Mesoscale Precipitation Discussion 0949
NWS Weather Prediction Center College Park MD
341 PM EDT Wed Aug 05 2026

Areas affected...portions of the upper OH Valley

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

Valid 051939Z - 060100Z

Summary...Slow moving thunderstorms will maintain a threat for
flash flooding into the evening across portions of the Upper OH
Valley over the next 3-6 hours. High rain rates on the sub-hourly
scale will likely result in peak rainfall totals of 2 to 3 inches
(locally higher) through about 00Z.

Discussion...1920Z radar imagery showed scattered thunderstorms
aligned in a SW to NE axis on the warm side of a diffuse
quasi-stationary front extending from central KY into a low over
southeastern OH, and northward along an inverted trough axis into
far western NY. The front was aligned with a slow moving mid to
upper-level shear axis on water vapor imagery with modest
divergence aloft within the right-entrance region of a 50-60 kt
upper level jet max extending northeastward from eastern OH. A
gradient existed in precipitable water values with 1.5 to 2.0
inches seen on blended TPW imagery and RAP analyses along and just
to the warm side of the front, falling back to about 0.75 inches
over northwestern OH.

low level flow was weak but aligned with the front and deeper
layer mean steering flow from the SW which is a favorable setup
for training. However, the lack of organization of cells due to
the weak shear has resulted in limited residence time for most
cells and outflow dominance. Still, the high moisture environment
has resulted in MRMS-derived rainfall of 0.5 to 1.25 inches in 15
minutes and hourly rainfall of 1 to 2 inches, locally in excess of
2 inches, from northern KY into southern and eastern OH. With slow
movement of synoptic scale forcing over the next 6 hours, cells
will likely continue to take advantage of the 1000-2000 J/kg
MLCAPE in place near and east of the front from KY into OH,
eventually reaching portions of western PA/WV into central WV
which tend to be more hydrologically sensitive to high rain rates.
High short term rates are expected to result in storm total
rainfall of 2 to 3+ inches on a localized basis which may result
in a few areas of flash flooding through 01Z.

Otto

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

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

LAT...LON   41678032 41487960 40137931 38528035 37588174
            37508317 37828439 38438459 39178371 40148206
            41108123