Storm Forecast
Valid: Sun 24 Oct 2010 06:00 to Mon 25 Oct 2010 06:00 UTC
Issued: Sun 24 Oct 2010 05:14
Forecaster: SCHLENCZEK
A level 1 was issued for parts of the W Mediterranean and NE Spain mainly for severe wind gusts and large hail and to a lesser extent for tornadoes.
A level 1 was issued for Sicily mainly for excessive precipitation and to a lesser extent for large hail and severe wind gusts.
SYNOPSIS
A strong low pressure system is centered over Denmark and the southern tip of the associated upper trough over France will extend southward into the W Mediterranean. This feature should be the most important one with respect to severe convective weather on Sunday. Remnants of warm and unstable air over the central Mediterranean will be advected northeastwards towards the S Adriatic / Ionian Sea.
DISCUSSION
...NE Spain, W Mediterranean, Balearic Islands...
The cold front of the low pressure system over France will reach the Mediterranean coast during the afternoon and some hundred J/kg CAPE will be created in its vicinity. Deep layer shear may locally reach values between 20 and 30 m/s and some 200 - 300 mē/sē SRH3 and strong QG forcing in place with the instability should be sufficient for some organized storms which may pose a risk of severe wind gusts and large hail. A low cloud base and locally 10 m/s LLS suggest that an isolated tornado cannot be ruled out. It is questionable whether southern France will get any convection or not as the Mistral winds will probably reduce instability in a significant way. A marginal level 1 is issued for the regions further south where shear is somewhat weaker but more CAPE is expected.
...Central Mediterranean...
A plume of warm and unstable air from Tunisia / Libya will overspread the central Mediterranean. MLCAPE in order of 1000 J/kg and locally > 15 m/s shear should be sufficient for some organized multicells and / or a MCS. Some marginally severe hail and isolated severe wind gusts are possible with the strongest storms. GFS shows accumulated precipitation sums in order of 50mm / 6h which requires a level 1 for excessive precipitation over Sicily.
...N Adriatic and Gulf of Genoa...
Ahead of the developing surface low, some low-end CAPE and 15 m/s deep layer shear are in place. SRH3 is locally enhanced and a few mesocyclones are not ruled out. Isolated severe wind gusts and marginally severe hail are possible with the strongest storms but overall threat does not warrant a level 1.
...Netherlands and Belgium...
In the wake of the cold front, steep lapse rates and a few hundred J/kg CAPE should be available, leading to showers and thunderstorms. Even though LL winds are quite strong and shear is rather weak, an isolated tornado is not ruled out.
