Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 231445
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
1045 AM EDT Sun Jul 23 2017


.UPDATE...
A recent analysis of GOES-R imagery reveals a decaying MCS across
IN/OH/KY...with an upstream perturbation across the Lake Superior.
Down toward the CWA...most notable mid/upper level synoptic
features remained displaced to the north and south...however at
the sfc a weak trough stemming from the Piedmont of the Carolinas
is evident across north Georgia.

Have adjusted POPs through this afternoon to account for what
looks to be an outflow boundary moving into north Georgia from the
KY MCS. Think this outflow will interact with higher terrain and
perhaps the weak sfc trough to enhance convection over north
Georgia the next few hours /already seeing showers popping up/.
Elsewhere...12z FFC RAOB has sampled a very moist and unstable
airmass. Weak CIN should allow for convective initiation in the
next few hours just about anywhere in the CWA. Could see a few
strong downburst winds today as PW values lie near 2 inches and
water vapor mixing ratios are well over 15g/kg. Although
convection will be possible anywhere given this airmass...recent
trends suggest possible enhancement across the mountains and in
the vicinity of where the sfc trough resides /likely to be north
Georgia/.

Probably goes without saying temps will be hot with highs upper
80s to lower 90s. With dewpoints in the 70s...humidity will
create unpleasant conditions through the day so be sure to stay
hydrated and be careful if outdoors.

Kovacik

&&

.PREV DISCUSSION... /Issued 734 AM EDT Sun Jul 23 2017/

PREV DISCUSSION... /Issued 404 AM EDT Sun Jul 23 2017/

SHORT TERM /Today through Monday/...

Shower and thunderstorm coverage will increase today as the upper
level ridge that brought increased convective suppression over the
past few days retreats westward. Plentiful Gulf moisture that has
continued to filter northward into the area will interact with
daytime heating to produce scattered afternoon and evening
thunderstorms. With PWATs around or above 2 inches, locally heavy
rainfall can be expected in convection today, especially with any
slower moving thunderstorms that linger over an area.

Meanwhile, as the upper trough takes influence over the eastern US,
weak disturbances will spark showers and thunderstorms to our north
over the Tennessee Valley. Some of this activity may progress
southward into our area this evening into tonight. Given this
potential, PoP trends will not be solely diurnal in nature, with
slight chance to chance PoPs lingering into the overnight hours,
especially across the northern half of the area. Monday will once
again bring enhanced thunderstorm chances as disturbances interact
with afternoon heating and instability.

While widespread severe weather is not anticipated today or Monday,
given decent afternoon instability and high PWATs, a few strong to
severe thunderstorms will be possible. With high freezing levels
tending to limit the hail potential, damaging downburst wind gusts
would the primary threat.

As far as temperatures are concerned, with increased convection and
associated cloud cover, high temperatures will be held down a few
degrees as compared to the last several days. Highs today and Sunday
will generally be held into the upper 80s to low 90s. Therefore,
peak heat indices today will remain below advisory criteria, ranging
from the upper 90s to just above 100.

RW

LONG TERM /Monday Night through Saturday/...

Long term looks consistent with the forecast area remaining under
the ridge aloft. We can expect a continuation of mostly diurnal
convection which may be influenced by various outflow boundaries
each day. A front may sink into the TN Valley by Tuesday but
models indicate it may stall over the southern Appalachians. GFS
and ECMWF do show a weak trough/upper low across the state mid
week. So in summary...chance pops look good for the forecast area
each day. A trough deepening across the Great Lakes and into the
southeast by Saturday may push a front into north GA. In this case
a drying trend should begin across the northern counties at the
end of the period and extend into the weekend. Temperatures look
near normal through the period.

41

AVIATION...
12Z Update...
This morning brings mostly clear skies to ATL/AHN area TAF sites
with a couple of isolated showers already developing in vicinity
of MCN. The scattered cumulus cloud deck will develop by midday
with more widespread scattered convection increasing areawide by
afternoon. Some showers and thunderstorms may persist into the
late evening before beginning to diminish overnight. Winds will
remain from the west side through the period as high as 8-10
knots during the day.

//ATL Confidence...12Z Update...
High confidence on all elements.

RW

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          93  74  90  73 /  50  40  50  30
Atlanta         90  74  89  74 /  50  40  50  40
Blairsville     87  68  85  67 /  50  40  50  30
Cartersville    90  73  88  72 /  50  40  50  40
Columbus        92  75  91  75 /  50  40  50  30
Gainesville     89  73  87  73 /  50  40  50  30
Macon           92  74  91  74 /  50  40  50  40
Rome            91  73  89  72 /  50  40  50  40
Peachtree City  90  73  89  72 /  50  40  50  40
Vidalia         91  74  91  75 /  50  40  50  30

&&

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

$$

SHORT TERM...Kovacik
LONG TERM....17
AVIATION...Kovacik



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