Scientific Forecaster Discussion
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Area forecast discussion...updated
National Weather Service Peachtree City Georgia
602 PM EST sun Dec 15 2019
Update for aviation...
Previous discussion... /issued 221 PM EST sun Dec 15 2019/
Short term /tonight through Monday/...
Synoptically, a broad longwave trough will begin digging into the
southwestern conus, forcing moist, southwesterly flow into the Gulf
states. This plume of moisture, following a warm front, will bring
dense cloud cover and isolated showers from the northwestern corner
of Georgia all the way through the I-85 corridor, starting late
tonight. Any showers that develop should remain light with minimal
accumulations if any. By Monday, a cold front will begin making it's
way through the southeast with a line of showers and thunderstorms
making its way towards the area. Before the system arrives
temperatures will increase into the unseasonably warm mid-60s to mid-
70s, around 10-15 degrees above normal. Some isolated prefrontal
showers will be possible, but precip chances will really begin to
increase Monday evening as the cold front reached the northwestern
corner of the state. More details discussed below.
Heading into the evening hours (monday), will be closely monitoring
ongoing severe weather coming out of Louisiana, Mississippi and
Alabama. Hi-res/short-term models continue to show an overall
weakening trend of storm organization/intensity as broken line of
showers/storms approach northwest and west-central Georgia between 6 PM
and midnight Monday evening. However, low-mid 60s dewpoints yielding
just enough instability along with 40-50kt low lvl (0-3km) winds to
support small pockets of organized convection that could result
in strong to damaging winds and perhaps even a brief/spin-up
tornado. Axis of heaviest rain with this system will be across
north Georgia where a more prolonged period of heavier rain is likely.
As much as 1 to locally 2 inches is expected with lesser amounts
south/east of I-85.
Risk for severe includes areas along and west/north of I-85 through
daybreak Tuesday morning (12z/tues). After 12z/tues, potential for a
few stronger storms will exist east/south of I-85 from Columbus to
Macon and points south. However, weakening low lvl wind shear and
overall support should end overall severe threat across these areas.
Cold front gets through the atl area around daybreak Tuesday and
will continue advancing south and east, clearing the entire forecast
area by mid afternoon. Gusty northwest winds 15-30 miles per hour will usher in
much colder and drier air. Maximum "high" temps will likely occur
early in the day for most locations, with temps steady or slowly
falling through the day. Djn.83
Long term (wednesday through sunday)...
Cooler (but near seasonal) temperatures will exist across the area
Wed and thurs but it will be dry. Next chance for precipitation
arrives late Friday into the weekend with a lot of model run-to-run
inconsistencies. Latest solutions showing a rather significant
closed upper low diving far south then tracking along the Gulf
Coast. Given the inconsistencies seen with the models and the fact
we are still 5-7 days out, am leaning towards a more conservative
forecast with just low chance pops spreading across the area late
Friday into Saturday.
No major warm periods or cold snaps seen affecting the area through
potential for MVFR ceilings to increase or continue overnight
with some potential for brief IFR ceilings toward daybreak.
Improvement to VFR is expected for most locations Monday.
Surface winds calm or light southeast-SW overnight and less than 10 kts
on Monday. Light rain or showers possible late tonight and
//Atl confidence...00z update...
low confidence for ceilings heights
medium to high confidence all other elements.
Preliminary point temps/pops...
Athens 45 67 58 63 / 10 20 80 80
Atlanta 51 66 60 63 / 20 30 90 80
Blairsville 47 60 53 57 / 20 50 90 70
Cartersville 52 67 55 59 / 20 40 90 60
Columbus 50 71 63 65 / 10 20 80 80
Gainesville 48 64 58 62 / 20 30 90 80
Macon 45 73 61 66 / 5 10 70 80
Rome 52 68 53 57 / 20 50 90 60
Peachtree City 50 69 60 63 / 20 30 80 80
Vidalia 46 76 61 73 / 5 10 40 70