CONVECTIVE FORECAST
VALID 06Z SAT 27/09 - 06Z SAT 27/09 2003
ISSUED: 26/09 18:28Z
FORECASTER: DAHL

General thunderstorms are forecast across E Iberia ... SW and central Mediterranean.

SYNOPSIS

Broad meandering upper frontal zone over the N Atlantic/N Europe ... is progged to split into two seperate frontal zones as southern-stream short-wave trough ATTM S of Island is amplifying. This trough will affect the British Isles and W France towards the end of the forecast period. Upper trough ATTM over central Europe ... currently present within unified SRN and NRN frontal zones ... will lift NE with substantial weakening of its southern-stream portion. Yet another frontal zone ... present only at high levels ... is extending across the S Mediterranean.

DISCUSSION

...Iberia ... Mediterranean...
Soundings across the Mediterranean are only weakly stable or even slightly unstable ... and in the presence of several small vort maxima ... (widely) scattered TSTMS could occur especially over Isles and over the southern half of the Italian peninsula. Also ... eastward-moving WAA regime over Spain may support scattered possibly elevated TSTMS. Upper-level shear will likely be rather strong (possibly around 50 kts in the 200/400 hPa layer) ... but should not be supportive of storm organization as majority of the storms will likely be too shallow ... yielding 20 to at best 30 knots primarily in the upper portions of the convective layers.

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