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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