Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 270235

Area Forecast Discussion
National Weather Service Peachtree City GA
1035 PM EDT Mon Oct 26 2020


The big issue for the overnight period will be the prospects for
dense fog to develop. Low clouds already well ahead of schedule
and feel it is only a matter of time before dense fog develops.
GLAMP is onto this and is painting a large area along and east of
an Atlanta to Macon line in dense fog. Will need to monitor for
possible Dense Fog Advisory. Otherwise, will continue to run TCM
winds for the possible tropical effects later this week.



.PREV DISCUSSION... /issued 746 PM EDT Mon Oct 26 2020/

PREV DISCUSSION... /issued 339 PM EDT Mon Oct 26 2020/

.Monday Afternoon Forecast Discussion...

SHORT TERM /Tonight through Tuesday Night/...

Thanks to some weak CAD in the Carolinas, combined with the recent
rainfall driving dewpoints into the low to mid 60s, have formed a
dense low-level cloud deck that is slowly eroding away generally
from Georgia`s state boarders inward. The cloud cover has helped
keep the forecast area cooler today with highs around 70 for most of
North Georgia with some upper-70s in central Georgia.

Tomorrow, as the wedge is forced out, slightly less cloud cover will
help drive temps up to the mid 70s to low 80s, roughly 7-8 degrees
above normal for this time of year.

By Tuesday night into early Wednesday morning, a wave of tropical
moisture will be moving into the area ahead of what is now Tropical
Storm Zeta, that will push PWAT values from below an inch to near 2
inches. This increased flux of moisture will override existing
weak stationary frontal boundaries to increase rain chances
through the area, though coverage is still uncertain.


LONG TERM /Wednesday through Monday/...

No major changes made to the extended forecast. The extended
forecast starts off with the remnants of Zeta moving through then
things appear to clear out and cool off.

The GFS and ECMWF have come into much better agreement with the
timing and strength of the upper low that is progged to move
through the southeast states during the mid to late part of the
week. Both models have the low starting to eject out of the desert
SW on Tuesday and then continuing east across the Gulf States
through Friday. The upper low with a longwave trough should move
through the CWA during the day on Friday. The upper level low
associated with Zeta will move onshore and move east ahead of the
main upper low and then across the CWA sometime late
Wednesday/early Thursday.

At the surface, a stationary frontal boundary should stretch from
the Middle Atlantic states back through eastern Texas late Tuesday
into early Wednesday. The official NHC track for Zeta has it making
landfall Wednesday evening along the LA gulf coast and eventually
becoming absorbed into this frontal system by Thu morning. The
combined systems move east late Wednesday and finally across the CWA
during the day on Thursday. Both the GFS and ECMWF are very similar
with the timing of the surface systems also.

High pressure will build back in behind the front/tropical remnant
system. The upper flow briefly turns NW, but should return to a more
zonal pattern by early next week.

The axis for highest rainfall remains along and north of the
Interstate 85 corridor. This seems reasonable. Amounts keep changing
from run to run, but widespread 2" to 3" are likely north of I-85
with locally higher amounts possible. The heavy rain axis/total QPF
will be heavily dependent upon the track of Zeta`s remnants and may
shift slightly over the next few runs.



It is now almost a certainty that CSG will be the only site with
partial clearing this evening. As the sun sets, evidence that
clouds have already stopped their retreat and MVFR will be the
rule for the next several hours. Guidance has picked up on this
trend and is dropping cigs much more rapidly through the overnight
period and will follow suit. This will result in IFR quickly
developing later this evening and LIFR by early Tue morning. Could
be a slow improvement much like today with VFR not anticipated at
ATL until at least 21Z. Winds should be straightforward at least
with values less than 5kts and remaining out of the east.


Medium of VLIFR potential Tue morning.
High on remaining elements.



Athens          59  75  61  75 /   5   5  30  50
Atlanta         62  76  64  74 /  10  10  40  50
Blairsville     56  72  56  68 /  10  10  30  50
Cartersville    61  76  62  74 /  10  10  40  60
Columbus        65  82  67  79 /  10  20  30  50
Gainesville     59  74  61  71 /  10  10  30  50
Macon           61  83  65  82 /   5  10  20  50
Rome            61  78  63  75 /  20  10  40  60
Peachtree City  62  78  64  75 /  10  10  30  50
Vidalia         63  83  67  85 /   5   5  10  40


Flash Flood Watch from Wednesday morning through Thursday
evening for the following zones: Banks...Barrow...Bartow...
Heard...Jackson...Lumpkin...Murray...North Fulton...Paulding...
Pickens...Polk...South Fulton...Towns...Union...Walker...White...



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