Storm Forecast
Valid: Sun 25 Jan 2015 06:00 to Mon 26 Jan 2015 06:00 UTC
Issued: Sat 24 Jan 2015 18:15
Forecaster: TASZAREK

A level 1 was issued for W Turkey mainly for excessive convective precipitation


SYNOPSIS

Long and extensive long-wave extends from Scandinavia to Central Mediterranean where cut-off is located over Italy and Balkan Peninsula. Tongue of mild and moist air is situated ahead of the main trough and stretches from E Mediterranean to Black Sea. Most of European continent is under influence of cold air advection of polar air mass origin where convection is unlikely over continental areas. Azores High with ridge inserting into western European countries results in dry weather patterns without any significant instability. Strong cyclogenesis with Icelandic Low lowering to 970 hPa provides dynamic weather with atmospheric fronts north of the British Isles without any severe convective storms. Since continental areas have relatively cold and dry boundary layer, mid and low-level advection of cold air in the wintertime favors convection and thus thunderstorm occurrence over marine areas. Water is a source of heat and moisture that provides instability when lapse rates in air masses above are exceeding 6-7 C/km, thus thunderstorms in the forecast period are expected over marine areas of Mediterranean. The combination of not impressive mixing ratios of around 5-6 g/kg and lapse rates exceeding 7 C/km results in CAPE up to 800 J/kg. Since there is no good overlap with wind shear, and boundary-layer moisture content is relatively low, there are no good conditions for severe convective storms.

DISCUSSION

...W Turkey ...

Overlap of PW value exceeding 20mm, slow thunderstorm motion and orographic lifting that result from SW flow of convective cells create risk for excessive convective precipitation. Precipitation over this area are expected from morning hours until end of the forecast period.

...Mediterranean...

It is expected that numerous waterspout can occur over whole 15% lightning probability area (especially W part). Low wind shear, high vertical lapse rates, increased low-level CAPE and sea warmer than inflowing air mass create good conditions for non-mesocyclonic tornadoes.