Storm Forecast
Valid: Thu 23 Dec 2010 06:00 to Fri 24 Dec 2010 06:00 UTC
Issued: Thu 23 Dec 2010 01:27
Forecaster: DAHL

A level 1 was issued across the W Balkans ... S Italy ... the Ionian Sea ... the S Adriatic Sea ... mainly for severe wind gusts ... hail ... excessive rainfall ... and tornadoes.

SYNOPSIS

... SYNOPSIS ...

A deep quasi-stationary upper long-wave trough extends into the Mediterranean Sea ... with an imbedded short-wave moving northwards along its eastern periphery on Thursday, which should envigorate the extensive Mediterranean SFC low. Weak instability is expected to persist over parts of the Mediterranean in the warm-sector air mass of this system.

... DISCUSSION ...

... western and central Mediterranean ...

It seems that weak instability will persist over the western Mediterranean during the period. In addition, a plume of rather steep mid-level lapse rates should spread across the Ionian Sea late in the period leading to some instability there as well.

Low-level shear seems to be in the 7 to 10 m/s range across most of the area, and 10 m/s over Italy and the western Balkans. However, deep shear will be limited to the Ionian and S Adriatic Sea ... where capping will likely be strongest.

Overall it seems that there exist some chances that a brief/isolated tornado forms especially along the western coastal regions given the strong LLS. But weak DLS should generally limit storm longevity.

Towards the Ionian Sea, S Italy and the S Adriatic Sea, the instability and the kinematic support improve, but storm development is uncertain. If storms form, these may develop into line segments and/or supercells, capable of damaging winds and hail. Along the southeastern parts of the Balkans, frictionally-enhanced low-level shear may in addition support a tornado.

The eastern Balkan States will likely see prolonged, partly convectively-enhanced rainfall.