SPC AC 220053

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0753 PM CDT Thu May 21 2020

   Valid 220100Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE SOUTHERN AND CENTRAL HIGH PLAINS...

   ...SUMMARY...
   Scattered severe thunderstorms are expected this evening over the
   central and southern High Plains. A marginal severe threat will be
   possible in southern Arkansas.

   ...Central and Southern High Plains...
   Latest water vapor imagery shows an upper-level trough over the
   southern Rockies. Large-scale ascent ahead of this feature is moving
   into the central High Plains, providing support for a developing MCS
   in western Kansas. These storms will move east-southeastward this
   evening along a northwest-to-southeast oriented corridor of moderate
   instability from southwest Kansas and into northwest Oklahoma. The
   RAP is estimating MLCAPE from 2000 to 3000 J/kg along this corridor.
   The WSR-88D VWP at Dodge City has strong directional shear in the
   lowest 2 km AGL with speed shear in the mid-levels. This is
   resulting in about 50 kt of 0-6 km shear which will be favorable for
   supercells. The storms are forming on the nose of a plume of steep
   mid-level lapse rates. This combined with the moderate deep-layer
   shear will support a large hail threat this evening. The stronger
   more dominant supercells could produce hailstones of greater than 2
   inches in diameter. A tornado can not be ruled out as low-level
   shear increases this evening due to a strengthening low-level jet.
   As cells congeal into a larger convective cluster later this evening
   and move across southwest Kansas and into northwest Oklahoma, the
   wind damage threat may increase.

   Further south across the Low Rolling Plains, two small clusters of
   strong to severe storms are ongoing. This convection is located to
   the east of a dryline and will move eastward into stronger
   instability over the next couple of hours. For this reason, the
   severe threat is expected to continue. Moderate deep-layer shear and
   steep mid-level lapse rates, evident on the latest RAP, will support
   supercells with large hail. The stronger downdrafts may also produce
   damaging wind gusts.

   ...Arkansas...
   The latest surface analysis shows a very moist airmass in place
   across the Arklatex where dewpoints are in the lower 70s F. This has
   resulted in a west-northwest to east-northeast oriented axis of
   moderate instability from southern Arkansas into central
   Mississippi. Thunderstorms are ongoing along this corridor near the
   strongest instability in southwest Arkansas. As this small
   convective cluster moves eastward across southern Arkansas over the
   next few hours, marginally severe wind gusts and hail will be the
   primary threats.

   ...North Carolina...
   An upper-level low will move slowly northeastward across the Ohio
   Valley tonight as an associated upper-level trough moves through the
   Carolinas. At the surface, a mesolow will move northward across
   central North Carolina as a moist airmass remains across eastern
   North Carolina. Surface dewpoints in the upper 60s F should result
   in a small pocket of moderate instability with MLCAPE near 1000
   J/kg. In addition, low-level shear will be maximized in eastern
   North Carolina where rotating storms could have a marginal tornado
   or wind damage threat. The greatest potential for a marginal severe
   threat would be in the late evening and overnight period to the east
   of the mesolow from Wilmington to Jacksonville and northward to
   Greenville.

   ..Broyles.. 05/22/2020

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