Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
305 PM EST Tuesday Jan 27 2015
Short term /tonight through Wednesday night/...
deep East Coast upper trough will keep a northwest flow aloft across
the forecast area through Wednesday...but flow should become more
westerly Wednesday night. Next short wave to affect the area beyond
36 hours. Expecting dry weather through the short term. Gusty
northwest winds should diminish this evening with cloud cover also
decreasing. Temperatures showing a gradual warming trend into
Long term /Thursday through Tuesday/...
little change in terms of large scale changes to the long term.
Still two systems to focus on. Precipitation should start late enough on
Thursday to not be a concern with wintry weather Thursday
morning...however potential still exists for some snow across the
far north Thursday night.
Still holding off on the precipitation not starting until Saturday night
with the second system. At this point...temperatures only support winter
precipitation across northern Georgia...however as mentioned below in the
previous discussion...this is something we will need to watch
closely with The Wedge set up. With continuing precipitation and low
temperatures...have also mentioned winter precipitation again for north Georgia
Sunday night. See the previous discussion for details...
/issued at 407 am EST Tuesday Jan 27 2015/
models continue to become in better phase with the main
influencing features of the long term. These consist of two main
systems...the first of which is a weaker shortwave that is a bit
more moisture starved as well as it is prognosticated to traverse the
upper flow near the Tennessee Valley Thursday afternoon into
overnight. Have kept probability of precipitation down to low end chance mainly across the
north...and still cannot rule out a transition to light snow or
flurries in the higher elevations based on the model thermal
profiles before lingering low level moisture exits.
The second system will likely be of more concern with future
updates as a strong 1030+mb parent surface high looks to set up a
classical cad wedge across the area for Saturday...then while
guidance is in good agreement with ample Gulf moisture
overrunning The Wedge...there are discrepancies on timing of
precipitation onset. The GFS advects moisture faster than the
European model (ecmwf)...bringing in by late Saturday night into Sunday morning
which would make for a more interesting situation. Forecast soundings
and surface wetbulb temperatures by 12z Sunday would support possibility of
wintry mix mainly into parts of the north and east. The forecast
of p-type with this system will greatly depend on the strength of
The Wedge and timing of precipitation onset for the degree of diabatic
enhancement. For now have included chance for snow in parts of the
far north Saturday night into Sunday morning...then again Sunday
night before system exits...though updates may need to shift focus
to northeast Georgia and mixed p-type potential if models show some
relative humidity dropping below 25 percent for several hours across
the northeast tomorrow afternoon. However fuels are still wet and
may not dry enough by then. So at this time...no fire weather
concerns are expected.
scattered to broken clouds at or above 035 should linger until around 23z-
00z. Expect mostly clear skies overnight and on Wednesday.
Northwest winds will gust until around 00z then diminish to less
than 10kt overnight. Models are indicating winds may swing over to
east or southeast after 18z Wednesday.
//Atl confidence...18z update...
medium on timing of scattered ceilings. High on all other elements.
Preliminary point temps/pops...
Athens 28 52 31 54 / 0 0 5 10
Atlanta 30 51 35 55 / 0 0 5 10
Blairsville 26 50 30 49 / 0 0 5 30
Cartersville 28 51 31 56 / 0 0 5 20
Columbus 33 55 36 60 / 0 0 0 0
Gainesville 29 51 34 52 / 0 0 5 20
Macon 29 54 30 58 / 0 0 0 0
Rome 27 51 30 55 / 0 0 5 20
Peachtree City 28 52 30 57 / 0 0 5 5
Vidalia 34 54 34 61 / 0 0 0 0