Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 010552 AAC
AFDFFC

Area Forecast Discussion...Updated
National Weather Service Peachtree City GA
145 AM EDT THU SEP 1 2016


UPDATE...
Greatest upcoming forecast concern is Tropical Storm Hermine
currently located in the eastern Gulf of Mexico.

As per recent radar imagery...remaining shower/convective
activity mainly confined to north Ga where a lee sfc trough has
provided necessary lift amidst diurnal heating this afternoon.
Shower activity is also lingering across SE Ga where greater
tropical moisture and upper level support exists. Expect this
activity to diminish as the boundary layer decouples this
evening. Mainly clear skies expected across N Ga...with some pesky
low-mid level clouds lingering across C Ga. Low temps upper 60s
mountains to lower 70s elsewhere.

For Thursday...greater coverage of convection expected as TS
Hermine creeps towards the FL panhandle and a cold front
approaches the CWA from the NW. Expect highest coverage of precip
across the mountains ahead of the cold front and across central Ga
where deep layer tropical moisture resides. High temps in lower
90s.

TROPICS: TS Hermine`s mid-level circulation is located NE of
Yucatan peninsula with sfc reflection located a touch further
north. Hermine is expected to make landfall along FL coast after
sunset Thurs. It is possible Hermine could intensify into a
hurricane before making landfall...with SSTs well above normal
across the Gulf. Regardless of it being a hurricane or tropical
storms...feel threat of at least tropical storm conditions are
possible across parts of central Ga near the close of the work
week. After collaboration with neighboring offices this
afternoon...have put TS winds in the grids as well as issued a TS
and Flash Flood Watch. It is important to keep up to date with the
latest forecast information...as a slight shift in the projected
path could result in dramatic changes to the forecast. See
previous AFD discussion and latest information from NHC for
further details on this TS.

Kovacik

PREV DISCUSSION... /Issued 334 PM EDT WED AUG 31 2016/

.Tropical Storm Hermine likely to produce significant impacts
in parts of middle and east Georgia Thursday night and Friday...

SHORT TERM /Tonight through Thursday/...
The next 24 hours should be fairly quiet, even with the active
tropics. The main impacts within the first three periods will be
increasing chances for precipitation...including locally heavy
rainfall by Thursday night.

Diurnal cu and showers should begin to diminish late this
evening/overnight with the loss of heating. Skies should mostly
clear out across the ATL metro...while lingering across central GA
overnight.

The weak frontal boundary currently stretching from the eastern
Great Lakes back through the central US will slowly begin to sag
southward tomorrow. This boundary is expected to settle across
northern portions of GA by tomorrow night.

Not too confident on how far south this boundary will make it, but
the models are progging a brief wind shift to the NW tomorrow
afternoon before the synoptic flow turns back to the east ahead of
Hermine. For much of tomorrow, the pops should be highest across
northern GA (with the front) and central GA (showers coming off the
Atlantic in the deep easterly flow). Have gone ahead and painted a
slight chance across the I-20 corridor...as showers can pop up
anytime in this type of airmass.

NListemaa

LONG TERM /Thursday Night through Wednesday/...
Primary concern is timing and impacts of Hermine. 12Z models not
backing off on intensity after Hermine makes landfall on North FL
coast around midnight Friday morning. While convection not as active
as it was this morning, looks much stronger than this time
yesterday. Still seeing a slight west/north shift and slower track
compared with previous runs.

Main message we want to share with partners is even when a storm
is nearing landfall, do *NOT* focus on the center of storm! Wind,
heavy rain and even isolated tornado impacts will be felt quickly
and WELL AHEAD of the the center reaching middle GA. This one
could surprise us.

Wind impacts may be substantial for what is only been just named
a Tropical Storm as strengthening, or at least a lack of
weakening, is forecast even after landfall. We have not seen
tropical storm force sustained winds in over 10 years in our CWA
based on our internal records. Sustained winds of 25 to 35 mph
with gusts to 50 mph may be possible as the center moves into our
southern and southeastern counties. Another impact is an isolated
tornado threat late thursday night and friday as this area is in
favorable northeast quadrant. Slight risk area in SPC day 2
outlook looks good given current forecast...but would need to be
adjusted north if track changes.

