CONVECTIVE FORECAST
VALID 06Z FRI 26/03 - 06Z SAT 27/03 2004
ISSUED: 26/03 03:34Z
FORECASTER: VAN DER VELDE

General thunderstorms are forecast across coastal areas of the Iberian Peninsula

General thunderstorms are forecast across central Italy, Adriatic, SWrn Balkan

General thunderstorms are forecast across Ukraine, Belarus

SYNOPSIS

Upper trough from the Iberian Peninsula, the Alps into Eastern Europe with SFC low pressure near Srn Spain, Italy and the Ukraine provide weak instability due to cold air aloft with triggering factors available in the form of convergence at low levels and vorticity maxima aloft. Most lift will take place over the theta-e plumes below the jetstream over southern Spain and central Italy into the SWrn Balkan, with good shear conditions.

DISCUSSION

...Srn Spain...
Weak instability signal from GFS (some CAPE, LI less than 2), but deep layer shear is moderate and SREH values reach over 150 m²/s², so any storms that may form may locally produce marginally large hail. Convergence along the theta-e wave may provide enough lift to destabilize enough.

...SWrn Balkan...
around Albania... GFS forecasts 0-1 km shear over 10 m/s and 0-6 km shear over 30 m/s... enough for shallow supercells, especially with SREHs in the 150-300 m²/s² range forecast by GFS. Marginally large hail, and perhaps also a tornado are possible given the low LFCs/LCLs.... but key concern is wether instability will be enough to support sustained convection in the first place.

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