CONVECTIVE FORECAST
VALID Fri 09 Dec 06:00 - Sat 10 Dec 06:00 2005 (UTC)
ISSUED: 08 Dec 16:12 (UTC)
FORECASTER: TUSCHY

SYNOPSIS

Highly amplified weather pattern continues over Europe during the forecast period...Downstream of a well developed polar vortex over eastern Canada, strong WAA regime will be present over most parts of the eastern Atlantic... This pressure configuration helps to further strengthen a ridge, west of Europe...Between the ridge and a cold Russia low pressure area, cool and dry air will be advected over most parts of central Europe....accompanied by a strengthening low level high pressure area ( center is forecasted to be placed somewhere over Germany with about 1040hPa during the night hours )... This high pressure area introduces a slow southward movement of a cut off over the central Mediterranean during the next 24 hours... This system will be the main focus for convection activity.

DISCUSSION

...central Mediterranean area...
Pressure fall already underway over the Ligurian Sea [ 1015hPa depression at 15 UTC, 08.12.05] with GFS as the main forecast model during the next 24 hours, because it mastered the time/location/strength of depression very well... As a consequence of widespread rising pressure north of the depression and strongest mid- / UL - jet upstream of the cut-off, center of low level pressure will shift slowly southward over the central Mediterranean, reaching the northern coast of Africa during the latter part of the forecast period... SST around 16°C between Sardegna and central Italy under the base of a cold UL-trough will be enough for widespread instability release ( in the range of 300-400 J/kg SBCAPE )... Low kinematic parameters should suppress organisation, although environment will become more favorable for waterspout development, especially along the coastal areas of Corse, Sardegna and western-central Italy ( with steepening lapse rates and maximum of instability in the lower levels).

Main focus for some storm organisation will be an area between the Islas Baleares and Sardegna during the night hours, when pool of cold mid-level airmass ( -30°C at H5 ) will move over 17-18°C warm water...MM5 shows slightly negative LI-values and up to 400 J/kg instability in this area, combined with a strengthening wind field... Exact track of low-level depression uncertain ATM so don't want to point out an area of highere severe wx. probabilites, but storms will have a chance for producing severe wind gusts, especially, when they string together.

Final area will be the Ionian Sea... Models indicate broad area of SBCAPE values in the order of 500 J/kg... Strong mid-/UL -jet coming out of the base of the trough, will help for strengthening UVV values....this, combined with low CIN values forecasted, will be conducive for widespread TSTM development... DLS up to 20m/s will be present so there should be the risk for a few severe wind gusts.

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