Storm Forecast
Valid: Wed 10 Mar 2010 06:00 to Thu 11 Mar 2010 06:00 UTC
Issued: Tue 09 Mar 2010 23:39
Forecaster: PUCIK

SYNOPSIS

A large cyclonic vortex is forecast to translate from Southern France to the Adriatics region by the end of the forecast period, slowly filling. At its base, strong mid and upper level jet is forecast, covering most of the southern half of the Mediterranean and SouthEastern Europe. To the northwest, an anticyclone has settled over the British Isles.

At the surface, a deep surface low centered over the Tyrrhenian Sea will start filling, but intense pressure gradients will maintain very strong flow at 925 - 700 hPa at its forward flank during morning and early noon. Frontal system of the low is expected to occlude and the main precipitation shield will stream to the north and northeast.

A very dangerous, albeit non-convective situation is in store for coastline and adjacent western steep slopes of Slovenia and Northern Croatia. With very strong easterly and northeasterly flow at lower levels, strong bora is forecast with wind gusts reaching possibly over 200 km/h at exposed spots. Gusts should be the strongest between 06 and 09 UTC, then dimnishing in intensity.

Generally speaking, conditions for deep, moist convection are unfavorable over most of European continent, apart from few regions over the Mediterranean.

DISCUSSION

... Southern Italy ...

Strong frontal uplift and swift advection of humid airmass within the low level jet seem to be favorable for an heavy rainfall event across much of Italy with amounts of precipitation simulated exceeding 50 mm/6h at certain locations. Ahead of the cold front, marginally unstable airmass is simulated with low-end CAPE values (up to 500 J/kg) and slightly negative values of LI. Deep convection might be maintained at the southern end of the precipitation band, quickly giving way to broad stratiform precipitation shield. It seems that the contribution of convection to the overall precipitation amounts will not be significant enough to warrant a Level 1, but still, embedded convection in the stratiform clouds might enhance the rainfall amounts even well north of any lightning reports.