Aug 23, 2014 1630 UTC Day 1 Convective Outlook
Updated: Sat Aug 23 16:18:35 UTC 2014 (20140823 1630Z Day 1 shapefile | 20140823 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20140823 1630 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 92,561 1,672,422 Sioux Falls, SD...Fargo, ND...Moorhead, MN...Aberdeen, SD...Watertown, SD...
Probabilistic Tornado Graphic
20140823 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.
Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
10 % 14,000 177,676 Aberdeen, SD...Watertown, SD...Brookings, SD...Huron, SD...Madison, SD...
5 % 42,798 609,011 Sioux Falls, SD...Mitchell, SD...Pierre, SD...Yankton, SD...Marshall, MN...
2 % 61,005 1,298,561 Fargo, ND...Sioux City, IA...Moorhead, MN...Norfolk, NE...Columbus, NE...
Probabilistic Damaging Wind Graphic
20140823 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.
Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 91,699 1,671,030 Sioux Falls, SD...Fargo, ND...Moorhead, MN...Aberdeen, SD...Watertown, SD...
5 % 270,419 30,756,638 Chicago, IL...Indianapolis, IN...Nashville, TN...Minneapolis, MN...St. Louis, MO...
Probabilistic Large Hail Graphic
20140823 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.
Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 52,183 378,004 Aberdeen, SD...Watertown, SD...Brookings, SD...Mitchell, SD...Pierre, SD...
5 % 146,828 2,175,774 Sioux Falls, SD...Fargo, ND...Rapid City, SD...St. Cloud, MN...Bismarck, ND...
   SPC AC 231618

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1118 AM CDT SAT AUG 23 2014

   VALID 231630Z - 241200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN PLAINS
   INTO UPPER MS VALLEY...

   ...SUMMARY...
   WIDELY SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS
   PARTS OF THE NORTHERN PLAINS INTO WESTERN MINNESOTA TODAY INTO
   TONIGHT.  LARGE HAIL...DAMAGING WINDS...AND A FEW TORNADOES MAY
   OCCUR.

   ...SYNOPSIS...

   AN UPPER LOW OVER THE NRN INTERMOUNTAIN REGION WILL UNDERGO FURTHER
   DEEPENING WHILE DEVELOPING EWD INTO THE NRN HIGH PLAINS...DUE IN
   PART TO THE PROGRESSION OF A VORTICITY MAXIMUM AND ASSOCIATED
   MID-LEVEL JET STREAK PROGRESSING FROM THE GREAT BASIN INTO THE NRN
   PLAINS. THIS VORTICITY MAXIMUM WILL BE PRECEDED BY A PERTURBATION
   WHICH WILL WEAKEN WHILE TRACKING FROM THE CNTRL HIGH PLAINS THROUGH
   THE MID MO VALLEY.

   AT THE SURFACE...MID-MORNING MESOANALYSIS REVEALED A COUPLE OF
   SURFACE LOWS...ONE OVER SWRN SD AND THE OTHER OVER FAR SWRN NEB.
   THESE TWO FEATURES WILL GRADUALLY CONSOLIDATE INTO A DEEPENING
   CYCLONE WHICH WILL DEVELOP NWD THROUGH CNTRL SD INTO CNTRL
   ND...ALONG THE ERN EDGE OF A WEDGE OF COOLER AIR SETTLING SWD
   THROUGH THE NRN HIGH PLAINS. AN ASSOCIATED WARM FRONT WILL PIVOT WWD
   THROUGH THE ND-MN RED RIVER VALLEY WHILE A MORE
   PROMINENT...SECONDARY WARM FRONT DEVELOPS NWD THROUGH THE MID MO
   VALLEY. MEANWHILE...A COLD FRONT ASSOCIATED WITH THE GREAT BASIN
   SHORT-WAVE TROUGH WILL EMERGE FROM THE HIGH TERRAIN OF WY/CO BEFORE
   SURGING EWD ACROSS WRN PARTS OF SD/NEB.

   ...NRN PLAINS/UPPER MS VALLEY THIS AFTERNOON/EVENING...

