Flood Potential Outlook
Issued by NWS Mobile, AL

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FGUS74 KMOB 232121

Hydrologic Outlook
National Weather Service Mobile AL
421 PM CDT Wed May 23 2018

...Multi-Day Heavy Rainfall Event Likely Unfolding for the Central Gulf
Coast Region...

Between this Saturday and the middle of next week, a developing heavy
rainfall pattern associated with both a tropical plume of
moisture and potential Gulf of Mexico surface low development will
bring very heavy to potentially excessive rainfall, at times, to
the Central Gulf Coast Region.

Current basin average rainfall forecasts during this period are
forecast to range between 6-12 inches along the coastal counties
of Alabama and the western Florida Panhandle to 5-8" across
interior portions of southwest and south Central AL and also
interior southeast Mississippi. This discounts localized higher
rainfall totals. Despite there being still some uncertainty in
the exact forecast track of a Gulf of Mexico surface low, the
ingredients for very heavy rainfall will be in place during this
rather prolonged time period.

Current thinking is a continuous rain would overspread the region
from the south on Saturday as the Gulf of Mexico surface low
further develops and moves northward. A more continuous rainfall
continues through late Sunday and potentially into Monday.

After Monday, additional showers and thunderstorms would only add
to flooding concerns as the surface low is forecast to stall to
our west and slowly wind down. Also, as area rivers drain runoff towards
the immediate coast from late weekend on, rainfall runoff will
interact with already elevated coastal water levels to further complicate

Please realize, the above scenario discounts rainfall which may further
soak soils beyond their current state even before the aforementioned
more continuous rainfall begins on Saturday.

Confidence is high, if this amount of rainfall is realized, most
of area rivers will easily experience moderate flooding, and in some
cases major flooding.

Please also realize, while flash flooding may come to an end,
river flooding could very well extend days beyond that.

A Flash Flood Watch will likely be issued by late tomorrow or
possibly very early Friday morning. /23 JMM


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