Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 062345
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
645 PM EST Sat Mar 6 2021

.SYNOPSIS...
High pressure will steadily build into the region through
Monday. The high will move off the coast by the middle of next
week and remain the primary feature through late in the week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 640 PM: KCLX detected a few clusters of light
reflectivity across the outer GA waters. This area will be
highlighted with SCHC PoPs through mid-evening. A few very weak
returns were detected over portions of SE GA, these returns were
likely associated with moist mid-level clouds. A first look at
moisture and temperatures late tonight, the frost potential
across inland GA and portions of SC were increased from patchy
to scattered.

Previous Discussion:
Surface high pressure will build into the area as a shortwave
trough continues to slid south of the area across the Atlantic.
For the rest of the afternoon, there could be some lingering
light sprinkles, mainly along the coast, coastal waters and the
Charleston tri-county area where PWATs are between 1/2-3/4". By
late this evening, subsidence and drier air will push into the
area and the overnight should be rainfree. Cloud cover will
steadily decrease over the afternoon and through the evening,
before eventually clearing out overnight.

The main concern for tonight is the chance for frost and/or freezing
temperatures. The low temperatures will be dependent on how quickly
clouds actually clear out and how light winds become. Overall
though, it does not look like a great radiational cooling night. The
best chance for freezing temperatures would be in our far inland
counties where 850 mb temperatures will be less than -2 C.
Elsewhere, sfc temperatures will be in the mid to upper 30s.
For frost, have maintained mention of patchy frost for most
areas as RH`s will be favorable.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Sunday through Tuesday: Aloft, the deep trough will shift east of
the forecast area on Sunday and northwest flow will prevail into
Tuesday. At the surface, an expansive area of high pressure will
gradually shift across the region through the period. Mostly clear
skies will prevail Sunday and Monday, with a modest increase in
cloud cover by Tuesday. Highs will start off quite chilly on Sunday,
with temperatures topping out in the upper 50s for most of the
forecast area (nearly 10 degrees below normal). Temperatures will
then moderate nicely, with about a 5 degree gain each day Monday and
Tuesday, culminating in upper 60s by Tuesday afternoon. The biggest
forecast challenge during this period will be low temperatures and
the potential for frost/freeze conditions. Under clear skies and
very light to calm winds, we should see excellent radiational
cooling conditions Sunday night and Monday night. Sunday night
should be the coldest night, with the forecast depicting most of the
area away from the immediate coastline in the 30-32 degree range.
Lows will be a few degrees warmer Monday night, but still low enough
for some areas to reach 32 or to at least see patchy frost. A Freeze
Watch looks like it will eventually be needed Sunday night, with
most of the area needing a Freeze Warning. Areas closer to the coast
could get away with a Frost Advisory. The area needing frost/freeze
headlines will be smaller Monday night and likely more focused
inland.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Models are in excellent agreement for the long term forecast.
They keep high pressure off the coast, with it`s periphery
stretching into the Southeast U.S. Dry conditions with above normal
temperatures are expected.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR through 0Z Monday. Northwest winds are expected gusts
between 15-20 kts at KCHS Sunday afternoon.

Extended Aviation Outlook: VFR.

&&

.MARINE...
Rest of today and tonight: As high pressure shifts closer to the
area and a shortwave moves further east across the Atlantic, the
pressure gradient will slightly relax. Winds across the
nearshore waters will slowly come down this evening. The Small
Craft Advisory currently in effect for the SC nearshore waters
will come down this evening. Then, the GA nearshore waters SCA
could need to be extended through tonight but as of now, winds
will be 15-20 knots. For the outer Georgia waters, the Small
Craft Advisory will remain in effect through the overnight for
NE winds at 20-25 knots and seas 4-6 feet.

Sunday through Thursday: High pressure will build in through
early next week and remain the primary weather feature through
late in the week. Winds will be strongest on Sunday as the
pressure gradient remains tight enough to support 15 to 20 knots
across most of the local waters, with gusts to 25 knots across
the outer Georgia waters into the early afternoon. A Small Craft
Advisory remains in effect for the outer Georgia waters until
Sunday afternoon. Winds will then steadily decrease through
Monday as the gradient relaxes and the high settles in. Winds
and seas will remain below advisory thresholds through Thursday.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for AMZ352.
     Small Craft Advisory until 4 PM EST Sunday for AMZ374.
     Small Craft Advisory until 10 PM EST this evening for AMZ354.

&&

$$

NEAR TERM...NED
SHORT TERM...BSH
LONG TERM...
AVIATION...RAD
MARINE...BSH



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