209
AGUS74 KWCO 141500
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1000 AM CDT SAT JUN 14 2025

.Synopsis...
Ongoing river flooding and new flash flood potential for portions of East
Texas and Southern Louisiana... Flash flood potential continues this
weekend for the Southern Plains into the Lower Mississippi Valley and Mid
Atlantic... Potential increasing for flooding impacts by mid next week
across the Upper Midwest... Snowmelt-driven flooding potential across
Northern Alaska... Isolated flooding impacts across Puerto Rico through at
least mid next week...

.East Texas and Southern Louisiana...
Minor to isolated moderate and major river flooding is ongoing and forecast
into early next week from the San Antonio basin in south central TX to the
Sabine basin in northeast TX. The major river flooding is currently
confined to the Neches and Navasota rivers, with crests on both forecast to
occur this weekend.

Flash and small stream flooding are possible today along the upper TX Gulf
Coast into southwest Louisiana, including portions of the Houston
metropolitan area, due to isolated areas of 1 - 2"+ of rainfall expected.
This area has received 2 - 4"+ of rainfall over the past 72 hours (MRMS),
leaving soils saturated and the hydrologic environment primed for
additional/renewed flooding impacts.

.Southern Plains into the Lower Mississippi Valley...
Isolated flash flooding is possible today across southern KS, OK, AR,
western TN, and northwest MS due to convective rainfall. Portions of AR,
western TN, and northwest MS have received 2 - 4" of rainfall over the past
72 hours (MRMS), leaving them sensitive to additional/renewed flooding
impacts. Southern KS and OK has seen generally less than 1" of rain over
the past 72 hours, but rainfall rates are expected to be quite high today
and streamflows are still above normal, so flash and small stream flooding
will remain possible. The threat for flooding impacts will continue through
day 2 (Sun) as additional rounds of heavy rainfall are expected, especially
across central/eastern OK. The National Water Model (NWM) is showing
potential for isolated rapid onset flooding both day 1 (Sat) and day 2
(Sun) across the entire region, however widespread significant responses on
streams and smaller rivers are not likely at this time. New isolated minor
river flooding will be possible.

.Mid Atlantic...
Isolated flash flooding is possible through day 2 (Sun) due to multiple
rounds of convective rainfall this includes the National Capital Region.
Rainfall forecasts continue to indicate that the highest totals are
expected across eastern VA between Richmond and Norfolk, with 3 - 7"
possible by the end of the weekend. Intense rainfall rates with this event
will be the primary driver of any flooding impacts, especially over the
complex terrain in WV/western VA. Any small stream or higher magnitude
flooding impacts will be somewhat dependent on the location of the highest
rainfall amounts each day and whether any location or area sees repeated
heavy rainfall over the event. Isolated mainstem river flooding will be
possible by early next week, especially across eastern VA.

Further north across the I-80 corridor in central PA, small stream and
flash flooding is possible day 1 (Sat) as well, as a prolonged period of
moderate rainfall may set up across the region. The NWM short range
forecast is indicating increasing probabilities for small stream responses,
however, significant flows are very isolated and confined to headwaters,
even with reasonable QPF forcing from the HRRR, decreasing confidence in
any significant flooding impacts.

.Upper Midwest...
Multiple days of priming rainfall (1 - 2.5" cumulative totals through day 3
(Mon)) are expected across southern MN and northern IA ahead of a heavier
rainfall event on day 4 (Tue) into day 5 (Wed), where another 1 - 3" of
rainfall in a 24-hour period will increase the flooding potential across
the region. The potential extent of flooding impacts remains uncertain,
given that antecedent conditions are not particularly vulnerable and much
of the threat will be dependent on if the same basins see the consecutive
days of heavier rainfall leading up to the day 4 - 5 (Tue - Wed) period.
The NWM Medium Range Forecast (both the GFS and NBM forced) show potential
for rapid onset flooding, with peak flows in the mid-to-late week time
period. There are some indications for locally significant small stream
rises as well on smaller tributary rivers in southern MN/northern IA, but
any significant flooding potential remains uncertain at this time, and will
likely come into better clarity over the next couple of days as we see how
the priming rainfall plays out. Isolated mainstem river flooding is likely.

.Northern Alaska...
Flooding along North Slope rivers is possible through mid next week. An
above average late season snowpack combined with temperatures rising into
the 60s and 70s is expected to cause a rapid snowmelt. With ice intact on
larger rivers, such as the Sag and Colville, ice jams could result from the
snowmelt entering the rivers and lead to sudden rises and flooding. High
flows or flooding could lead to bank erosion that could threaten nearby
roads. River levels are likely to crest late this weekend into early next
week.

.Puerto Rico...
Urban and small stream flooding and isolated flash flooding is possible
through at least mid next week due to an expected increase in daily shower
and thunderstorm activity over northern and western portions of the island,
including the San Juan metro area.

//JEC

$$