511
AGUS74 KWCO 091500
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT THU OCT 9 2025

.Synopsis...
Significant flooding impacts are expected across the Southwest...Coastal
flooding is expected in the Southeast and Mid-Atlantic Coast...Urban and
small stream flooding possible in Puerto Rico and the USVI...Flash flood
threat in American Samoa...Ongoing coastal flooding and rain on snow in
Alaska...

.Southwest...
Multiple days of tropical moisture will bring the potential of flooding to
the region through early next week with the heaviest rainfall expected
Friday into Saturday (days 2-3). While most top-soils in the region are
dry, areas in northern NM and southeastern AZ are starting to become wet
(NASA SPoRT). Moderate to locally heavy rainfall will start in northern AZ
and will continue south and eastward into portions of NM. Locally
significant flooding is expected in areas surrounding Flagstaff and
Phoenix, AZ, increasing the potential for flooding within the region.
Furthermore, any heavy rainfall over recent burn scars, slot canyons and
urban areas could trigger the potential for flash flooding and debris flows.

The National Water Model (NWM) Medium Range Forecast (MRF) continues to
signal rapid onset flooding (ROF) generally near 25-50% in areas of
southeastern AZ with associated annual exceedance probabilities below 10%,
suggesting a higher potential of small stream flooding by late this
weekend. Initially, the primary impacts are expected to be rapid rises on
small streams, along with urban and arroyo flooding. However, as the event
continues, confidence is increasing that significant impacts may be
possible, including the potential for isolated river flooding over the
weekend.

.Southeast and Mid-Atlantic Coast...
A low will move up the east coast, bringing the potential of significant
coastal flooding through the weekend. Additionally, as the low moves up the
coast, it will bring the potential for moderate to locally heavy rainfall.
This could result in flash and urban flooding within coastal communities in
the region.

.Puerto Rico and the US Virgin Islands...
Urban and small stream flooding is possible Friday through the weekend as
Tropical Storm Jerry passes northeast of the islands.

.American Samoa...
Isolated flash flooding with associated landslides possible through today.

.Alaska...
A coastal flood event is ongoing across portions of western Alaska bringing
high winds, locally heavy rainfall, and storm surge. This event is expected
to last through today.

//TMK





$$