Storm Forecast
Valid: Fri 21 Oct 2016 06:00 to Sat 22 Oct 2016 06:00 UTC
Issued: Thu 20 Oct 2016 14:34
Forecaster: TUSCHY

A level 1 was issued for the Ionian Sea and surrounding areas mainly for excessive rain, isolated large hail and a few tornado events.

SYNOPSIS and DISCUSSION

Extensive cold-core low sits over CNTRL Europe, trapped by two strong ridges up- and downstream. South of that low, brisk westerlies affect the Mediterranean, where temporal/regional overlap with a moist and unstable air mass results in augmented thunderstorm probabilities.

The Ionian Sea will be the main focus for strong to severe thunderstorm activity. Undisturbed BL air mass with rich moisture (0-500 m mixing ratios in excess of 13 g/kg) surges NE ahead of the deep vortex over CNTRL Europe. A 20 m/s 500 hPa speed max crosses the Ionian Sea and pushes 0-6 km bulk shear to 15-20 m/s. MLCAPE of 1000 J/kg over the Ionian Sea decreases to the north as mid-level lapse rates and BL moisture subside. MUCAPE plume of the Ionian/S-Adriatic Sea however spreads far to the NE and affects parts of the SW-Balkan States.

The Ionian Sea will experience a prolonged period with repeatedly developing thunderstorms, which cluster betimes and move NE towards Greece. Strongest activity remains offshore, but a few severe storms may also affect the W/SW coast of Greece and S Albania. The main hazard will be a few large hail reports and heavy rain. Along the east coasts of the Ionian and the SE Adriatic Sea, a few waterspout events will be possible. Daytime driven thunderstorms on an isolated scale may spread well inland and therefore the lightning area was expanded to the N/NE.

From SE Spain to Sicily, isolated strong to severe convection is possible with divergent QPF signals in model data. In general, up to 800 J/kg MLCAPE and 15-20 m/s DLS support a few organized multicells with large hail, gusty winds and heavy rain. An isolated tornado event is not ruled out. No real focus for any enhanced severe risk exists and therefore no level area was issued.

A strong impulse approaches SW-Portugal after 21 UTC from the west. Advection of a subtropical air mass ahead of the trough probably results in a mess of numerous showers/a few thunderstorms. The main hazard will be excessive rain and an isolated waterspout event due to increasing LL CAPE.