CONVECTIVE FORECAST
VALID 06Z WED 10/12 - 06Z THU 11/12 2003
ISSUED: 09/12 16:19Z
FORECASTER: GATZEN

General thunderstorms are forecast across the Mediterranean

SYNOPSIS

Upper-level broad long-wave ridge dominates Europe at the beginning of the forecast period. Over the western Mediterranean ... cut-off low will be present. This cut-off is forecast to weaken while merging to the frontal zone over north-western Europe. East of it, warm air advection will continue over the central and eastern Mediterranean.

DISCUSSION

...East-central Mediterranean ...
East of the upper trough over the western Mediterranean ... moderate southerly flow will dominate the eastern and central Mediterranean. GFS model output suggests several weak vort-maxima crossing the region on Wednesday. At lower levels ... warm airmass originating from northern Afrika is advected northward, and 850 hPa temperature is forecast to reach in excess of 10 Celsius over the southern Mediterranean at the end of the forecast period. This airmass should be well mixed. Underneath the capping inversion ... cold boundary-layer airmass is expected at the beginning of the forecast period. Today's observations indicate just 10 to 12 Celsius temperature over the south-eastern part of the forecast area. During Wednesday ... this airmass should recover as latest model output suggests up to 20 Celsius and moisture will likely increase underneath the cap. However ... it is still questionable if convection will develop. Best chances will persist in the afternoon and evening, when another vort-max will cross the region. If thunderstorms will develop, they probably become surface-based. Severe thunderstorms are not likely as low-level shear will be rarther weak. During the evening ... thunderstomrs may possibly merge into an MCS producing strong wind gusts.

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