CONVECTIVE FORECAST
VALID Sat 23 Jul 06:00 - Sun 24 Jul 06:00 2005 (UTC)
ISSUED: 22 Jul 22:52 (UTC)
FORECASTER: DAHL

SYNOPSIS

Extensive upper low is centered over NE Europe/Baltic Sea ... and should rotate slowly NEWD during the period ... partly in response to approaching Atlantic trough which will reach the British Isles late on Saturday ... altogether resulting in moderately strong westerly mid/upper flow over the SRN portions of Europe ... featuring several imbedded small-scale vort maxima. At the SFC ... main feature should be fairly intense quasistationary low over the Baltic Sea ... and deepening SFC low W of the British Isles ... otherwise ... several weak mesoscale SFC lows are expected to exist beneath meandering mid/upper flow across SRN and ERN Europe.

DISCUSSION

...NE Spain...
It seems that rather rich BL moisture (about 14 g/kg mean mixing ratios) is present over the SW Mediterranean Sea which has not been affected by the NWLY flow farther E ... and that this moisture will be advected into extreme NE Spain in the afternoon/evening hours. This coupled with upslope flow S of the Pyrenees may support an isolated TSTM or two. 500 hPa flow of about 15 m/s may support multicellular organization with an attendant severe wind threat ... particularly as the mid levels should be rather dry. Also ... marginally severe hail could occur. Uncertainty about storm initiation and coverage precludes a SLGT ATTM.

...N Italy ... Balkan States...
Current indications are that NRN Italy will see the deepest LL moisture ... sufficient for MLCAPEs in the range of 500 - 1000 J/kg ... locally maybe somewhat higher. Similar thermodynamic setup is expected to persist across the Balkans. Weak CINH should be eroded by insolation and large-scale ascent accompanying the various vort maxima overspreading the region. Deep shear of about 15 m/s ... and 0-1 km shear just below 10 m/s should be common in the afternoon ... locally augmented by outflow boundaries ... orography and other mesoscale features. This suggests that an isolated mesocyclone or bow echo may occur ... though primary mode should be multicellular. The most intense cells may produce severe straight-line winds and some hail ... but probably of rather limited spatial coverage so that a SLGT does not seem to be warranted ATTM.

...Scandinavia ... Baltic States...
Weakly to moderately unstable subtropical air is wrapping around Scandinavian SFC low ... providing focus for pesistent convective development. It seems that TSTMS may tend to be elevated ... especially at the NWRN fringe of the theta-e tongue. Though some cells may tap boundary-layer air ... the shear profiles are progged to be rather weak within the theta-e plume ... and chances of severe evolution should be limited. However ... storms should also develop in modified polar air S and E of the low center ... which should benefit from somewhat stronger kinematic setup ... though it seems that best shear will be just outside the regions where convection is expected to develop. Allover severe threat should thus be limited to an isolated severe TSTM event or two.

...S UK and Ireland...
Sustained low-level theta-e advection may eventually support isolated/weak elevated TSTMS over the SRN UK and Ireland. Indcations are that lightning activity will be too isolated for a TSTM area.

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