439
AGUS74 KWCO 101522
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT FRI OCT 10 2025

.Synopsis...
Significant flooding impacts are expected across the Southwest...Coastal
flooding possible in the Southeast and Mid-Atlantic Coast...Urban and small
stream flooding possible in Puerto Rico and the USVI...Ongoing coastal
flooding in Alaska...

.Southwest...
Multiple days of tropical moisture will bring the potential for significant
flash flooding across north-central AZ, especially the Mogollon Rim, and
portions of UT through tonight with flash and urban flooding continuing
elsewhere, mainly across the entire Southwest and Four Corners region,
through early next week. While much rainfall today is limited to AZ,
moderate to locally heavy rainfall will continue south and eastward across
the Mogollon Rim eventually into portions of southeastern NM. Although most
top-soils in the region are dry, areas in northern NM and central AZ are
becoming wet (NASA SPoRT) given rainfall over the past 24 hours. Given the
widespread and long duration of the rainfall expected over the next several
days, additional significant flooding impacts are becoming increasingly
possible across areas of southeastern AZ and southwestern NM beginning late
in the weekend. Furthermore, any heavy rainfall over recent burn scars,
slot canyons and urban areas could trigger the potential for flash flooding
and debris flows.

While there has been a slight downward trend in the QPF from the GFS, the
National Water Model (NWM) Medium Range Forecast (MRF) continues to signal
rapid onset flooding (ROF) in areas of southeastern AZ with associated
annual exceedance probabilities at 50%, suggesting out-of-bank rises are
possible. Initially, the primary impacts are expected to be rapid rises on
small streams, along with urban and arroyo flooding. There is still
forecast uncertainty late into the weekend, however, as the event
continues, confidence is increasing that locally significant impacts may be
possible.

.Southeast and Mid-Atlantic Coast...
Heavy rain is possible as a low continues to move up the east coast,
bringing the potential of significant coastal flooding through the weekend
into early next week. This could result in flash and urban flooding within
coastal communities across the region.

.Puerto Rico and the US Virgin Islands...
Urban and small stream flooding is possible through Saturday (Day 2) in
response to heavy tropical rainfall.

.Alaska...
A coastal flood event is ongoing across portions of western Alaska bringing
high winds, locally heavy rainfall, and storm surge. This event will
continue through today. Additional coastal flooding will be possible late
this weekend into next week.

//TMK





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