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Mesoscale Discussion 657
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   Mesoscale Discussion 0657
   NWS Storm Prediction Center Norman OK
   0220 PM CDT Thu May 21 2020

   Areas affected...far southeast CO...western KS and portions of the
   OK Panhandle

   Concerning...Severe potential...Watch likely 

   Valid 211920Z - 212045Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Thunderstorms are expected to develop in the next couple
   of hours. Very large hail and locally damaging gusts will be the
   main hazards with these storms into this evening. A watch will
   likely be issued by 21z.

   DISCUSSION...Vertically developing CU has been increasing across
   parts of southwest KS near a surface low. Morning cloud cover has
   diminished across this area, allowing temperatures to warm into the
   mid and upper 70s. Surface dewpoints generally in the low 60s are
   being maintained on southeasterly low level flow. Some increase in
   dewpoints may still occur as mid-to-upper 60s dewpoints reside just
   downstream across OK/TX, and MLCAPE is expected to increase to
   around 1500-2500 J/kg across the discussion area. While capping is
   still in place, MLCIN will continue to erode in the short-term,
   aided by additional heating and increasing ascent from an eastward
   ejecting shortwave impulse. As a result, convective initiation is
   expected near the surface low in the vicinity of the KS/CO border in
   the next 1-2 hours. 

   Deep layer flow is not particularly strong across the region,
   however vertically-veering winds are resulting in 30-40 kt effective
   shear. This should support rotating updrafts, while very steep
   midlevel lapse rates favor large hail production. Storm clusters,
   including supercells, are expected initially. With time, some
   upscale growth may occur with eastward extent via strong downdrafts
   resulting in outflow interactions. Low level moisture is somewhat
   modest, with mean mixing ratios around 10-12 g/kg. Nevertheless,
   backed low level flow with result in 0-3 km SRH around 150 m2/s2,
   suggesting some low-end potential for a landspout/tornado or two.

   ..Leitman/Hart.. 05/21/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...ICT...OUN...GID...DDC...GLD...AMA...PUB...

   LAT...LON   37670243 38280235 38820213 39010191 39370151 39500102
               39590036 39489966 39269924 38769896 38419894 38079900
               37699908 37039960 36640030 36430123 36560175 36940219
               37670243 

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Page last modified: May 21, 2020
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