CONVECTIVE FORECAST
VALID 06Z SAT 24/07 - 06Z SUN 25/07 2004
ISSUED: 23/07 18:36Z
FORECASTER: DAHL

General thunderstorms are forecast across SW Europe ... E-central Europe ... E Europe and the Mediterranean Regions.

SYNOPSIS

Atlantic upper long-wave trough ... exhibiting several perturbations at its periphery ... is making slow eastward progress. Weak upper frontal zone is stretching from central France across the central Mediterranean ... with a weak embedded vort max progged to cross Italy during the day. The rest of Europe will remain synoptically quiescent. Main frontal boundary at low levels ... expected to stretch from SW Scandinavia across Germany and France into N Spain by Saturday 06Z ... will move east and should extend from the central Baltic Sea across central Poland into the N Mediterranean late in the period.

DISCUSSION

...east-central and east Europe ... Balkan States...
TSTMS will likely redevelop during the day along and ahead of the main SFC front over W Poland ... the Chech Republic and Austria. CAPE should be on the order of 500 J/kg ... and given weak shear ... severe evolution is unlikely.

Scattered TSTMS should also develop farther east over eastern portions of Europe and W Russia as well as over the Balkans in weakly unstable/weakly capped environment. 500 hPa flow in the range of 10 to 15 m/s is progged over the Balkan States ... and an isolated severe wind gust accompanied by some hail may occur. However... organized severe TSTM threat is expected to be too low for a SLGT.

...Italy...
Pocket of unstable air mass is expected to persist across NRN portions of Italy and over the Ligurian and the N Tyrrhenian Sea with expected CAPEs of about 1500 J/kg. It looks that best shear will be just upstream of the largest CAPEs ... with Corsica and Sardinia possibly seeing the best kinematic/thermodynamic setup. However ... initiation is questionable and will refrain from issuing a SLGT ATTM. TSTMS forming over Italy may briefly/isolated pose a large-hail and severe-wind threat especially if mesocyclones can form ... aided by orographically induced low-level flow perturbations. Severe threat should be too low for a SLGT though.

...Spain ... Portugal...
Scattered ... diurnally driven TSTMS will likely form over Spain and Portugal ... quite dry CBL will likely promote strong evaporative cooling of the precip and support strong/severe outflow winds ... also ... 15+ m/s 500 hPa flow over N Spain may support short lines ... with some chances for bow echoes if strong cold pools can form. Coverage is expected to be rather low ... and a SLGT is not warranted ATTM.

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