Finally heavy rain and flash flood threat may also be very
significant. Warm advection/warm front pattern expected to setup
east and northeast of Hermine, much like a PRE (predecessor rainfall
event), where heavy rain develops along and north of warm front like
feature. Models differ on where this PRE band of heavy rain will set
up exactly but expect heavy rain to develop Thursday night and
continue Friday as center tracks over south into east GA. At this
time...expecting 3 to 5 inches of rain thru Sat morning mainly
east of Lexington to Macon to Cordele line. Flash flood watch has
been issued but may need to be adjusted based on track of storm.

Another set of grid updates will be done around 5pm after the new
NHC package comes in. Based on this may need a Tropical Storm
watch shortly after.

The remainder of the extended forecast should be fairly quiet as
high pressure settles across the east half of the country. Temps
should be a little bit cooler and the airmass a bit drier behind
Hermine. Temps may end up dropping below 70 degrees overnight
Saturday night/Sunday morning...breaking the current streak.

NListemaa/BDL/SNELSON

AVIATION...
06Z Update...

VFR conditions are expected to predominate across the forecast area
through the majority of this forecast period. Will see some local
MVFR or lower visibilities developing between 06Z and 14Z...mainly
in traditionally fog-prone areas. May also see some MVFR or lower
cigs develop across the Georgia/South Carolina coastal plain that
could spread into eastern and southern portions of the forecast
area. Conditions will become progressively worse across the forecast
area after 00Z with MVFR ceilings spreading north...lowering to IFR
most areas by 12Z Friday. Isolated to scattered convection is likely
again this afternoon and evening. After 00Z more widespread area of
significant shower and thunderstorm activity will begin spreading
north into the area associated with Tropical Storm Hermine. Winds
will remain southeasterly...3-7KT through 12-14Z...becoming westerly
4-8kt through 16-18Z before swinging back to easterly. Main impacts
from the tropical system approaching the forecast area will be after
this forecast period.

//ATL Confidence...06Z Update...

Medium on MVFR development and wind direction...high all
other elements.

20

&&


.PRELIMINARY POINT TEMPS/POPS...
Athens          71  92  72  79 /  10  30  50  60
Atlanta         73  91  72  83 /  10  30  40  50
Blairsville     65  86  66  77 /  20  30  40  50
Cartersville    70  92  71  84 /  20  30  30  40
Columbus        73  91  74  85 /  20  50  50  60
Gainesville     71  90  70  79 /  20  30  40  50
Macon           72  91  73  81 /  20  50  60  60
Rome            70  92  71  86 /  20  30  30  40
Peachtree City  70  91  72  83 /  10  40  40  50
Vidalia         73  90  74  83 /  30  50  80  80

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from late Thursday night through Saturday
morning FOR THE FOLLOWING ZONES: Baldwin...Bibb...Bleckley...
Crisp...Dodge...Dooly...Emanuel...Glascock...Greene...Hancock...
Houston...Jefferson...Johnson...Jones...Laurens...Montgomery...
Oglethorpe...Pulaski...Putnam...Taliaferro...Telfair...Toombs...
Treutlen...Twiggs...Warren...Washington...Wheeler...Wilcox...
Wilkes...Wilkinson.

Tropical Storm Watch FOR THE FOLLOWING ZONES: Bleckley...Crisp...
Dodge...Dooly...Emanuel...Glascock...Houston...Jefferson...
Johnson...Laurens...Macon...Montgomery...Peach...Pulaski...
Schley...Sumter...Telfair...Toombs...Treutlen...Twiggs...
Washington...Wheeler...Wilcox...Wilkinson.

&&

$$

SHORT TERM...Kovacik
LONG TERM....39
AVIATION...Kovacik



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