Aug 31, 2015 1630 UTC Day 1 Convective Outlook
Updated: Mon Aug 31 16:27:22 UTC 2015 (20150831 1630Z Day 1 shapefile | 20150831 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150831 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 23,023 4,501,940 Phoenix, AZ...Mesa, AZ...Glendale, AZ...Chandler, AZ...Scottsdale, AZ...
Probabilistic Tornado Graphic
20150831 1630 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20150831 1630 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 23,023 4,501,940 Phoenix, AZ...Mesa, AZ...Glendale, AZ...Chandler, AZ...Scottsdale, AZ...
Probabilistic Large Hail Graphic
20150831 1630 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 311627

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1127 AM CDT MON AUG 31 2015

   VALID 311630Z - 011200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
   CENTRAL AZ...

   ...SUMMARY...
   ISOLATED DAMAGING WINDS MAY OCCUR THIS AFTERNOON AND EVENING ACROSS
   PARTS OF ARIZONA.  OTHERWISE...SCATTERED THUNDERSTORMS ARE EXPECTED
   ACROSS THE CENTRAL ROCKIES AND HIGH PLAINS...AND ALONG PARTS OF THE
   GULF AND ATLANTIC COASTS...AS WELL AS THE OHIO AND MID MISSISSIPPI
   VALLEYS.

   ...SYNOPSIS...
   A MIDLEVEL SHORTWAVE TROUGH WILL CONTINUE TO EJECT ENEWD FROM ND/SRN
   MANITOBA TO WRN ONTARIO...WELL TO THE E OF A LOW-AMPLITUDE TROUGH
   THAT WILL APPROACH THE PAC NW.  A MONSOONAL MOISTURE PLUME AND
   ASSOCIATED DIURNAL CONVECTION WILL PERSIST FROM THE CENTRAL ROCKIES
   TO THE DESERT SW.  FARTHER E...A DIFFUSE TROUGH WILL PERSIST FROM
   THE OH VALLEY TO TX WITH EMBEDDED VORTICITY CENTERS OVER
   INDIANA...AR...AND S TX.  A SEPARATE VORTICITY MAX WILL SLOWLY
   WEAKEN EJECT NEWD/ENEWD OVER THE MID ATLANTIC COAST TODAY...WITH A
   TROPICAL MOISTURE PLUME ACCOMPANYING THIS SYSTEM NEAR THE SC/NC
   COASTS ALONG A STALLED FRONT.  SCATTERED THUNDERSTORMS ARE EXPECTED
   WITH THE EMBEDDED VORTICITY MAXIMA...BUT THE SEVERE STORM RISK WILL
   BE LIMITED BY POOR LAPSE RATES AND/OR WEAK VERTICAL SHEAR. 

   ...CENTRAL AZ THIS AFTERNOON/EVENING...
   A LOW-END TRANSITION-TYPE EVENT IS UNDERWAY AS A WEAK SRN STREAM
   SHORTWAVE TROUGH TRANSLATES SLOWLY EWD TO THE LOWER CO RIVER
   VALLEY...WITH SW FLOW ALOFT OVER CENTRAL AND WRN AZ.  BOUNDARY LAYER
   DEWPOINTS IN THE 60S REMAIN ACROSS S CENTRAL AZ...AND THE MODIFIED
   12Z PHX SOUNDING SUPPORTS AFTERNOON MLCAPE AOA 1500 J/KG WITH DCAPE
   NEAR 1500 J/KG.  SCATTERED THUNDERSTORM DEVELOPMENT IS EXPECTED THIS
   AFTERNOON OVER THE RIM WITH OTHER STORM DEVELOPMENT POSSIBLE INTO
   THE LOWER DESERTS ON CONVECTIVE OUTFLOW.  THE ENVIRONMENT WILL FAVOR
   SUBSTANTIAL PRECIPITATION LOADING AND STRONG DOWNDRAFTS IN A STEEP
   LOW-LEVEL LAPSE RATE ENVIRONMENT...WITH THE POTENTIAL FOR ISOLATED
   DAMAGING OUTFLOW WINDS.

   ..THOMPSON/MOSIER.. 08/31/2015

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z