Categorical Graphic
Probabilistic Tornado Graphic
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.

   SPC AC 171243
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0743 AM CDT WED AUG 17 2011
   
   VALID 171300Z - 181200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE CNTRL HIGH PLAINS...
   
   ...SYNOPSIS...
   DEEP CYCLONE OVER SCNTRL CANADA WILL CONTINUE EAST WITH STRONGEST
   HEIGHT FALLS AND DYNAMIC FORCING FOR ASCENT OCCURRING PRIMARILY
   NORTH OF THE GREAT LAKES. IN THE WAKE OF THIS SYSTEM...A BELT OF
   ZONAL/WLY MID LEVEL FLOW OF 40-50KT WILL EXIST FROM THE NRN GREAT
   BASIN AND ROCKIES ACROSS THE NRN PLAINS...TO THE NORTH OF A BROAD
   UPPER RIDGE CENTERED SOUTHEAST OF THE FOUR CORNERS REGION. THE COLD
   FRONT ASSOCIATED WITH THE LOW IN CANADA WAS SITUATED FROM THE UPPER
   MIDWEST SWWD TO KS AND THEN WWD AND NWWD...BANKED UP INTO THE HIGH
   PLAINS/FRONT RANGE. A NUMBER OF WEAK PRESSURE TROUGHS AND RESIDUAL
   CONVECTIVE OUTFLOW BOUNDARIES PRECEDE THE DEEPER STALLED SYNOPTIC
   FRONT...FROM KS SOUTH ACROSS OK/TX/NM...BENEATH WEAKER FLOW ALOFT.
   
   EXPECT DIURNAL STORM DEVELOPMENT AIDED BY MONSOON MOISTURE TRAPPED
   WITHIN UPPER RIDGE ACROSS THE HIGHER TERRAIN OF THE SRN ROCKIES AND
   MEXICAN ESCARPMENT TODAY. THE FRONT RANGE/ADJACENT HIGH PLAINS AND
   SRN PLAINS WILL ALSO EXPERIENCE AT LEAST SCATTERED TSTM
   DEVELOPMENT...SOME OF WHICH COULD BE SEVERE. ADDITIONALLY...A FEW
   STRONGER STORMS COULD DEVELOP IN A NARROW WINDOW OF SPACE AND TIME
   AS THE AFOREMENTIONED FRONT MAKES SOME EASTWARD PROGRESS ACROSS THE
   MIDWEST THROUGH EARLY EVENING.
   
   ...CNTRL HIGH PLAINS...
   A MOIST POST-FRONTAL AIR MASS AND SURFACE HEATING WILL RESULT IN AN
   AXIS OF STRONG DESTABILIZATION FROM NERN NM ACROSS ERN CO AND INTO
   THE NEB PANHANDLE THROUGH THE AFTERNOON. SBCAPE VALUES IN THIS
   CORRIDOR ARE EXPECTED TO REACH 2000 J/KG BENEATH A MODEST CAP. WHILE
   LARGE-SCALE FORCING FOR ASCENT WILL BE SUBTLE/WEAK...IT DOES APPEAR
   THAT A WEAK PERTURBATION MAY BE MOVING EAST AROUND THE UPPER RIDGE
   AXIS...OVER NV/UT THIS MORNING. BACKGROUND ASCENT WITH THIS
   IMPULSE...COMBINED WITH TERRAIN INFLUENCES AND PERSISTENT
   CONVERGENCE NEAR RESIDUAL FRONT...FROM ERN CO/WY INTO NEB...SHOULD
   PROMOTE SCATTERED TSTM DEVELOPMENT LATER THIS AFTERNOON. ONCE
   INITIATION IS UNDERWAY...VERTICAL SHEAR WILL CONTRIBUTE TO
   PERSISTENT UPDRAFTS AS WEAK LOW LEVEL SLY FLOW IS TOPPED BY UP TO
   40KT OF WLY TO WNWLY FLOW. A CONSISTENT SIGNAL FOR SEVERE STORM
   DEVELOPMENT AMONGST LATEST GUIDANCE IS SITUATED FROM NERN CO INTO
   NEB IN THE 21-00Z TIME FRAME...AND THEN INTO WRN KS DURING THE
   00-03Z TIME PERIOD. THE NW FLOW/HIGH PLAINS PATTERN APPEARS
   SUPPORTIVE OF SCATTERED SUPERCELLS WITH POTENTIALLY VERY LARGE HAIL
   AND A COUPLE OF TORNADOES INITIALLY...THEN EVENING/LATE NIGHT
   EVOLUTION INTO AN MCS OR TWO FROM SRN NEB ACROSS KS.
   
   ...SRN HIGH PLAINS/NERN NM ACROSS KS/OK...
   LESS PERSISTENT AND MORE WIDELY SPACED STORMS APPEAR LIKELY FROM
   NERN NM ACROSS KS/OK COINCIDENT WITH MAX HEATING NEAR RESIDUAL
   BOUNDARIES...AND WITHIN/NEAR POCKETS OF GREATER INSTABILITY GIVEN
   SOME AREAS OF CLOUDINESS THIS MORNING. WEAKER FLOW FIELDS ACROSS
   THESE AREAS SUGGEST GENERALLY PULSE STORMS POSING A BRIEF THREAT FOR
   STRONG TO DAMAGING DOWNBURSTS.
   
   ...MIDWEST...
   AS MENTIONED ABOVE...A WINDOW OF OPPORTUNITY MAY OPEN FOR A COUPLE
   OF STRONGER STORMS ACROSS IL/IND AS THE COLD FRONT MOVES INTO THESE
   AREAS LATER TODAY. INSTABILITY WITHIN THE ZONE OF FRONTAL LIFT WILL
   BE LIMITED BY MARGINAL MID LEVEL LAPSE RATES AS WELL AS LOW LEVEL
   AIRMASS TRAJECTORIES EMANATING FROM DRIER/MORE STABLE REGIME
   ASSOCIATED WITH RETREATING SURFACE RIDGE. ONLY A LOW PROBABILITY
   WIND/HAIL THREAT WILL BE MAINTAINED ACROSS THE AREA WITH THIS
   OUTLOOK.
   
   ..CARBIN/GRAMS/EDWARDS.. 08/17/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z