Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
858 PM EDT Fri Aug 14 2026
Day 2
Valid 12Z Sat Aug 15 2026 - 12Z Sun Aug 16 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
CENTRAL OHIO AND INTO EASTERN INDIANA...

...Midwest and Ohio Valley...

A Moderate Risk has been introduced in the update Day 2 outlook
across portions of east-central Indiana into central Ohio, between
Fort Wayne and Zanesville. The latest 12Z CAM guidance suite has
impressive QPF totals on the order of 2 to 4+ inches, with the
RRFS, ARW, and ARW2 more widespread with these higher totals, and
the HRRR generally has a narrower axis. In addition, the HREF 3
hour flash flood guidance exceedance probabilities are impressive
at nearly 60% for this region during the 00Z-09Z time period
Sunday, and low end probs for 100-year ARI. There is still some
latitudinal differences in the main QPF axis, but given the
severely saturated ground conditions across this region from
antecedent rainfall over the past few days, there is now enough
confidence for the Moderate Risk area.

A Slight risk extends from northern Illinois eastward into West
Virginia. A favorable environment for convective training will
persist along the northern periphery of the broad upper ridge and
near a lingering surface frontal zone. At 12z Sat, an MCS will
likely be ongoing, with additional afternoon and overnight
redevelopment expected along this corridor. PW values around 2.2"
and CAPE exceeding 2000 J/kg will readily support intense rainfall
rates. This axis may overlap areas heavily impacted by flash
flooding on prior days, where saturated soil conditions will
heighten hydrologic sensitivity.

...Central Plains to the Northern Rockies...

A Slight risk is maintained from eastern CO into western KS and
southwest NE. The overall synoptic setup will resemble previous
days, with shortwave forcing riding the periphery of the ridge and
interacting with a moist, unstable airmass. While model spread
remains regarding the exact location of the heaviest QPF footprint,
good spatial overlap exists among the 00z RRFS, Gem Reg and AIGFS.
The Slight risk was shifted a bit south to reflect this consensus.

For the 20Z Update, the Slight Risk was extended a little eastward
across northern Kansas given 12Z CAM guidance trends. The Marginal
Risk was also extended back across northern Wyoming into northeast
Idaho and western Montana where some isolated but potentially
heavy showers and storms could develop during the afternoon and
evening hours.

Chenard/Hamrick


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt