Area Forecast Discussion
Issued by NWS Atlanta, GA

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880
FXUS62 KFFC 260018 AAA
AFDFFC

Area Forecast Discussion...UPDATED
National Weather Service Peachtree City GA
818 PM EDT Tue Apr 25 2017

.UPDATE...
Near term forecast doing well. Clouds not expected to increase
ahead of next system until early Wednesday evening.

SNELSON


&&

.PREV DISCUSSION... /Issued 257 PM EDT Tue Apr 25 2017/

SHORT TERM /Tonight through Wednesday Night/...
Upper low off the North Carolina coast will continue to pull away
taking what moisture is left with it. Skies will become clear
tonight as a weak upper ridge builds over the CWA. The next system
is already dropping into the southern plains and will start
spreading low level moisture in the form of clouds into the CWA late
tonight, mainly over west central Georgia. However dry air aloft
will remain in place and as soon as mixing occurs Wednesday morning
the clouds should dissipate. All models agree with a short wave
being kicked out of the main trough and moving into the Tennessee
Valley late Wednesday night. This will bring increasing pops to
northwest GA late Wednesday night. MOS guidance temps look
reasonable although have made minor adjustments based on local bias
tables.

17

LONG TERM /Thursday through Tuesday/...
Only tweaks to the long term based on the latest guidance.
Still decent chances for showers and storms on Thursday.
The risk for severe storms still looks to be marginal.

BDL

PREVIOUS GUIDANCE...
Dry conditions from the short term period will carry over into the
long term for a brief period of time. On Wednesday night...a weak
mid level shortwave ridge will be pushing east of the local
area...with associated weak area of sfc high pressure also moving
east with it into the Atlantic. Although conditions will remain dry
into the very early morning hours Thursday...a cold front will be
approaching from the west. Plenty of instability along and in the
near vicinity of the frontal boundary will help sustain
thunderstorm activity. As of right now...widespread severe weather
does not seem likely...however enough shear in the vicinity of a
LLJ across northwest and portions of north central Georgia may be
enough for isolated severe weather in the morning hours. This
isolated threat may shift to central Georgia Thursday afternoon as
better shear moves into this area ahead of the frontal boundary
and may be able to work in tandem with diurnal heating. Main
threats Thursday look to be gusty winds and hail /as mid level
lapse rates expected to remain over 6C/km/...though a brief...very
isolated tornado isn`t out of the question across northwest
Georgia Thursday morning /0-1km shear >30kts with dewpoints rising
to near 60/.

At least a portion of this frontal boundary will stall across
Georgia Thursday night into Friday as the parent system moves well
north. As this occurs...a closed mid level low will begin developing
across the Southern Rockies within a broad cyclonic flow regime. The
digging nature of this feature will help build a midlevel
subtropical ridge into the Southeast /with Bermuda sfc high also
building into the region/. This will lift the stalled frontal
boundary north as a warm front and push a rather moist and unstable
/dewpoints perhaps mid-upper 60s/ airmass into the Southern US. This
unstable airmass will promote the development of diurnally driven
thunderstorm activity Friday through Sunday...where warm frontal
forcing/orographic forcing will likely also enhance lift for
thunderstorms on Friday across far north Georgia. Anything severe
Fri-Sun would be of the pulse variety at this point. As the closed
low induces sfc cyclogenesis over the Southern Plains this
weekend...it will pivot northeast into the Great Lakes by early
next week. This will push another cold front towards the area
Monday. Too early to determine severe potential...though shear
improves with better upper level jet support. A return to stable
and cooler conditions will follow this fropa just outside of the
extended.

Kovacik

&&

.AVIATION...
00Z Update...
No aviation impacts and VFR conditions expected thru forecast. Sfc
winds will decrease and become near due south at most airports
6-8kts around 18Z. Sfc wind direction at KATL could go to 170deg
as early as 18Z but for now have fcst around 21Z. Winds should
stay SSE after 21Z.

//ATL Confidence...00Z Update...
Medium confidence on sfc wind direction Wednesday afternoon.
High confidence on all other elements.

SNELSON

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          57  85  61  80 /   0   0  10  70
Atlanta         60  83  63  78 /   0   0  10  70
Blairsville     51  82  56  75 /   0   0  10  70
Cartersville    53  86  62  78 /   0   0  20  60
Columbus        61  85  63  82 /   0   0  10  70
Gainesville     59  83  62  77 /   0   0  10  70
Macon           56  86  60  83 /   0   0   5  70
Rome            54  86  61  78 /   0   0  30  70
Peachtree City  54  83  61  79 /   0   0  10  70
Vidalia         59  86  63  87 /   0   0   5  20

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...SNELSON
LONG TERM....41
AVIATION...SNELSON



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