Storm Forecast
Valid: Tue 14 Sep 2010 06:00 to Wed 15 Sep 2010 06:00 UTC
Issued: Mon 13 Sep 2010 20:41
Forecaster: KOROSEC

A level 1 was issued for southern Italy and northern Tunisia mainly for excessive convective rainfall and lesser extent for marginally large hail and strong wind gusts.

A level 1 was issued for northern Germany, parts of Netherland, Denmark and southern Sweden mainly for strong wind gusts and excessive rainfall.

SYNOPSIS

The main large and rather intense upper trough moves from NE Atlantic across the north Sea into Scandinavia. Accompanied by this trough, a frontal system affects southern Scandinavia and extends into northern Germany. The upper low over Thyrrenian sea continues moving SSE into the southern Mediterranean by Wednesday morning.

DISCUSSION

... North Sea across southern Scandinavia into northern Germany ...

An intense frontal system enters North Sea during the daytime hours and quite rapidly shifts southeastwards. Models simulate weak instability to build up along/just ahead of the cold front. Accompanied by this trough, strong mid-level jet provides strong deep-layer shear which should support some organized storms. Expect some organized convection mainly along the cold front where convective lines will be possible with the strong wind gusts as the main threat. A level 1 was issued over the areas where this threat seem to be maximized. Behind the front, CAA overspread rather warm SST of North Sea and yields some LL instability and steeper lapse rates. There, as well as around Denmark and northern Germany coastal areas, a couple of funnel clouds/spout type tornadoes cannot be excluded.

... southern Italy ...

Areas from Thyrrenian sea southwards into the southern Mediterranean will be affected by the slowly moving upper low. Moderate instability seems to become available, which should support deep convection. Despite the rather limited shear in place, as the mid-level jet slowly weakens, numerous organized storms will form. Multicells and a couple of rotating storms can be possible. Given their rather slow moving nature, they should bring threat for intense rainfalls as well as some marginal hail in the beginning before they cluster. Train-effect of the storms should locally enhance flash floods. Warm SSTs and steep LL lapse rates could also result in a couple of waterspouts.