AGUS74 KWCO 162310
AHDNWC

Area Hydrological Discussion #087 - EXPERIMENTAL
NWS National Water Center - Tuscaloosa, AL
600 PM CDT Fri May 16 2025

POTENTIAL IMPACTS: Isolated flash, urban, and small stream flooding
WHERE: Portions of Tennessee, Kentucky, Indiana, and West Virginia
WHEN: Through tonight

FORECAST RAINFALL AND ANTECEDENT CONDITIONS... 
QPF: 1 - 3", locally higher (HRRR)
QPE: 1 - 2.5" (MRMS) 
Rain Rates: 1 - 2"/hr (HRRR)
Soil Moisture: 50 - 80% (0 - 100 cm RSM, NASA SPoRT)
Streamflows: Normal to above normal (USGS)

DISCUSSION...
Progressive, heavy rainfall throughout tonight may cause isolated
flash, urban, and small stream flooding across the area of concern,
some of which may be locally significant. Priming rainfall early
today has wetted top soils while also elevating base flows of streams
and creeks. High rainfall rates and terrain enhancement are the
primary drivers for the flood threat. Some isolated significant
flooding is possible if training rainfall were to align with the
basin orientation. Fortunately, the progressive nature of the
rainfall will generally help to mitigate the extent and severity of
flooding impacts that may materialize.

The NWM SRF has consistently signaled rapid-onset flooding
probabilities of 26% - 75% across the area of concern. The Maximum
High Flow Magnitude forecast is suggesting 50 - 20% annual exceedance
probabilities (AEPs) with some isolated low AEPs (10% and less) on
the smaller order streams and tributaries. Peak flow arrival time
indicates the timing of stream flows will peak within the next 8 - 10
hours. While widespread flooding is unlikely, these factors would
suggest isolated flooding will be a concern overnight.

GRAPHICAL REPRESENTATION weather.gov/owp/operations-ahd

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

//JAC

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