DAY 2 CONVECTIVE OUTLOOK
VALID 06Z THU 03/04 - 06Z FRI 04/04 2003
ISSUED: 02/04 20:38Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS CENTRAL EUROPE.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE MEDITERRANEAN.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS NORWAY.

SYNOPSIS

VIGOROUS UPPER TROUGH AT THE MOMENT OVER CENTRAL EUROPE IS RAPIDLY AMPLIFYING ... AND IS EXPECTED TO CLOSE OFF INTO AN UPPER CUT-OFF LOW OVER THE CENTRAL MEDITERRANEAN REGIONS ON THURSDAY. REMNANT NORTHERN STREAM TROUGH IS PROGGED TO MOVE EAST AND STRETCH FROM THE CZECH REPUBLIC INTO THE NORTHERN BALTIC STATES TOWARDS FRIDAY MORNING. DEEP POLAR/ARCTIC AIRMASSES ARE SPREADING ACROSS CENTRAL AND SOUTHWESTERN EUROPE INTO THE MEDITERRANEAN REGIONS WITH FAIRLY INTENSE CYCLOGENESIS CURRENTLY TAKING PLACE OVER THE GOLF OF GENOA.

DISCUSSION

...CENTRAL EUROPE...
POTENTIAL PROBLEM WITH CONVECTION IN THE DEEP POLAR AIRMASS ACROSS NORTH-CENTRAL EUROPE MAY TURN OUT TO BE SLIGHT SURFACE RIDGING IN THE WAKE OF THE UPPER TROUGH ... AND LEE EFFECTS OF THE SCANDINAVIAN MOUNTAINS ... THE LATTER OF WHICH IS EXPECTED TO RESULT IN SIGNIFICANT DRYING OF THE NORTHERLY LOW-LEVEL FLOW OVER EASTERN GERMANY AND WEST POLAND ... WHERE BEST UPPER SUPPORT WOULD BE PRESENT. BEST CHANCES FOR A FEW LIGHTNING STRIKES SHOULD EXIST IN A NARROW SECTOR OVER HOLLAND AND WESTERN GERMANY WEST OF THE DRY LOW-LEVEL FLOW ... AND EAST OF THE LOW-LEVEL RIDGING. WILL PLACE A GEN THUNDER AREA IN THIS REGION ... AN ISOLATED LIGHTNING STRIKE OR TWO MAY ALSO OCCUR S AND E OF THIS AREA.

...MEDITERRANEAN...
AIRMASS OVER THE MEDITERRANEAN REGIONS AHEAD OF THE COLD FRONT ASSOCIATED WITH THE UPPER TROUGH ... IS MARGINALLY UNSTABLE AND ONLY WEAKLY CAPPED PER 12 Z RADIOSONDE DATA. THE COLD FRONT IS EXPECTED TO EXTEND FROM NW ITALY INTO EASTERN TUNESIA BY THURSDAY 12Z. WARM AIRMASS E OF THIS FRONT ... IS EXPECTED TO WRAP AROUND THE SOUTHWARD SHIFTING LOW CENTER ... RESULTING IN AN EASTWARD PROGRESSION OF THE COLD FRONT OVER THE S MEDITERRANEAN TOWARDS LATE AFTERNOON ... WHICH ALSO APPEARS TO BE ASSOCIATED WITH A VORT MAX RAPIDLY MOVING EAST AT THE SOUTHERN PERIPHERY OF THE UPPER LOW. PRIND THAT MOST VIGOROUS CONVECTION WILL BE ASSOCIATED WITH THIS SOUTHERN PORTION OF THE COLD FRONT ... SOUTH OF THE ITALIAN PENINSULA.

OROGRAPHICALLY FORCED THUNDERSTORMS SHOULD BE POSSIBLE IN THE WARM-SECTOR AIRMASS OVER ITALY DURING THE AFTERNOON ... BUT SEVERE THREAT APPEARS TO BE MINIMAL GIVEN VERY WEAK LAPSE RATES AND MINIMAL VERTICAL SHEAR. WEAK ELEVATED THUNDERSTORMS COULD DEVELOP NORTH OF THE SFC LOW IN STRONG LOW-LEVEL WAA REGIME ... TSTMS MAY SPREAD INTO THE WESTERN MEDITERRANEAN SEA TOWARDS THE END OF THE FCST PERIOD. IN THE WESTERN PORTION OF THE GEN THUNDER AREA ... DEEP-LAYER SHEAR APPEARS TO BE RATHER STRONG DURING THE AFTERNOON/EVENING ... AND STORMS DEVELOPING IN THE DEEP POLAR AIRMASS WOULD BENEFIT FROM THIS FLOW REGIME ... AND MAY PRODUCE STRONG WIND GUSTS AND SOME HAIL ... WHICH MAY BRIEFLY APPROACH SEVERE LEVELS.

...NORWAY...
A FEW LIGHTNING STRIKES MAY ACCOMPANY SHALLOW BUT VIGOROUS POSTFRONTAL CELLULAR CONVECTION. EXPECT WIDESPREAD WIND GUSTS EXCEEDING 50 KNOTS IN ASSOCIATION WITH THE STRONG GRADIENT FLOW ... BUT VERTICAL MOMENTUM TRANSFER THROUGH CONVECTIVE MIXING WILL LIKELY ENHANCE THE WIND GUSTS LOCALLY.

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