Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Peachtree City Georgia
144 PM EDT Thursday Sep 18 2014
Previous discussion... /issued 1037 am EDT Thursday Sep 18 2014/
current satellite trends show that the cloud deck is breaking up
across the metropolitan area. Expect the current forecast to be on track.
Hires guidance suggests the threat of thunder today remains low.
However with The Wedge in place...low level moisture and a ripple
in the upper level flow...thunder and rain cannot be ruled out.
Especially across the eastern part of the County Warning Area. No changes to the
forecast were made and no further updates are expected at this time.
Previous discussion... /issued 735 am EDT Thursday Sep 18 2014/
Short term /today through Friday/...
/issued at 439 am EDT Thursday Sep 18 2014/
latest surface analysis shows a nearly stationary cold front near an
Americus to Swainsboro line where it will likely meander today.
Models hint at a series of disturbances developing a wave along the
frontal boundary that could help provide a focus for at least
isolated convection across mainly the southeast and east central
portions of the state this afternoon and evening. Local hires model
precipitation fields also suggest this potential. Will continue to show a
slight chance of showers and thunderstorms across the eastern half
of the forecast area for today. A cold dome of high pressure
currently across the Ohio and Tennessee valleys will drift east and
establish a cool easterly flow tonight. This will spread ample low
clouds into the state overnight... then set up a cool reinforcing
wedge of high pressure across much of the state on Friday. Models
also show an upper disturbance settling over the state on Friday.
This has the potential to enhance clouds and rain chances on Friday.
Although cannot rule out an isolated thunderstorm over the far south
and southeast zones Friday afternoon... will only mention rain
showers for now as model instability fields suggest any thunderstorm
threat will be closer to the Georgia coast and further south into
As for temperatures... the cool northerly flow and increasing clouds will
result in near or slightly cooler than normal highs for today and
tonight. The cloudy easterly flow and spotty showers should result
in cooler than normal highs on Friday. A mav and met blend for temperatures
and probability of precipitation looked reasonable with uncertainty on timing and coverage
of clouds and rain potential...especially tonight and Friday.
Long term /Friday night through Wednesday/...
/issued at 439 am EDT Thursday Sep 18 2014/
the extended forecast starts out with a slightly the drier
airmass over the region and a wedge of high pressure building in
from the NE. This wedge will bring Atlantic moisture back in across
the area with mainly overcast skies for the weekend. There may be a
few showers and thunderstorms across central Georgia but not much
expected. This wedge is expected to continue across the region
through Sunday night before another frontal system moves in from
the northwest Monday morning. As the next frontal system moves into north
Georgia the frontal boundary weakens a bit with the majority of the
moisture staying north and east of the state. Have decided to
continue with only a slight chance of showers and thunderstorms
Sunday night and Monday. Once this next front exits the state
Monday night...another dry airmass and high pressure ridge build
in from the Great Lakes states through day 7.
main concern through the forecast period is the chance of IFR
ceilings tomorrow morning. Wedge should start to build into the
area and bring with it low ceilings. There is a possibility that
the low clouds could last longer than forecast...especially if The
Wedge is stronger than forecast. Winds should shift to the east
and stay that way through the period.
//Atl confidence...18z update...
medium confidence on ceilings and duration of ceilings...high on
all other elements.
Preliminary point temps/pops...
Athens 83 64 81 63 / 20 20 20 20
Atlanta 84 66 82 65 / 10 10 20 10
Blairsville 78 59 77 58 / 10 10 20 20
Cartersville 84 60 82 65 / 10 10 20 10
Columbus 89 67 86 68 / 10 10 20 10
Gainesville 81 65 79 63 / 20 10 20 20
Macon 87 65 84 65 / 20 20 20 20
Rome 85 59 83 65 / 10 10 20 10
Peachtree City 84 61 83 64 / 10 10 20 10
Vidalia 87 67 84 67 / 20 20 30 20