Storm Forecast
Valid: Fri 21 Sep 2012 06:00 to Sat 22 Sep 2012 06:00 UTC
Issued: Thu 20 Sep 2012 18:36
Forecaster: TUSCHY

SYNOPSIS and DISCUSSION

The main cyclonic vortex is centered over the North Sea/Denmark with cool and dry air affecting most parts of N/C-Europe. Two cold-core lows, one over Bulgaria and the other one west of Portugal, shift slowly eastwards and cause unsettled conditions with showers and thunderstorms.

Of synoptic interest might be the CMC/GFS model solution, showing some type of shallow warm core depression evolving W/NW of Portugal during the end of the forecast period with a constant movement to the NE. GFS even has clear signals of a well structured subtropical cyclone in the extended (t=36-48 h) period. This scenario will be closely monitored in later model runs and if necessary discussed in more detail in tomorrow's outlook.

Numerous areas were highlighted with low probability lightning areas. Limited CAPE precludes any severe DMC in all cases and therefore no severe thunderstorm risk is expected for this forecast period. Sporadic lightning activity may occur outside of the lightning areas (e.g. Scotland and most parts of the North Sea), but missing foci for CI and sporadic nature preclude a broad lightning area for now.

The only area with a low-end severe risk may evolve over W-C France in case LL moisture is as robust as GFS forecasts. Shear would be adequate for an isolated stronger storm with marginal hail/strong wind gusts. Confidence however is low (e.g. more representative EZ regarding BL moisture keeps CAPE below 200 J/kg).