Scientific Forecaster Discussion
fxus62 kffc 230017
Area forecast discussion
National Weather Service Peachtree City Georgia
817 PM EDT Mon Jul 22 2019
Coverage of showers and isolated thunderstorms are waning into the
evening hours as a wide areas of storms along and ahead of a cold
front slowly advances towards northwest Georgia. Model runs are aiming
towards a dying line of storms in NE Georgia overnight, with
reformation around the I-85 corridor tomorrow morning. The line
is then expected to sweep southeastward through the evening
hours. With all that said, overnight convective lines of storms
are one of the hardest things for short-term model prediction,
and therefore, the situation will remain fluid throughout the
Previous discussion... /issued 240 PM EDT Mon Jul 22 2019/
Short term /tonight through Tuesday night/...
Main concern continues to be a slow moving cold front across the
Ohio to lower/mid MS valleys that is forecast to move across the area
on Tuesday and possibly into far northwest Georgia late tonight. The front will
likely stall over se Georgia Tuesday night. An axis of deep moisture is
associated along with an upper level trough/short wave.
The airmass out ahead of the front across Tennessee into far N Georgia is fairly
unstable and there is the possibility for isolated severe storms
across far N GA, mostly likely this evening, as per the Storm Prediction Center day 1
outlook, with damaging winds as the main hazard along with frequent
lightning and locally heavy rainfall.
Rain and storm chances will increase tonight and Tuesday across the
area from north to S as the front and deep moisture approach. A few strong
thunderstorms can be expected on Tuesday and isolated severe storms
can not be ruled out.
Rain chances will decrease and end for N and portions of West Georgia late Tuesday
into Tuesday night.
Forecast low temperatures are running about 2-7 degrees above normal
across the area tonight and then around normal to as cool as 7 degrees below
normal Tuesday night as a cooler airmass moves over the area, especially
Forecast high temperatures are running near to about 12 degrees below
normal on Tuesday.
Overall confidence is medium to high.
Long term /Wednesday through Monday/...
A cooler and drier airmass will be setting up over the area behind
the cold frontal boundary as it pushes from northwest to southeast.
Some lingering chance pops will be in place as the period begins on
Wednesday morning, but will diminish as the front moves southward
out of the forecast area by Wednesday evening. Wednesday night and
Thursday are then not anticipated to see any precipitation after the
front clears the area entirely, with the only exception being some
slight chance pops in the far southeastern corner of the forecast
area. Temperatures will be consistently cooler than average behind
the frontal boundary, with high temperatures mainly in the low to
mid 80s on Wednesday and mid to upper 80s on throughout the
remainder of the week. Low temperatures will similarly be mainly in
the 60s, with even some upper 50s in the higher elevations of
Some model disagreement still exists with respect to the
redevelopment of weak troughing and associated moisture return to
the area. While the latest European model (ecmwf) keeps the area mostly dry through
the early parts of next week, it is starting to come into better
agreement with the GFS, which indicates a return of deeper
moisture and precipitation across central Georgia starting Friday
and gradually spreading northward on Saturday and Sunday. Have
continued to lean closer to the more consistent GFS solution, with
slight to low-end chance pops on Friday through the remainder of
the period. However, will continue to monitor these trends as the
end of the week approaches.
vcsh will remain across the area most of the early evening as a
line of rain showers advances into the forecast area. Best timing for
northern taf sites (incl atl) will be from 12-21z with multiple
rounds of storms possible and cigs expected to drop to MVFR/IFR
range. Rain showers/thunderstorms and rain expected to reach southern taf sites by late
morning or early tomorrow afternoon. Otherwise VFR expected
through the evening. Surface winds S-west 10 kts or less becoming west-north
//Atl confidence...00z update...
high confidence on rain showers/thunderstorms and rain coverage.
Low to medium confidence on timing and cigs.
Medium confidence on all elements.
Preliminary point temps/pops...
Athens 72 80 65 85 / 60 80 50 10
Atlanta 72 78 66 84 / 70 80 30 10
Blairsville 67 75 57 79 / 80 80 20 10
Cartersville 71 79 63 84 / 70 80 20 5
Columbus 73 82 69 86 / 40 90 50 20
Gainesville 71 77 64 83 / 70 80 30 10
Macon 73 87 68 85 / 40 80 80 30
Rome 71 80 63 85 / 70 80 10 5
Peachtree City 72 79 66 84 / 70 80 40 10
Vidalia 74 92 71 81 / 20 80 80 60