Storm Forecast
Valid: Sun 18 Mar 2018 06:00 to Mon 19 Mar 2018 06:00 UTC
Issued: Sat 17 Mar 2018 15:14
Forecaster: TUSCHY

A level 1 was issued across N-Morocco and far NW-Algeria mainly for isolated severe wind gusts and a low-end tornado risk.

A level 1 was issued for parts of the W-CNTRL Mediterranean mainly for isolated large hail.

A level 1 was issued for far NW-Italy and surrounding areas mainly for excessive rain and an isolated waterspout risk.

A level 1 was issued for parts of W-CNTRL Italy and the W-CNTRL Balkan States mainly for excessive rain.

A level 1 was issued for the E-Ionian Sea mainly for isolated large hail.

SYNOPSIS

A deep trough is centered over W-/CNTRL-Europe. A cold and dry airmass affects most of Europe excluding marginal better BL moisture surrounding/atop the Mediterranean. Embedded low amplitude waves cricle that trough and add temporal lift to most areas over the Mediterranean.
Numerous frontal boundaries affect the Mediterranean and the Black Sea but they are more of interest for phase changeover (rain/snow) than for organized DMC activity.

DISCUSSION

... Mediterranean ...

Three foci for higher rainfall amounts are forecast. One is placed over far NW-Italy beneath a decaying vortex, which advects modified marine air mass onshore. Slow moving showers and thunderstorms are expected with a localized heavy rainfall risk. Enlarged LL temperature gradients offshore also add an isolated waterspout risk - enough for a small level 1.

The other two areas are the west facing coasts of CNTRL-Italy and the Balkan States, which see a prolonged period of onshore flow of a marine airmass beneath the left exit of a strong upper jet. Repeatedly onshore moving convection results in higher rainfall amounts with local amounts matching the level 1 criterion. Hence small areas were added.

An isolated large hail risk ecists over the N-Aegean Sea during the day as an upper trough lifts to the NE. 15 m/s DLS and 400-600 J/kg SBCAPE support a few better organized thunderstorms with isolated large hail. A low-end waterspout risk is anticipated despite LL staying a bit warm (lessening the LL lapse rates). Due to the isolated and short nature of any severe risk, no level area was added.

N-Morocco and far NW-Algeria sees a decent overlap of moderate CAPE and strong LL/DLS. Weak mid-level lapse rates probably limit the hail risk, but isolated severe wind gusts and a localized tornado event along the coast can't be ruled out....daytime convection.

As cold mid-levels overspread the W-Mediterranean, enlarging mid-level CAPE profiles with 400-800 J/kg SBCAPE and 10-15 m/s DLS indicate an isolated large hail risk with pulsating convection....nighttime convection.

During the end of the forecast, a flare-up of convection is anticipated over the E-Ionian Sea ahead of a sharpening trough with enhanced WAA ahead. Shear/CAPE offshore and along the coast is supportive for isolated large hail. Heavy rain accompanies convection but late onset probably limits rainfall amounts until 06 UTC.