990
AGUS74 KWCO 061526
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
1015 AM CDT SUN OCT 6 2024

.Synopsis...
Tropical Storm Milton brings the potential for locally considerable
flooding impacts to the Florida Peninsula and Coastal Georgia... Flash
flooding likely in the Mariana Islands... Flooding possible in Puerto Rico
and the USVI... Lingering river flooding across the Southeast...

.Discussion...

Florida Peninsula and Coastal Georgia...
Tropical Storm Milton will bring the potential for locally considerable
flash and urban flooding as heavy rainfall impacts the area mid-week. Ahead
of Milton, locally heavy rainfall will impact portions of FL early this
week, priming soils for TS Milton. As of now, soil conditions are average
to wet in portions of FL (0 - 10 cm RSM, 50-80%, NASA SPoRT) and
streamflows are much above normal (USGS). Expected rainfall amounts of 5 -
8 inches are forecast for the Florida Peninsula with local totals as high
as 12 inches. Soils have some capacity to absorb rainfall, at least
initially however, as rains persist over the next few days, soil capacity
will likely become overwhelmed, leading to rapid rises in small streams.
The most likely impacts ahead of TS Milton include standing water on roads,
overflowing of storm drains and culverts, as well as flooding in poorly
drained and low-lying areas. Mid-week, impacts are expected to ramp up as
TS Milton approaches and crosses the FL Peninsula.

The National Water Model (NWM) Medium-Range Forecast (MRF) is signaling
rapid-onset flooding potential (probabilities of 25 - 75%) from
Jacksonville southward with higher probabilities located in the southern
peninsula. Annual-exceedance probabilities are present throughout FL and
widely range from 50 - 2% depending on location. Widespread minor to
moderate river flooding is likely with major flooding possible near maximum
rainfall totals. Minor river flooding is forecast for areas surrounding
Tampa and river ensemble forecasts (HEFS) are indicating the potential for
isolated moderate river flooding in the Peace-Tampa Bay River Basin.

Mariana Islands...
Moderate to locally heavy rainfall is forecast thru day 3 (Tue) as a
developing tropical disturbance brings the potential for flash flooding.
There is still uncertainty with this system with regards to rainfall
amounts and the likelihood of impacts.

Puerto Rico and the USVI...
Moderate to locally heavy rainfall bringing the potential for flooding is
forecast through day 2 (Mon).

.Southeast...
Flows will continue to route downstream across the Coastal Plain of GA. The
Alapaha and Ogeechee rivers will continue to rise over the next few days
with crests expected early this week.

//Kirkpatrick



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