Mesoscale Precipitation Discussion 1064
NWS Weather Prediction Center College Park MD
1130 PM EDT Sat Aug 15 2026

Areas affected...Upper OH Valley...Central Appalachians

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

Valid 160330Z - 160930Z

SUMMARY...Developing and expanding clusters of heavy showers and
thunderstorms are expected tonight. Wet antecedent conditions and
high rainfall rates will foster areas of flash flooding. Some of
this may be significant and locally life-threatening.

DISCUSSION...The latest GOES-E IR satellite imagery shows a
well-defined MCV advancing slowly eastward across northwest OH
which is connected to the strong early-day MCS that impacted
upstream areas across the Midwest with heavy rainfall. This MCV is
in close proximity to a quasi-stationary front draped across the
Upper OH Valley and central Appalachians.

RAP data shows a rather substantial pooling of warm-sector
instability across the OH Valley with MUCAPE values locally as
high as 2000 to 3000 J/kg. A subtle increase in a west-southwest
low-level jet is expected overnight around the southern flank of
the MCV which will increase the moisture and instability transport
into the front and in an elevated fashion farther downstream.

This resulting isentropic ascent and forcing near the MCV itself
will foster the development and expansion of heavy showers and
thunderstorms overnight that will be capable of very high rainfall
rates. The PWs are 1.75 to 2.0 inches, and this coupled with the
instability will support rainfall rates capable of reaching 1.5 to
2.5 inches/hour.

Corridors of cell-training are likely by later tonight, and the
latest hires multi-model consensus supports as much as 3 to 5+
inches across portions central to southeast OH. Some of this heavy
rainfall is also expected to advance into northwest WV.

The antecedent conditions are very sensitive across the region
from heavy rainfall earlier in the week, and these additional
rains tonight will likely result in areas of flash flooding.
Significant and life-threatening impacts will be possible. This
will include a combination of urban flash flooding and also
terrain-driven impacts where rugged topography along the western
slopes of the central Appalachians will enhance runoff.

Orrison

ATTN...WFO...CLE...ILN...IWX...PBZ...RLX...

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

LAT...LON 41478292 41278111 40757993 39877948 38917976
38478046 38528127 38698185 39128272 39718339
40558428 41218402