CONVECTIVE FORECAST
VALID 06Z TUE 09/03 - 06Z WED 10/03 2004
ISSUED: 08/03 22:12Z
FORECASTER: DAHL

General thunderstorms are forecast across the S Adriatic ... Ionian ... Aegean Sea ... Greece.

SYNOPSIS

Large-scale upper ride ATTM covering the North Sea and the NE Atlantic ... will continue to build ... and move NEWD ... covering Scandinavia/NW Russia by the end of the FCST period. Upper low at its E periphery ATTM located over N Germany ... will track southwards ... and merge with the upper cut-off low centered over the central Mediterranean. Vort maxima currently at the southern rim of this feature will continue to move eastwards ... altogether resulting in an elongated E-W oriented upper low reaching from S France into the Black Sea by Wednesday morning. At the SFC ... large high pressure area is covering the northern parts of Europe ... pushing dry/cold continental air masses deep into central and SW parts Europe. Vort max expected over the Tyrrhenian Sea by Tuesday 00Z is progged to re-strengthen the SFC low currently centered over the Adriatic/W Balkan. Expected this low to be located over Bulgaria/Romania towards the end of the FCST period.

DISCUSSION

...S Adriatic Sea ... Ionian Sea ... Greece ... Aegean Sea...
Central Mediterranean vort max is currently inducing a wave cyclone at the S periphery of the extensive Mediterranean SFC low. Problematic is once more the lack of radiosonde data over the S-central Mediterranean Sea ... it appears that warm-sector air mass will be rather dry ... especially as low-level air from the N Sahara desert is tapped and advected into the Ionian/Aegean Sea ahead of the vort max. This is also supported by GFS 12Z which does not propose any buoyant instability within this air mass. Chances of deep convection fueled by the warm-sector air mass appears to be rather unlikely ATTM given anticipated lack of low-level moisture. However ... TSTMS currently present NW of the developing wave low will likely continue given increasing dynamic forcing for upward motion. Though exact location of maximum convective activity with this feature is quite uncertain ATTM ... confidence exists that at least scattered TSTMS will be persist throughout the perdiod. Given about 50 m/s 500 hPa flow ... short line segments and brief bow echoes may occur ... posing primarily the threat for a few severe straight-line wind gusts. Uncertainties regarding details of the convective scenario ... and marginal thermodynamic setup precluding a SLGT ATTM.

Convective mixing will be present over large parts of the western and central Mediterranean Sea in the polar air mass ... despite there being no significant vort max/DCVA-related lift ... mixing should be sufficiently deep for the taller Cu's to glaciate ... and to produce a few lightning strikes. These TSTMS are currently expected to be very isolated and short-lived ... and a GEN THUNDER outlook is not necessary with this activity ATTM.

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