Mesoscale Discussion 1349
NWS Storm Prediction Center Norman OK
0238 PM CDT Wed Jun 18 2025
Areas affected...northern IN...southern Lower MI...northwest OH
Concerning...Tornado Watch 434...
Valid 181938Z - 182145Z
The severe weather threat for Tornado Watch 434 continues.
SUMMARY...Northern, fast-moving portion of a QLCS should progress
across the rest of northern Indiana into southern Lower Michigan and
northwest Ohio through early evening. Damaging winds should be the
main threat, but a tornado or two will be possible. Downstream watch
issuance expected by 21Z.
DISCUSSION...The northern portion of a QLCS has been steadily
progressing east around 45 kts with a history of estimated to
measured gusts of 55-70 mph. This fast-moving portion of the line
has likely outpaced stronger low-level shear across southwest IN,
per comparison of VWX and IWX VWP data. Given largely veered surface
winds downstream and recent HRRR guidance, an outflow-dominated line
will likely persist as it spreads into southern Lower MI and
northwest OH through early evening. Damaging winds should remain the
primary hazard, with a tornado or two possible in any QLCS
mesovortices across northern IN.