Aug 17, 2011 1730 UTC Day 2 Convective Outlook
Updated: Wed Aug 17 17:21:05 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110817 1730 UTC Day 2 Outlook Graphic
Probabilistic Graphic
20110817 1730 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
   SPC AC 171718
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1218 PM CDT WED AUG 17 2011
   
   VALID 181200Z - 191200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS NRN PLAINS...UPPER-MS
   VALLEY...CNTRL PLAINS...MID MO VALLEY AND NRN OZARKS...
   
   ...NRN PLAINS/UPPER MS VALLEY/MID MO VALLEY...
   AN UPPER-LEVEL RIDGE WILL BE IN PLACE THURSDAY ACROSS THE CNTRL
   ROCKIES WITH WEST TO NORTHWEST FLOW LOCATED FROM THE NRN PLAINS TO
   THE MID MS VALLEY. AT THE SFC...A COLD FRONT WILL ADVANCE SEWD
   ACROSS THE NRN PLAINS AND UPPER MS VALLEY. AHEAD OF THE FRONT...A
   BROAD ZONE OF MODERATE TO STRONG INSTABILITY SHOULD EXIST BY MID-DAY
   ON THURSDAY ACROSS THE NRN PLAINS...UPPER MS VALLEY SEWD INTO THE
   OZARKS AND MID MS VALLEY. THUNDERSTORM DEVELOPMENT IS FORECAST TO BE
   MOST NUMEROUS ALONG AND JUST AHEAD OF THE FRONTAL BOUNDARY THURSDAY
   AFTERNOON BUT POCKETS OF SCATTERED CONVECTION SHOULD INITIATE SEWD
   ACROSS THE WARM SECTOR. SEVERAL THUNDERSTORM CLUSTERS SHOULD PERSIST
   INTO THE EVENING AS A FRAGMENTED LOW-LEVEL JET STRENGTHENS ACROSS
   THE REGION.
   
   FORECAST SOUNDINGS THURSDAY AFTERNOON SHOW THE STRONGEST INSTABILITY
   FROM CNTRL NEB NNEWD THROUGH ERN SD INTO WRN MN WHERE MLCAPE VALUES
   ARE FORECAST TO BE FROM 2500 TO 4000 J/KG. IN ADDITION...MODERATE TO
   STRONG DEEP LAYER SHEAR SHOULD EXIST ACROSS THE WARM SECTOR AS
   MID-LEVEL FLOW INCREASES DUE TO A SUBTLE SHORTWAVE TROUGH MOVING
   ESEWD OUT OF THE TOP OF THE UPPER-LEVEL RIDGE. THE
   INSTABILITY...SHEAR AND LARGE-SCALE ASCENT SHOULD BE ADEQUATE FOR A
   SEVERE THREAT ACROSS MUCH OF SD AND MN EXTENDING SWD INTO THE OMAHA
   AREA FROM LATE THURSDAY AFTERNOON INTO THE EVENING. ALTHOUGH THE
   SHEAR ENVIRONMENT WILL BE SUPPORTIVE OF SUPERCELL DEVELOPMENT...THE
   DOMINANT STORM MODE MAY DEPEND ON WHETHER STORMS LINE OUT ALONG THE
   FRONTAL BOUNDARY. IF SUPERCELL STRUCTURES CAN PERSIST...THEN THE
   STEEP MID-LEVEL LAPSE RATES SHOULD AID A THREAT FOR LARGE HAIL. THE
   HAIL THREAT WOULD BE GREATEST IN AREAS WHERE INSTABILITY IS
   MAXIMIZED. A WIND DAMAGE THREAT SHOULD ALSO EXIST ESPECIALLY WITH IF
   A LINEAR MCS CAN DEVELOP AND MOVE SEWD ACROSS THE SLIGHT RISK AREA
   THURSDAY EVENING. A TORNADO THREAT COULD ALSO DEVELOP BUT THIS
   THREAT SHOULD BE CLOSELY TIED TO HOW MANY STORMS CAN REMAIN
   DISCRETE. THE NAM AND GFS ARE IN GOOD AGREEMENT ON THE TIMING OF THE
   SHORTWAVE TROUGH SUGGESTING THE GREATEST SEVERE THREAT SHOULD EXIST
   FROM NCNTRL SD SEWD INTO ERN NEB AND WRN IA WHERE AN ENHANCED SEVERE
   THREAT MAY BE WARRANTED IN THE OUTLOOK. ATTM...WILL DEFER AN UPGRADE
   TO 30 PERCENT SEVERE PROBABILITY TO LATER OUTLOOKS. NEW MODEL RUNS
   SHOULD HELP BETTER PINPOINT THE EXACT CORRIDOR OF AN ENHANCED SEVERE
   THREAT.
   
   FURTHER SOUTHEAST ACROSS THE CNTRL PLAINS...OZARKS AND MID MS
   VALLEY...FORECAST SOUNDINGS AT 21Z THURSDAY SHOW MODERATE
   INSTABILITY WITH 30 TO 40 KT OF DEEP LAYER SHEAR SUGGESTING THE
   ENVIRONMENT SHOULD SUPPORT A SEVERE THREAT. ISOLATED LARGE HAIL AND
   WIND DAMAGE MAY OCCUR ESPECIALLY IF A CONVECTIVE CLUSTER CAN
   ORGANIZE AND PERSIST INTO THURSDAY EVENING.
   
   ..BROYLES.. 08/17/2011
   
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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z