Sep 1, 2017 1630 UTC Day 1 Convective Outlook
Updated: Fri Sep 1 16:19:28 UTC 2017 (20170901 1630Z Day 1 shapefile | 20170901 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170901 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 12,124 3,587,961 Charlotte, NC...Fayetteville, NC...Gastonia, NC...Concord, NC...Rock Hill, SC...
SLIGHT 41,760 6,871,429 Raleigh, NC...Durham, NC...Columbia, SC...Cary, NC...High Point, NC...
MARGINAL 82,518 6,726,511 Greensboro, NC...Winston-Salem, NC...Savannah, GA...Charleston, SC...Wilmington, NC...
Probabilistic Tornado Graphic
20170901 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
10 % 12,125 3,587,695 Charlotte, NC...Fayetteville, NC...Gastonia, NC...Concord, NC...Rock Hill, SC...
5 % 25,005 4,895,330 Raleigh, NC...Durham, NC...Cary, NC...High Point, NC...Asheville, NC...
2 % 40,725 4,703,796 Greensboro, NC...Winston-Salem, NC...Columbia, SC...Wilmington, NC...Greenville, NC...
Probabilistic Damaging Wind Graphic
20170901 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
15 % 40,099 6,882,378 Charlotte, NC...Fayetteville, NC...Columbia, SC...Gastonia, NC...Concord, NC...
5 % 96,475 10,312,008 Raleigh, NC...Greensboro, NC...Durham, NC...Winston-Salem, NC...Savannah, GA...
Probabilistic Large Hail Graphic
20170901 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 011619

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1119 AM CDT Fri Sep 01 2017

   Valid 011630Z - 021200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS
   AFTERNOON/EVENING FOR NORTHERN SC AND PARTS OF CENTRAL NC...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   ENHANCED RISK AREA ACROSS THE CAROLINAS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEASTERN
   TN INTO SOUTHEASTERN KY THIS AFTERNOON...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK AREAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
   AFTERNOON/EVENING FOR EASTERN ND AND NORTHWESTERN MN...

   ...SUMMARY...
   Severe thunderstorms capable of producing tornadoes and damaging
   wind gusts are expected over the Carolinas and southern Appalachians
   vicinity this afternoon into this evening.

   ...Eastern TN/KY to the Carolinas through this evening...
   Remnants of tropical cyclone Harvey will continue moving
   northeastward today over TN/KY while weakening slowly.  East of the
   circulation center, a belt of stronger low-midlevel southwesterly
   flow (30-50 kt per 12z soundings and recent VWPs) extends over the
   southern Appalachians and Carolina piedmont.  At the surface, a
   surface trough/weak cold front will move slowly eastward across
   northern GA through the afternoon, while some consolidation of a
   baroclinic zone should occur across central NC.  Broken bands of
   convection will form late this morning into this afternoon along and
   east of the surface trough, and the storms will spread northeastward
   across the Carolinas into this evening.

   There will be a narrow window of opportunity for rotating storms by
   midday or early afternoon from northeastern TN into eastern KY, near
   and just north of the surface triple point where limited surface
   heating may occur in small cloud breaks.  The more substantial
   supercell/tornado threat area will be farther east into the
   Carolinas this afternoon, where warm sector storms interact with the
   east-west oriented front across NC.  Here, low-level shear and
   hodograph curvature will be enhanced (within and just east of the
   belt of stronger low-midlevel flow), along the northern edge of the
   warm sector where surface temperatures warm into the 80s with
   dewpoints in the low-mid 70s F.  

   ...Eastern ND/northwestern MN this afternoon/evening...
   A lead shortwave trough is passing over the eastern Dakotas as of
   late morning, with a band of rain/weak convection preceding the
   wave.  Some destabilization may occur in cloud breaks this afternoon
   across eastern ND, though storm initiation will have to rely on only
   shallow ascent along a surface cold front late this
   afternoon/evening.  Vertical shear and buoyancy could become
   sufficient for supercells, thus will maintain a MRGL area to reflect
   the conditional severe threat.

   ..Thompson/Gleason.. 09/01/2017

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