256 
ACUS11 KWNS 261821
SWOMCD
SPC MCD 261820 
ILZ000-WIZ000-IAZ000-261945-

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