Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
303 am EST Sat Dec 27 2014
Short term /today through Sunday/...
models generally consistent with moving a slow moving cold front...
now over the middle U.S. ... north Georgia late Sunday. Increasing deep
moisture in the SW flow aloft ahead of the front will increase today
and tonight with rain chances increasing as well. Highest probability of precipitation will
be over north Georgia with a period of moderate to possibly heavy rain later
tonight into Sunday.
No instability whatsoever through tonight with MUCAPES 100 or less on
the west side of the forecast area on Sunday...slightly higher on
the European. This will keep thunderstorm chances too low to
mention at this time but may need to be added later.
Highest precipitation amounts are expected over north Georgia through Sunday with
amounts in the 1 to 2 inch range. Will need to monitor the area for
a Flood Watch if amounts increase any.
With a warming airmass...forecast high temperatures running 7-11
degrees above normal today and 9-14 degrees above normal
Sunday...using a model blend. Forecast low temperatures running 14-
17 degrees above normal tonight.
Overall confidence is medium to high.
Long term /Sunday night through Friday/...
GFS/European model (ecmwf) in pretty good agreement with the exiting system early in
the long term. As the next low digs over the southwest U.S. A nearly
zonal flow develops with a low level north to northeast flow. This
should keep a steady stream of upper level clouds moving across the
southern U.S. This will also keep temperatures at or just slightly below
normal through much of the week. Differences develop in the models
with the timing of the next system. The European model (ecmwf) is faster with
bringing moisture into the County Warning Area Thursday night but it also has a
deeper low over the southern rockies. This brings in ample moisture
Thursday night with a warmer southerly flow while the GFS is slower
and a little cooler as it holds on to the surface high over the County Warning Area.
Will go with a compromise on timing of probability of precipitation but at least both
indicate moisture moving into the County Warning Area so will go with low chance
Thursday night...and high chance to likely beginning Friday. There
still remains the question of winter precipitation Thursday night. Both
models push the 0c 850 temperature north of the County Warning Area with the European model (ecmwf) pushing
the 0c line the furthest north...into Kentucky. Low level thicknesses
indicate all liquid precipitation. At this time...will go with a chance of
r-/zr- in the mountains late Thursday night. Confidence in this
happening is low.
06z update... VFR conditions expected with increasing clouds and
rain chances through tonight. Increasing IFR to MVFR ceilings tonight
with MVFR visibilities due to rain and fog. Light and variable winds 5
kts or less...favoring southeast during the day.
//Atl confidence...06z update...
medium to high confidence on all elements through today.
Preliminary point temps/pops...
Athens 62 47 63 51 / 20 80 80 80
Atlanta 63 51 64 51 / 40 100 80 80
Blairsville 61 45 56 47 / 20 100 100 80
Cartersville 59 48 60 48 / 40 100 90 80
Columbus 64 54 70 54 / 30 60 40 70
Gainesville 59 49 59 48 / 30 100 100 80
Macon 65 51 71 56 / 20 40 20 60
Rome 58 48 60 48 / 50 100 100 80
Peachtree City 64 51 66 51 / 40 90 70 80
Vidalia 68 53 73 59 / 5 20 10 30