Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 221757
SWOMCD
SPC MCD 221756
ILZ000-WIZ000-IAZ000-222000-
Mesoscale Discussion 1372
NWS Storm Prediction Center Norman OK
1256 PM CDT Sat Jun 22 2024
Areas affected...Portions of northeastern IA...northern IL...and
southern WI
Concerning...Severe potential...Watch likely
Valid 221756Z - 222000Z
Probability of Watch Issuance...95 percent
SUMMARY...Severe storms capable of producing damaging winds, a
couple tornadoes, and isolated large hail are expected this
afternoon into the evening. A watch is likely in the next hour or
two.
DISCUSSION...Latest visible satellite imagery indicates filtered
diurnal heating/destabilization of a very moist boundary layer
(middle 70s dewpoints) along/south of an east/west-oriented
stationary boundary extending across portions of northern IA into
southern WI. Over the next couple hours, a weak frontal wave
currently near far northwest IA will track eastward along the
boundary, promoting scattered thunderstorm development -- aided by
the aforementioned destabilization and modest midlevel height falls
ahead of a midlevel trough.
Around 50 kt of midlevel westerly flow atop a 30-40-kt southwesterly
low-level jet (per regional VWP) will promote organized
surface-based storms (including a few supercells) near the boundary.
Easterly storm motions and deep-layer shear parallel to the boundary
may favor congealing cold pools and localized upscale growth, though
the favorable shear profile (large clockwise-curved low-level
hodographs) should encourage a few sustained semi-discrete
supercells. Damaging winds up to 70 mph, a couple tornadoes, and
isolated large hail are all possible with this activity. Current
thinking is that severe storms will develop/mature in the 19-20Z
time frame and persist into the evening hours. A watch is likely for
parts of the area in the next hour or two.
..Weinman/Hart.. 06/22/2024
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LOT...MKX...DVN...ARX...DMX...
LAT...LON 41729328 41889371 42309395 42769393 43079356 43249277
43389085 43338912 43088858 42328852 41908884 41708959
41649094 41679239 41729328