976
FXUS62 KFFC 181044
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
644 AM EDT Thu Jul 18 2024



...New 12Z Aviation Discussion...

.SHORT TERM...
(Today through Friday)
Issued at 326 AM EDT Thu Jul 18 2024

The region becomes fully entrenched in the base of an
upper trof located to the north over the great Lakes
and sandwiched between upper ridging over the Atlantic
and over the western US. The lack of any real
convective inhibitor combined with deeper moisture in place
including 1.7"+ PWATs, should allow us to see well above climo coverage
of showers and storms through the short term. In addition a weak
surface boundary sinks south with the aforementioned trof to our
north and becomes a focus for diurnal convection later today...and
again on Friday. CAMs all suggesting the 18z-00z window as the
most likely time period to see convection which initiates along
that surface boundary over northern GA before sinking southward
through the day. Not expecting any widespread severe weather as
parameters in general are not too impressive, however, similar to
Wednesday, cannot rule out an isolated severe or two for damaging
wind. Given the PWAT values, expect heavy rainfall to be the
primary risk along with lightning.

By Friday..models suggest some weak mid level energy lifts NE
toward the area from the Gulf Coast around the western periphery
of the Atlantic Ridge and into the base of the upper trof.
Combined with the stalled surface boundary, expect widespread
coverage of showers and tstorms across the area during the day
Friday. NBM guidance putting out 90 pops for a large portion of
the area and CAMs, particularly the ARW, FV3 and NSSL WRF,
basically support the idea of more coverage of storms on
Friday...with potentially something more organized moving
northward during the day. A deeper look into the parameter space
yields the presence of a little bit of mid level energy including
deep layer shear values 30kt to as high as 45kt across middle
GA...which in turn would increase the likelihood there could be
some severe potential on Friday. Of course this will be very
dependent on how much diurnal heating can occur before storms
develop and stabilize the column. The HRRR and NAMnest both
suggestive of more CAPE on Friday than Thursday with values
potentially exceeding 3000 j/kg  in some areas along or near the
stalled surface boundary..where there could be a pooling of
moisture. Currently the SPC outlook still highlights general
thunder but the CSU ML severe has picked up on the subtle
features enough to trigger some severe probabilities. Will
continue to monitor trends and communicate with SPC on future
outlooks for any potential upgrades in the outlook Friday.
Regardless, its summer and we typically don`t need but subtle
amounts of shear to trigger a little more severe coverage. Similar to
Thu, heavy rain/higher rainfall rates will again be a primary risk
areawide on Friday.

30

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 326 AM EDT Thu Jul 18 2024

At a glance:

-No big changes to the previous forecast

-Showers and thunderstorms will be likely every afternoon.

The only real change from the previous long term is tacking on
another day at the end of long term that will likely have a high end
chance of PoPs. Otherwise, not much has changed or varied from the
previous forecast.

Drought conditions may get some relief as we head into this rainy
period. Precipitable waters will range from the 2 to 2.5 inch range
into early next week so depending on where the strongest bands set
up, we could see some significant rain totals. 7 day QPF totals are
in the 3 inch range with locally higher amounts expected for
isolated areas. Widespread severe weather is not expected, but a few
afternoon storms could warrant a SVR warning with winds being the
primary concern. Given MU CAPE values in the vicinity of 2000+ J/KG
most of our afternoon convection will likely have strong winds,
periods of heavy rain, and frequent lightning.

As far as temps go, we`ll be on the cool side of the climatological
norms with highs around 3 degrees below normal. Highs beginning
Friday will be in the mid 80s to low 90s from north to south; areas
of higher elevations may struggle to get out of the 70s. Overnight
lows will be in the upper 60s and lower 70s. It`s worth noting that
high temps may be significantly different from the forecast in areas
where rain keeps temps from peaking during the afternoon.

Vaughn

&&

.AVIATION...
(12Z TAFS)
Issued at 634 AM EDT Thu Jul 18 2024

A little more diurnal convection expected this taf cycle.
Model guidance still honing in on the 18z-22z period as the
key period, however, there is potential for some TSRA or SHRA
to linger beyond 22z through 00z or so which may need to be
accounted for with updates through the day. For ATL, needed to add
a prob30 group in the 12z-18z window for Friday as shra or tsra
may start a little earlier tomorrow which looks to be a fairly
busy day with convection coverage overall.
CIGS should for the most part will be VFR CU or mid level cloud
debris from storms however there is a lower MVFR deck very near
the metro sites this AM. Will maintain a MVFR level for a few
hours this morning which will tease metro sites but should raise
to VFR levels once surface heating commences. Winds will remain
out of the west through this cycle with the exception of in TSRA
where VRB with higher gusts is included in the tempo groups.

//ATL Confidence...12Z Update...
Medium confidence on convection timing
High confidence all other elements

30

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          70  85  69  87 /  50  70  70  70
Atlanta         71  84  70  85 /  50  80  70  80
Blairsville     65  79  65  78 /  30  80  70  80
Cartersville    69  84  68  85 /  40  80  70  80
Columbus        73  89  72  89 /  60  80  50  80
Gainesville     71  83  70  83 /  40  70  70  70
Macon           71  90  70  91 /  50  70  50  60
Rome            69  85  69  85 /  30  70  70  80
Peachtree City  69  85  69  86 /  60  80  70  80
Vidalia         74  94  74  93 /  50  70  40  60

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...30
LONG TERM....Vaughn
AVIATION...30