May 23, 2018 0600 UTC Day 1 Convective Outlook
Updated: Wed May 23 05:32:37 UTC 2018 (20180523 1200Z Day 1 shapefile | 20180523 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180523 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 26,144 231,627 Rapid City, SD...Scottsbluff, NE...Rapid Valley, SD...Torrington, WY...
MARGINAL 416,800 8,793,304 Virginia Beach, VA...Raleigh, NC...Norfolk, VA...Chesapeake, VA...Lubbock, TX...
Probabilistic Tornado Graphic
20180523 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
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20180523 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 % 22,743 213,657 Rapid City, SD...Scottsbluff, NE...Rapid Valley, SD...
5 % 416,534 8,747,680 Virginia Beach, VA...Raleigh, NC...Norfolk, VA...Chesapeake, VA...Lubbock, TX...
Probabilistic Large Hail Graphic
20180523 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 % 6,840 57,114 Scottsbluff, NE...Torrington, WY...
5 % 432,974 8,645,998 Virginia Beach, VA...Raleigh, NC...Norfolk, VA...Chesapeake, VA...Lubbock, TX...
   SPC AC 230532

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1232 AM CDT Wed May 23 2018

   Valid 231200Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE NEBRASKA
   PANHANDLE AND BLACK HILLS...

   ...SUMMARY...
   Isolated severe thunderstorms are possible this afternoon and
   evening across the High Plains and eastern portions of
   Virginia/North Carolina.

   ...High Plains...
   Southerly low-level flow across the Great Plains will maintain a
   fetch of modest moisture in the High Plains as a lee trough moves
   little.  A belt of stronger southwesterly mid-level flow will extend
   from the Desert Southwest northeastward into the central High Plains
   and Black Hills to the southeast of a weakening mid-level low. 
   Steep 700-500 mb lapse rates and strong heating through mid
   afternoon will yield moderate buoyancy (1000-2000 J/kg MLCAPE).  The
   local erosion of a capping inversion will result in isolated to
   scattered thunderstorms developing in the vicinity of the lee trough
   by late afternoon.  The potential for organized storms appears
   greatest over parts of the central High Plains where vertical shear
   is forecast to be strongest.  Models suggest higher storm coverage
   and severe potential from far eastern WY northeastward into western
   NE/Black Hills.  Large hail and severe gusts will be the primary
   threats before storms grow upscale as a LLJ strengthens during the
   evening and the wind threat persists while the hail risk gradually
   lessens as storms move into western SD.  Farther south, isolated
   strong to severe thunderstorms will pose an attendant hail/wind
   threat with the stronger cores.  This activity will likely weaken
   during the evening coincident with a cooling boundary layer.

   ...VA/NC...
   A cold front extending southwestward from southern NJ across central
   VA to middle TN is expected to shift southeastward throughout the
   day.  Temperatures ahead of the front will likely reach the mid-80s
   amidst dewpoints in the upper 60s, which is supportive of airmass
   destabilization and modest instability.  Deep-layer shear is
   forecast to favor multicells with some upscale growth into small
   segments capable of isolated damaging wind with the strongest
   water-loaded downdrafts.

   ..Smith/Cook.. 05/23/2018

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