CONVECTIVE FORECAST
VALID 06Z SUN 30/05 - 06Z MON 31/05 2004
ISSUED: 29/05 17:54Z
FORECASTER: DAHL

General thunderstorms are forecast across the Iberian Peninsula ... France ... the British Isles and the W Mediterranean.

General thunderstorms are forecast across Italy ... Balkan States.

General thunderstorms are forecast across northeast and east Europe.

SYNOPSIS

Vort max ejecting from the east-central Atlantic ... will cross the British Isles and France on Sunday ... reaching extreme W Germany late in the period. Upper low over the Balkans is progged to accelerate eastwards ... reaching the W Black Sea/W Turkey Monday night. As intense upper low over Scandinavia moves into the Baltic States ... weak cyclogenesis is expected over Estonia/S Finland during the day. Quiescent conditions will persist across much of E Europe.

DISCUSSION

...France...
Weak CAPE will likely develop within weakening theta-e plume which will cross E France ... BeNeLux and extreme W Germany during the period. Shape of thermodynamic profiles is somewhat uncertain ... but there are no indications of substantially strengthening mid-level lapse rates and of low-level moisture.

TSTMS should inidiate/re-develop early in the day amidst strong DCVA-related UVV regime ahead of negatively-tilted trough. Deep-layer shear will only be on the order of 10 m/s ... with negligible large-scale low-level shear ... suggesting that allover severe threat is quite low. Nonetheless ... cell interactions with orography or unresolved meso- and convective-scale boundary-layer features may favor a rotating updraft or two ... posing some threat for large hail. This threat is too conditional for a categorical severe TSTM outlook.

...Iberia...
Rather high-based TSTMS will likely form again in nearly uncapped/neutral environment over the Iberian Peninsula. Large-scale thermodynamic and kinematic fields suggest minimal severe TSTM threat ... though strong wind gusts will likely be favored by deep/dry sub-cloud layers.

...Balkans ... Italy...
Scattered diurnally driven TSTMS are expected over the Balkans and Italy again in weak-CAPE environment. Complex orography and outflow boundaries laid out by Saturday's convection may locally yield low-level shear profiles supportive to rotating updrafts ... with an attendant threat for large hail. Threat will be too low for a SLGT though.

...Greece...
Band of moderately strong mid-level winds ahead of vort max will graze Greece late on Sunday. Depth of low-level moisture has shown to be very variable across Greece ... and some TSTMS may form in inverted-V type environments ... while others may form in richer low-level moisture. Also ... the low-level wind field will be subject to various small-scale modifications such as see-breeze fronts and orographic features. This coupled with 20+ m/s 500 hPa flow suggests that an isolated severe TSTM event may occur ... primarily large hail and severe straight-line winds. Threat is too conditional for a SLGT.

...NE Europe...
Cyclogenesis over Estonia is progged to sharpen thermal gradient along trailing cold front ... progged to stretch across the eastern Baltic Sates on Sunday afternoon. Though instability will be meager ... 500 hPa flow of 20+ m/s suggests that a few strong wind gust and small hail may be possible with the stronger storms.



...British Isles...
Showers and scattered TSTMS will likely form as upper thermal trough axis overspreads the British Isles. However ... DAVA-forced large-scale descent may limit extent of spatial window of where sufficiently deep convective mixing will occur. Low WBZs may favor small hail ... but organized-severe TSTM threat should be minimal with this activity.

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