MD 2198 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF EXTREME EASTERN IOWA INTO NORTHERN ILLINOIS
Mesoscale Discussion 2198
NWS Storm Prediction Center Norman OK
0120 PM CDT Tue Sep 26 2023
Areas affected…portions of extreme eastern Iowa into northern
Illinois
Concerning…Severe potential…Watch unlikely
Valid 261820Z – 261945Z
Probability of Watch Issuance…20 percent
SUMMARY…Isolated instances of hail and perhaps a brief tornado are
possible this afternoon. A WW issuance is not expected.
DISCUSSION…The boundary layer continues to warm beneath cooler
mid-level temperatures associated with a 500 mb cut-off low centered
over far eastern IA. Surface temperatures have warmed into the mid
70s to 80 F amid 58-70 F dewpoints, with 7.5-8.5 C/km boundary layer
lapse rates contributing to 1500 J/kg MLCAPE, with well over 100
J/kg of CAPE established in the lowest 3 km. Though vertical wind
shear is mediocre beneath this upper low, -14 to -16 C 500 mb
temperatures may encourage a couple bouts of hail with the stronger
cells. Furthermore, sufficient vertical vorticity is in place to
support a brief tornado wherever one of the stronger, longer-lasting
storms can thrive in locally higher 0-3 km CAPE. Nonetheless, the
severe threat should remain sparse and localized, likely precluding
a WW issuance.
..Squitieri/Guyer.. 09/26/2023
…Please see www.spc.noaa.gov for graphic product…
ATTN…WFO…LOT…ILX…MKX…DVN…
LAT…LON 40388972 41229098 41699143 42089127 42479056 42528952
42278851 41888786 41408762 40918760 40528790 40338847
40388972
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