Storm Forecast
Valid: Mon 20 Dec 2010 06:00 to Tue 21 Dec 2010 06:00 UTC
Issued: Mon 20 Dec 2010 08:03
Forecaster: DAHL

No threat levels have been issued.

SYNOPSIS

A broad upper westerly flow is present over the central and southern parts of Europe. The associated low-level front is stretching roughly from France eastward into NE Europe, and will remain largely stationary during the forecast period. Cyclogenesis currently is underway ahead of an imbedded upper trough and should affect the Iberian Peninsula on Monday.

DISCUSSION

... western Iberian Peninsula ...

Weak instability is forecast to exist in the warm-sector air mass of the Atlantic system that will affect Iberia on Monday. QG ascent will likely support scattered thunderstorms along the warm front as well as in the warm-sector air. Deep shear is simulated to be quite weak, but LLS of about 10 m/s is expected. However, storms may be slightly elevated given the isentropic lift / WAA. It thus is somewhat uncertain if the low-level shear can be tapped. In addition, the weak DLS and overall poor thermodynamic support suggest that any severe threat will be quite short-lived and isolated. Although an isolated/brief tornado cannot be discounted, the threat does not seem to warrant a LVL1 threat.

... Ionian Sea ... Greece ... Aegean Sea ...

Farther east ... instability seems to be somehwat more robust, but weak deep-layer shear remains a limiting factor. However, there should be some 10 m/s LLS along the Balkan and Aegean west coasts. Again, a brief/isolated tornado seems possible, but the weak deep-layer shear should limit storm organization/longevity. A LVL 1 threat thus does not seem to be necessary.

... eastern Atlantic south of the British Isles ...

Very sporadic lightning could accompany rather shallow cellular polar-air convection S of the British Isles early in the period.