CONVECTIVE FORECAST
VALID 06Z SAT 12/07 - 06Z SUN 13/07 2003
ISSUED: 11/07 19:09Z
FORECASTER: DAHL

General thunderstorms are forecast across the Iberian Peninsula.

General thunderstorms are forecast across eastern half of Europe.

SYNOPSIS

Amplifying upper flow pattern present across Europe ... with a slowly eastward-progressing digging trough ATTM over the central Atlantic ... and a building upper ridge progged to reach W Europe late in the FCST period. Strong short-wave trough ATTM over N Germany ... will affect eastern portions of central Europe on Saturday. Another vort max will cross the black sea and Turkey. At low levels ... Deep polar air will cover the northern half of central Europe ... while marginally unstable subtropical air is residing over the Mediterranean regions and northeast Europe/W Russia.

DISCUSSION

...East-Central Europe...
Within narrow plume of rather high theta-e associated with occluded frontal system ahead of the central European upper trough ... a few TSTMS should re-develop during the day. However ... degree of dynamic forcing for upward motion associated with DCVA is expected to decrease as well as the strength of the theta-e plume. Given that CAPE was quite meager today ... instability may be even more problematic tomorrow as destabilization through mid/upper adiabatic cooling associated with vertical motion should be weaker than today. Even GFS ... which uses to be quite optimistic with respect to CAPE ... suggests minimal/no CAPE within the narrow warm sector. Nonetheless ... a few TSTMS will likely develop along and ahead of the cold front/occlusion ... Very weak thermodynamic fields along with marginal shear will limit severe threat.

In the postfrontal environment ... shallow TSTMS will likely form with diurnal heating in the uncapped weakly unstable polar airmass. At the periphery of the upper cold pool ... shear profiles will be quite strong ... possibly as high as 60+ knots in the cloud-bearing layer. This along with rather low WBZ heights suggests that a few strong wind gusts along with small hail may occur. Nonetheless ... given very weak thermodynamic support organized-severe threat should be quite low.

...Iberia...
A few TSTMS are expected late in the day over Iberia within weak upslope-flow regime ... aided by weak DCVA-related lift ahead of small vort max. Expect weak CAPE ... but quite deep dry-adiabatic subcould layer. Shear will be minimal ... but thermodynamic setup should promote strong outflow winds ... which may briefly exceed severe levels. TSTMS are expected to be quite isolated and short-lived though ... and a SLGT is not necessary.

Otherwise ... chance of organized severe thunderstorms is very low.

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