Aug 31, 2014 2000 UTC Day 1 Convective Outlook
Updated: Sun Aug 31 19:49:08 UTC 2014 (20140831 2000Z Day 1 shapefile | 20140831 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20140831 2000 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 237,664 41,723,820 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Kansas City, MO...
Probabilistic Tornado Graphic
20140831 2000 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
5 % 41,023 2,059,421 Omaha, NE...Lincoln, NE...Sioux City, IA...Council Bluffs, IA...Bellevue, NE...
2 % 169,865 44,144,184 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Kansas City, MO...
Probabilistic Damaging Wind Graphic
20140831 2000 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
30 % 73,801 3,116,463 Omaha, NE...Lincoln, NE...Sioux City, IA...Council Bluffs, IA...Ames, IA...
15 % 161,928 38,581,003 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Kansas City, MO...
5 % 231,526 28,087,752 Boston, MA...Wichita, KS...Providence, RI...Worcester, MA...Springfield, MA...
Probabilistic Large Hail Graphic
20140831 2000 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
SIG SEVERE 40,547 1,922,537 Omaha, NE...Lincoln, NE...Sioux City, IA...Council Bluffs, IA...Bellevue, NE...
30 % 58,553 2,318,830 Omaha, NE...Lincoln, NE...Sioux City, IA...Council Bluffs, IA...Bellevue, NE...
15 % 140,206 9,681,953 Kansas City, MO...Minneapolis, MN...St. Paul, MN...Des Moines, IA...Overland Park, KS...
5 % 171,412 4,412,449 Wichita, KS...Cedar Rapids, IA...Davenport, IA...Duluth, MN...Iowa City, IA...
   SPC AC 311949

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0249 PM CDT SUN AUG 31 2014

   VALID 312000Z - 011200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
   PLAINS...MID MO VALLEY AND UPPER MS VALLEY...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF FAR SE
   NY...NJ...SE PA...NRN DE...MD AND FAR NRN VA...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG A COLD FRONT THIS
   AFTERNOON AND EVENING FROM MINNESOTA SOUTHWESTWARD ACROSS WESTERN
   IOWA TO CENTRAL AND EASTERN NEBRASKA INTO KANSAS.  LARGE
   HAIL...DAMAGING WINDS...AND A COUPLE OF TORNADOES ARE EXPECTED WITH
   THIS ACTIVITY.  ISOLATED STRONG TO DAMAGING WINDS WILL ALSO BE
   POSSIBLE THIS AFTERNOON AND EARLY EVENING ACROSS NORTHERN VIRGINIA
   AND MARYLAND TO SOUTHERN NEW ENGLAND.

   THE ONLY CHANGE TO THE OUTLOOK IS TO REMOVE THE SLIGHT RISK AREA
   FROM NRN MN AND PARTS OF NRN WI. THE AREA HAS YET TO DESTABILIZE AND
   MODEL FORECASTS KEEP CONVECTIVE COVERAGE VERY ISOLATED. ALTHOUGH
   HAIL AND STRONG GUSTY WINDS MAY OCCUR THERE...ANY SEVERE THREAT IN
   NRN MN AND NRN WI IS EXPECTED TO REMAIN MARGINAL.

   ..BROYLES.. 08/31/2014

   .PREV DISCUSSION... /ISSUED 1127 AM CDT SUN AUG 31 2014/

   ...CENTRAL PLAINS INTO UPPER MIDWEST...
   A LARGE...PROGRESSIVE UPPER TROUGH IS MOVING ACROSS THE NORTHERN AND
   CENTRAL ROCKIES TODAY.  THIS FEATURE WILL EMERGE INTO THE PLAINS
   STATES THIS AFTERNOON AND EVENING...LEADING TO A ROUND OF SEVERE
   THUNDERSTORMS FROM MN INTO KS.

   SATELLITE LOOPS SUGGEST THAT DEEPENING MOISTURE AND SOME LARGE SCALE
   ASCENT ARE SPREADING INTO WESTERN NEB/EASTERN CO.  CLOUDS WILL SLOW
   DESTABILIZATION IN THESE AREAS...BUT 12Z MODEL SOLUTIONS ARE
   CONSISTENT IN THE DEVELOPMENT OF ISOLATED THUNDERSTORMS OVER THE
   HIGH PLAINS OF WESTERN SD/NEB/KS AND NORTHEAST CO BY MID AFTERNOON. 
   EFFECTIVE SHEAR OF 30-40 KNOTS IN THIS REGION COUPLED WITH MLCAPE
   VALUES UP TO 1000 J/KG MAY RESULT IN A FEW SUPERCELL STRUCTURES
   CAPABLE OF HAIL AND GUSTY WINDS.

   FARTHER EAST...LATEST SURFACE ANALYSIS SHOWS A PRONOUNCED BOUNDARY
   EXTENDING FROM SOUTHWEST MN INTO CENTRAL NEB.  STRONG
   HEATING/DESTABILIZATION ALONG THIS BOUNDARY SHOULD WEAKEN THE CAP
   AND RESULT IN SCATTERED THUNDERSTORM DEVELOPMENT BETWEEN 20-22Z. 
   BACKED/SOUTHERLY LOW LEVEL WINDS IN VICINITY OF THE BOUNDARY COUPLED
   WITH MLCAPE VALUES OVER 2500 J/KG WILL RESULT IN A FAVORABLE
   ENVIRONMENT FOR SUPERCELL STORMS.  INITIAL ACTIVITY WILL POSE A RISK
   OF VERY LARGE HAIL AND ISOLATED TORNADOES.  SOME CONCERN REGARDING
   THE QUALITY OF LOW LEVEL MOISTURE AND HIGH LCLS SUGGEST THAT STORMS
   WILL TRANSITION TO LINEAR STRUCTURES BY EARLY EVENING...WITH AN
   INCREASING RISK OF DAMAGING WINDS.  ACTIVITY WILL SPREAD EASTWARD
   ACROSS MUCH OF IA/SOUTHERN MN/NORTHERN MO BEFORE WEAKENING AFTER
   MIDNIGHT.

   ...MID ATLANTIC REGION...
   VISIBLE SATELLITE LOOPS SHOW RATHER STRONG HEATING OCCURRING IN A
   CORRIDOR FROM NORTHERN VA TO THE NYC AREA.  PWAT VALUES AROUND 2
   INCHES AND 30-40 KNOT WESTERLY MID LEVEL WINDS WILL CONTRIBUTE TO A
   RISK OF A FEW INTENSE STORMS THIS AFTERNOON AND EARLY EVENING. 
   TRANSIENT SUPERCELL/BOWING STRUCTURES ARE POSSIBLE...ALONG WITH
   GUSTY/DAMAGING WINDS IN THE STRONGEST CORES.

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z