CONVECTIVE FORECAST
VALID 06Z SAT 01/05 - 06Z SUN 02/05 2004
ISSUED: 30/04 22:07Z
FORECASTER: DAHL

General thunderstorms are forecast across south and central Europe.

SYNOPSIS

Not much changes expected in the upper flow regime during the period ... extensive SW European upper low is progged to remain in place ... and weaken somewhat during the period ... with meandering NRN upper frontal zone stretching across N and N-central parts of Europe. At low levels ... very weak and extensive low pressure region covering central and SW Europe ... with plume of weakly unstable air mass advecting across central Europe E of the low-pressure system.

DISCUSSION

...Central Europe...
Friday's 12Z soundings indicate weakly unstable and nearly uncapped air over much of central and S Europe ... with boundary layers becoming deeper/drier towards the SE of Europe. Weak baroclinic zone associated with the theta-e plume wrapping around the SW European low-pressure system will likely turn out to be one focus for convective development again ... Also ... GFS consistently advertises weak DCVA overspreading the baroclinic zone over E Germany towards Saturday evening. Large-scale shear will likely be very meager ... but it appears that mesoscale wind field along the frontal boundary may be sufficient to supporz short-lived mesocyclonic TSTMS ... which will pose primarily a threat of marginally severe hail. Orographic forcing may promote additional TSTM development over SE central Europe. Though small-scale modifications of the low-level wind field may lead to brief updraft rotation with a concomitant threat for marginally severe hail ... allover severe TSTM threat appears to be too low to warrant a SLGT ATTM.

...Balkans...
Further ... diurnally driven TSTMS will likely form over the Balkan States ... deep/dry subcloud layers suggest that a few strong outflow wind gusts may occur ... but allover weak thermodynamic profiles and weak shear should limit severe threat.

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