Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 201847

Area Forecast Discussion
National Weather Service Peachtree City GA
247 PM EDT Sat Jul 20 2019

.SHORT TERM /Tonight through Sunday Night/...
To begin the short term period, broad and weak low pressure and an
associated enhanced moisture field are in place over the northern
Gulf and southeastern CONUS. These features will propagate slowly
westward through the remainder of the weekend. Heavy rain and
thunderstorms are ongoing across far northern Georgia, but
convection has been slow to fire elsewhere across north and central
Georgia, as stubborn cloud cover and earlier precipitation have kept
temperatures down and inhibited convective initiation. Regardless,
scattered showers and thunderstorms remain possible from the mid-
afternoon into the evening. Mainly chance PoPs are in place across
the area, with the exception of likely PoPs across the far northern
tier, through the remainder of the afternoon before diminishing

Precipitable water values are around 2 inches across the area,
indicating ample deep moisture, and boundary layer winds are once
again quite slow. As a result, there is still a potential for some
localized flash flooding concerns where slow-moving stronger cells
produce persistent rainfall over a given area. With tall, skinny
CAPE indicated by the thermal profile and SBCAPE values of 2000-3000
J/kg , there is a chance that a few thunderstorms could be strong
and capable of producing gusty winds, frequent lightning, and heavy
rainfall. An isolated severe storm cannot be ruled out. As the axis
of heavier moisture shifts to the west of the area on Sunday, PoPs
will be a bit lower than today. The highest PoPs will be focused
across northwest Georgia with high-end chance PoPs, with slight
chance to low-end chance PoPs elsewhere across the forecast area.

High temperatures will be near climatological averages today and
tomorrow, in the mid 90s in east and central Georgia and in the
upper 80s and low 90s elsewhere across the forecast area. With
dewpoints in the low to mid 70s and humid conditions, heat indices
could reach into the low 100s in locations in central and east
Georgia this afternoon and Sunday afternoon. However, heat indices
are not expected to reach Heat Advisory criteria either this
afternoon or tomorrow afternoon.


.LONG TERM /Monday through Saturday/...
Only tweaks to the long term based on the latest guidance.


Main concerns in long term period continue to be timing for
convection and likelihood that front will push through CWA next

Model guidance still indicating large elongated upper ridge will be
replaced by more amplified pattern with high amplitude ridge over
the western CONUS and upper trough over the east half. Prior to and
during this transition, noticeable weakness in the upper ridge will
remain just to our west with deep moisture and slightly cooler mid
level temps.

Convection coverage may decrease a bit at start of long term period
on Monday with slightly drier air moving in from the east. However
as shortwave and front approach from the NW, moisture from weakness
gets pooled ahead of front so expect more widespread convection on
Tuesday. Guidance blend PoPs nearing categorical which matches well
with neighboring WFOs. Can`t rule out chc of slightly more organized
strong/severe storms on Tuesday as well tho abundant clouds and
lingering stratiform precip in the morning may significantly limit
afternoon heating and instability. Heavy rain also likely in this
pattern but hopefully mean winds aloft and vertical wind shear will
be sufficient to keep storms moving and not remaining in any one
place for too long.

Models in better agreement on how far front will push but still
skeptical based on subjective knowledge of fronts making it that far
south in July. Guidance not going too crazy with cooler/drier air at
the surface so only small modification to model blend temps/
dewpoints. Did adjust PoPs a bit to keep slight chc and TSRA
lingering longer behind front based on uncertainty mentioned earlier.



18Z Update...
Low-end MVFR cigs were slow to improve throughout the morning,
but have mainly scattered out to begin the TAF period. A cu field
at 035-040 is expected to be in place this afternoon. Scattered
TSRA/SHRA is anticipated to develop in the mid-afternoon, and have
maintained a TEMPO for TSRA at 19-23Z at the metro sites for the
most likely time for thunderstorms in the area. Winds will remain
SW at generally 3-7 kts through the period, with the only
exceptions being any variable gusts where TSRA occurs. Some MVFR
vsby restrictions due to patchy fog are possible in the early
morning tomorrow, but are expected to remain away from TAF sites
at this time.

//ATL Confidence...18Z Update...
Medium confidence on all elements.



Athens          72  93  73  93 /  20  20  10  30
Atlanta         73  90  73  89 /  40  20  20  40
Blairsville     67  83  67  81 /  40  40  30  80
Cartersville    72  90  72  90 /  40  40  30  50
Columbus        73  92  74  93 /  20  20  10  30
Gainesville     72  89  72  88 /  30  20  20  50
Macon           73  94  74  94 /  20  20  10  30
Rome            72  90  72  90 /  40  50  30  60
Peachtree City  71  91  72  91 /  30  20  20  40
Vidalia         74  96  74  96 /  10  30  20  30




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