DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 041218
SWODY1
SPC AC 041216

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0716 AM CDT THU APR 04 2013

VALID 041300Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS TODAY AND TONIGHT ACROSS THE
FLORIDA PENINSULA...AND PARTS OF NORTHERN FLORIDA INTO SOUTHERN
GEORGIA...

...SYNOPSIS...
THE MID-LATITUDE WESTERLIES REMAIN SPLIT ACROSS THE EASTERN PACIFIC
INTO WESTERN NORTH AMERICA...BUT FLOW WILL CONTINUE TO TREND TO A
MORE ZONAL REGIME...AS A SIGNIFICANT SHORT WAVE IMPULSE FLATTENS
SOUTHERN STREAM RIDGING ACROSS THE INTERMOUNTAIN WEST AND ROCKIES.
DOWNSTREAM...A PAIR OF SIGNIFICANT SHORT WAVE IMPULSES WILL CONTINUE
TO DIG EAST SOUTHEASTWARD. ONE...IN THE NORTHERN STREAM...TO THE
SOUTH OF HUDSON BAY...LIKELY WILL BE ACCOMPANIED BY ANOTHER
INTRUSION OF COLD AIR INTO THE GREAT LAKES REGION AND NEW ENGLAND.
THE OTHER...IN THE SOUTHERN STREAM...MAY CONTRIBUTE TO SURFACE
CYCLOGENESIS ALONG THE SOUTH ATLANTIC COAST DURING THE LATTER HALF
OF THE PERIOD...AS IT ACCELERATES A BIT ACROSS THE LOWER MISSISSIPPI
VALLEY/WESTERN GULF COAST REGION...INTO THE EASTERN GULF COAST AND
GULF OF MEXICO BY 12Z FRIDAY.

A WEAK AREA OF LOW PRESSURE ALREADY HAS FORMED OVER THE NORTHEAST
GULF OF MEXICO. THIS IS ALONG THE BAROCLINIC ZONE ASSOCIATED WITH
THE SHALLOW SOUTHERN EDGE OF THE RECENT COLD INTRUSION WHICH REACHED
GULF COASTAL AREAS...WHILE THE DEEPER FRONTAL SURGE STALLED ACROSS
PARTS OF THE TENNESSEE VALLEY AND NORTHERN GULF STATES INTO THE
SOUTH ATLANTIC SEABOARD. THE LOW MAY TRACK INLAND ACROSS NORTHERN
FLORIDA AND SOUTHERN GEORGIA TODAY...BUT LITTLE SUBSTANTIVE
DEEPENING APPEARS LIKELY UNTIL IT REACHES CAROLINA COASTAL AREAS
LATER TONIGHT. AS A RESULT...GUIDANCE GENERALLY SUGGESTS ONLY A
WEAK TO MODEST /30 KT OR SO/ SOUTHWESTERLY 850 MB FLOW DEVELOPING
INLAND ACROSS THE CENTRAL PENINSULA AND NORTHEAST FLORIDA THROUGH
THE DAYTIME HOURS. STILL...THIS SHOULD BE SUFFICIENT TO ENHANCE THE
RISK FOR SEVERE STORMS...IN THE PRESENCE OF AT LEAST MODERATELY
STRONG DEEP LAYER SHEAR...AND A MOISTENING BOUNDARY LAYER.

...FLORIDA AND ADJACENT SOUTHERN GEORGIA...
SPC STORM-SCALE ENSEMBLE MEMBERS DO NOT APPEAR TO HAVE A GOOD HANDLE
ON CURRENT CONVECTIVE DEVELOPMENTS OVER THE GULF OF MEXICO. IT IS
NOT CLEAR THAT THE LAST FEW RUNS OF THE HIGH RESOLUTION RAPID
REFRESH DO EITHER. BUT CONSIDERABLE OTHER MODEL DATA...AS WELL AS
OBSERVATIONAL DATA...DO APPEAR TO PROVIDE SUPPORT FOR THE GENERAL
IDEA OF INCREASING SEVERE WEATHER POTENTIAL BY EARLY AFTERNOON
ACROSS THE CENTRAL FLORIDA PENINSULA. THIS IS EXPECTED TO OCCUR IN
ASSOCIATION WITH THE EASTWARD PROGRESSION OF A PERTURBATION
ASSOCIATED WITH THE ONGOING CLUSTER OF STORMS OVER THE EASTERN GULF
OF MEXICO.

DIFLUENT AND DIVERGENT HIGH LEVEL FLOW...BETWEEN THE SOUTHERN STREAM
JET NOSING ACROSS THE NORTHERN GULF OF MEXICO...AND THE SUBTROPICAL
JET EXTENDING EAST NORTHEASTWARD ACROSS THE SOUTHERN GULF OF MEXICO
THROUGH THE BAHAMAS...MAY PROVIDE CONTINUING SUPPORT FOR THE
CONVECTIVE CLUSTER...WHICH MAY PROGRESS INLAND NEAR/SOUTH OF TAMPA
BY 17-20Z. AROUND THE SAME TIME...OR SHORTLY THEREAFTER...IT ALSO
APPEARS THAT BOUNDARY LAYER WARMING AND DESTABILIZATION...IN THE
WAKE OF WEAK CONVECTION CURRENTLY OVERSPREADING THE CENTRAL
PENINSULA...WILL BECOME SUFFICIENT TO SUPPORT INCREASING DISCRETE
STORM DEVELOPMENT ALONG THE SEA BREEZE ACROSS THE EAST CENTRAL
PENINSULA.

ALTHOUGH NOT PARTICULARLY STRONG...LOW-LEVEL HODOGRAPHS APPEAR
SUFFICIENT...COUPLED WITH THE RELATIVELY HIGH BOUNDARY LAYER
MOISTURE CONTENT AND HUMIDITY...TO SUPPORT THE RISK FOR A FEW
TORNADOES WITH THE DISCRETE STORMS...IN ADDITION TO THE POTENTIAL
FOR LARGE HAIL. OTHERWISE...DAMAGING WIND POTENTIAL WILL BE HIGHEST
WITH THE STORM CLUSTER PROGRESSING INLAND OFF THE GULF OF
MEXICO...AND ANY POSSIBLE UPSCALE CONVECTIVE GROWTH OVER THE EASTERN
PENINSULA LATER THIS AFTERNOON AND EVENING.

TO THE NORTH...ANY STORM DEVELOPMENT CLOSER TO THE SURFACE LOW
ACROSS NORTHERN FLORIDA AND SOUTHERN GEORGIA IS EXPECTED TO BE MORE
ISOLATED IN NATURE. INSTABILITY IS ALSO EXPECTED TO REMAIN
CONSIDERABLY WEAKER. BUT FORCING/SHEAR IN THE EXIT REGION OF THE
APPROACHING SOUTHERN STREAM JET MAY PROVIDE SUPPORT FOR SUPERCELLS.

..KERR.. 04/04/2013

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