Storm Forecast
Valid: Sun 09 Oct 2016 06:00 to Mon 10 Oct 2016 06:00 UTC
Issued: Sun 09 Oct 2016 00:47
Forecaster: PISTOTNIK

A level 1 was issued from the Balearic Islands towards N Algeria large hail, severe convective wind gusts and excessive convective precipitation.

SYNOPSIS

A "high-over-low" blocking pattern remains in place. A strong anticyclone with a sea level pressure above 1040 hPa sits over Scandinavia. An extensive upper-level low filled with polar air covers much of the continent from France to the Ukraine, from S Norway to the N Balkans.
Isolated non-severe thunderstorms are possible in the second half of the forecast period over the North Sea, where the coldest drop at 500 hPa will slip westward, and in its first half along the Ukrainian/Russian border, where a tongue of warm, moist and marginally unstable air wraps around the dominant surface cyclone and is overspread by strong geostrophic lift.
Otherwise, thunderstorm activity will be confined to parts of the Mediterranean Sea, discussed below.

DISCUSSION

... W and central Mediterranean ...

Several upper-level vorticity maxima overspread this region at the southern flank of the big cut-off low. Seasonably rich low-level moisture allows a few hundred J/kg of CAPE, which will more likely be released into isolated to scattered storms as the forecast period proceeds.
Vertical wind shear is weak near the surface but increases at mid levels, yielding values of 10-15 m/s across the lowest 3 km. Convection may organize from the Balearic Islands towards Algeria, where steeper lapse rates may support CAPE up to 1000 J/kg and storms may grow deep enough to benefit from this stronger shear. Large hail, severe wind gusts and heavy precipitation are possible, and a level 1 seems to be warranted despite somewhat uncertain convective initiation.
Further north and east, meager CAPE and a mostly embedded nature of convection should keep its severe weather risk low. A diffuse low-pressure area starts to deepen over the Tyrrhenian Sea. One or two waterspouts are not ruled out in its converging wind field, especially towards Monday morning along the Italian west coast.