Storm Forecast
Valid: Tue 05 Jun 2007 06:00 to Wed 06 Jun 2007 06:00 UTC
Issued: Tue 05 Jun 2007 09:28
Forecaster: VAN DER VELDE

SYNOPSIS

With high pressure over Scandinavia and low pressure near the Balkan, eastern flow is present over central and western Europe. A couple hundred J/kg MLCAPE should be present over a large area, but forcing is limited to orography, mostly. Three mid level lows are present on the map, over northeastern Spain, Greece, and northern Germany. A trough of the low near Greece stretches out over Italy and the northwestern Balkan.
Low level convergence zones during the afternoon are predicted by GFS over France (the west, to south side Massif Central, Jura, Vosges), northern Germany/Poland, Hungary, northern Italy, southern Romania, Alpine region, and Albania, Greece and northern Turkey.
Vertical shear is somewhat enhanced over northwestern Poland, eastern Spain, the Slovenia/Croatia region, Serbia/western Bulgaria, and northwestern Turkey.

DISCUSSION

Marginal severe weather chances exist where shear and/or buoyancy are enhanced. Mostly marginally large hail can be expected in the level 1 areas, as deep layer and low level shear seem only marginally sufficient to support supercells.

...E Spain...

Deep layer shear over 25 m/s, SREH3 up to 250m2/s2, would be sufficient for supercells, but instability is not forecast to be great.

...NW Poland...

Around 12 m/s 1-8 km shear and 8 m/s 0-1 km shear, both moderate, and good instability, should be sufficient for some organized multicell/marginal supercell storms. Large hail should be possible.

...Slovenia and Croatia...

SREH and 2-4 km lapse rates are enhanced here but with rather poor deep layer shear vectors... still think this is sufficient for large hail.

...Serbia, W Bulgaria, S Romania...

Marginal instability is forecast and good convergence. A band of > 13 m/s 0-1 km shear and more westward 15 m/s 0-6 km shear and 100-200 m2/s2 SREH3 are though to pose some chances for marginal supercells, with some chance of a tornado (low LCLs) and hail.
00Z Bucharest sounding shows potential for MLCAPE around 1000 J/kg.

...Slovakia area...

MLCAPE based on 00Z soundings in the area (Cluj-Napoca, Uzhhorod, Poprad-Ganovce) may reach around 1000 J/kg during the afternoon. Convergence in this region may produce strong multicells capable of large hail and severe gusts despite relative absence of shear.

...S France...

MLCAPE of around 500-1000 J/kg (Nimes 00Z) may support large hail. The convergence zone is bordered by deep layer shear of 10-15 m/s, sufficient to support long-lived multicells.

...NW Turkey...

GFS forecasts instability and moderate/strong (around 20 m/s) deep layer shear. In addition with LCL heights over 2000 m, if organized stoms could develop they may pose a threat of severe gusts. 00Z soundings are not showing great chances for convection, though, so no level 1 is given.
More northwestward, surface-based instability seems to disappear in the model.