Storm Forecast
Valid: Sun 22 Mar 2009 06:00 to Mon 23 Mar 2009 06:00 UTC
Issued: Sun 22 Mar 2009 00:44
Forecaster: SCHLENCZEK

SYNOPSIS

An upper trough over the eastern Mediterranean is forecast to travel eastward during the period. Cold upper air in the wake of the trough will lead to some hundred J/kg CAPE over parts of Greece / SW Turkey and thunderstorms are expected to develop in the eastern Mediterranean region.

Further upstream, a low pressure system near Iceland moves southeastward. Between this feature and a large upper ridge west of Ireland, a strong 65 m/s upper jet streak stretches from southern Greenland towards central Europe. The upper trough of the low pressure system will affect southwestern Norway and Denmark / northern Germany in the evening / night hours. In the wake of the cold front, showers and weakly electrified thunderstorms may evolve. Lightning will be too sporadic for a highlighted thunderstorm area. In extreme southern Norway and northwestern Denmark, a strong gradient flow may lead to isolated severe non-convective gusts.


DISCUSSION

...SW Turkey...

A small region of SW Turkey will show quite good conditions for organized multicells and perhaps a few mesocyclones. Deep layer shear in order of 25 m/s and enhanced 10 - 15 m/s LLS are present and low LCL heights may allow an isolated tornado. A limiting factor will be the rather dry airmass (nearly all soundings in the vicinity of Izmir show a dry BL and therefore little or no CAPE). A categorical threat level is not introduced as convective initiation in the region with acceptable kinematic conditions is uncertain.

...E Mediterranean...

In the wake of the trough, showers and thunderstorms will develop in an environment with a few hundred J/kg of CAPE. Especially in the Aegean region, low level lapse rates reach values around 10 K/km in a region with weak vertical shear. This may result in a few waterspouts but overall threat will stay below the LVL1 threshold.

...W Iberia...

Some low-end instability is expected over western Portugal where an upper trough translates westward. Kinematic conditions are not favourable for organized storms (less than 15 m/s DLS, weak forcing) and showers / thunderstorms that may develop are probably non-severe.