Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
207 PM EST Tuesday Dec 10 2013
Short term /tonight through Wednesday night/...
skies quickly clearing behind exiting short wave and associated
surface cold front this afternoon. Upper flow remains essentially
zonal through the short term forecast period with surface high
pressure dominating. Very dry airmass settles into the region with
the ridge. Medium range models do show a short wave sweeping into
the Ohio Valley tailing south into the Tennessee Valley late
Wednesday...however little moisture available for more than an
increase in high-level cloudiness. Temperatures will be much more
seasonal than we have seen in the past week or so.
Long term /Thursday through Tuesday/...
rain event still looks on track starting later Friday night into
early Sunday. Mainly tweaked probability of precipitation higher to reflect greater
confidence for rain chances. Bdl
extended begins with long wave trough dominating the eastern half of
the country...with another shortwave diving through the Central
Plains. This dry wave will push into the southeast Thursday morning
but will bring a reinforcing shot of cool air to the region. Weak
ridging builds in aloft Friday ahead of a strong system over the
Desert Southwest. Surface low will push into the Southern Plains
Friday night...with strong southerlies pumping Gulf moisture back
into the southeast. Precipitation overspreads the area Friday night and
especially Saturday...and given agreement between GFS and European model (ecmwf) as
well as run-to-run consistency...have increased probability of precipitation to categorical
on Saturday. Looks like easily another inch of rain across the area.
There may be enough instability creeping into southern zones
Saturday afternoon to warrant adding thunder to the forecast...but
have left it out for now.
Complicating factor is diabatically enhanced classical cad
developing Friday night and early Saturday...though right now
thicknesses across Georgia for the most part look too warm for any
wintry precipitation...but later forecasts will have to be reevaluated.
Did add a brief rain/snow mix extreme north Sunday morning as the
cold front pushes through. GFS is just a tad faster than the European model (ecmwf)
by this point so uncertainty is increasing. Cool and windy behind
the front but clearing into early next week.
we will likely see a few hours with relative humidity at or below 25
percent Wednesday afternoon and again Thursday afternoon for some
areas. Winds will be less than 10 miles per hour on Wednesday and 10 to 15
miles per hour for some areas on Thursday. However 10-hour fuels are wet
from recent rains. How much they dry over the next 2 days will
need to be monitored.
MVFR to VFR conditions currently with VFR conditions area wide by
19-21z...continuing through the remainder of the forecast period.
Winds will remain northwesterly 10-16kt west/ g18-28kt through 22-24z...becoming
northwest-north 3-6kt by 04z and eventually NE 3-5kt by 12-14z.
//Atl confidence...18z update...
Preliminary point temps/pops...
Athens 28 54 29 50 / 5 5 5 0
Atlanta 28 55 30 48 / 5 5 5 0
Blairsville 24 51 23 43 / 5 5 5 0
Cartersville 24 53 24 46 / 5 5 5 0
Columbus 33 59 34 55 / 5 5 5 0
Gainesville 28 52 30 47 / 5 5 5 0
Macon 29 58 29 55 / 5 5 5 0
Rome 24 52 24 45 / 5 5 5 0
Peachtree City 26 56 27 49 / 5 5 5 0
Vidalia 36 60 37 57 / 5 5 5 0