SWODY1
SPC AC 140550
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1150 PM CST SUN NOV 13 2011
VALID 141200Z - 151200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH VALLEY
AND MID-MS VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF RIO GRAND
VALLEY AND TX HILL COUNTRY...
...OH VALLEY/MID-MS VALLEY...
AN UPPER-LEVEL TROUGH WILL GRADUALLY DEAMPLIFY AND MOVE EWD FROM THE
GREAT PLAINS INTO THE MS VALLEY TODAY. AHEAD OF THE UPPER-LEVEL
TROUGH...AN 80 TO 95 KT MID-LEVEL JET AND DEEPENING SFC LOW WILL
MOVE NEWD ACROSS THE OH VALLEY. A TRAILING COLD FRONT WILL ADVANCE
EWD ACROSS LOWER MI...IND AND IL THIS AFTERNOON WITH THUNDERSTORMS
INITIATING JUST AHEAD OF THE BOUNDARY AROUND MIDDAY. THE GREATEST
CHANCE FOR DISCRETE STORMS SHOULD EXIST EARLY AS STORMS DEVELOP
ACROSS SRN IND AND SW OH WHERE A POTENTIAL WILL EXIST FOR SUPERCELLS
DUE TO THE STRONG DEEP LAYER SHEAR IN PLACE. FORECAST SOUNDINGS
AROUND INDIANAPOLIS AT 21Z SHOW 30 TO 40 KT OF 0-1 KM SHEAR WITH SFC
DEWPOINTS IN THE LOWER 60S F AND SBCAPE VALUES AROUND 1000 J/KG.
THIS ENVIRONMENT SHOULD BE ENOUGH FOR AN ISOLATED TORNADO THREAT IF
STORMS CAN OBTAIN SUPERCELL CHARACTERISTICS BEFORE A LINE OF STRONG
THUNDERSTORMS ORGANIZES. FOR THIS REASON...HAVE ADDED A 5 PERCENT
TORNADO FROM INDIANAPOLIS SEWD TO NEAR THE OH RIVER WHERE THE
COMBINATION OF PARAMETERS APPEARS MOST FAVORABLE FOR TORNADIC
STORMS. AN ISOLATED LARGE HAIL THREAT MAY ALSO EXIST IN THIS AREA
BUT THE MAIN THREAT ACROSS THE REGION SHOULD BE WIND DAMAGE AS A
NEARLY CONTINUOUS LINE ORGANIZES FROM THE UPPER OH VALLEY SWWD INTO
THE MID-MS VALLEY LATE THIS AFTERNOON.
...RIO GRAND VALLEY AND TX HILL COUNTRY...
AN UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS NRN MEXICO TODAY AND
CLOSE-OFF TONIGHT APPROACHING THE RIO GRAND VALLEY. AHEAD OF THIS
SYSTEM...INCREASING SLY LOW-LEVEL FLOW WILL HELP ORIENT A MOIST AXIS
ACROSS SRN AND ECNTRL TX WHERE SFC DEWPOINTS ARE FORECAST TO BE
MOSTLY IN THE 60S F. MODEL FORECASTS BY EARLY THIS EVENING DEVELOP
MODERATE INSTABILITY ON THE WRN EDGE OF THE MOIST AXIS WHERE
SCATTERED THUNDERSTORMS SHOULD INITIATE FROM THE WRN HILL COUNTRY
SWD TO AROUND DEL RIO. FORECAST SOUNDINGS JUST EAST OF DEL RIO AT
03Z SHOW MLCAPE AROUND 1500 J/KG WITH 70 KT OF 0-6 KM SHEAR AND SFC
DEWPOINTS IN THE MID 60S F. THIS ENVIRONMENT WOULD EASILY SUPPORT
SUPERCELLS IF STORMS CAN INITIATE DURING THE EARLY EVENING WHEN THE
ENVIRONMENT WILL BE MOST FAVORABLE. THE GREATEST SEVERE THREAT WOULD
BE FOR WIND DAMAGE AS THE STORMS CONGEAL INTO A ORGANIZED LINEAR
MCS. HOWEVER...MODEL FORECASTS ARE IN DISAGREEMENT CONCERNING THE
TIMING OF INITIATION. IF STORM INITIATION HOLDS OFF UNTIL AFTER
06Z...THE WIND DAMAGE THREAT COULD BE MORE ISOLATED WITH THE LINE
MOVING EWD ACROSS SCNTRL TX LATE IN THE PERIOD. WILL MAINTAIN THE
SLIGHT RISK AREA WHERE THE ENVIRONMENT APPEARS MOST FAVORABLE BUT
THE SEVERE THREAT SHOULD BE CONDITIONAL UPON AN EARLY EVENING STORM
INITIATION.
..BROYLES/GARNER.. 11/14/2011
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