Aug 4, 2015 0600 UTC Day 1 Convective Outlook
Updated: Tue Aug 4 06:00:09 UTC 2015 (20150804 1200Z Day 1 shapefile | 20150804 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150804 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 103,447 37,504,753 New York, NY...Philadelphia, PA...Boston, MA...Washington, DC...Newark, NJ...
MARGINAL 335,254 23,215,805 Baltimore, MD...Kansas City, MO...Omaha, NE...Wichita, KS...Lincoln, NE...
Probabilistic Tornado Graphic
20150804 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
2 % 212,703 37,714,552 New York, NY...Philadelphia, PA...Boston, MA...Washington, DC...Newark, NJ...
Probabilistic Damaging Wind Graphic
20150804 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 104,081 37,499,109 New York, NY...Philadelphia, PA...Boston, MA...Washington, DC...Newark, NJ...
5 % 334,074 23,093,569 Baltimore, MD...Kansas City, MO...Omaha, NE...Wichita, KS...Lincoln, NE...
Probabilistic Large Hail Graphic
20150804 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 104,081 37,499,109 New York, NY...Philadelphia, PA...Boston, MA...Washington, DC...Newark, NJ...
5 % 334,074 23,093,569 Baltimore, MD...Kansas City, MO...Omaha, NE...Wichita, KS...Lincoln, NE...
   SPC AC 040600

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT TUE AUG 04 2015

   VALID 041200Z - 051200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ERN NEW ENGLAND SWWD TO THE
   MID-ATLANTIC REGION...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SWRN NEB/NWRN KS
   VICINITY...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM NEW ENGLAND SWWD INTO
   CENTRAL VA...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM ERN MT SEWD TO KS/MO/NRN
   OK...

   ...SUMMARY...
   ISOLATED STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE TUESDAY
   FROM EASTERN PORTIONS OF NEW ENGLAND SOUTHWESTWARD TO PORTIONS OF
   THE MID-ATLANTIC STATES.  STRONG TO SEVERE STORMS WILL ALSO BE
   POSSIBLE FROM THE NORTHERN HIGH PLAINS SOUTHEASTWARD INTO THE
   CENTRAL PLAINS.

   ...SYNOPSIS...
   A LARGE MID- AND UPPER-LEVEL TROUGH CENTERED INVOF JAMES BAY AT THE
   START OF THE PERIOD WILL DRIFT VERY GRADUALLY EWD WITH TIME...WHILE
   BROADER CYCLONIC FLOW REGIME SURROUNDING THE LOW CONTINUES TO AFFECT
   THE NORTHEAST U.S./GREAT LAKES REGION.  FARTHER W...A WEAKER CYCLONE
   ALOFT SHOULD LINGER OVER BRITISH COLUMBIA...WHILE SHORTER-WAVELENGTH
   TROUGHING ROTATING AROUND THIS FEATURE SHIFTS INTO THE PAC NW AND
   PHASES WITH A VORT MAX SHIFTING OUT OF THE PACIFIC INTO NRN CA
   THROUGH THE SECOND HALF OF THE PERIOD.  IN BETWEEN THE TWO MAIN
   UPPER LOWS...WEAK RIDGING WILL PREVAIL ACROSS THE ROCKIES/HIGH
   PLAINS -- THOUGH INTERRUPTED BY NEGATIVE-TILT SHORTER-WAVELENGTH
   TROUGHING SHIFTING ENEWD OUT OF THE ROCKIES AND INTO THE PLAINS.

   AT THE SURFACE...THE PRIMARY FEATURE WITH RESPECT TO SEVERE
   POTENTIAL WILL BE A WEAK COLD FRONT EXTENDING FROM ERN CANADA SSWWD
   ACROSS NEW ENGLAND TO THE MID-ATLANTIC REGION...WWD ACROSS THE
   CENTRAL APPALACHIANS AND TN VALLEY AREA TO THE MID MS VALLEY...AND
   THEN NWWD ACROSS THE CENTRAL PLAINS INTO THE NRN HIGH PLAINS.  THIS
   FRONT WILL MAKE GRADUAL EWD PROGRESS ACROSS NEW ENGLAND...WHILE
   RETURNING SLOWLY NWD AS A WARM FRONT ACROSS THE PLAINS THROUGH THE
   PERIOD.

   ...ERN NEW ENGLAND SWWD TO THE MID-ATLANTIC REGION...
   WEAK HEIGHT FALLS SHIFTING GRADUALLY ACROSS NEW ENGLAND AND FOCUSED
   LOW-LEVEL ASCENT INVOF A WEAK COLD FRONT SHIFTING EWD THROUGH THE
   DAY SHOULD SUPPORT ISOLATED STORM DEVELOPMENT -- FUELED BY AFTERNOON
   HEATING/DESTABILIZATION LIKELY PUSHING MIXED-LAYER CAPE INTO THE
   1000 TO 2000 J/KG RANGE.  WITH THE CONVECTION EVOLVING WITHIN A
   KINEMATIC ENVIRONMENT FEATURING MODERATELY STRONG SWLY FLOW THROUGH
   A DEEP TROPOSPHERIC LAYER... FAST-MOVING...SEMI-ORGANIZED
   STORMS/STORM CLUSTERS ARE EXPECTED THROUGH THE AFTERNOON -- WITH
   ISOLATED DAMAGING WIND/HAIL RISK EVIDENT.  THUS -- WILL EXPAND
   SLIGHT RISK NWD FROM THE MID-ATLANTIC REGION ACROSS ALL OF ERN NEW
   ENGLAND THROUGH EARLY EVENING.

   ...NRN HIGH PLAINS INTO THE KS/NEB VICINITY...
   WHILE A REMNANT MCS SHIFTS ACROSS PORTIONS OF S CENTRAL KS/OK EARLY
   IN THE PERIOD...DESTABILIZATION IS FORECAST TO COMMENCE FARTHER N/NW
   -- I.E. ACROSS NWRN KS AND INTO THE NRN HIGH PLAINS.  AS A MID-LEVEL
   TROUGH SHIFTS NEWD ACROSS THE AREA THROUGH THE DAY AND REMNANTS OF
   THE SE-TO-NW-ORIENTED COLD FRONT RETREATING NWD ACROSS THIS REGION
   FOCUSES LOW-LEVEL ASCENT...AFTERNOON STORM DEVELOPMENT WILL LIKELY
   OCCUR IN THE SWRN NEB/NWRN KS VICINITY.  WITH 35 TO 45 KT MID-LEVEL
   WNWLYS PROGGED TO SPREAD ACROSS THIS AREA ATOP LOW-LEVEL SLYS...THE
   VEERING/INCREASING FLOW WITH HEIGHT SHOULD YIELD SHEAR SUPPORTIVE OF
   ORGANIZED/ROTATING STORMS.  THUS...HAVE INTRODUCED 15%/SLIGHT RISK
   AREA ACROSS THE SWRN NEB/NWRN KS VICINITY GIVEN LARGE HAIL/LOCALLY
   DAMAGING WIND POTENTIAL WITH A FEW STRONGER/SUPERCELL STORMS. 
   CONVECTION SHOULD SPREAD SEWD WITH TIME...BEFORE WEAKENING BY MID TO
   LATE EVENING.

   ..GOSS/GLEASON.. 08/04/2015

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