756
AGUS74 KWCO 231506
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT SAT AUG 23 2025

.Synopsis...
Isolated flash, urban, and small stream flooding possible in the
Southeast... Localized flash and urban flooding expected across the
Southwest and the Intermountain West... Urban and small stream flooding
possible in Puerto Rico... Potential for flooding across the Central and
Southern Plains... Heavy rainfall forecast in Alaska...

.Southeast...
Isolated flash, urban, and small stream flooding is possible through early
day 2 (Sun) across portions of GA and SC, where slow-moving thunderstorms
are expected to produce 1 - 3" of rainfall, with isolated areas receiving
4" or more. These areas remain hydrologically sensitive due to rainfall
over the past several days. Given these conditions, even modest additional
rainfall could trigger renewed flood responses. This is supported by the
National Water Model Short-Range Forecast which is highlighting the
potential for rapid onset flooding across central and southern GA and
coastal SC. While widespread impacts are not expected, isolated flooding
could develop quickly where storms repeatedly track over the same areas.

.Southwest and the Intermountain West...
Daily monsoonal showers will continue into next week across the region,
with localized flash and urban flooding possible. While widespread flooding
is not expected, rapid rises on small streams in steep terrain and shallow
soils, as well as in arroyos, slot canyons, and normally dry washes, remain
possible where heavy rainfall occurs. Debris flows are also possible near
recently burned areas. The greatest potential for flash flooding today is
across portions of north-central AZ and the Sangre de Cristo Mountains in
CO.

.Puerto Rico...
Urban and small stream flooding, along with isolated flash flooding, is
possible today across the interior and northern parts of the island,
including the San Juan metro area, as a tropical wave (Invest 90L) passes
northeast of the island and brings periods of moderate to heavy rainfall.

.Central and Southern Plains...
A wet weather pattern bringing daily rounds of rainfall through the
forecast period will increase the potential for flooding impacts.
Confidence is low regarding which areas may see hydrologic responses due to
uncertainties in the placement and magnitude of the heaviest QPF each day.
However, models generally agree that 7-day rainfall totals of 2 - 5"
(locally up to 7") are possible from central CO into western AR. Antecedent
conditions remain very dry (less than 40% RSM, 10 - 40 cm, NASA SPoRT), and
streamflows are mostly near to much below historical normal (USGS), which
should help mitigate widespread responses and limit any flooding impacts to
urban and other flood-prone areas.

.Alaska...
Multiple rounds of heavy rain are forecast across western and interior AK
through early next week, with rainfall totals exceeding 3" across the
Middle Kuskokwim, Yukon, Koyukuk, and Kobuk river basins. While widespread
river flooding is not expected at this time, sharp rises are likely on
tributaries to these basins this weekend, with mainstem rivers responding
early next week. High snow levels may add runoff from glacier melt, and
additional rain later in the week could keep water levels elevated.

//Freeman



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