   CONSIDERABLE EARLY-DAY CLOUDS ARE PRESENT ACROSS THE REGION WHICH
   WHEN COUPLED WITH WEAK LAPSE RATES ALOFT MAY SLOW THE
   DESTABILIZATION PROCESS. HOWEVER...LATEST MODEL GUIDANCE SUGGESTS
   THAT STRONG BOUNDARY-LAYER HEATING WILL OCCUR IN THE WAKE OF THE
   OVERNIGHT MCS ACROSS PORTIONS OF ERN NEB AND IA...ALONG AND TO THE
   SOUTH OF THE NWD-MOVING WARM FRONT. THIS HEATING IN CONJUNCTION WITH
   DEWPOINTS IN THE UPPER 60S TO LOWER 70S WILL FOSTER A CORRIDOR OF
   MODERATE INSTABILITY BY AFTERNOON WITH MLCAPE OF 1500-2500+ J/KG.

   CURRENT THINKING IS THAT SURFACE-BASED STORM DEVELOPMENT WILL BECOME
   INCREASINGLY LIKELY BY LATE AFTERNOON OR EARLY EVENING INVOF THE
   DEEPENING SURFACE LOW OVER S-CNTRL SD EWD/SEWD ALONG THE WARM FRONT
   INTO SERN SD/FAR NERN NEB. THOUGH THE DEEP-LAYER FLOW FIELD WILL BE
   LARGELY MERIDIONAL...BACKED NEAR-SURFACE WINDS ALONG THE WARM FRONT
   WILL YIELD SIZABLE...CLOCKWISE-CURVED HODOGRAPHS IN THE LOW LEVELS.
   AND WHILE A MIXTURE OF STORM MODES IS EXPECTED...THE ENHANCED
   STREAMWISE VORTICITY AND MOIST...LOW LCL BOUNDARY LAYER WILL BE
   SUPPORTIVE OF LOW-LEVEL MESOCYCLOGENESIS AND A RISK FOR A FEW
   TORNADOES. OTHERWISE...EXPECT THAT DAMAGING WINDS AND SOME HAIL WILL
   BE THE PRIMARY HAZARDS AS STORMS CONTINUE NEWD INTO PARTS OF WRN MN
   THIS EVENING INTO TONIGHT. 

   ...OH VALLEY/MIDWEST THIS AFTERNOON/EVENING...

   THE 12Z DVN/ILX SOUNDINGS SAMPLED THE PRESENCE OF A VERY MOIST AIR
   MASS /LOWEST 100-MB MEAN MIXING-RATIOS OF 18-19 G PER KG/ WHICH WHEN
   COUPLED WITH DAYTIME HEATING WILL CONTRIBUTE TO A STRONGLY UNSTABLE
   ENVIRONMENT BY AFTERNOON WITH MLCAPE OF 3000-4000+ J/KG. LARGE-SCALE
   FORCING FOR ASCENT WILL REMAIN GENERALLY WEAK OWING TO THE PROXIMITY
   OF THE UPPER RIDGE. HOWEVER...AN ACTIVE COLD POOL ATTENDANT TO THE
   REMNANTS OF A NOCTURNAL MCS CURRENTLY ONGOING OVER FAR ERN IA INTO
   SWRN WI AND NRN IL IS EXPECTED TO FOCUS THE REDEVELOPMENT OF
   VIGOROUS STORMS THIS AFTERNOON. 

   BOTH VERTICAL SHEAR AND MID-LEVEL LAPSE RATE WILL REMAIN
   WEAK...LIMITING THE POTENTIAL FOR ORGANIZED STORM MODES.
   NONETHELESS...THE DEGREE OF INSTABILITY AND HIGH PW AIR MASS SUGGEST
   THE POTENTIAL FOR EXCESSIVE WATER LOADING IN CONVECTIVE DOWNDRAFTS
   AND A RISK FOR DAMAGING SURFACE WINDS.

   FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE MCD 1602.

   ...PORTIONS OF THE NRN/CNTRL HIGH PLAINS THIS AFTERNOON/EVENING...

   INCREASING HEIGHT FALLS AND VERTICAL SHEAR ASSOCIATED WITH THE GREAT
   BASIN VORTICITY MAXIMUM WILL INTERACT WITH A MODESTLY UNSTABLE
   /MLCAPE OF 500-1000 J PER KG/ ENVIRONMENT TO FOSTER A BAND OF TSTMS
   ALONG THE COLD FRONT OVER PARTS OF THE NEB PNHDL AND NERN CO
   /PERHAPS INTO SWRN SD/ LATER THIS AFTERNOON. SOME HAIL AND/OR
   LOCALLY DAMAGING WINDS MAY ACCOMPANY THE STRONGEST STORMS INTO THE
   EVENING HOURS.

   ..MEAD/MARSH.. 08/23/2014

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