Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Peachtree City Georgia
715 PM EDT Sat Jul 12 2014
Previous discussion... /issued 353 PM EDT Sat Jul 12 2014/
Short term /tonight through Sunday night/...
afternoon showers and thunderstorms have generally been restricted
to the southern/southeastern County Warning Area where diffuse boundary
remains...and in the higher elevations where orographic influence
has allowed for diurnal development. Overall...anticipate storms to
be garden variety...although there is potential for a few storms to
become strong to severe. Main concern will continue to be heavy
rain...with weak boundary layer winds keeping storm movement
minimal. Damaging winds and lightning are also a concern. Short term
models continue to advertise a diurnal trend with this activity...
and have dropped off probability of precipitation quickly overnight.
With southeast winds overnight...anticipate increasing ample low
level moisture...enough to produce fog-restricted visibilities...
especially across the far southern and southeastern County Warning Area.
Forecast is a similar story for Sunday...with diffuse boundary
remaining across south Georgia...the majority of the convection is
expected to remain farther south...with generally isolated chances
of storms over north and central Georgia. Have mentioned chance probability of precipitation
in the northeast Georgia mountains and across the very southern tier
of counties where best potential exists. As with today...a few
strong to severe storms are possible. The main concerns will once
again be winds and heavy rain.
Better rain chances are expected into Monday as trough approaches
Warm temperatures expected through the weekend...and have generally
gone with a model blend.
Long term /Monday through Saturday/...
with the approach of an unseasonably deep trough expect the
extended period to be diverge from the typical Summer pattern. Models peg
a front approaching the area on Monday and into Tuesday. Most of
the upper level support associated with this front will shift out
of the area late Tuesday. However...deep layer shear is larger
than the norm for this time of year which could lead to more
organized thunderstorms. As the front interacts with a moist Gulf
airmass...thunderstorms are likely...especially across north
Georgia. Storm Prediction Center day 3 outlook brings the slight risk just to the
Tennessee/Georgia border. The possibility exists for strong thunderstorms on
Monday night into Tuesday. Then we transition into a northwest flow
regime with drier air entering the area. Previous long term is
attached below with an apt discussion on the low humidity expected
Previous discussion... /issued 329 PM EDT Sat Jul 12 2014/
long term /Sunday night through Friday/...pattern still expected
to become dominated by large upper trough over the eastern Continental U.S. By
Tuesday and persist through Friday. 00z medium range model guidance again
in good agreement. Front associated with leading edge of
westerlies to move into state on Tuesday so bumped probability of precipitation to likely. As
model guidance starts to hone in on specifics and with less weight
on climatology...beginning to appear that Tuesday/Wednesday will be
significantly drier and moderately cooler than normal after frontal passage.
Wednesday maximum temperatures may remain in the 70s in higher elevations of north
Georgia. Dewpoints should be in the 50s. As front washes out and lifts
north Thursday/Friday will likely see return to scattered diurnal showers and
thunderstorms. Used dynamic blend for forecast temperatures which weights
raw models and uncorrected MOS guidance in areas of rain and
clouds and bias corrected MOS guidance in areas of no rain and
any showers and thunderstorms will dissipate during the evening.
Mainly VFR conditions expected tonight except for areas of MVFR
visibilities late night and early morning. Surface winds becoming calm or
light and variable. Wind direction shift for atl Sunday morning.
//Atl confidence...00z update...
medium confidence for clouds and visibilities during the early morning.
Otherwise high confidence during the overnight.
Preliminary point temps/pops...
Athens 70 93 71 95 / 30 20 10 30
Atlanta 72 91 73 92 / 20 20 10 40
Blairsville 66 87 66 87 / 30 30 20 50
Cartersville 70 92 70 93 / 20 20 20 50
Columbus 73 93 73 94 / 30 20 10 40
Gainesville 71 91 72 91 / 30 20 10 40
Macon 70 92 71 95 / 30 20 10 30
Rome 70 92 71 94 / 20 20 20 50
Peachtree City 67 91 69 92 / 20 20 10 30
Vidalia 72 92 73 95 / 30 30 20 30