Storm Forecast
Valid: Tue 13 Sep 2011 06:00 to Wed 14 Sep 2011 06:00 UTC
Issued: Mon 12 Sep 2011 21:59
Forecaster: KOROSEC

A level 1 was issued for Baltic sea and surrounding areas, Denmark, S Sweden, SW Finland and parts of Baltic States mainly for very strong to severe wind gusts and tornadoes.

SYNOPSIS

Extra-tropical storm Katia which affected northern UK yesterday transforms into intense and deep cyclone when it moves across the central Scandinavia. It is still accompanied by strong wind field and will affect parts of Scandinavia on Tuesday.

A blocking pattern remains in place across the southern Europe. Mainly daytime driven convective activity is expected where terrain induced storms will be possible over parts of SW Balkans and S Italy.

DISCUSSION

... Baltic sea and surrounding areas, Denmark, S Sweden, SW Finland and parts of Baltic States ...

An intense deep low moves across the central Scandinavia while it gains a slight intensification and deepens to near 970mb during the second half of the forecast period. Different models show weak signals of marginal instability developing ahead of the main frontal zone, as some WAA is expected ahead of it. Being placed beneath an impresive 40-50 m/s mid-level jet, environment will be conductive for strong/severe wind gusts.

With deep-layer shear in excess of 30 m/s and especially very strong low-level shear (10-20 m/s) with enhanced helicity an occurence of funnel clouds/tornadoes cannot be ruled out. Though with very limited instability, convection should remain rather shallow. Also, expect very strong non-convective wind gusts across the Baltic Sea and across the level 1 area, while any storms that occur could produce strong wind gusts as well.