453
AWUS01 KWNH 300121
FFGMPD
MDZ000-VAZ000-WVZ000-OHZ000-KYZ000-300720-

Mesoscale Precipitation Discussion 0516
NWS Weather Prediction Center College Park MD
920 PM EDT Sat Jun 29 2024

Areas affected...Far Southern OH...Northeast KY...Much of WV

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

Valid 300120Z - 300720Z

SUMMARY...New bands of heavy showers and thunderstorms are
expected to develop this evening which may drive isolated to
widely scattered instances of flash flooding.

DISCUSSION...An anomalously moist and moderately unstable airmass
remains in place this evening across the Upper OH Valley and into
the central Appalachians. A couple of broken bands of convection
are currently noted over northeast KY, far southern OH and parts
of northern WV, and surface observations show much of the focus of
this along an elongated surface trough which is at least partially
a result of convective outflow from earlier convection.

MLCAPE values across areas of the region remains as high as 1500
to 2500 J/kg, and there continues to be a fair amount of shear
with the latest RAP analysis showing effective bulk shear values
of about 30 to 40 kts. This environment will be largely in place
through the remainder of the evening hours with a slow decrease in
boundary layer instability given the loss of solar insolation.

However, the arrival of a modest MCV which is currently situated
over southern OH along with some uptick in southwest low-level
flow ahead of a cold front approaching the Upper OH Valley is
expected to help generate some new bands of heavy shower and
thunderstorm activity later this evening and into a portion of the
overnight period.

The greatest instability pool coupled with placement of the
aforementioned surface trough would suggest areas of northeast KY
through central WV would tend to the primary corridor for renewed
convection going into the overnight hours.

PWs across the region remain anomalously high with values of 2.0
to 2.25 inches and with the CIRA-ALPW data confirming a deep
entrenchment of this moisture through the vertical column.
Rainfall rates with the additional storms may reach 2 inches/hour,
and some localized repeating of storms over the same area may
result in some rainfall amounts locally going through 06Z of 3 to
4 inches.

Given the heavier rainfall rates, and locally rugged terrain of
the central Appalachians, there may be some isolated to widely
scattered instances of flash flooding.

Orrison

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

ATTN...WFO...ILN...JKL...LMK...LWX...PBZ...RLX...RNK...

ATTN...RFC...MARFC...OHRFC...NWC...

LAT...LON   39628051 39397931 38547942 37588102 37328274
            37508403 38148444 38808393 39458233