697
AGUS74 KWCO 051505
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT THU JUN 5 2025

.Synopsis...
Widespread flooding, including considerable flash and river flooding,
remains possible across the Central and Southern Plains into the Ozarks...
Isolated flash and river flooding possible in the Lower Mississippi Valley
into the Southeast... Isolated flash and small stream flooding in the
Northeast and the Lower Ohio Valley into Missouri...

.Central and Southern Plains into the Ozarks...
The threat for considerable flash and urban flooding continues this week as
rounds of locally heavy rainfall return tonight and continue through the
weekend across portions of north TX and OK. The same pattern will continue
to bring the threat of flash and urban flooding elsewhere across much of
the Southern Plains as the heavy rainfall continues through the weekend and
then shifts southward into TX early next week. Rainfall totals of 3 - 5"
(WPC) are expected over the next 7 days across a larger portion of
southeast OK and generally 2 - 3" elsewhere across OK and much of TX. Some
areas could see locally higher amounts given the convective nature of the
system. Recent widespread rainfall of 2 - 3" has left portions of east and
north TX, eastern OK, and southeastern KS well on the saturated side.
Relative soil moisture is generally over 50% with many areas greater than
65% (NASA SPoRT), suggesting that any remaining infiltration capacity will
quickly be overwhelmed and result in rapid runoff. USGS stream gages tell a
similar story with the majority of the gages reporting streamflows greater
than the 95th percentile for historical flows indicating minimal available
channel capacity. This suggests that it will take less runoff to reach
out-of-bank flows.

The models tend to vary with the overall placement of the initial rounds of
QPF over the weekend, the GFS-forced National Water Model (NWM) Medium
Range Forecast (MRF) continues to suggest the greater streamflow responses
across the MO/AR Ozarks. Conversely the NBM-forced NWM MRF suggests
responses across north TX and Oklahoma. Despite the differences, both
models suggest isolated but significant responses generally on smaller
streams and rivers.

Looking ahead into the extended range, the models tend to come into better
agreement as the system drops down into TX bringing rainfall to much of the
State. Both NWM MRF models suggest stream and river responses mid next week
across north TX; however some uncertainty remains given that the signals
are in the extended range. Nevertheless, much of the Southern Plains will
need to be monitored closely in the coming days.
Considerable river flooding continues across the Lower Middle Arkansas,
Upper Neosho, and Upper Osage basins in KS after recent heavy rainfall.
Most rivers will continue to crest over the next few days. Much of the
heaviest forecast QPF is expected to fall south in OK; however, extreme
southern KS could still receive 1 - 2" of rainfall over the weekend which
could prolong elevated flows across the area.

.Lower Mississippi Valley into the Southeast...
Isolated flash flooding and river flooding may be possible for portions of
LA, MS, and AL on days 4 - 5 (Sun - Mon). Recent rainfall has left
upper-layer soils across the region wet but not saturated, allowing for
better absorption of additional rainfall into the system and reducing the
overall flood threat. However, multiple days of rain, as well as periods of
higher rainfall rates, could still lead to some flooding impacts.

.Northeast...
Isolated flash and small stream flooding will be possible across the
Adirondacks, Green, and White Mountains Friday and Saturday due to locally
heavy rainfall. Soil moisture is near normal; however many streams are
running on the higher side suggesting some vulnerability to out-bank flows
on smaller streams if heavy or repeating rounds of rainfall were to
materialize. Impacts are likely to be isolated; however, with forecast QPF
and elevated streamflows, the region bears watching.

.Lower Ohio Valley into Missouri...
Potential for isolated flash and small stream flooding exists over parts of
the lower Ohio Valley/Missouri through tomorrow. Rainfall totals of 1 - 4"
have fallen in the last 24 hours already, and an additional 1 - 3"+ is
expected. Antecedent conditions were near normal prior to this current
round of rainfall, but no doubt the area will be more hydrologically
sensitive leading into the next round. Signals from both the SRF and MRF
NWM are muted, but as the additional precipitation comes into range of the
SRF signals will likely increase.


//Smith



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