Mesoscale Precipitation Discussion 0718
NWS Weather Prediction Center College Park MD
1040 PM EDT Wed Jul 16 2025

Areas affected...Southern Middle & Eastern TN...Far Western
VA...Ext Southeast KY...

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

Valid 170240Z - 170830Z

SUMMARY...Slow moving, short-term repeating cells capable of 2"/hr
and localized 2-3" totals pose potential localized flash flooding,
particularly in rugged terrain of the Cumberland Plateau and
portions of the Appalachians.

DISCUSSION...CIRA LPW & TPW fields show a narrow band of enhanced
deep layer moisture along the northern periphery of the larger
scale tropical upper-tropospheric trough (TUTT) connected to
tropical disturbance 93L.  A narrow strand of this enhanced
moisture is propagated through the 850-700mb layer where
retrograding easterly flow south of the Appalachians rapidly veers
from south to southwest stretching toward the mid-level westerly
flow across the Ohio Valley.  This provides total PWats of 1.9-2"
within confluent/convergent flow; while a weak/elongated sheared
shortwave feature can be seen across Western KY/northern Middle TN
sliding eastward along with oblique right entrance ascent along
the southern edge of the westerly flow providing weak but
sufficient outflow aloft to support a few updraft cycles to
convection.

Current RADAR and 10.3um EIR shows a few thunderstorms along the
northeast edge of the axis trying to back-build out of W VA into
NE TN; while area of best low level convergence is sprouting
cooling tops across Warren to Cumberland county, with a few cells
further south toward the central AL/TN border.  Further south,
deep layer steering will be near zero near the ridge axis; but
orientation of the moisture plume and the outflow regime may allow
for short-term training/repeating cells.  Gradient of higher
instability (2000+ J/kg MLCAPE) lies along the upwind edge in
Middle TN; so some confluence from the western side of the flow
should keep buoyancy sufficient for moisture flux and loading to
support up to  2"/hr rates; with training/repeating or stationary
motions further south, spotty totals could reach 2-3" in 1-2 hours
before exhausting instability and given hourly FFG values of
1.5-2" and 3hr in the 2-3" range (lower further northeast into
VA), incidents of widely scattered flash flooding are considered
possible over the next few hours.

Gallina

ATTN...WFO...HUN...JKL...MRX...OHX...RLX...RNK...

ATTN...RFC...ORN...TIR...NWC...

LAT...LON   37348095 36738108 35808333 35258490 34968609
            34868687 34958777 35568723 36098614 36788364
            37258212