437
AWUS01 KWNH 211331
FFGMPD
WIZ000-ILZ000-MNZ000-IAZ000-211800-

Mesoscale Precipitation Discussion 0297
NWS Weather Prediction Center College Park MD
930 AM EDT Tue May 21 2024

Areas affected...Upper Mississippi River Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 211330Z - 211800Z

SUMMARY...Lines of robust thunderstorm activity will track over
areas that received heavy rainfall overnight and earlier this
morning. Flash flooding is possible in areas sporting more
saturated soils or where rainfall rates up to 1.5"/hr occur.

DISCUSSION...GOES-16 IR imagery shows clusters of thunderstorms
tracking E-NE to the north of a stationary front draped W-E over
the Midwest. Storms are taking advantage of lingering MUCAPE over
central IA that is >1,000 J/kg. Not only is the instability in
place, but RAP mesoanalysis shows as much as 50-60kts of effective
bulk shear in central IA helping to sustain these thunderstorms
for longer periods of time. As the upper trough in the Central
Plains amplifies, mean steering flow will direct the line of
storms in central IA more to the northeast where some locations in
northeast IA and southwest WI received over 1" of rainfall this
morning. MUCAPE is being exhausted in these areas this morning but
with healthy synoptic-scale ascent aloft and the LLJ/strengthening
IVT still intersecting the stationary front, expect heavy rainfall
rates as high as 1.5"/hr within these storm to linger through the
late morning hours. Flash flooding remains possible with northeast
IA and southwest WI most at risk.

Mullinax

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ARX...DMX...DVN...MKX...

ATTN...RFC...NCRFC...NWC...

LAT...LON   44139126 44078994 43208963 42259051 41609171
            41349350 41759403 42869380 43619273