CONVECTIVE FORECAST - UPDATE
VALID 09Z THU 08/05 - 06Z FRI 09/05 2003
ISSUED: 08/05 09:00Z
FORECASTER: GATZEN

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN CENTRAL EUROPE

GENERAL THUNDERSTORMS ARE FORECAST ACROSS SOUTHWESTERN, CENTRAL AND EASTERN EUROPE

SYNOPSIS

CUT-OFF LOW PLACED OVER IBERIAN PENINSULA GETS CONNECTED TO NORTHERN JET STREAM ... AND UPPER JET STREAK VISIBLE IN WATER VAPOR IMAGE RAGES NORTHEASTWARD INTO CENTRAL GERMANY. OVER CENTRAL EUROPE ... FRONTAL BOUNDARY EXTENDING FROM NORTHERN FRANCE ... CENTRAL GERMANY ... SOUTHERN POLAND TO SOUTHERN WHITE RUSSIA.

DISCUSSION

...CENTRAL EUROPE...
FRONTAL BOUNDARY OVER CENTRAL EUROPE WILL BE THE FOCUS OF EXPECTED CONVECTION. TO THE SOUTH ... MOISTURE WITHIN THE WARM AIRMASS HAS RECOVERED DURING THE NIGHT, ESPECIALLY DUE TO MOISTURE TRANSPORT THROUGH THE RHONE VALLEY INTO SOUTHWESTERN GERMANY AND AROUND THE EASTERN ALPS INTO CZECH REPUBLIC. SOUNDINGS INDICATE DEW POINTS NEAR 10C UP TO 850 HPA IN THIS REGIONS. ABOVE THE BOUNDARY LAYER ... STEEP LAPSE RATES SITUATED OVER PARTS OF SOUTHERN CENTRAL EUROPE. GFS MODEL SUGGESTS MORE THAN 1500 J/KG MUCAPE OVER SOUTHWESTERN GERMANY AND CZECH REPUBLIC IN THE AFTERNOON. AT THE SURFACE ... COLD FRONT OF LOW OVER SWERN EUROPE MOVES EASTWARD INTO SOUTHERN GERMANY. DURING THE DAY ... CONVECTIVE INITIATION IS EXPECTED ALONG THE TRIPLE POINT OVER SOUTHWESTERN GERMANY. DEEP LAYER SHEAR IS NOT TOO LOW AS 300 HPA FLOW WILL INCREASE TO >50 KN OVER SWERN GERMANY. AT LOWER LEVELS ... MODEL OUTPUT SUGGESTS WESTERLY WINDS, AND DIRECTIONAL SHEAR SEEMS TO BE LIMITED SOMEHOW. HOWEVER ... LARGE INSTABILITY AND MODERATE SYNOPTIC SCALE FORCING SHOULD ALLOW DEEP CONVECTION. DEEP LAYER SHEAR SEEMS FAVOURABLE FOR STORM ORGANIZATION ... ENHANCED LOW LEVEL SRH DUE TO OROGRAPHIC EFFECTS AND CELL INTERACTION SHOULD ALLOW FOR SUPERCELLS. LARGE HAIL, DAMAGING WINDS AND A FEW ISOLATED TORNADOS SHOULD BE POSSIBLE. THUNDERSTORM ACTIVITY SHOULD SPREAD NE-WARD ALONG THE FRONTAL BOUNDARY AND TO THE NW OF THE JET STREAK, WHERE UVM SHOULD BE STRONGEST. ISOLATED THUNDERSTORMS/ SUPERCELLS ARE EXPECTED OVER CENTRAL GERMANY DURING THE AFTERNOON. THUNDERSTORMS SHOULD WEAK DURING THE NIGHT, REACHING EASTERN GERMANY/ POLAND ... ANOTHER FOCUS OF CONVECTION WILL BE SOUTHEASTERN CENTRAL EUROPE. UNSTABLE AIRMASS OVER CZECH REPUBLIC SHOULD LEAD TO THUNDERSTORM DEVELOPMENT ALONG EASTWARD MOVING COLDFRONT. INCREASING DEEP LAYER SHEAR MAKES ORGANISED THUNDERSTORMS LIKELY. ISOLATED SUPERCELLS ARE EXPECTED WITH A CHANCE OF LARGE HAIL AND DAMAGING WIND GUSTS ... OVER THE CENTRAL ALPS ... THUNDERSTORMS SHOULD FORM DURING THE DAY DUE TU DIABATIC HEATING AND OROGRAPHIC EFFECTS. SYNOPTIC SCALE UVM SHOULD BE LIMITED UNDERNEATH THE JET STREAK'S RIGHT EXIT ... HOWEVER ... IN THE EVENING, THUNDERSTORMS SHOULD PROPAGATE EASTWARD OVER BAVARIA. LARGE HAIL AND STRONG WIND GUSTS ARE FORECAST IN ASSOCIATION WITH STRONGER CELLS.

...ADDITIONAL RISK AREAS...
SEE TEXT OF PREVIOUS OUTLOOK.

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