Storm Forecast
Valid: Sun 15 Mar 2009 06:00 to Mon 16 Mar 2009 06:00 UTC
Issued: Sat 14 Mar 2009 21:22
Forecaster: SCHLENCZEK

SYNOPSIS

A large low pressure complex near Iceland will travel northeastward during the period, affecting Iceland, Greenland and extreme NW Norway. High pressure is present over central and eastern Europe, leading to cool and stable conditions. Convection is expected to develop in the vicinity of weak upper level disturbances in the western Mediterranean. Another upper trough over S-central Europe will move across N Italy towards the Tyrrhenian Sea.

DISCUSSION

...NW Maghreb States, S Iberia...

Upper level cooling and diurnal heating will create a few hundred J/kg of CAPE over southern Spain / Portugal and N Morocco / Algeria. LL mixing ratio should be in order of 7 g/kg and low level convergences / orographic features may provide enough lift for convective initiation. Showers and weakly electrified thunderstorms may develop in an environment with very weak vertical shear. Recent soundings from LXGB and Murcia show a strong cap around 850hPa which will make convective initiation difficult. Low values of the least-capped layer depth hint at a rather shallow moist boundary layer. There are a lot of negative influences but a few storms may develop over N Morocco / N Algeria. Over Portugal and Spain, the capping inversion is probably too strong for thunderstorm development.


...N Adriatic, N Italy...

In the early afternoon, an upper trough over Switzerland will move southwestward across northern Italy. A small region with enhanced QG forcing will overspread the northwestern Tyrrhenian Sea. Upper level cooling and moderately warm SSTs will create a few hundred J/kg CAPE and weakly electrified thunderstorms may evolve. Deep layer shear around 10 - 15 m/s will be present and storms should be poorly organized. Besides possible local flooding, severe weather is not expected.