CONVECTIVE FORECAST
VALID Sat 15 Oct 06:00 - Sun 16 Oct 06:00 2005 (UTC)
ISSUED: 14 Oct 17:21 (UTC)
FORECASTER: TUSCHY

There is a slight risk of severe thunderstorms forecast across Balearic Sea and coastal areas of southern France

SYNOPSIS

During the forecast period, the change-over towards a strong omega-pattern will be performed ( 2 strong upper-level troughs and in-between strengthening ridging ). During this phase, a weakening upper-level low over Spain will be included on the eastern side of the east-Atlantik trough and will therefore move northward....Otherwise, most parts of central Europe and the southeastern Mediterranean area will see stable conditions.

DISCUSSION

...Balearic Sea and coastal areas of southern France...
Main focus for convective development will be the northward shifting and weakening upper-level low, exiting the mainland of Spain and crossing the Bay of Biscay.... Strongest jet will be found on the upstream side of departing system ( covering SW France ), and accompanying right rear entrance region with upper-level divergence will be situated over the SLGT area.
Strong onshore flow should carry somewhat higher dewpoints inward during the forecast period...this combined with slightly cooler mid levels [ a result of northward swiveling trough axis ] should offer SBCAPE values of about 300 J/kg....Most parts of the SLGT will see strong background flow with DLS values up to 25m/s and this should help for an enhanced severe wind gust threat, although threat for widespread organized storms will diminish during the latter part of the forecast period from south to north as a consequence of increasing upper-level convergence and rising geopotential heights....Along the coastal areas of southern France, enhanced LLS ( up to 12m/s ), and influx of higher dewpoints ( low LCLs) should pose a threat for an enhanced tornado and severe wind gust risk.

During the evening and night hours,cold-core of upper-level low shifts northward over the Bay of Biscay... Steepening lapse rates and low kinematic parameters should support the development of a few waterspouts.

...extreme northeastern Baltic Sea,Gulf of Finland,Lake Ladoga,Latvia,Estonia and southern Finland...
Strong upper-level low pressure area will cross the SEE TEXT area with very cold mid-level temperatures....Exact track of depression not that sure ATM, so went with a rather broad SEE TEXT area ( especially towards the west)...Lake Ladoga and the eastern parts of the Gulf of Finland should see the best conditions for waterspout development... If storms will develop further towards the west, they would be in an environment more conducive for a severe wind gust threat, but confidence in this scenario is too low ATM for issuing higher probabilities.

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