876
FXUS62 KCHS 010619
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
119 AM EST Mon Dec 1 2025

.SYNOPSIS...
A storm system will pass through the region late today into
Tuesday. High pressure then returns for the middle to end of
this week ahead of the next frontal system that could impact
the area Friday into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
During the pre-dawn hours, the cold front will surge southward
across GA and the adjacent Atlantic waters. Behind the front, high
pressure will build across the forecast area, remaining centered
over the Mid-Atlantic States. By this afternoon, an H5 shortwave
will ripple over the Southern Plains with a 150 kts H25 jet crossing
the Arklatex. Sfc low pressure should gradually organize near the
Mississippi Delta along the cold front. The developing low should
support strengthening south H85 winds over the sfc ridge across the
Southeast U.S. this afternoon through tonight. This afternoon,
deepening isentropic lift and moisture should support thick cloud
cover across the forecast area. Mostly cloudy to cloudy conditions
combined with northeast sfc winds should keep high temperatures
limited to the upper 50s inland to the low to mid 60s along the
coast and extreme SE GA. Coniditons through the daylight hours should
remain dry. However, isolated showers may cross extreme SE GA late
this afternoon.

Tonight, high resolution guidance indicates that H85 winds will
strengthen overnight, reaching 60 kts across much of the CWA by 12Z.
The sfc ridge should remain across the forecast area tonight, until
the sfc low tracks NE along the coast by day break. Models indicate
strong forcing develop along and ahead of the sfc low. The deepening
forcing along with PW values in excess of 1.5 inches should result
in widespread rainfall after midnight. Rainfall rates will likely
become moderate during the pre-dawn hours, thunderstorms possible
near the coast. Low temperatures are forecast to range from the mid
40s inland to the low to mid 50s across the coastal counties.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Tuesday: In the upper levels of the atmosphere, a jet streak will
start to splinter over the Ohio River Valley with an area of low
pressure beginning to move northeast across southeast Georgia.
Simultaneously, an area of high pressure over the Canadian Maritimes
responsible for the northeast winds today, will slowly move east
while widespread rain falls into the CAD. This precipitation falling
into the CAD will act to reinforce the northeast winds and keep
Tuesday morning rather cold and wet. However, the key question is
when will the CAD weaken and by how much. Three subtle but important
scenarios are possible with this system:

Scenario 1 (~50% chance): The CAD is slightly stronger and the area
of low pressure rides northeast along a stalled boundary across
inland GA and SC. Peak rainfall amounts of 1" - 2" from a Candler GA
to Hampton SC to Berkeley SC county line.

Scenario 2 and 3 (50% chance): The CAD collapses more quickly/
weaker with the peak rainfall axis being in the Midlands or even
approaching the Upstate of SC.

Either scenario has the peak rainfall amounts avoiding the urban
area of Savannah and Charleston.

Hourly Rainfall Rates: Latest run of the HREF shows the most likely
rates to be around .10"/ hour with some rates nearing 0.25" an hour.
Probabilities of rainfall amounts exceeding 1" in 6 hrs are less
than 20%.

Timing: Sprinkles will start 8 PM Monday to 12 AM Tuesday with peak
precipitation rates between 3 AM and 2 PM Tuesday. Precipitation
will then end from west to east 4 PM - 8 PM Tuesday as a cold front
crosses GA and SC.

Wednesday and Thursday: Surface high pressure will move east over
the Ohio River Valley with no precipitation expected. Winds
initially Wednesday morning will be out of the northwest, with a
reinforcing cold front then crossing the zones from the northeast.
Expect temperatures to be 5 to 10 degrees below normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A return of multiple rounds of precipitation looks possible for next
weekend as a long wave trough axis centers across the central United
States. Some guidance is showing a more amplified pattern (~65%)
while a mix of GEFS/ GEPS/ EPS members how a less amplified pattern
(~35%). The more amplified pattern allows multiple rounds of
shortwaves to traverse the region along with multiple rounds of
precipitation. The less amplified pattern, keeps most of the
rainfall further south and east of the region. At this point,
precipitation for Friday into Saturday at times appears likely
(>60%) with temperatures slightly below normal.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Prior to the 6Z TAFs, the sfc cold front was near KCHS and KJZI,
pushing seaward. MVFR ceilings have developed near the front,
impacting KCHS until 7Z. In the wake of the front, winds will shift
from the northeast and ceilings should remain VFR. During the
daylight hours, a sfc ridge will build across the terminals and low
pressure organizes near the Mississippi Delta. Isentropic lift and
moisture should increase from the south after mid-morning. KSAV is
timed to see MVFR ceilings by 17Z, then reaching KJZI and KCHS by
21Z. HREF indicates that the leading edge of a shield of rain will
reach KSAV between 3-6Z, highlighted with a PROB30. Ceilings are
expected to lower to IFR with the arrival of the rain. Rain may
reach KCHS and KJZI shortly after 6Z Tuesday.

Tuesday: A storm system will bring higher probabilities (50-80%) of
flight restrictions tonight into Tuesday, with both low ceilings and
lowered vsbys possible in addition to rain showers and isolated to
scattered thunderstorms. Low level wind shear also appears likely
(>60% chance) at all terminals Tuesday morning.

Wednesday through Friday: VFR through Friday morning. Late Friday,
cloud bases will begin to lower ahead of the next storm system.

&&

.MARINE...
During the pre-dawn hours, the cold front will surge southward
across GA and the adjacent Atlantic waters. Behind the front, high
pressure will build across the forecast area, remaining centered
over the Mid-Atlantic States. This pattern will support gusty
northeast winds across the marine zones today, gusts reaching into
the low 20 kts. This evening, low pressure is expected to approach
from the west, resulting in winds veering from the south. South
winds should continue to strengthen through the rest of the night,
with gusts reaching 25 kts or more across the outer GA and
Charleston County nearshore waters during the pre-dawn hours. Wave
heights will increase late tonight, with 6 ft seas developing with
the SC nearshore and outer GA waters during the pre-dawn hours. The
wind and sea conditions will be highlighted with Small Craft
Advisories.

Tuesday: A surface low will approach the region from the southwest.
Northeast winds from the CAD will slowly weaken and turn from the
southeast then southwest by the morning hours. Sustained winds of 15
to 20 kt with gusts up to 25 kt appear likely as cooler shelf waters
limit mixing. Expect seas 5 to 8 ft. As such, a small craft advisory
has been issued for the offshore Georgia waters and nearshore SC
waters for Tuesday morning and evening. A cold front will then cross
the waters Tuesday evening with seas slowly falling 3 to 5 ft.

Wednesday through Friday: Northwest winds veering from the north
Wednesday morning 10 to 15 kt. Seas 2 to 4 ft. No precipitation is
expected.

&&

.TIDES/COASTAL FLOODING...
Chances for minor coastal flooding return with the Tuesday early
morning high tide, along the Charleston and Colleton county
coast. Astronomical tides will then continue to rise with the
morning high tide cycle through Friday and remain elevated
through the weekend. Coastal Flood Advisories will likely be
needed, primarily for the Charleston Harbor tide (Charleston and
coastal Colleton counties).

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from 4 AM Tuesday to 1 AM EST Wednesday
     for AMZ350-374.
     Small Craft Advisory from 10 AM to 7 PM EST Tuesday for AMZ352.

&&

$$

NEAR TERM...NED
SHORT TERM...Haines
LONG TERM...Haines
AVIATION...Haines/NED
MARINE...Haines/NED