CONVECTIVE FORECAST
VALID 15Z MON 05/05 - 06Z TUE 06/05 2003
ISSUED: 05/05 14:56Z
FORECASTER: GATZEN

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHWESTERN CENTRAL EUROPE, EASTERN SPAIN

GENERAL THUNDERSTORMS ARE FORECAST ACROSS GERMANY, NORTHERN ALPS

GENERAL THUNDERSTORMS ARE FORECAST ACROSS PARTS OF WESTERN EUROPE

SYNOPSIS

MODERATE SSWLY JETSTREAM EFFECTS WESTERN EUROPE. BENEATH THIS JET ... COLDFRONT EXTENDS FROM WESTERN SCANDINAVIA, NORTHWESTERN FRANCE ... INTO IBERIAN PENINSULA. ALONG THE SOUTHERN PART OF THIS BOUNDARY ... FRONTAL WAVE IS FORMING AS UPPER TROUGH STARTS TO CUT OFF.

DISCUSSION

...WESTERN EUROPE...
WEST OF MENTIONED COLDFRONT ... COLD AIRMASS HAS REACHED WESTERN EUROPE. SOME SHOWERS AND THUNDERSTORMS HAVE FORMED OVER NORTHWESTERN EUROPE. RAWINSONDE DATA SHOW RELATIVELY DRY BOUNDARY LAYER TO TO DAYTIME TURBULENCE. AS DIRECTIONAL SHEAR IS STRONG, SOME SHOWERS OR THUNDERSTORMS SHOULD BE ABLE TO PRODUCE STRONG WINDGUSTS.

...WESTERN CENTRAL EUROPE...
ALONG THE FRONTAL BOUNDARY ... MODEL OUTPUT SUGGESTS SYNOPTIC SCALE LIFT BENEATH THE JET AXIS FROM EASTERN SPAIN TO CENTRAL FRANCE AND BENELUX. SOUNDINGS DON'T SHOW LARGE INSTABILITY IN THIS REGION. HOWEVER ... ISENTROPIC LIFT ALONG THE WARM FRONT AND CVA SHOULD LEAD TO SYNOPTIC SCALE RAIN AND EMBEDDED THUNDERSTORMS. TO THE SOUTHEAST OF THIS FRONTAL BOUNDARY ... STEEP LAPSE RATES COULD LEAD TO MORE INSTABILITY, AND STRONG VERTICAL SHEAR COULD LEAD TO THUNDERSTORM ORANIZATION. IF THUNDERSTORMS MAY FORM DURING THE EVENING ... SEVERE POTENTIAL IS RELATIVELY HIGH. LARGE HAIL AND DAMAGING WINDS SHOULD BE THE MAIN SEVERE THREAD, AS BOUNDARY LAYER MOISTURE IS RATHER LOW.

...NORTHERN ALPS, CENTRAL GERMANY...
OVER GERMANY ... SURFACE CONVERGENCE WILL ENHANCE THUNDERSTORM ACTIVITY DURING THE EVENING. STEEP LAPSE RATES LEAD TO CAPE IN THE ORDER OF SOME 100 J/KG. SHEAR IS RELATIVELY LOW, AND ORGANISED THUNDERSTORMS ARE NOT EXPECTED. HOWEVER ... VERY DRY AND HOT BOUNDARY LAYER / SURFACE TEMPERATURES UP TO 33 C OVER SOUTHERN GERMANY / SHOULD LEAD TO STRONG DOWNDRAFT GUSTS AND LARGE HAIL. THUNDERSTORM ACTIVITY SHOULD WEAKEN DURING THE NIGHT.

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