Storm Forecast
Valid: Fri 06 Mar 2015 06:00 to Sat 07 Mar 2015 06:00 UTC
Issued: Thu 05 Mar 2015 18:39
Forecaster: TUSCHY

A level 2 was issued for the N Aegean Sea mainly for excessive rain.

A level 2 was issued for E-Greece mainly for severe wind gusts, a few tornadoes and excessive rain.

A level 1 surrounds the level 2 area mainly for excessive rain and an isolated large hail, severe wind gust and tornado risk.

Numerous level 1s were issued for parts of S-Italy, Greece and the Ionian Sea mainly for excessive rain and an isolated tornado event.

SYNOPSIS

High-index pattern evolves over the far NE Atlantic as the anticyclone over the Azores builds east towards France while mid-level heights over Iceland subside. This kind of pattern supports a strengthening and eastward building ridge over W-Europe.
A positive tilted trough over the CNTRL Mediterranean tries to drip off the westerlies but latest model guidance does not yet support a cut-off solution during the end of the forecast. This kind of process does not result in rapid motion and therefore a quasi-stationary but strong trough will affect SE Europe.

While a 1035 hPa high over France builds east, the main feature of interest in the lower troposphere is a sub-1010 hPa vortex over S-Italy. This depression drifts slowly to the SE over the Ionian Sea while filling. Widespread drop of surface pressure also occurs further east over the Aegean Sea as some models try to develop a zonal aligned surface trough. A pronounced baroclinic zone evolves over NE Greece and SE Bulgaria.

DISCUSSION

... S-Italy, Ionian Sea, Greece, Aegean Sea and adjacent areas ...

Main focus for scattered thunderstorms will be beneath the upper level low, as cold mid-levels reside over the warm SSTs of the offshore areas. Disorganized but slow moving DMC activity is forecast, with excessive rain the main risk. Weak background shear and local MLCAPE of near 800 J/kg (peak magnitude along the E-coast of the Ionian Sea) indicate a chance for a few waterspout events. Numerous level 1 areas were added mainly due to the rainfall risk.

S/E Greece and the Aegean Sea will see the main severe risk. This region resides in a pronounced warm conveyor belt with 20-25 m/s southerly LL winds. Prolonged period of enhanced BL moisture transport to the north inidcates an excessive rainfall risk with the highest probabilities over the NE Aegean Sea. Despite intense deep/mid-layer shear which would support an organized thunderstorm risk, modest MLCAPE of 300-600 J/kg may limit the overall risk. Also, strong isentropic lift and widespread CI will limit the chance for more discrete convection. Especially tail-end storms could become organized with an isolated large hail/tornado and severe wind gust risk (e.g. E-Greece). A level 2 area was issued for the N Aegean Sea mainly for the rainfall risk and over E-Greece for a tornado/severe wind gust and excessive rainfall risk.

NE Greece and SE/E Bulgaria will see a serious (freezing) rain/snow event as a pronounced baroclinic zone sets up. Forecast soundings support a NE ward fanning plume of weak MUCAPE, which could support embedded convection, locally increasing the ice/snowfall risk substantially. We therefore expanded the lightning area far to the NE.