598
AWUS01 KWNH 260350
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-260900-

Mesoscale Precipitation Discussion 0499
NWS Weather Prediction Center College Park MD
1145 PM EDT Tue Jun 25 2024

Areas affected...Southeaset MO...Southern IL...Southwest
IND...Western KY...Far Northwest TN...

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

Valid 260345Z - 260900Z

SUMMARY...Slow moving convection with capability of 1.5-2"/hr and
spots of 2-4" as it slides eastward pose possible flash flooding.

DISCUSSION...GOES-E 10.3um and Regional RADAR mosaic depict a
cluster of cooling thunderstorms near the confluence of the Ohio
and Mississippi River.  The weak MCV across S IL is starting to
slide eastward into the western edge of the larger scale positive
tilt trough across the Ohio Valley.  This has reduced forward
progression to the south, though meso-high/cold-pool across SE MO
is sharpening the moisture convergence along the western upstream
edge to bring back some increased vigor to the cells over the last
hour or so.  Cell mergers are resulting in spots of 2"/hr+ before
reducing to a more average 1.5"/hr along the length of the line.

While the area is stabilizing slightly and the outflow boundary is
starting to push, the overall environment will remain weakly
supportive of convection with southerly flow continuing to support
some moisture flux up the MS and TN Valleys  with 2500-4000 J/kg
of available weakly capped MUCAPE.  850-700mb layer is starting to
veer and become more west to east, parallel to the convective bow
and supporting 15-20kts of steering to allow for training profile,
while having 20-25kts of LLJ entering the upstream edge for some
favorable back-building.  This should support a few hours of west
to east training.  To make matters even further favorable, the
complex is moving into a divergent 500-1000 thickness pattern
reducing propagation vectors to 0-5kts through W KY, and as the
cold pool weakens...southward propagation should diminish.  While
training and limited southerly inflow at cloud base and
stabilizing lower atmosphere likely will reduce convective
coverage with time...spots of 2-4" are still possible through the
middle of the night, next 3-4 hours.

While the area, has been relatively dry; there is a narrow axis of
average to slightly above average soil saturation across SE MO
into W KY where relative soil moisture ratios are above 50%, and
therefore FFG values are within reach locally with 3hr values of
2-3" to be potentially exceeded over the next 3-5hrs.  As such,
flash flooding is considered possible through 09z, slowly
expanding eastward into SW IND.

Gallina

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

ATTN...WFO...LMK...LSX...MEG...OHX...PAH...

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

LAT...LON   38378761 38178643 37198667 36678723 36248817
            36078901 36149010 36679102 37069089 37399058
            38148905