CONVECTIVE FORECAST
VALID 06Z MON 17/05 - 06Z TUE 18/05 2004
ISSUED: 16/05 19:03Z
FORECASTER: GATZEN

General thunderstorms are forecast across southeastern Italy, southern Adriatic, southern Balkans and Agean Sea

General thunderstorms are forecast across Spain

SYNOPSIS

Strong ridge is present over western Europe ... while low geopotential will remain over eastern and southern Europe. Rather strong upper jet points from northern Europe into eastern Central Europe and further into the northeastern and eastern Mediterranean. Embedded short-wave has reached Italy and will continue move southeastward.

DISCUSSION

... Southeastern Italy, southern Adriatic, southern Balkans and Agean Sea...
Rather strong upper short-wave trough will cross southeastern Europe on Monday leading to DCVA. UVM is expected east of the upper trough where theta-e advection will be weak. Affected air mass should be rather moist west of Greek as revealed by latest ascends. Thunderstorms should initiate as weak CIN will likely be present. Over Greece ... boundary-layer should be mixed due to diurnal insolation and initially high-based storms should form. Rather strong deep layer shear ahead of the trough and moderate low-level wind shear with northeasterly surface winds may be sufficient for rotating updrafts. However ... as model output does not suggest strong instability ... a SLGT RISK seems not to be warranted ATTM. With any supercell that forms ... large hail and damaging wind gusts will be the preliminary threat. Chance for an isolated tornado will be enhanced in the western part of the "see text" area, where LCL heights will be lower.

...Spain...
Model output suggests instability building over the Iberian Peninsula during the day. However ... latest soundings are stable above relatively deep CBL. As UVM will be rather weak, only islolated thunderstorms should form where orography supports initiation. Over southwestern Spain ... thunderstorms should be more likely, as upper trough will reach the extreme western Mediterranean. Vertical wind shear should remain quite low, and organized thunderstorms will not be likely. However ... deep/dry boundary layers may support cold-pool formation ... and thunderstorm-clusters are not ruled out with strong wind gusts the main threat.

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