Storm Forecast
Valid: Tue 10 May 2011 06:00 to Wed 11 May 2011 06:00 UTC
Issued: Mon 09 May 2011 20:55
Forecaster: KOROSEC
A level 1 was issued for southern Mediterranean sea and Crete mainly for excessive rainfall, strong winds and a brief tornado.
SYNOPSIS
A broad omega-line pattern persists across much of south-central Europe with decaying deep upper low west of UK, moving north and emerging with the large scale trough near Iceland. Another weak upper low is moving across southern Mediterranean towards east. At surface, an extensive high pressure area extends from SW Mediterranean across central Europe towards NW Russia. A frontal zone associated with the Mediterranean upper low will be a focus for possible development of severe storms today. Another front extends from the large cyclone near UK across western France and central Iberia. A weak surface front moves across eastern Balkans towards south.
DISCUSSION
... south Mediterranean sea and Crete ...
Strong DCVA couplet will be a focus for today's convective activity. Cool mid levels and steep lapse rates will result in several hundreds J/kg of MLCAPE across the level 1 region, where it partly overlaps with the moderate shear in the southern side of the low. There, large scale ascent will support scattered to widespread convective storms, organizing into multicells as well as a few supercells. Those could bring intense rain, strong wind gusts as well as a brief tornado threat. Veered near surface wind profiles will result in enhanced helicity/LL shear ahead of the trough axis/front which may therefore support LL rotating updrafts. Later in the afternoon when peak heating will result in more unstable airmass, a low slightly deepens and an intensification of LL wind field will favour clustering storms. A MCS is expected to form, slowly moving east near island of Crete and towards SW Turkey. Very heavy rain and severe gusts cannot be ruled out along the possible convective line that my be embedded in the cluster.
... France, northern Iberia, Atlas mountains in Marocco ...
Mainly diurnal driven showers and thunderstorms are expected across the warm sector from central France towards northern Iberian peninsula. Strong surface heating will erode the capping inversion by early afternoon and scattered storms will form. Given the lack of wind field/shear in place, severe storms are unlikely to occur. Marginally large hail and some stronger gusts can still be expected.
Another favorable area for mostly daytime convection will be a broad area of unstable airmass ahead of the moving front across eastern Balkans and N Black Sea. Despite very limited shear, some briefly organized storms could form along the southwards surging cold front. Storms will diminish towards the sunset as instability vanishes.
Some convective activity is also expected along and just north of Atlas mountains in Marocco, as rich BL moisture and strong daytime heating should release few storms over the complex terrain. Some of those storms could become strong, but not reaching severe criteria.
... SW Scandinavia ...
A belt of warm/moist airmass advects into SW Scandinavia ahead of the surface cold front. Diurnal heating could result in marginal instability and a few storms may form there as well. However, despite moderate shear in place, no serious organized storms can be expected given the limited instability.
