325
AWUS01 KWNH 160047
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-160646-

Mesoscale Precipitation Discussion 0883
NWS Weather Prediction Center College Park MD
847 PM EDT Thu Aug 15 2024

Areas affected...Southern MO..OH River Valley

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

Valid 160046Z - 160646Z

Summary...Convective clusters are developing across portions of
southern Missouri and the Ohio River Valley. Periodic cell
training with rainfall rates of 2-2.5"/hr could lead to a few
instances of flash flooding tonight as additional storms form.

Discussion...Satellite and radar mosiac across the northern
fringes of the Ozarks and Ohio River Valley highlight expanding
thunderstorm coverage on the periphery of a shortwave to the north
in the Missouri Valley. Recently, a thunderstorm cluster was
exhibiting signs of reduced forward motion and cell training over
southern Illinois, leading to elevated CREST Streamflows of
100-200 cfs/smi.

Throughout the afternoon, a lack of robust forcing has kept the
area dry. The recent uptick in thunderstorm coverage can likely be
attributed to the approach of the shortwave working in tandem with
several weak convergence zones. Owing to strong surface heating
and moisture advection today, mesoanalysis estimates show 3000
J/kg MLCAPE, negligible CIN, and 2-2.1" PWATs in the vicinity of
these cells to foster new development with rainfall rates upwards
of 2-2.5"/hr. As new updrafts form along a west-east axis over the
next several hours, 20-25 kts of westerly effective shear parallel
to the convection is expected to support periods of training
clusters.

There is some disagreement within the 18z CAM suite as to where
the main axis of training sets up tonight, which will likely
depend on cold pool evolution as additional storms form. Even with
lingering uncertainty regarding the placement of the heaviest
rainfall, there is a general consensus for 2-4" rainfall totals
through 6z tonight in the highlighted area, leading to a 25-30%
chance of 6 HR QPF exceeding the 10 year ARI. While southern
Illinois and western Kentucky have been quite dry, portions of
south-central Missouri are comparatively more saturated (relative
soil moisture around 60-65%) and may be more susceptible to runoff
issues.

Asherman

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

ATTN...WFO...LSX...LZK...MEG...OHX...PAH...SGF...

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

LAT...LON   38458970 38158776 36838748 36328885 36399153
            36909338 37889353 38339243