Mesoscale Precipitation Discussion 0738
NWS Weather Prediction Center College Park MD
940 PM EDT Thu Jul 17 2025

Areas affected...Eastern KY...Eastern TN...Southern WV...Western
VA...Far Western NC...

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

Valid 180140Z - 180730Z

SUMMARY...Slow moving thunderstorms capable of 2"/hr rates and
widely scattered 2-3" totals in or in proximity to rugged/steep
terrain likely resulting in continued incident(s) of localized
flash flooding.

DISCUSSION...Very warm, moist and unstable environment remains
across the much of KY/TN into the central and southern
Appalachians.  RAP analysis shows much of the Appalachians is
starting to become a bit more stablized; however, there is
sufficient forcing from prior outflow boundaries and weak
southwesterly upslope flow for a few cooling/expanding
thunderstorms along the ridges from far S WV across SW VA into the
Smoky Mountains of NC/E TN.   Deep layer moisture with low 70s Tds
even though the Cumberland Plateau and solid moisture from
850-500mb per 00z RAOBs and CIRA LPW support 90th and above
percentile of deep layer moisture with PW values of 1.75" in the
peaks of the terrain to near 2" in the lower elevations of central
KY/TN.  Given 1000-2000 J/kg of MLCAPE and the moisture, cells
will be capable of 2"/hr rates.  

Deep layer steering is generally weak but west to east under
fairly zonal flow well south of the stronger jet core over the
Great Lakes.  Proximity to broad right entrance ascent may further
support cells along the edge across N KY into WV, but overall mean
cell motions will be weak at 5-10kts and driven mostly by
propagation off cold pools/outflow.  However, with low level
inflow and being on the northeast edge of a 500-1000mb thickness
ridge and ample upstream unstable, weakly or uncapped air;
additional back-building/propagation upwind into the instability
pool is possible across central KY/Middle TN, and may result in
effective zero cell motions.  As such, widely scattered incidents
of 2-3" are possible across the area of concern, though best
clustering/potential remains in the northern Cumberland Plateau of
E KY and NE TN through the early to middle overnight period.  
Given lower FFG values in/near terrain it is likely to have
additional incidents of highly focused flash flooding for the next
few hours, slowly diminishing deeper into the night.

Gallina

ATTN...WFO...GSP...JKL...LMK...MRX...OHX...RLX...RNK...

ATTN...RFC...ALR...ORN...RHA...TIR...NWC...

LAT...LON   38418162 38248043 37628010 36678090 35628245
            35048374 35488461 35648659 36138672 37128596
            38198546 38218327