Storm Forecast
Valid: Tue 09 Feb 2010 06:00 to Wed 10 Feb 2010 06:00 UTC
Issued: Tue 09 Feb 2010 00:10
Forecaster: KOROSEC
A level 1 was issued for the parts of southern Italy mainly for excessive convective rainfall, severe wind gusts and tornadoes.
SYNOPSIS
A large trough south of the main polar vortex over Europe becomes more pronounced and slowly shifts eastwards across Mediterranean. At surface, a new deep surface depression forms over western Mediterranean in the morning hours and moves towards southern Italy by Wednesday morning. The main convective activity will be mostly aligned to the frontal boundary. The rest of Europe will stay cool and stable.
DISCUSSION
... parts of southern Italy ...
Rapid LL moisture recovery will be on going during the day as the warm airmass advects towards Tyrrhenian sea and southern Italy ahead of the surface low. Placed beneath the upper-level divergence, strong QG forcing for thunderstorms initiation will exist. While the main convective activity seems mostly alighed to the main frontal boundary, WAA and increasing LL jet ahead of it could result in excessive convective rainfall locally as well. Especially across southern Sicily in the evening hours and over Calabria and Puglia regions overnight. Given the slow moving depression, persisting southerly flow combined with convective cells could lead into local flash floods.
With expected height falls and steepening lapse rates during the day, a marginal instability will result and overlap with near 20m/s of deep layer shear and near 10m/s of LL shear. Given the more enhanced LL shear and helicity along the frontal boundary and also along the coast, mesocyclones will be possible and therefore increased tornado threat. For this reason, along with the excessive convective rainfall, a level 1 threat was introduced where the higher chances for severe weather exist.
Towards the morning hours when the main vort-max shifts east, an additional pressure falls will be pushing WAA well into south-central Adriatic sea and large scale precipitation areas will move into Calabria/Puglia regions. There, convection becomes more likely along the front/tripple point, moving east.
