111
AWUS01 KWNH 240326
FFGMPD
KYZ000-INZ000-ILZ000-MOZ000-240924-

Mesoscale Precipitation Discussion 1046
NWS Weather Prediction Center College Park MD
1125 PM EDT Mon Sep 23 2024

Areas affected...southern Illinois, southern Indiana, northern
Kentucky

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

Valid 240324Z - 240924Z

Summary...A cluster of thunderstorms was intensifying over
southwestern Illinois and will move eastward across the discussion
area over the next 6 hours. Isolated instances of flash flooding
are possible with this activity.

Discussion...Recent radar/satellite imagery depicts expanding
convective coverage along an axis extending from near Mount
Vernon, IL southwestward through Cape Girardeau, MO.  These storms
were loosely organized, with a number of cell mergers across
south-central Illinois and a limited amount of training closer to
Cape Girardeau.  The storms were being forced by 1) a strong
mid-level wave just east of St. Louis and 2) sufficient
moisture/instability (~1000 J/kg MLCAPE and 1.7 inch PW values)
for strong updrafts and efficient rainfall.  Recent MRMS imagery
depicts a gradual increase in coverage of 1-1.5 inch/hr rainfall
rates that were beginning to approach one-hour FFG thresholds
across southern Illinois.

Models/objective guidance suggests that these trends will continue
with eastward extent toward southern Indiana and northern Kentucky
over the next 3-6 hours.  Storms should reach southwestern Indiana
and vicinity around 0530Z.  The loosely organized nature of the
storms (with occasional development but downstream and southwest
of the majority of ongoing convection) should continue to allow
for occasional cell mergers/training and spots of 1-2 inch/hr rain
rates at times.  These rates should fall on ground conditions
characterized by 1.5-2.5 inch/hr FFG thresholds, and the spotty
nature of the heavier rain rates suggest isolated flash flood
potential especially in low spots and urbanized areas.

Cook

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

ATTN...WFO...ILN...ILX...IND...LMK...LSX...PAH...

ATTN...RFC...LMRFC...NCRFC...OHRFC...NWC...

LAT...LON   39438581 39148495 38508490 37678540 37188737
            37198911 37748959 38648932 39208835