503
AWUS01 KWNH 180210
FFGMPD
PAZ000-WVZ000-OHZ000-INZ000-180800-

Mesoscale Precipitation Discussion 0739
NWS Weather Prediction Center College Park MD
1010 PM EDT Thu Jul 17 2025

Areas affected...Central IND...Central OH...Southwest
PA...Stovepipe of WV.

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

Valid 180210Z - 180800Z

SUMMARY...Narrow axis of training thunderstorms along well defined
surface front.  Scattered nature may limit overall overall
coverage to spotty 2-3" totals.  Additional incidents of flash
flooding remain possible through the early overnight period.

DISCUSSION...02z surface analysis shows a well defined flat
stationary front, generally parallel and positional to I-70 from a
weak shortwave feature/surface low near Terre Haute, IND through
past Wheeling, WV.   Separation of low 60s to mid-70s Tds is the
delimiting factor and with plenty of heating today across both
sides and active thunderstorm activity south of the boundary
mixing out the unstable environment across S OH/N KY, the
remaining pool of unstable 1000-1500 J/kg of MLCAPE defines the
boundary of potential stronger thunderstorms overnight.

Deep layer (boundary layer to jet) is nearly perfectly
unidirectional and parallel to the boundary supporting a training
profile; however, the lack of convergence at any level beside the
surface to boundary layer is limiting convective activity,
especially as winds are weak.  Still, dotted along the front are
some 5-10kt winds that are convergent (as noted between Columbus
and Zanesville, OH).  Thunderstorms will be efficient and fairly
slow moving to support 1.75-2"/hr rates and localized totals of
2-3" in 1-2 hours before exhausting the local instability pool.
There may be some increased duration in proximity to the mid-level
shortwave entering IND, but activity has help to stabilize the
near and downstream environment to reduce this potential in the
short-term; though may become more relevant toward the
mid-overnight period, but this evolution is lower confidence at
this time, and similar spotty 2-3" totals are more likely even
across east-central IND through 08z.

Gallina

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

ATTN...WFO...ILN...IND...PBZ...RLX...

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

LAT...LON   40348103 40318041 40177998 39837988 39478020
            39368121 39298222 39238357 39218497 39208614
            39528650 40008602 40208423 40198238