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AWUS01 KWNH 111811
FFGMPD
PAZ000-VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-120010-

Mesoscale Precipitation Discussion 0152
NWS Weather Prediction Center College Park MD
210 PM EDT Thu Apr 11 2024

Areas affected...Portions of the Upper OH Valley

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

Valid 111810Z - 120010Z

SUMMARY...Some expansion of shower and thunderstorm activity is
expected this afternoon through early this evening with pockets of
heavy rainfall rates. This coupled with moist antecedent
conditions may result in some instances of flash flooding.

DISCUSSION...GOES-E IR/WV imagery shows a strong mid-level trough
and an associated frontal zone currently crossing through the
Mid-South and taking aim on the OH Valley. Strong forcing
associated the energy aloft coupled with a gradually destabilizing
boundary layer out ahead it will set the stage for gradually
expanding areas of locally heavy showers and thunderstorms over
the next several hours.

Already the regional dual-pol radars show broken areas of shower
activity impacting large areas of the Upper OH Valley. Overall,
the instability profiles are rather modest though with MUCAPE
values of 500 to 1000 J/kg, with the greatest pooling of this seen
nosing up across central/eastern KY and western WV. However, over
the next few hours, some additional boundary layer destabilization
is expected which will drive an increase in convective coverage,
and the latest GOES-E visible satellite imagery does show some
areal breaks in the cloud cover facilitating an uptick in diurnal
heating.

Effective bulk shear values of locally 40 to 50 kts working in
tandem with the instability, and rather moist low-levels should
favor some relatively organized convective cells capable of
producing heavy rainfall rates. PWs across the broader OH Valley
region are on the order of 1.5 to 2 standard deviations above
normal, and the latest CIRA-ALPW data shows mid-level moisture
relatively concentrated over areas of eastern KY, central/eastern
OH and western WV which will tend to support somewhat greater
rainfall efficiency this afternoon. Rainfall rates across these
areas may reach as high as 1.5"/hour with the stronger cells and
this is supported by the consensus of the 12Z HREF guidance.

Some localized repeating/training of cells will be possible by
late afternoon as the convection attains greater levels of
organization, and with these heavier rates, some localized swaths
of additional rainfall reaching 2 to 3 inches will be possible.

The antecedent conditions are locally rather sensitive, with moist
soils and locally elevated streamflows. So, the additional
rainfall threat this afternoon may encourage some more notable
runoff concerns and potential for flash flooding.

Orrison

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

ATTN...WFO...CLE...ILN...JKL...LMK...MRX...OHX...PBZ...RLX...

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

LAT...LON   41858084 41727983 41197931 40787921 39927947
            39088009 38118110 36908234 36118301 35778361
            35768402 36148493 37178521 38638458 40068366
            41238235