May 23, 2018 1630 UTC Day 1 Convective Outlook
Updated: Wed May 23 16:51:24 UTC 2018 (20180523 1630Z Day 1 shapefile | 20180523 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180523 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 124,881 610,291 Rapid City, SD...North Platte, NE...Aberdeen, SD...Gillette, WY...Scottsbluff, NE...
MARGINAL 414,286 12,312,311 Denver, CO...Virginia Beach, VA...Raleigh, NC...Aurora, CO...Norfolk, VA...
Probabilistic Tornado Graphic
20180523 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
2 % 38,802 281,633 Rapid City, SD...Scottsbluff, NE...Spearfish, SD...Rapid Valley, SD...Sturgis, SD...
Probabilistic Damaging Wind Graphic
20180523 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 % 125,803 618,932 Rapid City, SD...North Platte, NE...Aberdeen, SD...Gillette, WY...Scottsbluff, NE...
5 % 393,693 10,894,158 Virginia Beach, VA...Raleigh, NC...Norfolk, VA...Chesapeake, VA...Lubbock, TX...
Probabilistic Large Hail Graphic
20180523 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
15 % 109,451 541,696 Rapid City, SD...Aberdeen, SD...Gillette, WY...Scottsbluff, NE...Pierre, SD...
5 % 377,879 10,331,512 Denver, CO...Virginia Beach, VA...Raleigh, NC...Aurora, CO...Norfolk, VA...
   SPC AC 231651

   Day 1 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   1151 AM CDT Wed May 23 2018

   Valid 231630Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
   NORTH-CENTRAL PLAINS...

   CORRECTED FOR THUNDER LINE

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

   ...Northern High Plains...
   Morning water vapor imagery shows a large upper trough over the
   western states, with an embedded shortwave trough lifting
   northeastward through the four-corners region.  Lift ahead of this
   feature should overspread parts of WY and southeast MT this
   afternoon and evening, leading to scattered thunderstorm
   development.  Strong daytime heating and surface dewpoints in the
   50s, coupled with steep mid level lapse rates and relatively cool
   temperatures aloft will yield afternoon MLCAPE values of 1000-1500
   J/kg and only a weak cap.  This, combined with favorable deep-layer
   shear will promote rotating updrafts capable of large hail and
   damaging winds.  As storms spread eastward into parts of SD/NE,
   outflow mergers will likely increase the risk of damaging wind gusts
   through the evening.

   ...Southern High Plains...
   Another round of afternoon/evening thunderstorms are expected to
   affect eastern NM and west TX.  Visible satellite imagery confirms
   that considerable low-level moisture is in place over this area, and
   as the low-clouds burn off this afternoon, a strongly unstable air
   mass should develop.  Despite the favorable thermodynamic setup,
   vertical shear profiles are quite weak and steering flow is 5-10
   knots.  This will lead to rather disorganized thunderstorms capable
   of locally damaging wind gusts and hail.  Through the evening, CAM
   solutions suggest that outflows may organize as they spread into
   west TX, with an increased risk of gusty/damaging winds in the more
   intense cores.

   ...VA/NC...
   A warm/humid air mass is present today over parts of southern VA and
   much of NC, leading to strong afternoon instability (MLCAPE values
   of around 1500 J/kg).  Models are in good agreement that scattered
   thunderstorms will affect this region later this afternoon and
   evening.  Forecast soundings suggest low-level wind fields will be
   quite weak with less than 10kt winds expected in the lowest 4-5km. 
   This suggests that isolated cells may briefly produce downbursts,
   but the threat of a more organized severe event is rather low.

   ...ME...
   Scattered thunderstorms are expected to affect parts of ME as a
   shortwave trough and associated cold front moves through the area. 
   Organized severe storms are not expected, but the strongest cells
   could produce locally gusty/damaging wind gusts - especially in the
   eastern parts of the state.

   ..Hart.. 05/23/2018

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