CONVECTIVE FORECAST
VALID 06Z MON 31/05 - 06Z TUE 01/06 2004
ISSUED: 31/05 00:02Z
FORECASTER: GROENEMEIJER

There is a slight risk of severe thunderstorms forecast across parts of Russia: Nizhegorod, Ryansk, Tula, Lipetsk, Orel, Kursk adm. regions.

General thunderstorms are forecast across Scotland, southeastern Spain, central Europe and the western and southern Balkans, parts of Turkay and a part of Russia.

SYNOPSIS

Monday at 06Z... warm advection is in place over a extensive area west of the Ural mountains south of a stationary and gradually southward moving frontal zone near a line from Kiev to Moscow to Vologda. A strong westsouthwesterly jet develops near the frontal zone as a vort max initially over southern Karelia accelerates eastward. Upstream.. a northwest-southeast oriented trough over the northern british Isles and the Low countries is expected to evelove in a cut-off low moving southeastward into central Europe.

DISCUSSION

...Russia...
Across the slight risk area.... 11-14 C dew point values and 22-25 C temperatures are expected south of the aforementioned frontal zone. It is expected that rather large CIN will inhibit development of deep convection until the late afternoon, but some convective development is expected not far from the frontal zone, where capping should be weakest. Mid levels winds are expected to increase strongly during the day so that deep-layer shear will be well in excess of 20 m/s range. As 200-300 m2/s2 storm relative helicity is expected supercells are a likely mode of convection. Low LCL-heights and strongly veering 0-1 km winds create a chance of tornadoes with this convection in additiona to a threat of large hail strong wind gusts.

...mid-Rhine Valley, western Alps...
Near the cut-off low that is expected to move southeastward over the indicated area during the forecast period, quite steep low and mid-level lapse rates are expected, yielding a few 100's of J/kg MLCAPE as the boundary layer is warmed by sunshine. On the southern flanks of the low quite strong deep-layer shear of 15-30 m/s is expected. Some of the southernmost convection may get organised as a result, and short-lived rotating updrafts are not excluded either, giving a chance of some large hail as well as gusty winds. Greatest chance should be on the northern Alpine flanks and across far southern Germany, where orographic flow modification should yield stronger shear profiles.

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