Mesoscale Discussion 1742
NWS Storm Prediction Center Norman OK
0909 AM CDT Tue Jul 30 2024
Areas affected...portions of southern Illinois and southern Indiana
into north-central Kentucky
Concerning...Severe Thunderstorm Watch 567...
Valid 301409Z - 301615Z
The severe weather threat for Severe Thunderstorm Watch 567 continues.
SUMMARY...Severe thunderstorms posing a damaging wind risk will
persist across southern Illinois within Severe Thunderstorm Watch
567. Areas across southern Indiana into adjacent north-central
Kentucky are being monitored for possible downstream watch issuance.
DISCUSSION...A small, but well organized bowing cluster of storms
continues to track east/southeast across south-central Illinois this
morning. This activity has produced gusts near 50 kt within the past
hour. Around 30 kt effective shear magnitudes are likely sustaining
organized activity as convection shifts east/southeast along an
instability gradient oriented northwest to southeast across the
lower Ohio Valley vicinity. A very moist downstream airmass is
evident, with surface dewpoints in the 70s. With continued heating, boundary-layer inhibition is expected to quickly erode by midday.
Damaging gusts may continue downstream of ongoing activity,
especially if additional convection can develop on the southern
flank of the ongoing cluster. Visible satellite imagery shows
deepening cumulus ahead of the southern flank, so this evolution
appears plausible. A downstream watch may be needed within the next
hour or so if current trends persist/increase.