STORM FORECAST
VALID Tue 21 Feb 08:00 - Wed 22 Feb 06:00 2006 (UTC)
ISSUED: 21 Feb 09:23 (UTC)
FORECASTER: GROENEMEIJER

A threat level 1 is forecast across southern Italy, Albania and adjacent waters

SYNOPSIS

Tuesday at 06 UTC... a large mid-level low pressure area is located over western Europe. On its southeastern flank a jet streak is moving northeastward. The air-mass is unstable over much of the western and central Mediterranean region.

DISCUSSION

...southern Italy, Albania and adjacent waters...
As a jet streak is moving northeastward out of Tunisia and Algeria deep-layer (0-6 km) shear of 30 - 40 m/s is to form across the area as is confirmed by 00 UTC soundings from Trapani and Brindisi. Latest GFS model run predicts the formation of a low level jet with speeds in excess of 20 m/s at 850 hPa across most of the level 1 area, which should give rise to considerable low-level shear. MLCAPE locally in excess of 500 J/kg and low LFC heights are forecast as mid-level temperatures drop due to strong rising motions in the jet-streak's left-exit region. This should create favourable conditions for the formation of rotating updrafts/supercells with a chance to produce tornadoes.

This night and morning, thunderstorms have been confined to an area north of the level-1 area, but aforementioned destabilisation and the erosion fo any CIN -if present- should be occurring within the risk area during the remainder of this morning and this afternoon, so that convective initiation is expected to occur within the area some time this afternoon. It is well possible that storms will initially be isolated, although they should rapidly cluster given the weak CIN and strongly-forced nature of the storms. Expect a threat of tornadoes -including a small possibility that they will exceed F1 intensity- as well as a threat of large hail and wind threat to be present. The threat is forecast to persist overnight across the level 1 area.

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