AGUS74 KWCO 151845
AHDNWC

Area Hydrological Discussion #044 - EXPERIMENTAL
NWS National Water Center - Tuscaloosa, AL
139 PM CDT Wed Apr 15 2026

POTENTIAL IMPACTS: Flash, urban, and small stream flooding likely
WHERE: Central Illinois, northern Indiana, southern Michigan, and
far-northwestern Ohio
WHEN: This evening through early tomorrow morning

FORECAST RAINFALL AND ANTECEDENT CONDITIONS?
QPF: 1 - 2", locally higher (HRRR)
Rain Rates: 1 - 1.5"/hr (HRRR)
Relative Soil Moisture: 45 - 75% (0 - 10cm; NASA SPoRT)

DISCUSSION...
Heavy rainfall is forecast this evening through early tomorrow and
will likely cause flash and urban flooding concerns along with new
and renewed rises on small streams and rivers. Isolated pockets of
heavy rainfall rates related to training thunderstorms are possible
over areas that have already received 1 - 3" of rainfall over the
past 48 hours (MRMS). While there is some room for mitigation in the
top soils it will likely not take too long to bring these soils to
saturation elevating the risk for rapid runoff. These factors
combined with elevated streams during the night can cause dangerous
flooding conditions with limited visibility. Additionally, river
flooding of minor to isolated moderate flooding is ongoing or
forecast, so basins are already susceptible to additional input.

The HRRR-forced NWM has continued to signal the possibility of
rapid-onset flooding across the area of concern. Peak flow arrival
time is also suggesting flows will begin their peak within the next 7
- 14 hours which is in line with the pulses of rainfall the HRRR has
been signaling. The consistency in the model guidance leaves a bit
more to be desired to have high confidence in the overall placement
and magnitude of response. As such a slight buffer to the selection
was used to encompass some of the variance of the extent.

GRAPHICAL REPRESENTATION: weather.gov/owp/operations-ahd

Additional National Water Center products are available at:
weather.gov/owp/operations

//JAC

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