Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
430 am EDT Wednesday Sep 3 2014
Short term /today through Thursday/...
persistent convection along shortwave energy in far north Georgia along
with some possible orographic enhancement has resulted in
significant rainfall totals of near 3-5 inches in some locations
early this morning and flooding concerns.
Another set of stormy days on tap through short term with diurnal
rounds of convection expected as deep Gulf/Atlantic moisture stays
entrenched across the region despite some ridging aloft. A bit
higher chance for showers and storms today as a lobe of positive vorticity advection slowly
pushes eastward across western and northern portions of the County Warning Area.
Have increased to likely probability of precipitation because of this and high chance
elsewhere due to the lingering Lee trough in the central portion.
Trended convective initiation and probability of precipitation on general hi-res
consensus...which suggests storms will be well widespread and
perhaps lingering through this evening. NAM precipitable waters near 2 inches and
low level lapse rates near 8.5 with decent cape indicate strong to
severe development is again possible with damaging winds...frequent
lightning...and heavy downburst rainfall as main threats. Flash
flood threat may be a bit higher as well given the hi-res trends
with what has been recently observed. North Georgia will have to be
watched closely given the aforementioned recent rain.
Similar regime present for Thursday though a bit less upper level
forcing so have gone with chance probability of precipitation area-wide by afternoon into
Temperatures still looking to be near to slightly above normal with highs
in upper 80s to low 90s for most areas.
Long term /Thursday night through Tuesday/...
warmer than normal temperatures and scattered afternoon and evening
showers and thunderstorms expected through early next week.
Weak upper level ridging will remain over the southeast...however
both European model (ecmwf) and GFS show a weak trough over the mouth of the
Mississippi River with an axis of vorticity across portions of west
and north Georgia. A surface front will wash out as it traverses
the forecast area through the latter part of the weekend providing
an additional focus for thunderstorm activity.
Some discrepancies noted in guidance temperatures Thursday but
generally in line through the extended periods with above normal
Previous discussion... /issued 216 am EDT Wednesday Sep 3 2014/
mainly VFR conditions though chance for morning MVFR visibilities at some
sites. Ceilings generally near 12 kft this morning with some scattered near
5 kft. Afternoon cumulus field likely in 4-5 kft range along with
decent thunderstorms and rain potential after 18-19z. Winds generally light and vrb
to calm initially becoming northwest to west under 7 kts today. Vrb gusts
and reduced visibilities again possible with any storm development.
//Atl confidence...06z update...
medium in precipitation timing.
High all else.
Preliminary point temps/pops...
Athens 93 71 90 70 / 50 40 40 30
Atlanta 89 73 90 73 / 60 40 40 30
Blairsville 85 66 84 68 / 60 40 40 30
Cartersville 89 69 91 73 / 60 40 40 30
Columbus 92 74 92 74 / 60 40 40 30
Gainesville 89 72 88 72 / 60 40 40 30
Macon 92 71 92 72 / 50 40 40 30
Rome 90 69 92 73 / 60 40 40 30
Peachtree City 89 70 89 72 / 60 40 40 30
Vidalia 91 73 92 74 / 40 40 40 30