Flood Potential Outlook
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FGUS72 KTAE 011410

Probabilistic Hydrologic Outlook
National Weather Service Tallahassee FL
910 AM EST Thu Mar 1 2018

...Spring Flood Potential Outlook...


...Existing Conditions...

In the Choctawhatchee Basin...

Rainfall since October 1, 2017 has been generally at or just below
normal over the basin. A significant stretch of dry conditions were
observed prior to January 1. After the first of the year, much of
the Choctawhatchee River Basin has seen above normal precipitation.
Much of the basin reported rainfall that was at least 125 percent of
normal. A storm system on February 10th brought sufficient rain for
a period of minor river flooding during the middle of February from
Newton, AL  through the bottom of the basin at Bruce, FL. At the
beginning of March 2018, stream flows across the basin are at normal

In the Apalachicola, Chattahoochee, Flint (ACF) Basin...

Much of the ACF basin below Whitesburg, GA and Peachtree City, GA
has seen well below normal precipitation since October 1, 2017.
Throughout the basin, many locations have rainfall deficits greater
than 6 inches, with the driest areas at the bottom of the basin
where rainfall departures greater than 8 inches are common. While
severe drought covered much of the central and southern portion of
the basin at the start of the month of February, a significant
rainfall event on February 10-11 resulted in significant drought
improvement. Longer term stream flows, however remain near to below
normal for this time of year.

Below Jim Woodruff Dam, the Apalachicola River after a period of
minor flooding in February at Blountstown, has returned to below
normal levels for this time of year. Peak discharge in the February
flood event was 53kcfs.

In the Ochlockonee Basin...
Rainfall within this basin since October 1st has been below normal,
with portions of the basin having rainfall deficits over this time
as great as 6 to 8 inches below normal. Even shorter term rainfall
amounts since January 1st have been slightly below normal. A
rainfall event in February resulted in stream flows returning to
normal levels, but ultimately cresting well below flood stages
throughout the basin.

In the Withlacoochee and Suwannee Basin...
Rainfall across the upper portions of the Withlacoochee and
Suwannee Basin has been considerably below normal since
October 1, 2017. Portions of the basin above Valdosta have seen
rainfall departures of 6-8 inches below normal. The middle and lower
portions of the Suwannee River Basin, however are closer to near
normal rainfall since October 1st. Over the short term, rainfall
surpluses in the Suwannee Basin are common below Ellaville. In
particular, Cross City has seen 130 percent of normal rainfall since
January 1st.

...Long Term Precipitation Outlook...

The three month precipitation outlook for March, April, and May
indicated equal chances of above normal, normal, and below normal
precipitation across South Georgia and Southeastern Alabama. There
is an increased chance for below normal precipitation across North
Florida. The one month outlook for March suggests an increased
chance for above normal precipitation across Southeast Alabama and
Southwestern Georgia. For reference, the monthly normal
precipitation for select stations across the region appear below:

Location                 Normal Precipitation
Tallahassee (Mar)              5.94 in.
Tallahassee (Apr)              3.06 in.
Tallahassee (May)              3.47 in.
Dothan (Mar)                   5.88 in.
Dothan (Apr)                   3.52 in.
Dothan (May)                   3.56 in.
Albany (Mar)                   5.05 in.
Albany (Apr)                   3.64 in.
Albany (May)                   2.69 in.
Valdosta (Mar)                 4.87 in.
Valdosta (Apr)                 2.87 in.
Valdosta (May)                 2.53 in.

Typically, April and May are drier months across the region, and in
the absence of significant rains in the month of March, river
flooding becomes less likely after mid April across the region as
fewer storm systems impact the region.

...Spring Flood Outlook Summary...

Persistent dry conditions across much of the region through the end
of 2017 have either been overcome or significantly diminished by
multiple rain events in January and one heavy rainfall event in
February. This has brought most area stream flows back to normal
across the region, and even produced a period of minor flooding
across the rivers in the western half of the region. With at least
some signal in the longer term guidance for at least normal
precipitation during the month of March, the flood risk for the
region for this spring is largely near normal across the region,
though some localized higher potential for river flooding exists
across the Choctawhatchee River Basin.



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