Apr 15, 2018 0600 UTC Day 1 Convective Outlook
Updated: Sun Apr 15 06:07:11 UTC 2018 (20180415 1200Z Day 1 shapefile | 20180415 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180415 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 15,540 4,546,968 Charlotte, NC...Greensboro, NC...Winston-Salem, NC...High Point, NC...Gastonia, NC...
SLIGHT 186,142 34,627,152 Jacksonville, FL...Virginia Beach, VA...Miami, FL...Raleigh, NC...Tampa, FL...
MARGINAL 87,410 15,732,310 Washington, DC...Atlanta, GA...Arlington, VA...Alexandria, VA...Sandy Springs, GA...
Probabilistic Tornado Graphic
20180415 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
10 % 15,608 4,563,288 Charlotte, NC...Greensboro, NC...Winston-Salem, NC...High Point, NC...Gastonia, NC...
5 % 53,372 8,483,267 Durham, NC...Richmond, VA...Columbia, SC...Charleston, SC...Cary, NC...
2 % 125,700 20,025,016 Jacksonville, FL...Virginia Beach, VA...Raleigh, NC...Tampa, FL...St. Petersburg, FL...
Probabilistic Damaging Wind Graphic
20180415 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 % 201,369 39,170,620 Jacksonville, FL...Charlotte, NC...Virginia Beach, VA...Miami, FL...Raleigh, NC...
5 % 88,813 16,136,552 Washington, DC...Atlanta, GA...Arlington, VA...Alexandria, VA...Sandy Springs, GA...
Probabilistic Large Hail Graphic
20180415 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
5 % 75,357 13,947,486 Charlotte, NC...Raleigh, NC...Greensboro, NC...Durham, NC...Winston-Salem, NC...
   SPC AC 150607

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0107 AM CDT Sun Apr 15 2018

   Valid 151200Z - 161200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   WESTERN NORTH CAROLINA...NORTHWEST SOUTH CAROLINA...AND A SMALL PART
   OF SOUTHWEST VIRGINIA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FLORIDA TO
   VIRGINIA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
   THE SOUTHEAST AND MID ATLANTIC...

   ...SUMMARY...
   Widespread thunderstorms, some severe, will spread across the Mid
   Atlantic and Southeastern states today into the evening. The
   greatest threat will be across parts of the Carolinas into southwest
   Virginia with a few tornadoes possible.

   ...Synopsis...
   An upper trough will pivot in a negative-tilt fashion from the MS
   Valley across the Southeast during day, continuing across the Mid
   Atlantic overnight. This will result in lift over a large area with
   rapid cooling aloft and height falls. At the surface, low pressure
   will deepen from OH across WV and across the lee of the
   Appalachians, with strong southeasterly low-level flow contributing
   to moisture advection as well as upslope flow into the higher
   terrain. Dewpoints into the low to perhaps mid 60s F will contribute
   to sufficient instability given extreme shear to support severe
   storms focused over the Enhanced Risk area, as well as farther south
   along the advancing cold front across GA and FL.

   ...Mid Atlantic...
   Surface winds will strengthen out of the southeast in response to
   the deepening low, with strong meridional flow aloft. Hodographs
   will favor supercells, and/or QLCS structures just ahead of or near
   the main front. Heating as well as upslope flow may contribute to
   destabilization and updraft strength. CAM solutions indicate a
   relative concentration of updraft helicity during the afternoon
   across the Enhanced Risk area where a few tornadoes will be
   possible. Given the strong backed low-level winds, an isolated
   severe threat may extend a bit farther west or north than currently
   depicted.

   Farther north, a stationary front will likely extend from northern
   VA across the Delmarva, with stable air to the north. As storms
   approach this boundary, they should cross quickly with only a
   marginal hail risk. A low chance of a severe storm or two may also
   exist across WV into OH, near the surface low and where shear will
   be strong but instability quite weak.

   ...Florida...
   A broken line of storms is expected to push eastward across the Gulf
   of Mexico, traversing the Florida Panhandle during the morning.
   Cells will likely affect much of the peninsula during the late
   afternoon and evening as they move ashore. Supercells will be
   possible given veering winds with height. Preceding the cold front,
   another broken line of storms is expected to form during peak
   heating, and affect mainly eastern FL and into southeast GA.
   Marginal hail, locally strong winds or a brief tornado will all be
   possible.

   ..Jewell/Cook.. 04/15/2018

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