Mesoscale Discussion 0246 NWS Storm Prediction Center Norman OK 0337 PM CDT Wed Mar 19 2025 Areas affected...eastern Illinois into far western Indiana Concerning...Tornado Watch 57... Valid 192037Z - 192230Z The severe weather threat for Tornado Watch 57 continues. SUMMARY...Strong to severe thunderstorm development is likely to continue to increase during the next few hours, including the potential for supercells with tornadoes across much of east central Illinois into the Indiana state border vicinity through 5-7 PM CDT. DISCUSSION...Aided by stronger mid-level forcing for ascent and cooling, within the exit region of the intense mid-level jet nosing through the middle Mississippi Valley, an intensifying and evolving broken line of thunderstorms appears likely to spread across and east of the Interstate 55 corridor of central Illinois through 21-22Z. This is where 20Z surface observations indicate that rapid (2-hourly in excess of 4 mb) surface pressure falls are maximized, and lower 50s surface dew points are being maintained with perhaps some further increase ongoing farther east, into the vicinity of the Indiana state border vicinity. More discrete thunderstorms are now initiating farther south, between Taylorville and Salem, which are likely to continue rapidly moving north-northeastward within 50-60 kt south-southwesterly deep-layer mean flow. Rapid Refresh forecast soundings continue to suggest that this will coincide with enlarging clockwise-curved low-level hodographs near/east of Kankakee, Champaign, Decatur vicinities, where south to southwesterly flow is forecast to intensify within the 850-700 mb layer through 22-00Z. And it still appears the low-level thermodynamic profiles may become conducive to supercell tornadoes, perhaps including a strong tornado or two. ..Kerr.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IND...PAH...LOT...ILX...LSX... LAT...LON 41618831 41418744 38798741 38288815 38388861 40008935 41618831
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