DAY 2 CONVECTIVE OUTLOOK
VALID 06Z TUE 25/03 - 06Z WED 26/03 2003
ISSUED: 24/03 23:58Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE IBERIAN PENINSULA.

SYNOPSIS

OMEGA BLOCK IS WEAKENING ... DEVELOPING INTO A RATHER STRONG MEANDERUNG NORTHERN FRONTAL ZONE STRETCHING ACROSS THE NORTHERN PARTS OF EUROPE ... WITH A WEAKER SOUTHERN FRONTAL ZONE EXPECTED TO EXTEND FROM SPAIN ACROSS THE MEDITERRANEAN SEA BY THE END OF THE FCST PERIOD. SMALL/WEAK VORT MAX ATTM OVER THE NORTH SEA IS PROGGED TO MIGRATE SLOWLY SOUTH ... AFFECTING POLAND ... GERMANY ... BENELUX AND N FRANCE ON TUESDAY. AT LOW LEVELS ... SEASONABLY MILD SUBTROPICAL AIRMASSES ADVECTING INTO CENTRAL EUROPE AT THE WEATERN RIM OF THE WEAKENING CENTRAL EUROPEAN SFC HIGH.

DISCUSSION

...IBERIAN PENINSULA...
AVAILABLE DATA DON'T REVEAL THE ORIGIN OF THE MOISTURE DRIVING THE STORMS N OF PORTUGAL VERY WELL. INDICATIONS ARE THAT POCKETS OF RATHER DEEP MOISTURE ARE PRESENT OVER THE S MEDITERRANEAN SEA WHICH ARE ADVECTED INTO WEST SPAIN AND PORTUGAL. OTHER SOURCE OF MOISTURE SEEMS TO BE THE SUBTROPICAL ATLANTIC ... AND IT APPEARS THAT BOTH MEDITERRANEAN AND ATLANTIC MOISTURE CONTRIBUTE TO PRESENT CONVECTIVE SCENARIO IN N SPAIN. MODEL FIELDS SUGGEST INCREASING 850 HPA THETA-E ADVECTION OVER S SPAIN BEGINNING TUESDAY AFTERNOON INTO TUESDAY NIGHT. GIVEN LOW-LEVEL MOISTURE INFLUX FROM THE S MEDITERRANEAN SEA ... WEAK INSTABILITY MAY DEVELOP OVER S SPAIN TOWARDS THE AFTERNOON/EVENING. MODELS INDICATE WEAK LOBES OF 500 HPA CVA ... AND WITH PEAK HEATING DURING THE LATE AFTERNOON ... A FEW SURFACE-BASED THUNDERSTORMS SHOULD DEVELOP. INCREASING WAA AND ASSOCIATED ISENTROPIC LIFT SHOULD SUPPORT DEVELOPMENT SLIGHTLY ELEVATED CONVECTIVE ACTIVITY THROUGH THE NIGHT. WEAK KINEMATIC AND THERMODYNAMIC PARAMETERS SUGGEST THAT SEVERE THREAT WILL BE MINIMAL THOUGH.

...S GERMANY ... LUXEMBOURG ... NORTH FRANCE...
PLUME OF MODERATELY HIGH 850 HPA THETA-E IS EXPECTED TO STRETCH ACROSS S GERMANY ... LUXEMBOURG ... AND NORTH FRANCE BY TUESDAY AFTERNOON. MODIFIED SOUNDINGS OF THIS AIRMASS INDICATE WEAK CAPE ... WHICH IS ALSO SUPPORTED BY GFS MODEL FIELDS. GIVEN SOME UVV'S AHEAD OF WEAK UPPER VORT MAX ... POTENTIAL EXISTS FOR A FEW SHOWERS AND WEAK THUNDERSTORMS DURING THE LATE AFTERNOON PRIMARILY ALONG WEAK BAROCLINIC ZONE AT THE N EDGE OF THE THETA-E PLUME. REFRAINING FROM OUTLOOKING A GEN THUNDER AREA ATTM BUT IF LOW-LEVEL DEWPOINTS INDEED CLIMB INTO THE 8°C RANGE, A GEN THUNDER AREA WILL LIKELY BE NECESSARY WITH TOMORROW'S OUTLOOK.

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