Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 092025
Area Forecast Discussion
National Weather Service Charleston SC
325 PM EST Fri Dec 9 2016
High pressure will prevail until the development and passage of a
coastal trough by Sunday night. A cold front will shift into the
area on Monday and linger in the vicinity through Tuesday. A
stronger cold front will push through in the latter part of next
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Cold and dry high pressure expanding into the region will
bring our area the coldest temperatures so far this season.
Light northerly winds will allow a fair amount of cold air
advection most of the night. But if winds do go calm, excellent
radiational cooling under clear skies could allow temperatures
to drop lower than forecasted. Lows are forecasted to range in
the mid/upper 20s across most of the area and the lower/mid 30s
along the immediate coast.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Saturday and Saturday night: Zonal flow will prevail aloft and high
pressure at the surface will prevail gradually shifting into the Mid
Atlantic overnight. Overall, the day will be quite similar to Friday
with plentiful dry air and cool temperatures. Temperatures will
start off quite cold in the mid to upper 20s for many areas, warming
into the low 50s by the afternoon. Saturday night won`t be quite as
cold, with lows around 30 inland ranging to the mid/upper 30s closer
to the coast.
Sunday through Monday: The zonal flow regime aloft will gradually
take on a more cyclonic curvature as shortwave energy embedded
within the progressive flow moves east of the Mississippi Valley.
Starting Sunday morning, a coastal trough will develop along the
coast and low level moisture will begin to increase across the
region. High pressure over the Mid Atlantic will shift eastward and
the trough will dissipate. There could be some isolated to scattered
showers across the coastal waters associated with the trough, with a
few perhaps moving onshore along the coast. Then for Sunday night,
the low level flow will turn more southerly as a cold front begins
to approach from the west. The bulk of the forcing and deep moisture
associated with the front look to stay north of the area on Monday,
but there should be enough of both for at least scattered showers
starting in the morning. The potential rain doesn`t look too be too
heavy however. Temperatures will moderate quickly, with highs
reaching the low to mid 60s in some areas on Sunday and then the low
to mid 70s everywhere for Monday.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A cold front will stall out over or near the area mid week while the
flow aloft becomes fairly zonal. Low pressure could develop along
the front and shift through the area but confidence in details is
low at this point. Either way unsettled conditions are likely with
increased rain chances. The front should then shift offshore
Thursday with colder high pressure to build in for late week with
temperatures dropping to near/below normal levels.
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
VFR will prevail at the CHS and SAV terminals through 18Z
Extended Aviation Outlook: Periodic MVFR ceilings will be possible
Sunday through Tuesday. Expect breezy southwest winds on Monday.
Tonight: Cold high pressure continues to expand across the
region. A northerly fresh breeze should prevail, with higher
gusts overnight. Winds will transition to the NNE by sunrise as
the center of the high tracks over the TN Valley. Seas will range
from 2-3 ft within 20 nm and 4-5 ft beyond 20 nm.
Saturday through Wednesday: High pressure will help to drive
elevated northeast flow across the waters into Saturday night before
a coastal trough develops. Some elevated southeast winds will be
possible on Sunday as the trough sharpens, mainly over the outer
waters. A cold front will approach from the west on Monday and lead
to increasing winds out of the south and southwest. The front will
then linger in the vicinity of the region into mid week with the
flow becoming more westerly. Overall, conditions will be below Small
Craft Advisory conditions, thought 15-20 knots of flow will be
possible Saturday in the northeast flow and Sunday where southeast
flow develops. Seas will average 2-4 feet.
Coastal Flooding...The upcoming lunar perigee and full moon along
with periods of northeast winds could push tides to advisory levels
near times of the early morning high tides Saturday through the
middle of next week, especially along the SC coast.