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Area Forecast Discussion (AFD)

Issued by Peachtree City, GA (FFC)

                            
769 
FXUS62 KFFC 211537
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
1037 AM EST Tue Nov 21 2017


.UPDATE...
Have just made minor tweaks to the POPs/weather, to lower light
rain chances to slight chance through this evening across mainly
central GA. Weak impulses look to stay outside of forecast area
with just isolated light showers expected. Otherwise temperatures
and cloud cover looks on track and only minor tweaks made to
hourly trends based upon current obs. Latest forecasts issued
shortly.

&&

.PREV DISCUSSION... /Issued 302 AM EST Tue Nov 21 2017/ 

SHORT TERM /Today through Wednesday/...
Surface high pressure over the western atlantic and eastern
seaboard is causing low level moisture/clouds to increase
across the forecast area. This low level flow will also aid
the potential for enough upward vertical motion to allow for 
mainly small chances for light rain across much of the forecast
area favoring only slightly the far ne mountains and the southern
portion of central GA. 

A weak cold front is forecast to move across the area tonight and
the first portion of Wednesday. This will continue mainly small
chances for light rain overnight favoring east and central GA and 
portions of central GA on Wednesday.

The increase of low level moisture today will allow for areas
of fog tonight and will need to monitor for dense fog potential.

Forecast high temperatures are running within 1-3 degrees of
normal today and Wednesday. Forecast low temperatures are running
4-8 degrees above normal tonight.

Overall confidence is low to medium.

BDL

LONG TERM /Wednesday Night through Monday/...

Models in the long term continue to vary from run to run on the
evolution of Thanksgiving Day system but fortunately have more
agreement among themselves than at any point in the last several
days. Both indicate a developing area of low pressure by the start
of the extended period over the Gulf of Mexico. The GFS is
slightly stronger and further north with the system than the ECMWF
but overall deep moisture profiles are very similar with this run.
By Wed night, precipitable water values in excess of 1.4 inches
are moving into portions of Central GA in increasing favorable
isentropic upglide environment. 

Given the good model agreement, will go with likely pops for the 
extreme southern tier but give a sharp gradient to pops with less 
than 20 for the Atlanta Metro. it should be noted though that it 
would take very little in surface low displacement northward to 
go from nothing to near washout for areas along I20 on 
Thanksgiving.

Model differences continue through Friday with GFS faster with the
progression of low and ECMWF remaining displaced southward
although both models show a Florida peninsula track. This should
allow drier air to be drawn in on the north side of the system
Friday into the weekend effectively ending rain chances. Fairly
benign pattern thereafter with just a dry front to contend with
before high pressure builds in for the remainder of the period.

Deese

AVIATION.../Issued 555 AM EST Tue Nov 21 2017/ 
12Z Update... 
MVFR-VFR ceilings with some overall improvement possible with 
higher level ceilings for parts of the day. Patchy to areas of 
light rain or even drizzle possible. Confidence for ceiling 
heights and rain/drizzle chances are low and will need to be 
monitored. Surface winds light SE-NE less than 10 kts becoming 
north tonight. Potential for low clouds and fog tonight.

//ATL Confidence...12Z Update...
High confidence for winds today.
Low to medium confidence for all other elements. 

BDL

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          60  46  64  41 /  20  20   5  10 
Atlanta         60  47  61  42 /  20  20   5  10 
Blairsville     56  40  57  34 /  20  20   0   0 
Cartersville    59  42  58  37 /  20  10   0   5 
Columbus        65  50  66  46 /  30  20   5  20 
Gainesville     57  45  61  40 /  20  20   0   5 
Macon           69  50  67  46 /  20  30  10  40 
Rome            60  41  58  35 /  10   5   0   0 
Peachtree City  62  45  63  41 /  20  10   5  20 
Vidalia         70  52  69  49 /  20  20  20  60 

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Atwell
LONG TERM....Deese
AVIATION...BDL