Storm Forecast
Valid: Tue 07 Feb 2012 06:00 to Wed 08 Feb 2012 06:00 UTC
Issued: Mon 06 Feb 2012 21:15
Forecaster: TUSCHY

A level 1 was issued for parts of NE Greece mainly for heavy rainfall amounts.

SYNOPSIS

A deep cold-core cyclonic vortex is situated over the Mediterranean. Further north, ridging builds in over NW/N-Europe, whereas numerous cold-core lows still affect E/NE Europe. This complex set-up results in widespread unstable conditions over offshore areas like the Mediterranean. Otherwise, a cold and dry air mass precludes deeper convection. Another intense/damaging katabatic wind event (bora) along the NE/E coast of the Adriatic Sea is expected with gusts exceeding 35, in favored spots 50 m/s.


DISCUSSION

... Mediterranean ...

Yesterday's rapid cyclogenesis over the far SE Ionian Sea slowly fills up and splits up into numerous smaller-scale vortices. SSTs in general range between 14-18°C, with somewhat lower values along the south coast of France and the N-Adriatic Sea. The only parameter, which keeps thunderstorm probabilities limited will be the utterly dry air mass, which advects atop the Mediterranean (0-1 km average mixing ratio below 2 g/kg). Hence a long fetch of BL moisture recovery is needed for adequate CAPE build-up. The main area of thunderstorm activity probably shifts south of Sicily/Italy, but we expanded the low-end thunderstorm probability far to the NW to account for some isolated storms over the W-Mediterranean. DLS remains in the 10-15 m/s range, so thunderstorms will be not well organized, given MLCAPE below 400 J/kg to work with. Marginal hail and strong wind gusts will be the primary risk.

Like yesterday, numerous convergence zones are expected atop the Mediterranean, which may be the foci for isolated waterspout development, given modest LL CAPE and gradually relaxing LL winds. However, given only slowly recovering LL thermodynamic profiles, pretty high LCLs and diffuse forecasts of any convergence zone, no level was added for that risk.

A localized heavy rainfall risk exists over Greece, the Aegean Sea and W/SW Turkey. The still pretty strong circulation of the depression may be the focus for locally enhanced convergence and better forcing. BL moisture atop the Aegean Sea is also sufficient for MLCAPE in excess of 500 J/kg. Also winds below 4 km AGL remain strong with velocity values of 15 m/s or more at 850 hPa forecast. Above that layer, winds weaken rapidly, so slow moving storms, experiencing good inflow, are forecast. We added a level 1 for heavy rainfall, placed along the N-fringe of the depression's circulation, where persistent easterly flow may result in repeatedly onshore moving showers and thunderstorms (although stratification of the air mass becomes too stabel betimes for DMC).