Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
251 PM EST Sat Jan 31 2015
Short term /tonight through Sunday night/...
high pressure will continue to shift offshore overnight in advance
of an early week cold front. High clouds will increase overnight.
Model soundings show sparse moisture below 600mb early in the day on
Sunday...so the lower level clouds are not expected until middle
morning or later. Temperatures mostly in the 30s are expected
Precipitation will begin to overspread the County warning forecast area by the late
afternoon hours ahead of the cold front on Sunday. The highest
amounts of rain are likely in the west...with up to half an inch
possible. In the east...less than a tenth of an inch. Conditions
should remain stable enough to preclude any thunder.
Cold air aloft begins to penetrate the northern County warning forecast area after 06z
Monday. Conditions will become favorable for a rain/snow mix at the
higher elevations in north Georgia. The timing for any accumulating
snowfall should be after 09z. Amounts are fairly modest...under an
inch through 12z and at elevations mainly above 1500-1800 feet.
Long term /Monday through Saturday/...
system from the short term will be exiting at the beginning of the
long term. With some wrap around moisture...could see light
snowfall at the beginning of the extended. This is supported by
the GFS bufr sounding at Brasstown Bald that shows saturation
below 800mb with temperatures less than freezing. Similar with the
NAM bufr but a little slower to bring in the freezing
temperatures. Given exiting moisture any snowfall amounts after
12z Monday should be relatively light and limited to the higher
elevations of far north Georgia. Precipitation should diminish by
late Monday morning.
Once the front and wrap around moisture move through...high
pressure returns for Tuesday. Models are slower with the return of
the rain for the late week so have cut back on probability of precipitation for Wednesday.
Still some big differences between the GFS and European model (ecmwf) in terms of
precipitation location for the late week system. European model (ecmwf) keeps the
rain south of the County Warning Area while the GFS spreads it across the whole
County Warning Area for late Wednesday night into Thursday night. Have continued
with the trend of the previous forecast spreading the
precipitation into north and central Georgia during this time
frame. Temperatures are cold enough to support a small area of
snow across far north Georgia Wednesday night and most of north
Georgia Thursday night. There is still a good bit of uncertainty
though with this given the lack of confidence in the chance of
precipitation. Something to watch though over the next few days.
high pressure will continue to move overhead through tonight. A
cold front is expected to move through the outlook area overnight
Sunday into early Monday...bringing widespread rainfall. In the
highest elevations of northern Georgia...rain may mix with snow at
times early Monday morning. Total rainfall amounts up to an inch
Fuel moistures remain low...and relative humidity values will continue at or below 25
percent for the remainder of the afternoon and early evening.
Extended the fire weather statement until 23z.
18z update... light and variable winds expected for the remainder
of the afternoon with speeds at or below 5kt. Winds will eventually Switch
Back around to the southeast for the overnight hours. A cold front will
move through the region tomorrow...bringing widespread rainfall.
MVFR ceilings expected by middle morning. There is some potential for
ceilings to dip to IFR during the late afternoon.
//Atl confidence...18z update...
medium confidence on ceilings...they could dip lower during the late
afternoon on Sunday. High confidence remaining elements.
Preliminary point temps/pops...
Athens 36 57 46 47 / 0 40 100 30
Atlanta 39 56 41 42 / 0 70 100 10
Blairsville 33 46 36 39 / 10 70 100 30
Cartersville 37 55 39 41 / 10 80 100 10
Columbus 40 63 47 48 / 0 60 100 10
Gainesville 36 51 41 43 / 5 70 100 20
Macon 36 65 51 52 / 0 30 90 20
Rome 36 54 38 41 / 10 80 100 10
Peachtree City 36 59 43 45 / 0 60 100 10
Vidalia 38 67 54 57 / 0 20 60 40