May 23, 2018 0100 UTC Day 1 Convective Outlook
Updated: Wed May 23 01:00:38 UTC 2018 (20180523 0100Z Day 1 shapefile | 20180523 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180523 0100 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 187,445 1,995,604 Sioux Falls, SD...Fort Collins, CO...Rapid City, SD...Bismarck, ND...Cheyenne, WY...
Probabilistic Tornado Graphic
20180523 0100 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 0100 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
5 % 98,147 762,798 Fort Collins, CO...Rapid City, SD...Cheyenne, WY...Casper, WY...Roswell, NM...
Probabilistic Large Hail Graphic
20180523 0100 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 % 186,877 1,980,182 Sioux Falls, SD...Fort Collins, CO...Rapid City, SD...Bismarck, ND...Cheyenne, WY...
   SPC AC 230100

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0800 PM CDT Tue May 22 2018

   Valid 230100Z - 231200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
   NORTHERN GREAT PLAINS AND SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   Isolated strong to severe thunderstorms are possible this evening
   into the overnight from eastern Wyoming east through South Dakota. 
   A few severe thunderstorms are possible this evening over the
   southern High Plains.

   ...Eastern WY east through SD and into southern MN/northern IA...
   A mid-level low over the Interior West will move little through
   early Wednesday morning while a ridge remains downstream over the
   Plains.  Widely scattered thunderstorms over the High Plains will
   gradually weaken during the evening as boundary layer instability
   diminishes.  In the meantime, an isolated hail/severe gust risk will
   accompany the stronger storms.  By mid-late evening, a strengthening
   southerly low-level jet over the central Plains and isentropic
   ascent in the vicinity of a warm frontal zone will likely lead to
   the development of isolated to scattered elevated thunderstorms.  A
   marginal hail risk may develop with this activity late tonight.

   ...Southeast NM and Far West TX...
   Isolated thunderstorms this evening will likely pose a localized
   wind/hail risk for the next 1-2 hours.  The 00Z MAF RAOB exhibited
   steep low-level lapse rates but weak flow in the mid levels and
   modest lapse rates above the boundary layer suggest the overall risk
   will be short-lived/limited to the early evening.

   Elsewhere, a convective line over the central Appalachians will
   continue to progress eastward this evening.  Cooling temperatures
   will result in increased convective inhibition and storm intensity
   will probably diminish further over the next hour or so.

   ..Smith.. 05/23/2018

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z