Storm Forecast
Valid: Tue 25 Nov 2008 06:00 to Wed 26 Nov 2008 06:00 UTC
Issued: Mon 24 Nov 2008 22:57
Forecaster: DAHL

SYNOPSIS

quite deep and large upper long-wave trough persists over the European continent ... attaining an allover positive tilt, with the trough stretching from S Iberia across the N Mediterranean into the Baltics towards early Wednesday morning. Main low-level baroclinic zone should be stretching from the SW Mediterranean northeastwards into the Ukraine at the beginning of the period, making some eastward progress during the period. Along this boundary, a rather large wave cyclone is simulated over the N Mediterranean early in the period, undergoing some weakening as it tracks into the Balkans through the remainder of the day. A large SFC high pressure area builds eastwards into Europe in the wake of the front.

DISCUSSION

... S Adriatic region ... SE Aegean, E Mediterranean ...

It does not seem that substantial CAPE will exist in the warm-sector air mass over the central Mediterranean and the Balkans, though persisting southerly flow from the N Sahara may steepen the mid-level lapse rates somewhat. Overlap of positive CAPE and favorable deep shear is somewhat patchy, but 20 m/s DLS will be present locally. Also, low-level shear is simulated to be larger than 10 m/s over the Adriatic coastal regions and S Italy, so that some threat for rotating thunderstorms, including a brief tornafo or two, exists. However, dominant mode should be weakly to moderately-well organized multicellular storms, the strongest of which may produce marginally severe wind/hail.

... W Mediterranean ...

In the wake of the front, comparatively shallow convection is likely to develop over the W Mediterranean Sea. Steep low-level lapse rates should boost the near-surface buoyancy, enhancing the chance of non-mesocyclonic tornaodes. 0-500 m lapse rates are simulated to exceed 25 K over the Gulf of Genoa late in the period, which is where the waterspout chances should be highest, though convection may be too shallow to be appreciably electrified over this region.