The Palm Sunday, March 28, 2010, Severe Thunderstorm Outbreak

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT SUN MAR 28 2010
   
VALID 281200Z - 291200Z
   
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
APPALACHIAN MTNS AND SRN ATLANTIC SEABOARD...
   
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL AND
SRN FL PENINSULA...
   
...CAROLINAS/SRN APPALACHIANS/GEORGIA/OH VALLEY...
AN UPPER-LEVEL TROUGH AND IMPRESSIVE 80 TO 95 KT MID-LEVEL JET WILL
MOVE ACROSS THE LOWER MS VALLEY AND INTO THE CNTRL GULF COAST STATES
TODAY. SCATTERED THUNDERSTORMS MAY BE ONGOING THIS MORNING IN THE
LEFT EXIT REGION OF THE JET ACROSS THE TN VALLEY NWWD INTO THE OH
VALLEY BENEATH THE CORE OF THE UPPER-LEVEL TROUGH. A THREAT FOR HAIL
MAY DEVELOP AS CONVECTION MOVES EWD ACROSS SRN IND AND KY THIS
AFTERNOON DUE TO COLD AIR ALOFT IN THE CORE OF THE UPPER-LEVEL
TROUGH. FURTHER SOUTH...THE CONVECTIVE CLUSTER IN TN AND ERN AL IS
FORECAST TO MOVE EWD INTO THE SRN APPALACHIAN MTNS EXPANDING SEWD
ACROSS CNTRL GA THIS AFTERNOON. AHEAD OF THE CONVECTION...A BROAD
LOW-LEVEL JET WILL RAPIDLY INCREASE LOW-LEVEL MOISTURE ACROSS GA
INTO SC WHERE SFC DEWPOINTS SHOULD REACH THE MID 50S TO LOWER 60S F
BY MID AFTERNOON.
   
FORECAST SOUNDINGS ALONG THE MOIST AXIS LATE THIS AFTERNOON SHOW
VERY STRONG DEEP LAYER SHEAR PROFILES ASSOCIATED WITH THE EXIT
REGION OF THE MID-LEVEL JET. THIS SHOULD OVERCOME THE WEAK
INSTABILITY CREATING AN ENVIRONMENT FAVORABLE FOR SUPERCELLS. STRONG
LOW-LEVEL SHEAR WILL LIKELY EXIST FROM MACON GA NEWD INTO SC WHERE
FORECAST SOUNDINGS SHOW 0-3 KM STORM RELATIVE HELICITIES IN THE 350
TO 450 M2/S2 RANGE. THIS ALONG WITH LOW LCL HEIGHTS SHOULD BE
FAVORABLE FOR TORNADOES. SUPERCELLS SHOULD ALSO BE CAPABLE OF
PRODUCING LARGE HAIL ESPECIALLY LATE THIS AFTERNOON AND EARLY THIS
EVENING WHEN INSTABILITY SHOULD BE MAXIMIZED. MODEL FORECASTS
GRADUALLY ORGANIZE A LINE OF STORMS THIS EVENING ALONG THE AXIS OF
THE MID-LEVEL JET AND AHEAD OF A COLD FRONT FROM SERN GA NEWD ACROSS
CNTRL SC INTO SRN NC. WIND DAMAGE WILL BE POSSIBLE WITH THIS LINE
ESPECIALLY ACROSS SC AND SRN NC WHERE LOW-LEVEL FLOW IS FORECAST TO
EXCEED 40 KT.
   
...FLORIDA...
WEST TO SOUTHWEST FLOW WILL BE IN PLACE ACROSS THE ERN GULF OF
MEXICO AND FLORIDA TODAY AS THE SRN END OF A BROAD UPPER-LEVEL
TROUGH APPROACHES FROM THE WEST. AHEAD OF THE SYSTEM...A LOW-LEVEL
JET IS FORECAST TO DEVELOP ACROSS THE FAR ERN GULF OF MEXICO MOVING
INTO CNTRL FL THIS AFTERNOON. MODEL FORECASTS MOVE A LARGE AREA OF
CONVECTION INLAND ACROSS THE NCNTRL PART OF THE FL PENINSULA THIS
AFTERNOON AS THE LOW-LEVEL JET MOVES INLAND. AHEAD OF THE
CONVECTION...SLY FLOW ACROSS THE FL PENINSULA SHOULD GRADUALLY
INCREASE LOW-LEVEL MOISTURE NWD WITH SFC DEWPOINTS REACHING THE MID
60S F AS FAR NORTH AS ORLANDO BY 21Z. THIS SHOULD ALLOW FOR
SUBSTANTIAL DESTABILIZATION WITH MLCAPE VALUES APPROACHING 1000
J/KG. THE INSTABILITY COMBINED WITH ABOUT 50 KT OF 0-6 KM SHEAR
SHOULD SUPPORT SUPERCELL DEVELOPMENT WITH STORMS THAT CAN REMAIN
DISCRETE. TORNADOES WILL BE POSSIBLE MAINLY AROUND THE ORLANDO AREA
WHERE HODOGRAPHS APPEAR MOST FAVORABLE AND 0-3 KM HELICITIES ARE
FORECAST IN THE 400 TO 500 M2/S2 RANGE. ALTHOUGH HAIL WILL BE
POSSIBLE WITH SUPERCELLS...THE GREATER THREAT IS EXPECTED TO BE WITH
LINEAR DEVELOPMENT THAT MOVES SWD ACROSS CNTRL FL LATE THIS
AFTERNOON INTO EARLY THIS EVENING.
  
..BROYLES.. 03/28/2010
   
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z