Area Forecast Discussion
Issued by NWS Atlanta, GA
FXUS62 KFFC 191947
Area Forecast Discussion
National Weather Service Peachtree City GA
247 PM EST Thu Jan 19 2017
.SHORT TERM /Tonight through Friday Night/...
Short term forecast marked by two rounds of activity as this active
pattern ushers systems into the region every one and a half to two
Currently, stationary front draped across the metro area will lift
northward as a warm front as a large low pressure system lifts
northward into the midwest and drags a cold front to the AL/GA
border. Activity has already increased along this cold front over
MS/AL and has begun spreading eastward this afternoon. The
atmosphere has already begun to destabilize this afternoon, and
models are consistent with showing better shear /30-40kts/ and CAPE
values /albeit modest/ nosing into western portions of the state
overnight tonight. At this time modeled best instability/shear and
dynamics are displaced somewhat, but still anticipate the potential
for a strong damaging wind/brief tornado threat across west Georgia
before the front looses its punch into early Friday. For now, SPC
does have north and central Georgia in a general thunder risk
(bordered by a marginal risk area), but strong storms cannot be
ruled out at this time.
Pops taper off quickly Friday as what remains of the overnight
convective activity dissipates and moves north and east of the area.
The area will have a brief period of reprieve Friday ahead of the
next round of activity on Saturday. Short term models are in
agreement with showing strong upper level jet dig southward across
the southwest U.S. and into Mexico, which will be the catalyst for
round two and eventually round three (in the long term, late in the
weekend). Pops increase early Saturday morning and into the extended
period as surface feature and associated plume of moisture lift from
the north Gulf of Mexico into the state. Better modeled CAPE values
with this second batch spreads into the state and will keep mention
of chance thunder in the grids through the remainder of the short
Fog will also remain a concern with ample moisture settling over the
area through the overnight periods tonight and Friday night. Have
mentioned patchy dense fog in the grids, and if restricted
visibilities become widespread, a dense fog advisory may be
necessary. For now, winds associated with tonight`s activity could
keep visibilities from tanking.
Rainfall amounts through the short term are generally two inches or
less, and should not amount to any major flooding concerns except in
areas where nuisance flooding results from a brief heavy downpour.
However, with minimal recovery period between systems, and with
additional rainfall expected through the weekend, the area will be
primed for quicker response times, and larger amounts of
runoff/lower amounts of soil infiltration. Flash flooding risk will
need to be monitored over the next several days as these three
rounds of activity play out through the long term.
.LONG TERM /Saturday through Thursday/...
No major changes made to the extended forecast. General trend
continues to look the same with several short waves crossing the
southeast states with increasing chances of showers and
thunderstorms. Southwest flow aloft will keep moisture and a warm
air mass over the region. Rain chances increase rapidly again
Friday night into Saturday and continue into Sunday. By that
time...the upper closed low will be moving from the lower MS
valley into the Southern Appalachians. There are some timing
differences between the GFS and ECMWF. However categorical showers
and scattered thunderstorms looks reasonable for Saturday into
Sunday. Timing of the upper low will affect rain chances on Monday
but precipitation should be ending during the day. Brief break on
Tuesday with ridge building aloft...rain returning late
Wednesday. A few strong to severe storms are possible Saturday and
again Sunday into Sunday night. The risk for severe will depend
on several factors...including existing cloudiness and ongoing
rain...combined with lapse rates and shear.
Daytime Temperatures will remain warm throughout...however cooler
nights are expected for the beginning of the week. For the period
including tonight through Sunday...rainfall totals should average
two to three inches. No hydrology issues anticipated at this time
since rain will be spread over several days.
Afternoon skies are generally VFR, with SCT-BKN high MVFR across
north GA. Showers and thunderstorms are expected to move into far
NW this afternoon, then push south and east overnight. Expected to
arrive to the Atlanta area after 02z. For now, instability at
onset is limited, so have opted not to include thunder in at this
time. Cigs will degrade quickly overnight with LIFR possible at
some locations. Restricted vsbys expected, especially in/near
precip. Winds have been VRB this afternoon, but expected them to
stay SE into the overnight period, then shift to the SW. Rain
should exit the area by Friday morning.
//ATL Confidence...18Z Update...
Medium on all elements.
.PRELIMINARY POINT TEMPS/POPS...
Athens 57 70 56 67 / 80 50 30 60
Atlanta 58 71 58 68 / 100 40 40 60
Blairsville 51 64 52 62 / 100 60 20 60
Cartersville 56 70 55 66 / 100 50 40 60
Columbus 60 75 61 72 / 100 40 60 80
Gainesville 56 68 56 65 / 90 60 20 60
Macon 58 74 60 70 / 70 30 50 80
Rome 55 71 54 67 / 100 40 40 60
Peachtree City 56 71 56 69 / 100 40 60 70
Vidalia 60 77 62 73 / 30 30 50 80