Storm Forecast
Valid: Sun 08 Oct 2006 06:00 to Mon 09 Oct 2006 06:00 UTC
Issued: Sun 08 Oct 2006 01:54
Forecaster: VAN DER VELDE

SYNOPSIS

An old low pressure area over Scandinavia may produce some isolated thundershowers.
Another old low near Greece and Turkey provides ingredients for widespread thundery activity in that area.
In the wake of the high over the European mainland a plume of warmer, moister air advects northward from Spain into western France and the UK, with the cold front coming in at the end of the forecast period touching SW England and Galicia, Spain.

DISCUSSION


...Mediterranean Sea...

Some waterspouts are expected. Steep near-surface lapse rates and low-level instability, and weak pressure gradients are in place near the core of an upper low. 00Z Cagliari sounding shows a pool of low-level moisture, with 00Z Pratica di Mare has very deep steep lapse rates, weak winds, and potential for strong parcel accelerations. IR imagery shows a vortex moving southward. Based on this, estimation is that the overall coverage of storms is to remain fairly small, which is reason not to issue level 1.
The area of the Aegean Sea shares some of the potential. Locally moderate deep layer shear could maintain organized storms with a slight chance of marginally large hail events.


...southern Baltic states...

This area may see some more enhanced convective activity at the left exit of the 300 hPa northwesterly jet. Instability will be up to a few hundred J/kg at most, and mostly over sea, while strongest deep layer shear borders does not overlap this area.
However, a few waterspouts may occur over the relatively warm Baltic Sea, although 10 m wind speeds are expected to limit the potential.

...Spain...

With deep layer shear near 10-15 m/s and marginal CAPE , storms are likely to be of garden variety, but very locally a chance of marginally large hail exists, not enough for level 1.