078
AGUS74 KWCO 191530
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT SAT APR 19 2025

.Synopsis...
Heavy rainfall across the Southern Plains into the Mississippi and Ohio
Valleys... Urban and small stream flooding possible in Puerto Rico... River
flooding continues in the Lower Ohio and Mississippi Valleys...

.Discussion...

.Southern Plains into the Mississippi and Ohio Valleys...
Heavy rainfall through day 2 (Sun) with totals of 1 - 4", locally higher,
(WPC QPF) may lead to flash, urban, small stream and river flooding from
northeast TX through OK and MO to the Ohio Valley. The highest chance of
strong thunderstorms and heavy rain are for today as locally considerable
flash and urban flooding is possible. Currently, top-layer soils are
starting to wetten from OK through AR to MO (55 - 70%, NASA SPoRT) and
streamflows are generally running normal to above normal (USGS) suggesting
there is infiltration capacity available, at least initially. This system
could bring a chance of encroachment upon previously impacted rivers which
are still elevated or in flood. Isolated minor to moderate river flooding
is possible with this system (MMEFS).

The National Water Model (NWM) Short-Range Forecast (SRF) is signaling for
rapid-onset probabilities generally between 25 - 50% with localized
probabilities greater than 50%, specifically in areas of southwest IN.
Associated annual exceedance probabilities are near 50% suggesting that
most rivers will stay within their channel however, local flooding impacts
are possible.

Finally, on days 4 - 7 (Tue - Fri) there will be a renewed round of
precipitation in areas of TX, OK, and the Lower Mississippi Valley but
uncertainty remains as to the magnitude and areal coverage of impacts.

.Puerto Rico...
Heavy rainfall bringing the potential for urban and small stream flooding
continues through day 2 (Sun). There is also a chance for isolated
mudslides in areas of steep terrain.

.Lower Ohio and Mississippi Valleys...
Minor, moderate, and major river flooding continues in the Lower Ohio
Valley to Lower Mississippi Valley Basins as a result of the recent
historic rainfall. While most of the rivers and their tributaries have
reached crest, lower portions of the Mississippi River are forecast to
remain in flood stage through at least next week due to water routing
downstream.

Another system, bringing the potential for heavy rainfall and renewed river
rises in portions of the same area, arrives today through day 2 (Sun).
Overall, impacts are ongoing and these regions remain vulnerable to any new
rainfall.

//Kirkpatrick



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