MD 0935 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR NORTHEASTERN KANSAS AND SOUTHEASTERN NEBRASKA INTO PARTS OF IOWA AND NORTHWESTERN MISSOURI
Mesoscale Discussion 0935 NWS Storm Prediction Center Norman OK 0630 PM CDT Thu Jun 18 2020 Areas affected...northeastern Kansas and southeastern Nebraska into parts of Iowa and northwestern Missouri Concerning...Severe potential...Watch possible Valid 182330Z - 190130Z Probability of Watch Issuance...40 percent SUMMARY...A few occasionally stronger storms within the discussion area will be capable of producing large hail and locally gusty/damaging winds. Risk may remain temporally and areally limited so as to preclude the need for WW issuance, but we will continue to monitor convective evolution. DISCUSSION...Latest radar loop shows an active zone of convection from southern Minnesota south-southwestward to north-central/northeastern Kansas, along and ahead of the slowly advancing surface front. The environment ahead of the front is characterized by low to mid 60s surface dewpoints, which combined with daytime heating is yielding mixed-layer CAPE on the order of 1500 to 2000 J/kg within the discussion area. This is fueling persistent storm development -- particularly from southeast Nebraska southwestward to Lincoln/Mitchell Counties in Kansas. Despite ample CAPE for robust updrafts, the deep-layer wind remains marginal for a more substantial severe event. Though ample veering with height -- from southerly to westerly through mid levels -- is yielding enough shear for multicell organization and some weak/transient updraft rotation, mid-level flow of 20 to 25 kt over Nebraska/Iowa, and weakening with southward extent, is observed. This suggests that the overall degree of risk will remain limited -- with maximum hail size in the 1" to 1.75" range, and severe-caliber wind gusts very local and brief. While the evolution of a low-level jet across this region over the next few hours will likely sustain convection, the most likely scenario appears that a southeastward-moving outflow will evolve, with storm redevelopment favored on the cool side of the outflow. The anafrontal/elevated nature of this convection -- particularly as the boundary layer cools -- likely precludes appreciable increase in wind risk, with marginal hail and locally heavy rainfall likely to be the most dominant risks after dark. ..Goss/Thompson.. 06/18/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...EAX...OAX...TOP...ICT...GID... LAT...LON 38499809 39359810 40659669 41739585 41939505 42059376 41669265 40439326 39039491 38459662 38499809
from SPC Mesoscale Discussions https://bit.ly/1FK23JU
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