VALID 00Z SUN 13/10 - 06Z MON 14/10 2002
ISSUED: SUN 13/10 11:54Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE CNTRL MEDITERRANEAN REGIONS AND THE S BALKAN STATES.

SYNOPSIS

UPPER LONG-WAVE TROUGH ATTM OVER THE CNTRL MEDITERRANEAN REGIONS...WILL SLOWLY CONTINUE EASTWARDS. JET STREAK ATTM REACHING THE W EUROPEAN COAST...IS EXPECTED TO CONTINUE PROPAGATING EASTWARDS...RESULTING IN ESTABLISHMENT OF FAST AND MAINLY ZONAL FLOW ACROSS CENTRAL EUROPE TOWARDS THE END OF DAY 1 PERIOD. BENEATH LEFT EXIT REGION OF THIS JET STREAK...SFC LOW /ATTM W OF THE BRITISH CHANNEL/ HAS DEVELOPED. ANOTHER... RATHER EXTENSIVE FILLING SFC LOW IS ASSOCIATED WITH THE MEDITERRANEAN UPPER TROUGH. ASSOCIATED COLD FRONT HAS REACHED THE AEGEAN W COAST PER LATEST OBJECTIVE SFC ANALYSES.

DISCUSSION

...CNTRL MEDITERRANEAN...S BALKAN ...
SCATTERED TSTMS PERSISTING BENEATH UPPER THERMAL TROUGH OVER THE S-CNTRL MEDITERRANEAN SEA AND ACROSS GREECE/ADJACENT STATES. ADDITIONAL TSTMS HAVE DEVELOPED OVER THE AEGEAN SEA AND E GREECE ALONG THE COLD FRONT. SOUNDINGS IN THE PREFRONTAL AS WELL AS IN THE POSTFRONTAL ENVIRONMENT INDICATE NEUTRAL TO WEAKLY UNSTABLE LAPSE RATES. HOWEVER...DEEP-LAYER SHEAR ON THE ORDER OF 40 TO 50 KNOTS IS PRESENT AT THE PERIPHERY OF THE UPPER TROUGH. THIS SUGGESTS THAT A FEW STORMS MAY BECOME MULTICELLULAR...APT TO PRODUCE ISOLATED MARGINALLY SEVERE HAIL AND A FEW STRONG WIND GUSTS. ALSO...AN ISOLATED MESOCYCLONE OR TWO MAY FORM IF LOW-LEVEL WIND FIELD CAN LOCALLY BE ENHANCED BY OROGRAPHY. IN THIS CASE...QUITE LOW LCL HEIGTS SUGGEST ENHANCED LIKELYHOOD LOW-LEVEL ROTATION WITH ANY SUPERCELL. THUS...AN ISOLATED TORNADO EVENT OR TWO MAY OCCUR. BEST CHANCES FOR THIS SCENARIO WILL BE E OF THE COLD FRONT WHERE WEAK LARGE-SCALE LOW-LEVEL VEERING IS PRESENT ALREADY. HOWEVER...ALLOVER SEVERE THREAT IS TOO LOW TO WARRENT A SLIGHT RISK ATTM.

...EXTREME NW SPAIN...N PORTUGAL ...
PLUME OF MOIST/SUBTROPIC AIRMASS EXPECTED TO GRAZE SPAIN/N PORTUGAL LATE IN THE PERIOD IN ASSOCIATION WITH A DEVELOPING FRONTAL WAVE... MOIST PLUME IS POORLY SAMPLED BY AVAILABLE RAWINSONDE DATA. HOWEVER...INDICATIONS ARE THAT INSTABILITY WILL BE VERY MEAGER WITHIN THIS PLUME. ALTHOUGH NARROW SHEETS OF POTENTIAL INSTABILITY MAY BE PRESENT...LOCALLY ENHANCING PRECIP CONVECTIVELY...TSTMS APPEAR TOO UNLIKELY ATTM FOR A GEN THUNDER OUTLOOK.

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