Mesoscale Discussion 0316 NWS Storm Prediction Center Norman OK 0303 PM CDT Tue Apr 06 2021 Areas affected...Parts of south central Nebraska into western portions of central Kansas Concerning...Severe potential...Watch possible Valid 062003Z - 062200Z Probability of Watch Issuance...40 percent SUMMARY...Scattered vigorous thunderstorm development is possible across the region by 5-6 PM CDT, with large hail expected to be the primary potential severe hazard into early evening. DISCUSSION...Seasonably strong boundary-layer heating/mixing is ongoing, within a narrow pre-cold frontal corridor wrapping into the vicinity of a modest surface cyclone centered west/northwest of Hill City, KS. To the east of this axis, weak to modest low-level moisture return on southerly low-level flow continues. Beneath rather steep mid-level lapse rates associated with warm and capping elevated mixed-layer air, it appears that this is contributing to mixed-layer CAPE up to around 1500 J/kg, east of Dodge City through Russell, KS, into the vicinity of Lexington, NE. Meanwhile, just to the west, it appears that at least weak mid-level cooling is underway in response to the east-northeast progression of an initial impulse within larger-scale mid-level troughing progressing across and east of the Rockies. As this begins to overspread the vicinity of the ongoing axis of boundary-layer destabilization, mid-level inhibition is expected to weaken sufficiently to contribute to the initiation of scattered vigorous thunderstorm activity within the next few hours. The past several runs of the Rapid Refresh and High Resolution Rapid Refresh have been suggestive that this may occur as early as 22-23Z. Although stronger southerly low-level flow, including 30-40+ kt around 850 mb, appears offset to the east of the instability axis, deeper-layer shear beneath 40 kt flow near the 500 mb level may contribute to sufficient shear for the evolution of supercell structures capable of producing large hail. Locally strong to severe surface gusts may also be possible, but a more general increase in risk for severe wind gusts probably will await interaction of upscale growing convection with a strengthening low-level jet later this evening. ..Kerr/Hart.. 04/06/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ICT...GID...LBF...DDC...GLD... LAT...LON 40870005 41179909 40719828 39149809 37969829 37609891 37629962 38789964 40069970 40870005
Storm Prediction Center Mesoscale Discussion 316
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