STORM FORECAST
VALID Sat 18 Mar 06:00 - Sun 19 Mar 06:00 2006 (UTC)
ISSUED: 18 Mar 00:54 (UTC)
FORECASTER: DAHL

SYNOPSIS

Dominant feature this period remains the upper low over SW Europe/E Atlantic ... with ejecting vort maxima expected to travel across the WRN Mediterranean Sea. Extensive SFC low pressure system is associated with the main upper low ... promoting low-level southerly flow across the WRN and central Mediterranean ... thereby advecting steep lapse rates from the N Saharan Desert across the SW/central Mediterraean. Otherwise ... cold air mass keeps sprawling across much of Europe ... maintaining hostile convective environment.

DISCUSSION

...western Iberian Peninsula...
Weak instability should develop with diurnal heating over W Iberia in the wake of frontal system crossing the Peninsula during the day. Shear profiles ... especially at low levels ... seem to be marginally supportive of severe evolution but current thinking is that coverage of severe will be too low for a categorical risk ... though the strongest cells may produce hail approaching severe levels and maybe even a brief tornado. An upgrade may be considered on Saturday.

...western Mediterranean...
Models do not show significant SFC-based CAPE beneath the EML over the W Mediterranean ... which is consistent with rather shallow/weak moisture in the boundary layer. However ... strong mesoscale ascent especially along the NE edge of the EML may support an isolated TSTM or two. Coverage is unlikely to be very high though ... but inclusion of this area in the TSTM forecast seems to be marginally warranted.

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