Scientific Forecaster Discussion
fxus62 kffc 211120 aaa
Area forecast discussion...updated
National Weather Service Peachtree City Georgia
620 am EST Thu Nov 21 2019
..12z aviation forecast discussion...
Short term /today through Friday/...
Transition day today as the upper ridge axis transits the region
from west to east and surface ridge axis shifts to the Atlantic
coast. Should see a wide mixture of sun and mid/upper-level clouds
through the day. Upper flow becoming increasingly southwesterly
overnight and Friday ahead of upper-level low moving across the
southern/Central Plains into the Mississippi Valley. Weak cold front
drops into the far north by Friday but stalls. Should see increasing
rain chances through the day Friday across the far north with a
relatively tight gradient in pops keeping the area south and east of
the I-85 corridor mainly dry. Temperatures remain mild through the
end of the workweek.
Long term /Friday night through Wednesday/...
Ongoing showers will be on the increase Friday night into Saturday
morning across north Georgia. Rainfall Friday night will initially
be focused in far north Georgia in the vicinity of the
aforementioned cold front. As a surface low develops over the
arklatex Friday night and quickly lifts northeastward into the Ohio
Valley Saturday, the front will progress eastward across the
forecast area. Widespread rainfall will thus spread across the area
through the day Saturday. While only very weak instability continues
to be expected ahead of the front (<200 j/kg sbcape), a mention of
slight chance thunder was added on Saturday given frontal forcing
with no concern for any strong/severe. Rain will end from west to
east Saturday night as the front clears the area. Healthy rainfall
totals continue to be expected, specifically across north Georgia
where widespread 1+" totals are forecast and localized totals in
excess of 2" are more likely in the mountains.
Sunday will bring cooler and sunny conditions with the forecast area
under the influence of Post-frontal high pressure. Dry conditions
will persist through Monday as the upper flow becomes zonal, and the
surface high begins to shift east of the area. Upper flow becomes
southwesterly by Tuesday as models begin to diverge regarding the
timing and strength of the next system. There is general agreement
that pops will begin to increase from the west by late Tuesday into
Tuesday night as the next cold front approaches.
Warm temperatures Saturday ahead of the front will drop to several
degrees below normal on Sunday. The coolest temperatures of the
forecast period will be Monday morning as the surface high settles
over the southeast with widespread mid-to-upper 30s across the County Warning Area.
Temperatures will begin to moderate by Monday as the surface high
shifts eastward with temperatures back to near to slightly above
normal by Tuesday and Wednesday.
VFR conditions will predominate across the forecast area through
this forecast period. Local MVFR or lower visibilities are possible
through 14z, however, no impacts are expected at the taf sites.
Winds will be light, 4kt or less, and variable in direction to begin
becoming southeast to south 4-8kt by 14-16z and eventually south to
southwest after 00z.
//Atl confidence...12z update...
Preliminary point temps/pops...
Athens 67 46 67 55 / 0 5 20 60
Atlanta 67 47 65 57 / 0 5 30 70
Blairsville 63 42 61 52 / 0 10 60 80
Cartersville 68 46 67 56 / 0 10 50 80
Columbus 71 48 70 58 / 0 0 10 20
Gainesville 65 46 64 55 / 0 5 40 70
Macon 70 46 69 56 / 0 0 10 10
Rome 69 46 65 56 / 0 10 60 80
Peachtree City 68 46 66 56 / 0 5 20 50
Vidalia 70 48 72 55 / 0 0 5 10