Storm Forecast
Valid: Sun 06 Apr 2008 06:00 to Mon 07 Apr 2008 06:00 UTC
Issued: Sat 05 Apr 2008 21:11
Forecaster: SCHLENCZEK

SYNOPSIS

A large low pressure complex at upper levels dominates major parts of Europe while high pressure is present over northern Africa and the Iberian Peninsula. Some embedded shortwave troughs should lead to unsettled conditions over W-central Europe, the Aegean Sea / Bosporus region and Ukraine / Belarus. Instability and vertical shear over western Europe are somewhat limited and mostly weak thunderstorms with isolated lightning may occur. The Baltic States and northwestern Russia may get a few hundred J/kg of CAPE but shear as well as forcing do not seem to be supportive for severe convection. Strong cold air advection is forecast in the wake of the frontal boundary that stretches from northern Spain via northern Italy and eastern Poland towards the Baltic Sea. Best conditions for deep convection are expected over the Aegean Sea.

DISCUSSION

Northwestern Iberia

Near the right entrance region of a 45 m/s jet streak over France, advection of warm and moist air at lower levels will provide some hundred J/kg of CAPE. GFS 12Z predicts some precip but convective initiation is still uncertain. Deep layer shear between 10 and 15 m/s suggest that a few multicellular storms may develop and isolated large hail is not completely ruled out. Convection should develop in the late afternoon / early evening.

Central France...Switzerland

In the wake of the trough, cold upper airmass will overspread the region and mid level lapse rates should steepen to nearly 8 K/km. Although low level and mid level clouds may hinder insolation, GFS predicts a few hundred J/kg of CAPE in the post-frontal airmass. Strong QG forcing in the left exit region of the 50 m/s jet streak over central France as well as 20 - 25 m/s deep layer shear should be supportive for some multicells or shallow lines that may produce gusty winds.

Aegean Sea...western Turkey

Showers and thunderstorms are forecast in the post-frontal airmass where some hundred J/kg of CAPE and weak vertical shear are expected. Rich BL moisture and locally enhanced low level shear may allow an isolated funnel / brief tornado but a threat level seems not warranted. During the morning hours, ongoing storms over western Turkey should move northeastward while weakening. Severe flooding may occur where storms persist.