AGUS74 KWCO 141807
AHDNWC

Area Hydrological Discussion #041 - EXPERIMENTAL
NWS National Water Center - Tuscaloosa, AL
1238 PM CDT Tue Apr 14 2026

POTENTIAL IMPACTS: Flash, urban, and small stream flooding likely
WHERE: Northeastern IA into southern WI
WHEN: Beginning late afternoon, continuing through the evening hours

FORECAST RAINFALL AND ANTECEDENT CONDITIONS?
QPF: 1 - 2", locally higher (HRRR/NAM/RRFS)
Rain Rates: 1 - 2"/hr (HRRR)
Relative Soil Moisture: Wet to Saturated (NASA SPoRT)

DISCUSSION:
Convection is expected to develop across northeastern IA
mid-afternoon and progress east over the course of the evening,
bringing the potential for robust rainfall rates and flash, urban,
and small stream flooding impacts, some of which may be locally
significant. Rainfall totals of 2 - 6" (locally higher) over the past
week have sufficiently moistened top soils, greatly diminishing any
infiltration processes. Additional rainfall tonight will immediately
runoff into already swollen streams, rivers, and urban drainages,
generating flooding. Significant flooding is also possible given the
combination of wet soils, backbuilding/training convection, and
intense rainfall rates in the heaviest storms, especially over
southern WI where soils are completely saturated. Rapid stream rises
and renewed small stream flooding is also possible in areas of
heavier rainfall. This rainfall may exacerbate ongoing river flooding
across the area of concern.

The HRRR-forced National Water Model has been consistent in
indicating the potential for small stream responses across the area
of concern, with peak flows expected late this evening. Corresponding
annual exceedance probabilities are most significant over
central/southern WI (AEPs of 20% and lower), where antecedent
conditions are more vulnerable to heavy rainfall/flooding impacts.
Given these factors, flash, urban, and small stream flooding impacts
are likely, with locally significant impacts possible in areas where
backbuilding/training convection materializes.

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

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

//JDP

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