241
AWUS01 KWNH 051132
FFGMPD
VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-051730-

Mesoscale Precipitation Discussion 0127
NWS Weather Prediction Center College Park MD
731 AM EDT Sat Apr 05 2025

Areas affected...Portions of the OH Valley

Concerning...Heavy rainfall...Flash flooding likely

Valid 051130Z - 051730Z

SUMMARY...Additional rounds of heavy showers and thunderstorms
moving into the OH Valley this morning over extremely
sensitive/saturated and locally flooded ground will further
enhance runoff concerns and flooding this morning.

DISCUSSION...Radar imagery shows a couple of bands of heavy
showers and thunderstorms advancing east across areas of western
KY and also western TN, with an axis of weaker and more fragmented
convection downstream across central and eastern KY which is
starting to move into parts of southwest WV.

The surface analysis shows a well-defined outflow boundary/front
across the region with a persistent southwest low-level jet of 30
to 40 kts overrunning this boundary and facilitating sustainable
isentropic ascent and transport of moisture and instability over
it. However, the best nose of instability with MUCAPE values of
500 to 1000 J/kg is situated over western TN and this is likely
going to be the area that sees some of the more organized
convection persisting through the morning hours.

One complicating factor to the forecast for rainfall this morning
though is the fact that there is some evidence of an MCV advancing
east across western KY, and this vort energy may continue to
interact with the low-level jet and outflow boundary in a manner
that may help to sustain the convective threat for a few more
hours downstream into areas of central and eastern KY. The
rainfall rates with this will likely be on the order of 1 to 1.5
inches/hour at most with the strongest cells, but the fact that
these additional rains will be falling over areas that are either
already flooded, or have at least very sensitive/saturated soil
conditions, suggests that additional areal flooding and flash
flooding concerns will occur over these areas.

The bigger and more significant concerns for high-end flash
flooding and life-threatening impacts this morning though will be
back across western TN and will be connected to upstream heavy
rainfall/flash flooding concerns evolving back into
central/eastern AR where there is a growing threat of significant
cell-training. Recent runs of the HRRR guidance suggest heavy
training rainfall over central and eastern AR will impact western
TN. Very high rainfall rates here of 2+ inches/hour will be
possible, with additional rains locally of 2 to 4+ inches by
midday over western TN. The additional downstream rains over KY
should tend to be more into 1 to 2 inch range.

Expect areal flooding and flash flooding to continue with locally
significant and life-threatening impacts as these additional rains
arrive over the next several hours.

Orrison

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

ATTN...WFO...ILN...JKL...LMK...MEG...MRX...OHX...PAH...RLX...

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

LAT...LON   38918449 38828204 37438196 36308489 35478827
            35838980 37088921 38048747