372
AGUS74 KWCO 121457
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT SUN OCT 12 2025

.Synopsis...
Locally considerable flooding impacts are expected across the
Southwest...Coastal flooding continuing on the East Coast...Flash flooding
possible in American Samoa...Considerable to locally catastrophic coastal
flooding in Alaska...

.Southwest...
Multiple days of tropical moisture will continue to bring the potential for
locally considerable flash and urban flooding across southern AZ, southwest
NM, and southwest CO through Monday (day 2). Recent rainfall over the past
several days has helped to moisten soils, particularly top-soils across
north-central AZ and southwest CO however, regardless of antecedent
conditions, these storms will likely produce areas of heavy rainfall very
quickly, overwhelming available filtration capacities and leading to
subsequent flooding impacts. Given rainfall expected over the next couple
days, additional significant flooding impacts remains possible across areas
of southern AZ, southwestern NM, and southwest CO beginning today.
Furthermore, any heavy rainfall over recent burn scars, slot canyons, and
urban areas could trigger the potential for flash flooding and debris flows.

While Medium-Range Forecast (MRF) signals are limited, the HRRR-Forced
National Water Model (NWM) Short-Range Forecast (SRF) signals for
rapid-onset flooding (ROF), generally near 25-50%, to areas surrounding
Phoenix and Tucson, AZ. Given these NWM signals, out-of-bank rises will be
possible. Initially, the primary impacts are expected to be rapid rises on
small streams, along with urban and arroyo flooding, with isolated river
flooding possible.

.East Coast...
A low pressure system will continue to move up the coast bringing
potentially significant coastal flooding through Monday (day 2). Heavy
rainfall associated with the low pressure system may result in flash and
urban flooding, especially for coastal communities.

.American Samoa...
Flash flooding, along with landslides in areas of steep terrain, is
possible through tonight in response to locally heavy rainfall.

.Western Alaska Coast...
Considerable to locally catastrophic and life-threatening coastal flooding
is expected through early Tuesday (day 3).

//TMK





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