Area Forecast Discussion
Issued by NWS Atlanta, GA

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000
FXUS62 KFFC 241146
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
746 AM EDT Thu May 24 2018



.PREV DISCUSSION... /Issued 445 AM EDT Thu May 24 2018/

SHORT TERM /Today through Friday/...
The area of mid-level low pressure and associated vort max is still
in place over the area, with little changes in the moist airmass
we`ve been in for days. PW`s will still be high (1.8-2.0 inches)
through the short term so any storms will be efficient rainfall
producers with high rainfall rates possible. Flash flooding could
also be a concern for any areas where heavy rain lingers.

The complex of storms currently on radar in west central GA has been
producing heavy rainfall in the area, but should diminish some by
later this morning. The Flash Flood Watch is still in place through
15z and based on model trends it currently looks okay. Will continue
to monitor activity to determine if any changes to the watch are
necessary. Scattered showers and thunderstorms are still expected to
fire up this afternoon and into the evening. Although activity will
be mostly diurnally driven, activity could again linger into the
overnight hours tonight as well. Expecting scattered showers and
thunderstorms again on Friday with a focus of precip in east central
GA as the mid-level wave moves northeast. Similar to today a strong
thunderstorm isn`t out of the question with a threat for heavy
rainfall.

QPF values through the short term period are around 1 to 2.5
inches with the bulk of the precip in central GA. As such, WPC
currently has central GA in a marginal risk for excessive rainfall
today and a marginal to slight risk in far east central GA for
Friday.

Max temps are generally in the 80s today, with 70s and 80s for
Friday. Low temps are expected to be in the 60s.

Reaves

LONG TERM /Friday Night through Wednesday/...
Rain is still expected every day through the extended...tho there
may be a glimmer of hope just outside of forecast period for a
pattern change. As we begin this forecast period on Friday
night...Pacific jet energy will help dig a trough across the western
GOM vicinity...while weak ridging downstream of this feature tries
to maintain existence across the SE and Mid Atlantic. A brief
glimpse of the tail end of several hi-res model runs reveals the
potential for a weak MCV to linger in place under the weak flow
pattern aloft which suggest that convection will likely be ongoing
into the night. This is supported by a plume of enhanced mid level
moisture noted in both the 00z EC and GFS. At this point it is
difficult to discern how long this convection will last but do think
its possible for it to last into Saturday morning. This being said
this feature looks to move north with time so could find the
atmosphere being somewhat more stable Saturday with less of a chance
for widespread thunderstorm development during hours of peak
heating. Therefore have lowered POPs for Saturday for now...tho
given absolutely no change in airmass it will still be possible for
at least some convection to initiate. Saturday`s forecast may
ultimately depend on evolution of Friday/Friday night MCV /if even
present/.

As if this was not enough to focus on...will also be closely
monitoring the potential for a tropical wave across the southern
Gulf to strengthen into a tropical depression and potentially merge
with the developing trough to its north. For Saturday...this system
will not impact the local area altho very heavy rainfall will exist
to our south across the eastern GOM and Florida. By day`s end
Saturday...the low should be located somewhere in the east-central
Gulf where strengthening should be well underway given absence of
land intrusions, moist air, and low shear. NHC currently outlines
this system as having a 70 percent chance of reaching at least
subtropical/tropical depression status.

Will see the tropical system begin to impact the local area by
Sunday as most guidance /ECMWF/NAM/ensembles/ indicate the low will
track into the northern GOM. This will place the CWA on the wetter
side and will allow for the influx of deep tropical moisture to
affect the state. Therefore...does not really matter the status of
the tropical system in the end because we will be receiving heavy
rainfall regardless. And unfortunately...this system will aid in the
development of an omega blocking pattern across the CONUS through at
least Tuesday. This means the feature will hardly move through that
time period and continue to create the potential for tropical
rainfall across the region. Right now current QPF values Sunday-
Tuesday are forecast in 2-4 inch range in addition to what has
already been received the last week or so. Flooding issues certainly
are a concern at this point. In term of severe weather...it is way
too early to determine and will rely on the evolution of the system
in the coming days.

As the blocking pattern breaks down by Wednesday...lingering lift
from the remnants of the system will exist and allow for continued
chances of rain and thunderstorms. However...there may be light at
the end of the tunnel as drier mid level ridging may try to build in
by the end of next week.

Kovacik

&&

.AVIATION...
12Z Update...
Mainly IFR with LIFR conditions across the TAF sites, with VCSH
at CSG and patchy dense fog near AHN. Expecting LIFR/IFR
conditions to lift by 14-15z with VFR conditions by 18z. Expecting
more scattered convection across the area this afternoon, with a
TEMPO for TSRA from 20z- 00z. Winds will remain light with an
easterly component, less than 7 kts during the day, with calm
winds possible at times through the forecast period.

//ATL Confidence...12Z Update...
Low to medium confidence on timing of IFR/MVFR cigs. Medium
confidence on all other elements.

Reaves

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          82  66  79  66 /  80  60  70  50
Atlanta         82  68  79  68 /  60  60  60  50
Blairsville     81  63  76  63 /  60  50  60  50
Cartersville    85  68  80  67 /  50  40  50  40
Columbus        84  70  85  69 /  60  50  60  50
Gainesville     81  66  76  66 /  70  60  70  50
Macon           81  69  83  67 /  70  60  70  50
Rome            87  68  82  67 /  40  30  40  40
Peachtree City  83  68  80  67 /  60  50  60  50
Vidalia         83  70  84  69 /  80  60  50  40

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 11 AM EDT this morning for the following
zones: Chattahoochee...Crawford...Crisp...Dooly...Harris...
Houston...Macon...Marion...Muscogee...Peach...Schley...Stewart...
Sumter...Talbot...Taylor...Upson...Webster.

&&

$$

SHORT TERM...Reaves
LONG TERM....Kovacik
AVIATION...Reaves


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