May 25, 2013 0600 UTC Day 1 Convective Outlook
Updated: Sat May 25 05:42:35 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130525 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130525 1200 UTC Day 1 Tornado Probabilities 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
20130525 1200 UTC Day 1 Damaging Wind Probabilities 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
20130525 1200 UTC Day 1 Large Hail Probabilities 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.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 128,152 676,000 Rapid City, SD...Grand Island, NE...North Platte, NE...Lexington, NE...Miles City, MT...
   SPC AC 250539

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1239 AM CDT SAT MAY 25 2013

   VALID 251200Z - 261200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS CNTRL THROUGH NRN HIGH
   PLAINS...

   ...SYNOPSIS...

   SYNOPTIC PATTERN WILL UNDERGO LITTLE CHANGE SATURDAY WITH AN UPPER
   RIDGE OVER THE CNTRL U.S. FLANKED BY TROUGHS OVER THE WRN AND ERN
   STATES. AT THE SFC A LEE TROUGH/DRYLINE WILL PERSIST OVER THE HIGH
   PLAINS WHILE A WARM FRONT LIFTS SLOWLY NWD THROUGH THE CNTRL/NRN
   PLAINS.  

   ...CNTRL AND NRN PLAINS AREA...

   SELY WINDS EAST OF LEE TROUGH WILL ADVECT UPPER 50S DEWPOINTS INTO
   THE NRN HIGH PLAINS WITH LOW-MID 60S FARTHER SOUTH OVER THE CNTRL
   PLAINS. MEANWHILE...WSWLY WINDS ALOFT WILL ADVECT STEEP MID-LEVEL
   LAPSE RATES ABOVE THE MOISTENING BOUNDARY LAYER CONTRIBUTING TO AN
   AXIS OF 1500-2500 J/KG MLCAPE. THE ATMOSPHERE WILL REMAIN CAPPED TO
   SURFACE BASED STORMS UNTIL MID AFTERNOON WHEN DIABATIC WARMING WILL
   AUGMENT OROGRAPHIC FORCING WHERE A MOIST SELY UPSLOPE REGIME WILL
   EXIST FROM NERN CO...ERN WY INTO ERN MT. STORMS ARE EXPECTED TO
   DEVELOP OVER THE HIGHER TERRAIN AND SUBSEQUENTLY SPREAD EWD INTO THE
   AXIS OF MODERATE INSTABILITY ACROSS THE HIGH PLAINS. THIS REGION
   WILL RESIDE ON SRN FRINGE OF STRONGER FLOW ALOFT WITH 35-40 KT WINDS
   AT 500 MB ABOVE SELY NEAR SFC WINDS RESULTING IN FAVORABLE VERTICAL
   SHEAR FOR SUPERCELLS. VERY LARGE HAIL WILL BE THE INITIAL PRIMARY
   THREAT...THROUGH ISOLATED TORNADOES MAY ALSO BE POSSIBLE. A FEW
   STORMS MAY EVENTUALLY CONGEAL INTO LINES/CLUSTERS WITH AN INCREASING
   DAMAGING WIND THREAT DURING THE EVENING...SUSTAINED BY A
   STRENGTHENING SLY LLJ. SEVERE THREAT IS EXPECTED TO GRADUALLY WANE
   TOWARD LATE EVENING.

   ...SRN HIGH PLAINS...

   ISOLATED TO WIDELY SCATTERED STORMS ARE EXPECTED TO ONCE AGAIN
   DEVELOP OVER THE HIGHER TERRAIN AND SPREAD EWD INTO THE SRN HIGH
   PLAINS. THESE STORMS WILL EXIST IN A WEAK SHEAR ENVIRONMENT...BUT
   STEEP LAPSE RATES...MODERATE INSTABILITY AND 25+ F LOW LEVEL
   TEMPERATURE-DEWPOINT SPREADS WILL SUPPORT A THREAT FOR ISOLATED
   LARGE HAIL AND DOWNBURST WINDS.

   ..DIAL/DEAN.. 05/25/2013

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z