Storm Forecast
Valid: Sun 16 Mar 2008 06:00 to Mon 17 Mar 2008 06:00 UTC
Issued: Sat 15 Mar 2008 21:06
Forecaster: SCHLENCZEK

SYNOPSIS

A high over low blocking pattern will build west / northwest of Ireland with a ridge over Iceland and an upper low west of Iberia, leading to strong cold air advection towards Scandinavia and central Europe in the following days.

The main focus for convective activity will be a low pressure system over the BeNeLux countries. Its cold front should be present along Zurich - Nuremberg - Frankfurt - Cologne while cold upper air overspreads the post-frontal airmass over eastern and central France.

In the wake of another upper trough over Scandinavia, showers and thunderstorms may evolve in the unstable arctic airmass. Sporadic lightning could occur but a thunderstorm area is not warranted.

An upper trough over Algeria will move eastward. Thunderstorms are not ruled out over the central Mediterranean where low CAPE and about 10 m/s deep layer shear are present but a thunderstorm area is not warranted as forcing will likely stay too weak to break the cap.


DISCUSSION

Eastern / central France, Belgium, western Germany

In the wake of the cold front, upper level cooling and diabatic surface heating should lead to a few hundred J/kg of CAPE, enough for diurnal driven showers and thunderstorms. Deep layer shear around 15 m/s may allow some organized multicellular storms, capable of producing mostly small hail and gusty winds.

Switzerland, southern Germany, northern Italy, Austria

In the afternoon, it cannot be ruled out out that convection develops behind the rain-band over southern Germany. If so, more than 30 m/s deep layer shear may cause these to become severe. However, given the very conditional nature of this development, a threat level is not issued.