe. At lower levels ... warm an unstable airmass characterized by rather steep lapse rates and rich boundary layer moisture is present from northern France to southern Germany and further to western Belarus ahead of the cut-off low. Atlas EML has spread across western and central Mediterranean.

DISCUSSION

Poland

Ahead of small cut-off low ... warm and unstable airmass will be present over eastern Poland and western Belarus. While cold front of the cut-off low moves eastward .... upper jet streak at the southern flank of the cut-off propagates eastward and should overspread the warm airmass. QG forcing as well as low level forcing along the frontal boundary/old outflow boundaries should yield to initiation during the day. Given 20 m/s DLS ... multicells and supercells may form ... capable of producing large hail and severe wind gusts. Threat seems to be lower than for the last two days.

France

It seems that CAPE will remain on the order of 500 to 1000 J/kg ... but S France should see some 15 to 20 m/s deep shear in the vicinity of rather weak and elongated vort max. 850 hPa flow of 5 to 10 m/s is advertised by MM5 ... altogether providing marginal deep-layer shear for organized severe. Given that reather widespread TSTM activity is anticipated ... back-ground shear should be augmented locally by numerous outflow boundaries from neighboring/previous convection ... and a few mesocyclones may develop ... though primary mode should be multicellular storms with a threat of marginally severe winds/hail. Hail threat may be augmented by the mesocyclones ... also ... a brief tornadfo cannot be ruled out though threat should be somewhat limited given weak background LL shear.