Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
333 PM EDT Thursday Aug 27 2015
Short term /tonight through Friday night/...
a gradual modification of the air mass should take place during the
short term. Long wave trough along the eastern states expected to
move east and fill...leaving an upper low west of the forecast area
Friday and Friday night. Drier air across north and central Georgia will
continue to give way to increasing moisture during the period as
winds become more south to southeast. Have kept a slight chance for
extreme east central zones overnight and slight chance to chance for
central Friday and Friday night. At the lower levels...easterly
winds should keep some clouds across the forecast area overnight and
into the day Friday. Have stayed close to mav/met temperatures.
Long term /Saturday through Thursday/...
moisture return in full swing at the start of the long-term with
pattern featuring 500 mb closed low in the Gulf and expansive surface high
pressure over the NE. 310k surfaces still indicating weak isentropic
ascent on Saturday as S/SW flow aloft rides atop east/southeast surface flow. This
should spark scattered showers across the area...perhaps a few
thunderstorms too as MUCAPES rebound between 1000-1500j/kg. Lead
shortwave will also eject out of gom closed low which may provide
additional background ascent to enhance precipitation coverage late in the
Closed low then ejects into the southeast overnight Sat into sun. DCVA
associated with this wave should sustain rain/storm chances during
this period...though coverage is uncertain as GFS/NAM bufr soundings
show weak instability. Modest middle-level flow/25-35kts/and precipitable waters
approaching 2in suggest any ongoing/additional storms could produce
heavy rain and gusty winds...especially across our southern counties.
Evidence of a dry slot as this system exits should lessen precipitation
chances from SW to NE during the day on sun. Subsidence in the wake
of this system should keep Monday mostly dry.
Remainder of the forecast blurred by Tropical Storm Erika. 12z
GFS/CMC ride this system along the East Coast of Florida while 12z European model (ecmwf)
brings a significantly weaker storm more westward into southern Florida. Still
unclear whether majority of County Warning Area will be affected...though any
persistent westward trend could make things interesting.
Aviation... 18z update... MVFR slowly improving and should be
VFR scattered-bkn040 or higher this afternoon. Ceilings lowering to MVFR
around 09z Friday morning and improving gradually to VFR by Friday
afternoon. No convection expected except a few thunderstorms
central Georgia Friday afternoon. Easterly wind this afternoon in the
12-14kt range with a few gusts then slowly subsiding to 5 to 8kt
or less after 00z.
//Atl confidence...18z update...
confidence high on all elements
Preliminary point temps/pops...
Athens 67 86 69 84 / 10 10 10 50
Atlanta 67 87 70 84 / 5 10 10 40
Blairsville 60 81 62 80 / 5 5 10 40
Cartersville 65 88 68 85 / 5 5 10 30
Columbus 69 89 72 87 / 10 20 10 50
Gainesville 67 84 68 82 / 5 10 10 40
Macon 67 90 71 87 / 10 20 20 50
Rome 64 88 68 85 / 5 5 10 30
Peachtree City 64 88 70 84 / 5 10 10 40
Vidalia 71 89 72 88 / 20 30 20 50