DAY 1 CONVECTIVE OUTLOOK
VALID 20Z FRI 13/12 - 06Z SAT 14/12 2002
ISSUED: 13/12 20:05Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE IBERIAN PENINSULA

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE SOUTH-CENTRAL MEDITERRANEAN SEA

SYNOPSIS

MEANDERING NRN FRONTAL ZONE STRETCHING ACROSS THE NORTHERN ATLANTIC NEAR 70N LATITUDE... WITH SRN BRANCH COVERING W EUROPE AND THE MEDITERRANEAN SEA. EMBEDDED SRN STREAM JETLET ATTM OFF THE IBERIAN W COAST...WILL RAPIDLY TRANSLATE EAST AND REACH W IBERIA AT THE BEGINNING OF DAY TWO. SFC ATTM LOW W OF IBERIA... WILL UNDERGO RAPID DEEPENING AS JET STREAK APPROACHES...AND IS PROGGED TO BE LOCATED OVER THE SW GULF OF BISKAY TOWARDS THE END OF THE FCST PERIOD. SRN STREAM VORT MAX OVER THE S CNTRL MEDITERRANEAN SEA... IS MAINTAINING RATHER WEAK SFC LOW OVER THAT REGION...WHICH WILL SHIFT INTO THE AEGEAN SEA BY SATURDAY 06Z. OTHERWISE... LARGE HIGH PRESSURE AREA IS COVERING MUCH OF NORTHEASTERN EUROPE AND PARTS OF RUSSIA.

DISCUSSION

...IBERIA...
LIGHTNING NETWORK AND IR SATELLITE IMAGERY SUGGEST DEEP CONVECTION ALONG THE COLD FRONT OF THE SYSTEM W OF IBERIA. THOUGH MOIST/SUBTROPICAL AIRMASS W OF THE COLD FRONT IS NOT SAMPLED BY RADIOSONDE NETWORK... GFS NUMERICAL ANALYSES SUGGEST A FEW HUNDRED JOULES OF CAPE AHEAD OF THE FRONT. GIVEN STRENGTHENING DYNAMIC UPWARD FORCING WITH THE ADVENT OF THE UPPER SPEED MAX... ADDITIONAL TSTMS MAY DEVELOP DURING THE NIGHT. GIVEN INCREASINGLY STRONG LOW-LEVEL SHEAR ALONG THE FRONT... A FEW DAMAGING WIND GUSTS COULD OCCUR. ALSO... SR-HELICITY SHOULD LOCALLY BE SUFFICIENT TO SUPPORT A ROTATING UPDRAFT OR TWO... IF SO... LOW DEWPOINT DEPRESSIONS IN THE PBL WOULD SUPPORT LOW-LEVEL MESOCYCLOGENESIS...AND CHANCE OF A BRIEF TORNADO OR TWO EXISTS. UNCERTAINTY ABOUT THERMODYNAMIC QUALITY OF THE AIRMASS AHEAD OF THE FRONT AND SUSPECTED MARGINAL THERMODYNAMIC FIELDS EXCLUDE A CATEGORICAL OUTLOOK ATTM.

...SOUTH-CENTRAL MEDITERRANEAN...
TSTMS HAVE FORMED OVER THE SOUTH-CENTRAL MEDITERRANEAN SEA AND S GREECE ALONG WEAK COLD FRONT AHEAD OF UPPER VORT MAX. INSTABILITY OF AIRMASS AHEAD OF THE COLD FRONT APPEARS TO BE QUITE WEAK. THOUGH RATHER STRONG BAND OF MID/UPPER WIND APPEAR TO ACCOMPANY THIS VORT MAX... CHANCE OF ORGANIZED SEVERE LOOKS TO BE QUITE LOW TONIGHT. HOWEVER...POSSIBILITY OF AN ISOLATED STRONG WIND GUST AND POSSIBLY A WATER SPOUT OR TWO SHOULD NOT BE DISCOUNTED.

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