875
AGUS74 KWCO 171517
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT TUE JUN 17 2025

.Synopsis...
Locally considerable flash and small stream flooding possible in Central
Plains and Mid-Mississippi Valley...Small stream and flash flood potential
for the Ohio River Valley and Central Appalachians...Ongoing river flooding
in East Texas...Snowmelt runoff concerns across Northern Alaska...

.Central Plains and Mid-Mississippi Valley...
Heavy rainfall (2 - 5"+, WPC) is expected across central KS through day 2
(Wed) and brings the potential for locally considerable flash and small
stream flooding with surrounding areas having the potential for isolated
flooding impacts. While antecedent conditions arent particularly conducive
for rapid runoff in portions of the northern half of KS, the southern
portion of KS into OK and southern MO is primed and wet (50 - 70%, 0 - 10
cm, NASA SPoRT). Streamflows in primed areas are much above normal (USGS)
and any repeated, heavy rainfall and training of storms, combined with
intense hourly rainfall rates, will be the primary drivers for flooding
impacts.

The NWM is presenting a very consistent, and locally significant, small
stream response across south-central KS, south of I-70 and in the vicinity
of I-35/135. The NWM is also suggesting over 90% of streams in many basins
across the aforementioned region will meet the ROF criteria, and
probabilities for ROF are rising into the 50 - 75%+ range with associated
AEPs of 4 - 10%. The combination of all of these signals suggests a fairly
rare response from the NWM in this region, and indicates potential for
considerable flooding impacts today. Peak flows are expected to begin late
this morning on smaller headwaters, and continue onto larger streams
through the afternoon and evening hours.

.Ohio River Valley and Central Appalachians...
Flash and small stream flooding impacts are likely through day 2 (Wed),
especially across the saturated region of southwest PA into northern WV,
due to multiple rounds of heavy rainfall falling in basins that have
already seen totals of 1 - 3" over the last 72 hours (MRMS). Streamflows
are elevated and saturated soils from past rainfall exist from KY to WV
into PA with top-soils ranging from 65 - 80% saturation.

The National Water Model (NWM) Short-Range Forecast (SRF) rapid-onset
flooding probabilities (ROF) are near 25 - 50% across PA, WV, OH and KY
with associated annual exceedance probabilities (AEPs) near 50%. This
supports the potential for locally significant flooding however, it also
suggests that most streams will likely stay within their banks.

.East Texas...
Minor and moderate river flooding is ongoing across the area, and major
flooding is ongoing in the Neches basin. Recent rainfall has caused renewed
rises on some rivers delaying the recession of floodwaters. Most rivers
will be in recession by the end of the week.

.Northern Alaska...
Rapid snowmelt and ice jams have caused flooding in rivers and streams
draining the Brooks Range across the North Slope, with conditions expected
to continue through day 2 (Wed). With ice intact on larger rivers, 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 and impact access to airstrips and low lying
infrastructure. River levels are likely to crest through early to mid week.

//TMK




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