CONVECTIVE FORECAST
VALID 06Z SAT 05/03 - 06Z SUN 06/03 2005
ISSUED: 04/03 17:41Z
FORECASTER: DAHL

General thunderstorms are forecast across the north-central Mediterranean.

General thunderstorms are forecast across the south-central Mediterranean including the Aegean Regions.

SYNOPSIS

Large-scale upper low centered over central Europe is still in place ... with several vort maxima rotating about its periphery. Cyclogenesis is in progress over the central Mediterranean ahead of one such vort max ... promoting plume of Saharan air mass to advect northwards. This feature will be focus for potentially severe convective evolution on Saturday. Otherwise ... more or less deep polar air masses are dominating over Europe.

DISCUSSION

...SEE TEXT area...
Substantial uncertainty exists on the evolution of the thermodynamic profiles E of the developing central-Mediterranea low. Saharan theta-e plume is not sampled by Friday's 12Z ascents ... and will have to rely strongly on model guidance. NMM22 and GFS 06Z agree fairly well on the evolution of CAPE amidst the theta-e tongue ... though depth of accumulated moisture beneath the Saharan air mass is quite uncertain.

Possible scenario is that TSTMS begin to develop late on Friday evening ... and last through the period. Wind fields should be more than adequate for severe evolution with deep shear on the order of 25 to 30 m/s. Low-level shear may be somewhat limited over the water owing to reduced friction ... but it may still be sufficient to be supportive to tornadic supercells ... especially as LCL heights should be fairly low. Main threats should be severe wind gusts and large hail however.

Will not issue a SLGT ATTM as there are no observational data that support the current model solutions with respect to the forecast thermodynamic profiles.

...British Isles ... France ... N-central Mediterranean...
Scattered showers and maybe a brief TSTM or two may form over the British Isles and France during the day ... but it appears that TSTM coverage will be very low so that a TSTM outlook is not necessary ATTM. Late in the period ... this activity may spread into ... and strengthen over ... the N-central Mediterranean.

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