CONVECTIVE FORECAST
VALID 06Z SAT 08/05 - 06Z SUN 09/05 2004
ISSUED: 08/05 19:18Z
FORECASTER: DAHL

General thunderstorms are forecast across north-central Europe ... NE Europe ... E Europe ... the N Balkans and the N Mediterranean regions.

General thunderstorms are forecast across extreme NW Iberia.

SYNOPSIS

Central European upper cut-off low is progged to shift eastwards ... stretching from the Baltic States into the the N Balkan States by Monday 06Z. Upper trough ATTM W of the British Isles ... will dig southwestwards reaching the western Iberian Peninsula late in the period. Polar air mass has spread across most of central and southern portions of Europe ... with weakly unstable subtropical air mass lingering over the northern portions of Europe.

DISCUSSION

...N-central Europe ... Scandinavia ... Finland ... NW Russia...
Mainly diurnally driven TSTMS will likely develop within weakly unstable and weakly capped air mass over Scandinavia ... Finland and NW Russia. Soundings reveal inverted-V type profiles over NW Russia and Finland ... and strong evaporative cooling of the downdrafts may promote gusty outflow winds. As this air mass is advected southwards into Holland ... Germay and W Poland ... TSTMS may spread into these regions as well. Weak CAPE and weak shear suggest that severe threat is rather low. An isolated TSTM or two may form outside the TSTM area ... especially over the British Isles ... within plume of warm air mass wrapping-around the central European low ... but coverage should be too small for an extra TSTM area.

...N Italy ... N Adriatic ... N Balkans ... NW Romania ... W Ukraine...
Vort maxima at S and E periphery of the central European upper low ... will affect the north-central Mediterranean and eastern Europe during the day. Profiles across N Italy and the N Balkans are saturated with neutral lapse rates. Aided by insolation ... rather shallow TSTMS should develop during the day ... possibly focused ahead of the vort maxima. Deep-layer shear will be on the order of 20 to 25 m/s ... and strong wind gusts will likely accompany the TSTMS. Isolated rotating updrafts may occur ... with an attendant threat for marginally severe hail. Also ... a tornado or two may occur given nearly saturated boundary layers. Severe TSTM events are expected to be too isolated for a categorical risk.

...Extreme NW Iberian Peninsula...
Beneath the upper thermal trough associated with the Iberian vort max ... cellular convection will likely develop ... with isolated TSTMS. This activity may spread into very NWRN Spain and N Portugal towards Sunday evening. Severe threat should be negligible owing to weak thermodynamic and kinematic parameters.

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