CONVECTIVE FORECAST
VALID 06Z WED 09/06 - 06Z THU 10/06 2004
ISSUED: 09/06 00:18Z
FORECASTER: GROENEMEIJER

There is a slight risk of severe thunderstorms forecast across northern, central and eastern Germany, Czech Republic, western Slovak Republic, eastern Austria, eastern Slovenia Hungary, eastern Serbia and Montenegro, western Romania

General thunderstorms are forecast across parts of Russia, the eastern and southern Ukraine, northwestern Turkey, much of the Balkans, central Europe, the Low Countries, France, the western and central Iberian Peninsula, northern Italy

SYNOPSIS

Wednesday at 06Z... a broad mid/upper ridge is expected over western Europe. A trough in the wake of a cold front over Belarus, the Ukraine and western Russia is expected to dig as the front moves southward into the eastern Balkan states. Over northern Germany the frontal zone is retreating northeastward. Atlantic air is slowly moving into far western continental Europe behind a decelerating cold front moving into France and the Low countries during the afternoon hours.

DISCUSSION

...slight risk area...
At 06Z.. a frontal zone is located from near Hamburg to near Prague to northern Romania. Over Germany it is expected to move eastward as a warm front, while it moves southward as a cold front over the eastern Balkans. A mostly elevated MCS is expected to be located over the southern North Sea and northern Germany associated with warm air advection and DCVA related ascent. Convective precipitation should move into northern Germany and southern Denmark during the morning hours. Isolated large hail should be possible with some of the storms.

A vorticity maximum is expected to be located north of the Netherlands at 06 Z. The vort max is expected to move into central Europe and the Balkans reaching the central Danube Plains at the end of the forecast period. Around early afternoon scattered storms should be able to form over eastern Germany and the Czech Republic aided by ascent ahead of the vorticity maximum.

It is expected that between 600 - 1200 J/kg MLCAPE will form over this area and round 20 m/s deep-layer (0-6 km) shear is forecast over the area. Well-organised multicells and... given 0-3 km SREH values of 120 - 200 m2/s2 ... a few supercells can be expected. These will be capable of producing large hail and damaging gusts.

Further south... scattered storms are expected to develop over the mid-Danube plains. Shear being smaller there, single- and multicells should be the main convective modes. The storms can produce a few large hail and strong wind events.

Convection over Germany/ the Czech Republic could cluster into an MCS that moves southward along the frontal zone affecting the Czech republic, the western Slovak republic eastern Austria, Hungary and possibly eastern Serbia and Montenegro and western Romania. The main threat of this system is expected to be severe wind gusts, altough isolated large hail events should remain possible as well.

...The Low Countries, France, western Germany, Switzerland...
Near and just ahead of a a cold front moving into the area, isolated to scattered storms are expected to develop. A few storms could also develop near/over the western Alps, Jura, Vosges, Alsace and Black Forest. Current indications are that lapse rates will become somewhat less steep than on Tuesday, so that with anticipated 15 - 17 C surface dew points 400 - 800 J/kg MLCAPE50 should be realised. Deep-layer shear near 10 m/s, will allow for the development of multicell storms, capable of producing a few large hail events.

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