CONVECTIVE FORECAST
VALID 06Z SAT 11/12 - 06Z SUN 12/12 2004
ISSUED: 10/12 20:25Z
FORECASTER: DAHL

General thunderstorms are forecast across the western and central Mediterranean Sea.

SYNOPSIS

Blocking upper high over central Europe will persist through the period ... with attendant extensive SFC high covering most of central ... western and southeastern Europe. Weakening quasi-stationary upper low is progged to remain in place over N Tunesia ... supporting favorable environment for TSTMS over the central and western Mediterranean Sea.

DISCUSSION

...central and western Mediterranean...
Some of Friday's 12Z launches indicate reasonably strong low-level shear (LIRE and LIBR) ... with others having weak shear but rather strong low-level lapse rates (LICT and LIEE). It appears rather likely that the latter thermodynamic profiles may locally coexist with the LIRE/LIBR kinematic setup ... which would suggest a slight chance for a few rotating updrafts with large hail and a tornado or two. This general setup is expected to persist across the western portions of the Mediterranean ... with band of 10+ m/s 850 winds stretching across the central and W Mediterranean on Saturday per model guidance. Deep shear should be quite marginal with 15 m/s or less ... but is looks that at least isolated briefly rotating updrafts with a concomitant severe TSTM threat will be possible.

...Norwegian W coast...
An isolated lightning strike or two could occur along the NW Norwegian coast in strong orographically forced upward motion regime during the evening hours. Any convection will likely augment strong gradient SFC flow ... but organized severe TSTMS should be unlikely. Low confidence in widespread lightning occurrence precluding TSTM outlook for this region ATTM.

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