Storm Forecast
Valid: Sat 03 Nov 2007 06:00 to Sun 04 Nov 2007 06:00 UTC
Issued: Fri 02 Nov 2007 22:59
Forecaster: DAHL

SYNOPSIS

Quasi-stationary large-scale upper ridge remains in place over western portions of Europe while an extensive upper cut-off low persists across the western Mediterranean. Intense and meandering upper zonal flow exists over northern parts of Europe, with an upper trough expected over south Scandinavia at the beginning of the period, being forecasted to dig southeastwards, extending into NE Germany and Poland towards the end of the period. At low levels ... persistent SFC high is anchored over western Europe, advecting polar air southward over central parts of Europe. Quiescent conditions and weakly unstable air remain in place over the Mediterranean regions.

DISCUSSION

... south-central Mediterranean Sea ...

It seems that best potential for appreciable CAPE will exist over the S Ionian Sea, Greece and the Aegean region, where reasonably steep low/mid-level lapse rates are expected, especially late on Saturday. However, depth of moist/saturated marine boundary layer is uncertain, and MLCAPE may remain rather weak where moisture is shallow. However, some confidence exists that locally sufficient moisture will accumulate to support MLCAPEs in excess of 1000 J/kg.

At the southern periphery of the Mediterranean upper low, band of moderately strong mid/upper winds will result in DLS magnitudes of 15 to 20 m/s, increasing towards the south.
With sustained DCVA-forced ascent thunderstorm activity should persist over this region, and kinematic/thermodynamic profiles suggest that isolated marginal severe storms are possible. Threat includes hail and straight-line wind gusts. Strong low-level buoancy should be present especially along the Tunesian coast, which may support a few waterspouts. Altogether severe threat appears to warrant a marginal categorical risk.

... S Scandinavia ... Baltic-Sea region ...

Sporadic lightning may accompany shallow convection associated with the Scandinavian upper trough. At the moment, it is anticipated that this activity will be too insignificant to necessitate a thunderstorm forecast.