Flash Flooding and Heavy Rain in Georgia, July 6 to 8, 2020

Area Forecast Discussion
National Weather Service Columbia SC
1037 PM EDT Sun Jul 5 2020

.SYNOPSIS...
Moisture will return to the area Monday as an upper trough along
the Gulf Coast slowly lifts northeastward through mid week and a
weak frontal boundary stalls over the region. This will bring
with increasing chances of showers and thunderstorms into the
middle of the week with heavy rain possible. The upper trough
may push offshore by the weekend.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
The upper trough along the Gulf Coast will begin to slowly lift
northeastward. Ahead of that lifting trough, a good surge of
moisture will begin pushing northward into our area through the
night. PWATs will rise to almost 2 inches by 12z across the CSRA
and southern Midlands with a gradient to lower values northward.
Cloud cover should increase towards morning. Limited instability,
and only expecting isolated to scattered showers to redevelop
closer to sunrise across the southern third of the forecast
area. Overnight lows will be mild and limited by the increasing
cloud cover and should be in the lower to mid 70s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Weak high pressure ridging over the area will continue to erode
Monday as the boundary that has remained to the south continues
to lift northward as a warm front. A steady increase in
moisture and isentropic lift will lead to the possibility of
showers over the CSRA early Monday morning. With mid-level flow
out of the SW, expect significant Gulf moisture to move over the
area with PWATs quickly climbing to near 2 inches by Monday
afternoon over the entire forecast area. Instability may be a
bit more limited but still expect thunderstorms over the area
through the afternoon which will likely produce locally heavy
rain. Some strong downdrafts will be possible with storms as
some dry air remains in the mid-levels, especially for central
and northern SC but overall the severe weather threat remains
low. Highs will remain below average with increased clouds,
remaining mostly in the mid and upper 80s. Showers will continue
to be possible overnight with positive vorticity advection from
a 500mb trough that will still be to the west.

Moisture transport will continue to increase Tuesday with PWATs
up near 2.5 inches, which based on upper air climatology, would
be near record for early July. With surface low pressure
developing and upper level energy associated with this trough
which models indicate will become negatively tilted, expect
significant rain during the day Tuesday with the potential for
some localized flooding. The good news is that strong
thunderstorm development will be limited be a lack of
instability with temperatures rising into the low 80s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
There is some question as to the progression of the low pressure
system after midweek. Tropical moisture will remain in the area
at least through Wednesday but again heavy rain will likely
be the main threat as instability will be severely limited.
Temperatures remain well below average in the mid 80s. ECMWF
supports upper level low development which would work to cut
off the steering flow and would keep surface low pressure at
least near the area but likely closer to the coast. This system
does have the potential for tropical development according to
the NHC but should continue to move away from our area. There
will be less of a chance for showers and storms with some
subsidence on the west side of the low and maybe some weak
ridging developing which at the very least will bring
temperatures closer to normal.

As this upper trough departs later in the week, lingering
moisture will continue to support at least diurnal thunderstorm
development. A drier pattern may be possible later in the
weekend with a strengthening ridge in the southwestern US and NW
flow for our area which would keep significant moisture at bay
with temperatures near normal.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
VFR conditions to start, then ceilings lowering to MVFR or IFR
late tonight in the CSRA. The low ceilings may spread into
central SC during the morning.

Mainly clear sky with VFR conditions through at 06z. A warm
front will move into the area from Ga late tonight and early
Monday morning. Expect ceilings to lower from south to north
through 15z with restrictions most likely near AGS/DNL. Expect
low clouds to mix out after 15z with scattered to numerous
showers develop due to insentropic lift and moisture flux.
Restrictions at times possible. Air mass becoming unstable so a
few thunderstorms possible mainly in the afternoon.

.EXTENDED AVIATION OUTLOOK...Increasing moisture into early
next week may lead to restrictions at times in showers and
thunderstorms and morning fog/stratus.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.

&&

Hazardous Weather Outlook
National Weather Service Columbia SC
510 AM EDT Sun Jul 5 2020

GAZ040-063>065-077-SCZ016-018-020>022-025>031-035>038-041-115-116-
060915-
Lincoln-McDuffie-Columbia-Richmond-Burke-Chesterfield-McCormick-
Newberry-Fairfield-Kershaw-Edgefield-Saluda-Lexington-Richland-Lee-
Aiken-Sumter-Barnwell-Orangeburg-Calhoun-Clarendon-Bamberg-
Northern Lancaster-Southern Lancaster-
510 AM EDT Sun Jul 5 2020

This Hazardous Weather Outlook is for the Midlands of South Carolina
and the Central Savannah River area of Georgia.

.DAY ONE...Today and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Thunderstorms are expected across the area Monday through Thursday.
Although the potential for severe weather is low locally heavy
rainfall is expected.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.