SWODY2
SPC AC 131730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT THU MAR 13 2008
VALID 141200Z - 151200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...OZARK PLATEAU...LOWER MS VALLEY AND TN VALLEY...
..SRN PLAINS/LOWER MS VALLEY/TN VALLEY...
LATEST WATER VAPOR IMAGERY SHOWS A WELL-DEFINED UPPER-LEVEL TROUGH
OVER THE SRN PLAINS. THIS FEATURE IS FORECAST TO MOVE EWD INTO THE
LOWER MS VALLEY TONIGHT AND ACROSS THE SERN STATES FRIDAY. SCATTERED
THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS A BROAD WARM SECTOR IN
PARTS OF LA...MS AND AR ASSOCIATED WITH WARM ADVECTION AND THE
LOW-LEVEL JET. AS THE SHORTWAVE TROUGH MOVES EWD DURING THE
DAY...CONVECTIVE COVERAGE ACROSS THE REGION APPEARS LIKELY TO
DECREASE. HOWEVER...A SECONDARY LOW-AMPLITUDE SHORTWAVE TROUGH IS
FORECAST TO APPROACH THE REGION FRIDAY NIGHT. LARGE-SCALE ASCENT
ASSOCIATED WITH THIS UPPER-LEVEL TROUGH SHOULD RESULT IN
REDEVELOPMENT OF CONVECTION ACROSS THE OZARKS AND THE TN VALLEY
DURING THE EVENING AND OVERNIGHT PERIOD.
CONCERNING THE SEVERE POTENTIAL...A BROAD ZONE OF 55 TO 65 KT
MID-LEVEL WIND SPEEDS IS FORECAST TO BE IN PLACE ACROSS THE SRN
PLAINS FRIDAY EXTENDING EWD ACROSS THE GULF COAST STATES. THIS
SHOULD RESULT IN MODERATE VERTICAL SHEAR PROFILES EARLY IN THE
PERIOD ACROSS A WARM SECTOR SUGGESTING STORM ORGANIZATION WILL BE
POSSIBLE BEFORE THE FIRST SHORTWAVE TROUGH EXITS TO THE EAST. THE
STRONG LOW-LEVEL FLOW AND COLD TEMPS ALOFT SHOULD SUPPORT A WIND
DAMAGE AND HAIL THREAT. THE INSTABILITY AXIS IS FORECAST TO REMAIN
WEST OF THE MORNING CONVECTION AND THIS COULD KEEP ANY SEVERE THREAT
ACROSS MS...TN...AL ISOLATED THROUGH MIDDAY. THE GREATER SEVERE
THREAT APPEARS LIKELY TO DEVELOP ALONG AND JUST NORTH OF A
STATIONARY FRONT AND SFC LOW TRACKING EWD INTO NRN AR BY LATE
EVENING. LIFT ASSOCIATED WITH THE EXIT REGION OF A 70 TO 80 KT
MID-LEVEL JET WILL ALSO LIKELY ENHANCE THE SEVERE POTENTIAL. THIS
JET IS ALSO FORECAST TO STEADILY INCREASE VERTICAL SHEAR PROFILES
ACROSS THE OZARK PLATEAU AND 0-6 KM SHEAR VALUES COULD REACH 75 KT
BY THE 00Z TO 03Z SAT TIMEFRAME AS SUGGESTED BY REGIONAL FORECAST
SOUNDINGS. THIS WOULD BE MORE THAN SUFFICIENT FOR SUPERCELLS
ESPECIALLY AS AN MCS ORGANIZES IN THE NWRN PART OF THE SLIGHT RISK
AREA AND MOVES EWD INTO THE TN VALLEY OVERNIGHT. STEEP MID-LEVEL
LAPSE RATES COUPLED WITH THE STRONG SHEAR SHOULD SUPPORT A THREAT
FOR LARGE HAIL WITH THE MORE PERSISTENT SUPERCELLS. NORTH OF THE
BOUNDARY...CONVECTION SHOULD REMAIN ELEVATED WITH THE PRIMARY THREAT
HAIL. SOUTH OF THE BOUNDARY ACROSS THE WARM SECTOR...SFC DEWPOINTS
ARE FORECAST TO BE IN THE UPPER 50S F AND LOWER 60S F RESULTING IN
MODERATE INSTABILITY. IN ADDITION TO LARGE HAIL...THIS COULD SUPPORT
A WIND DAMAGE THREAT WITH SFC-BASED STORMS REACHING NRN MS AND NRN
AL LATE IN THE PERIOD.
.BROYLES.. 03/13/2008
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