Storm Forecast
Valid: Sun 17 Dec 2006 06:00 to Mon 18 Dec 2006 06:00 UTC
Issued: Sat 16 Dec 2006 21:13
Forecaster: DAHL

SYNOPSIS

Broad meandering upper westerly flow is stretching across the northern and central parts of Europe with numerous vort maxima imbedded. Upper low centered over N Algeria on Saturday evening is expected to make slow eastward progress and move into the S-central Mediterranean Sea. At the surface ... large low-pressure complex is covering NE Europe and NW Russia but will weaken somewhat per model guidance, with weak high pressure building across W into central Europe. As Mediterranean upper low travels east, associated surface low is expected to deepen slightly.

DISCUSSION

... S Ionian Sea ...

Scattered thunderstorms should continue to accompany the central Mediterranean upper low. Indications are that CAPE will remain very weak but 500 hPa flow of 15 to 20 m/s and 850 hPa flow of up to 10 m/s may be indicative of slightly enhanced severe potential. It seems that greatest severe threat will exist late in the day/night as robust DCVA-forced ascent overspreads the S Ionian Sea. Main severe threats will likely be isolated severe wind gusts and a few tornadoes. Severe potential appears to be quite marginal owing to meager thermodynamic support but a level one threat seems to be marginally justified.

... North Sea ... extreme S Scandinavia ... Denmark ... extreme N Germany ...

Comma-cloud like convective system in developing into the northern North Sea ahead of upper vort max as of Saturday evening, and is expected to affect S Sweden Denmark and extreme N Germany on Sunday. It seems that the threat for an isolated tornado or two is somewhat enhanced in coastal areas where low-level shear is expected to exceed 10 m/s. However, at the moment it does not seem that a categorical risk is warranted. Lightning activity will likely remain rather weak, but will introduce a TSTM forecast nonetheless.