Storm Forecast
Valid: Thu 15 Jan 2015 06:00 to Fri 16 Jan 2015 06:00 UTC
Issued: Wed 14 Jan 2015 23:44
Forecaster: GATZEN

SYNOPSIS / DISCUSSION

A north-Atlantic trough amplifies across western Europe. Downstream, a south-westerly flow develops, pushing an east-European trough into Russia. A tongue of warm air spreads into Poland, whereas cold advection affects western Europe. Lapse rates become quite steep in the south-westerly flow across the west Mediterranean Sea and at the lee side of the Alps. Especially across the Mediterranean, these lapse rates overlap with low-level moisture and results in CAPE. Best lift is expected around the Ligurian Sea ahead of a cold front that travels east late in the period. Thunderstorms are expected that can organize into multicells due to moderate vertical wind shear. Given the rather weak low-level moisture and CAPE, potential of excessive precipitation is too marginal for a level one.

Across western Europe, intense height falls indicate the strong lift along the base of the amplifying trough. Lapse rates become steep and will spread south-eastwards, but latest models indicate that the low-level cold front will move eastward rather quickly. Therefore, low-level moisture remains separated from the good lapse rates and thunderstorms are not likely along the cold front. Near the base of the trough, the overlap of lapse rates with some maritime moisture in the polar air mass will be associated with scattered showers and thunderstorms. The weak vertical wind shear will not support organized storms, and a threat level is not issued.

South-western Norway will be affected by the strong south-westerly flow with embedded frontal systems through-out the period. During the day, showers and thunderstorms form near the centre of a mid-level vort-max. Strong wind gusts are forecasts with this convection, but the convective contribution is too uncertain to issue any threat level.