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AGUS74 KWCO 141159
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
700 AM CDT TUE APR 14 2026

.Updates...
For the Upper Great Lakes into the Middle Mississippi Valley, the
"Considerable" selection was extended slightly further south in Wisconsin
to cover Madison to Milwaukee on account of potential for additional storm
training over that area tonight. The "Limited" selection in Illinois and
Indiana was buffered slightly to cover some of the QPF expected over the
next 48 hours.

In Puerto Rico and the US Virgin Islands, the "Considerable" selection was
expanded to cover all of the island of Puerto Rico to more closely match
the Excessive Rain Hazards Graphic.

Talking points for the Mariana Islands remained unchanged.

//Bliss

Previous discussion as follows

...Considerable flooding impacts expected in the Mariana Islands and
portions of Puerto Rico and the USVI... Considerable rain- and
snowmelt-driven small stream and river flooding in the Upper Great Lakes
with additional flooding into the Middle Mississippi Valley possible...

.Mariana Islands...
No change this afternoon for the Mariana Islands as a Considerable flood
category remains as Super Typhoon Sinlaku moves through the region,
bringing widespread heavy rainfall. Periods of torrential rain and embedded
thunderstorms through Wednesday are expected to produce significant flash
flooding, with current forecasts indicating the highest rainfall totals of
15 - 25" near the center of the storm. The current track is expected to
pass near or over Tinian and Saipan, but Guam still could still see
rainfall totals between 6 - 12" with locally higher amounts. However, any
shift in the storms track could change the location of the heaviest
rainfall. This prolonged rainfall will also lead to saturated soils,
increasing the potential for mudslides, especially across central and
southern Guam. Substantial coastal impacts are also expected across the
CNMI.

.Puerto Rico and USVI...
Considerable urban and small stream flooding remains possible across
northern and eastern Puerto Rico and all of the U.S. Virgin Islands through
Wednesday. Expect the potential for flash flooding, urban and small stream
flooding, landslides, and rapid river rises. A limited flood threat remains
across southern Puerto Rico. Saturated soils and already elevated stream
levels will further enhance runoff and flooding impacts, especially in
response to repeated rounds of rainfall. Following this initial threat, a
continued wet pattern will help maintain possible flood conditions in the
extended period.

.Upper Great Lakes into the Middle Mississippi Valley...
Considerable river and small stream flooding is ongoing and forecast across
the Upper Peninsula and northern portions of Lower Michigan through the
week due to a combination of rainfall and rapid snowmelt.  Warm
temperatures, combined with multiple rounds of rainfall and saturated
soils, will enhance runoff, leading to additional rises on small streams
and rivers across the region, with widespread river flooding and moderate
to isolated major to record river flooding likely.

Elsewhere in the region, minor river flooding is ongoing with new and
renewed river small streams and flooding possible through the week.
Continued rainfall has helped to prime the hydrologic environment,
increasing the potential for additional responses.

//Fontenot

Additional National Water Center products are available at
www.weather.gov/owp/operations



$$