River Flood Warning 11, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1025 AM EDT Mon Mar 17 2014

.Near Term [Through Today]...
An amplified positively tilted upper level trough along the Gulf
coast of TX continues to slowly swing towards the northern Gulf
coast today. 13Z surface analysis shows an area of low pressure
slightly NW of Atlanta, GA with a cold front extending SWward to
Pensacola, FL and a warm front extending from the low SEward
across central GA, then curving back NEward to the GA-SC border
and mid-way up the SC Atlantic coastline. Near Tampa, a surface
trough is evident by the wind shift and radar imagery shows a
line of thunderstorms and heavy rain along this boundary. Between
the approaching cold front and the trough boundary that gave us
severe weather and heavy rain yesterday is a broad area of light
to moderate rain which will move slowly eastward through the day.
Rainfall totals today will generally run around 0.25-0.75", with
the lowest totals in SE AL and the highest totals in the FL Big
Bend. Today will be cool with persistant cloud cover and rain,
highs wil stay in the low to mid 60s, upper 60s near Cross City.

&&

.Aviation...
[Through 12Z Tuesday]...LIFR-IFR conditions will improve from west
to east around noon to MVFR, then later VFR after midnight as
the rain pushes off eastward. Variable winds this morning will
shift to northwesterly as the cold front, currently stretching
from Pensacola to near Atlanta, crosses the area this afternoon.

&&

.Prev Discussion [345 AM EDT]...

.Short Term [Tonight Through Wednesday]...
This evening, as the main upper level system approaches the
region, expect a redevelopment of rain across the northeastern Gulf
lifting northeastward across the region. Model guidance is split
on how extensive this rainfall will be, with the NAM having the
greatest coverage. The 17/00z Euro/GFS and hi-res guidance
suggests that the best forcing will converge across our eastern
counties after 00z and thus, have indicated the best chances in
these areas tonight. As the upper low moves across the region
tonight, expect rain chances to come to an end quickly as deep
layer forcing diminishes. There isn't much in the way of cooler
air coming in behind this system, and with post frontal
cloudiness, temperatures overnight should generally be in the
upper 40s to lower 50s.

Tuesday...As the upper low and attendant surface cyclone move out
into the Western Atlantic, surface ridging will build down the
eastern side of the Appalachians pushing a wedge of cooler air
toward our region from the northeast. Model guidance is
understandably having a difficult time showing how far south this
cooler airmass will get. With a more favorable sun angle in Mid
March, it is anticipated that the southward progress of the cool
wedge will be limited to mainly South Central Georgia, where
cloudy and cool conditions will prevail for Tuesday. Further to
the south, the cloud cover should scatter out by afternoon
allowing for temperatures to warm into the lower 70s.

Wednesday...A northern stream storm system will move through the
Great Lakes and try to push a cold front toward our region.
However, with the bulk of the energy staying well to the north,
expect this front to wash out north of our region. Expect what
remains of the cool wedge to be scoured out by this time, yielding
a mostly sunny day with temperatures inland warming into the mid
to upper 70s.

.Long Term [Wednesday Night Through Monday]...
Shortwave impulses will continue to propagate through the upper
level pattern through the long term period, but will stay too far
north of us to enhance rainfall in the southeast again until the
weekend. Temperatures will be near normal, with highs in the upper
60s to mid 70s and lows in the mid to upper 40s.

Friday night, a Srn stream shortwave impulse will move across Nrn
Mexico with a Nrn stream shortwave impulse over the Great Lakes,
this will enhance divergence aloft enough for a surface low to
develop over the Ohio valley and develop a cold front that extends
SWward to the Arklatex region, crossing our forecast area
Saturday-Sunday.

.Marine...
A cold front will move across the marine area this afternoon
shifting winds to offshore. With a relatively weak pressure
gradient in place behind the front, winds should gradually
decrease by Tuesday as high pressure moves over the water. Light
winds will continue throughout the week as a reinforcing area of
high pressure builds near the waters by Thursday.

.Fire Weather...
Widespread rain is expected into this evening before decreasing
tonight then ending from west to east Tuesday morning. Low mixing
heights and transport winds will lead to low dispersions especially
today. Red flag conditions are not expected during the entire work
week.

.Hydrology...
While the intensity of the rain has diminished early this morning,
widespread moderate rainfall amounts have piled up to around 4 to
6 inches across the Florida Panhandle and Big Bend with lesser
amounts in the 2 to 4 inch range across Southeastern Alabama and
Southwestern Georgia. Additional rainfall today and tonight should
not be of a great enough intensity to cause any flash flooding
concerns. As a result, the flash flood watch will be discontinued
later this morning.

With the bulk of the rainfall occurring across the lower portion
of the river basins, river flooding is not anticipated in our
Alabama and Georgia counties, perhaps with the exception at the
Ochlockonee River near Thomasville.

In North Florida, runoff from widespread 4 to 6 inch rainfall
amounts are producing sharp rises on area river points. The
heaviest rain was concentrated from Bay County eastward into Leon
County. As a result, portions of the Chipola and Ochlockonee
Rivers will move toward flood stage this week. Local runoff seems
to be causing a few points to track higher than previous forecasts
and this may result in the Chipola River at Altha reaching flood
stage sooner than predicted. The Ochlockonee is also climbing
fast at Concord and Havana. Rainfall was a little less further to
the east of Tallahassee, but it is still anticipated for the St
Marks River to reach minor flood stage later today, and possibly
moderate flood stage later this week.

For the latest hydrology information, please visit:
http://water.weather.gov/ahps2/index.php?wfo=tae

&&

.Preliminary Point Temps/PoPs...

Tallahassee   64  51  71  48  78 /  90  80  10   0   0
Panama City   64  51  69  51  73 /  90  60  10   0   0
Dothan        64  47  70  46  76 /  80  40  10   0   0
Albany        63  49  65  45  77 /  90  60  20  10  10
Valdosta      64  52  68  51  78 / 100  90  30  10  10
Cross City    70  53  75  51  79 / 100 100  20   0   0
Apalachicola  65  51  68  51  71 /  90  70  10   0   0

&&

.TAE Watches/Warnings/Advisories...

FL...High Rip Current Risk until 7 PM EDT /6 PM CDT/ this evening for
     Coastal Bay-Coastal Gulf-South Walton.

GA...None.
AL...None.
GM...None.

&&

NEAR TERM...MOORE
SHORT TERM...GODSEY
LONG TERM...MOORE
AVIATION...MOORE
MARINE...GODSEY
FIRE WEATHER...BLOCK
HYDROLOGY...GODSEY