Flood Potential Outlook
Issued by NWS
FGUS72 KTAE 021430
National Weather Service Tallahassee FL
930 AM EST Thu Mar 2 2017 /830 AM CST Thu Mar 2 2017/
...Spring Flood Potential Outlook for Southeast Alabama, Southwest
and South Central Georgia, and the Florida Panhandle and Big Bend...
...Near normal potential for river flooding in Southeast Alabama
and the Florida Panhandle this Spring...
...Below normal potential for river flooding in the Suwannee River
Basin this Spring...
In the Choctawhatchee Basin...
Rainfall since October 1, 2016 has been considerably above normal
across the upper portion of the Choctawhatchee River Basin in
Southeast Alabama. After a record dry October and November,
significant rains from December through January resulted in
surpluses through the end of February as much as 8 to 12 inches
above normal across portions of the Choctawhatchee Basin in
Southeast Alabama. Amounts nearer to normal have been observed
along and south of Interstate 10 in the Florida Panhandle. Several
minor to moderate river flood events occurred over the winter
months in this basin, and though rainfall over the last 30 days
has been near to slightly below normal, 28 day average streamflows
in this basin are at normal levels for this time of year.
In the Apalachicola, Chattahoochee, Flint (ACF) Basin...
Similar to the Choctawhatchee Basin, portions of the ACF basin in
South Georgia and Southeastern Alabama have seen above normal
rainfall since October 1st, though the bulk of this rainfall
occurred during December and January. Surpluses below Walter F
George Reservoir of 4 to 6 inches are fairly common on the
Chattahoochee portion of the basin. Amounts nearer to normal or 2
inches above normal are common on the Flint River side of the
basin below Lake Blackshear. In the middle and upper portions of
the ACF basin, above West Point, Georgia, drought conditions
continue and have only modestly improved through the winter.
Significant rainfall departures from normal are common in the ACF
basin above Atlanta, where severe drought conditions continue.
Below Jim Woodruff Dam, the Apalachicola River remains at normal
levels for this time of year. Through the winter months, a couple
of minor flood events occurred, with an early January flood
peaking around 75kcfs.
In the Ochlockonee Basin...
Rainfall within this basin since October 1st has generally been
near normal. Heavy rainfall in December and January was enough to
result in one instance of minor flooding across the basin in early
January. Since that time, rainfall has generally been below
normal, though the latest streamflows are still in the normal
range for this time of year.
In the Withlacoochee and Suwannee Basin...
Rainfall since October 1st across this basin has been below
normal, and significantly so in the Middle and Lower Suwannee
River Basins. Rainfall deficits of 4 to 6 inches since October 1st
are common across the basin, with some areas in the Middle and
Lower Suwannee reporting deficits of as much as 8 to 12 inches
below normal over this time frame. Some minor flooding did occur
across the Withlacoochee River basin in South Georgia in late
January, but flows were not sufficient to result in downstream
flooding within the basin into Florida. In fact, the flow
attenuated while progressing through the basin suggesting loss of
water into the Floridan Aquifer, as is fairly typical when
groundwater levels are below normal.
...Long Term Precipitation Outlook...
The three month precipitation outlook for March, April, and May,
indicates equal chances for above normal, normal, and below normal
precipitation across the area. The one month outlook for March
has been recently updated to reflect equal chances of above
normal, normal, and below normal precipitation across the area.
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 as fewer storm
systems impact the region.
...Spring Flood Outlook Summary...
The recent wet conditions across the western half of the region
suggest the Choctawhatchee River basin is the most vulnerable of
the river basins in the region to river flooding this Spring.
However, with no notable signal in the model guidance for above
normal precipitation in the first half of March, the river flood
risk in the Choctawhatchee River basin is near normal. Within the
ACF basin, taking into account the dry upstream conditions, the
river flood threat this Spring is also near normal, as above
normal precipitation would be needed to result in basin-wide
flooding. Further eastward into the Suwannee River Basin, the
persistent dry conditions and the potential for only normal
rainfall across this basin suggest that the river flood risk this
Spring will be below normal.