ZCZC SPCSWOMCD ALL ACUS11 KWNS 272230 SPC MCD 272230 OHZ000-MIZ000-INZ000-ILZ000-280000- Mesoscale Discussion 0838 NWS Storm Prediction Center Norman OK 0530 PM CDT Mon May 27 2019 Areas affected...Parts of northeastern Illinois...northern Indiana...southern Michigan and western Ohio Concerning...Tornado Watch 263... Valid 272230Z - 280000Z The severe weather threat for Tornado Watch 263 continues. SUMMARY...Isolated supercell development may continue, with the evolution of an increasingly organized convective system also possible through 8-10 PM EDT, accompanied by a continuing risk for tornadoes, and increasing potential for damaging wind gusts. A new severe weather watch likely will be needed east/southeast of tornado watch 263 within another hour or two. DISCUSSION...A low amplitude short wave trough, with one or two embedded MCVs, continues to gradually turn eastward into southern portions of the Great Lakes region. Associated forcing for ascent appears to be aiding upscale convective growth across and south of the Chicago area, but discrete supercell development persists, particularly along the warm frontal zone extending east-southeastward across northern Indiana into western Ohio. Into the 00-02Z time frame, large-scale lift supported by warm advection, in the presence of CAPE on the order of 2000 J/kg, seems likely to support considerable further upscale growth. This probably will evolve into an increasingly organized convective system in the presence of strong deep layer shear, with increasing potential for damaging surface gusts on the leading edge of a strengthening surface cold pool. Low-level shear remains maximized along the warm front, and supportive of continuing potential for tornadoes in discrete supercells, as well as with potential evolving mesovortices along the southeastward advancing gust front. While activity will tend to advect eastward in the presence of 40+ kt westerly deep layer mean ambient flow (toward the Toledo OH area), it appears there may also be a tendency to propagate southeastward toward the Interstate 70 corridor (near/east of Indianapolis IN toward Columbus OH). ..Kerr.. 05/27/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND...LOT...ILX... LAT...LON 42408736 42598605 41588325 40728304 39758392 39458496 39538577 39958685 40558830 41118793 42408736 NNNN