CONVECTIVE FORECAST
VALID 06Z SUN 20/03 - 06Z MON 21/03 2005
ISSUED: 19/03 20:06Z
FORECASTER: DAHL

General thunderstorms are forecast across Portugal and NW Spain.

SYNOPSIS

High-amplitude upper flow pattern persisting over Europe through the period ... with two extensive upper lows over the E Atlantic and E Europe, respectively ... and a weakening upper ridge in between over central Europe. At low-levels ... extensive SFC low covering NE Europe and NW Russia is promoting advection of continental polar/arctic air deep into SE Europe. Downstream from the Atlantic trough ... air from the subtropical Atlantic is spreading across the Iberian Peninsula and parts of France.

DISCUSSION

...Spain ... Portugal...
Subtropical air mass spreading across W Iberia may contain weak CAPE ... which is supported by recent TSTM activity in this air mass and by the models. This convection may affect Portugal and NW Spain throughout the period ... being mainly elevated and focused along baroclinic zone over the western portions of the peninsula. Confidence in widespread TSTMS is rather low however... and bulk of the activity may remain off-shore.

Sahara-generated EML has overspread the regions farther inland ... and will continue to support a formidable cap. Also ... low-level moisture looks to be quite meager ... and even development of positive CAPE is questionable ATTM. Despite increasing large-scale UVV's ... confidence in TSTM development is quite low. Will thus only introduce a TSTM area over extreme WRN portions of Iberia again.

...France...
Models are again quite generous with producing CAPE over France ... but latest soundings and SFC obs still suggest that low-level moisture will be insufficient for deep convection also on Sunday.

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