Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 231608
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1108 AM EST Fri Feb 23 2018

.SYNOPSIS...
Unseasonably warm high pressure will prevail through Saturday.
A cold front will approach the region late Sunday, then move
through the area Monday. High pressure is expected for the
middle of next week followed by another cold front late next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
This afternoon: Expect the deep layered ridge to remain over
the region. Temperatures once again are expected to be well
above normal, with highs in the lower 80s, except lower to mid
70s near the coast. The latest radar loop indicates some very
light sprinkles/showers, mainly around Charleston County. The
morning sounding indicated only very shallow moisture.
Therefore, not expecting any measurable precipitation today
other than a few brief sprinkles.

Fog has dissipated but the moisture is mixing into a strato-cu
deck. Expect with warming temperatures and more mixing this
afternoon, clouds will become more scattered.

Low level winds will be southeast to south 5 to 10 mph most
areas, slightly higher near the coast as they combine with a
weak seabreeze circulation.

Tonight: Models indicating the potential for fog and stratus,
possibly a little more widespread than this morning. Have
maintained areas of fog for most areas, and will continue to
monitor model trends for the potential for dense fog later
tonight. Lows will be in the upper 50s to lower 60s most areas.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
Saturday: The mid/upper levels will consist of strong high pressure
over Southern FL and the Bahamas, causing southwest winds over our
area. At the surface, Atlantic high pressure will be far offshore
while a cold front slowly approaches from the west. The western
periphery of the high will dominate the weather, so a dry forecast
is expected. Southerly flow and an unseasonably warm air mass may
lead to record temperatures.

Sunday: The mid/upper levels will consist of strong high pressure
over Southern FL and the Bahamas, shifting slowly southward.
However, southwest winds will prevail over our area. At the surface,
Atlantic high pressure will move away while a cold front slowly
approaches from the west. PWATs will rise to ~1.5" late, which is 2
standard deviations above normal per NAEFS. POPs will increase from
west to east with the approaching front, reaching their highest
numbers late at night. Measurable QPF is expected for much of the
area, especially far inland. There is some instability inland, so a
slight chance of thunderstorms is forecasted there in the afternoon.
Southerly flow and an unseasonably warm air mass may lead to record
temperatures.

Monday: The mid/upper levels will consist of strong high pressure
over Southern FL and the Bahamas in the morning, shifting into the
southern Gulf of Mexico overnight. The result will be southwest
winds over our area in the morning, becoming westerly in zonal flow
overnight. At the surface, a cold front will cross our area during
the day. PWATs will be ~1.5", which is 2 standard deviations above
normal per NAEFS. POPs reflect the expected showers during the day.
Measurable QPF is expected for much of the area, especially far
inland. Instability is weak, so no thunderstorms are forecasted.
Ahead of the front, temperatures will remain well above normal.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
A cold front will move offshore Monday night. High pressure will
pass to the north Tuesday, then move offshore Tuesday night. A weak
warm front may develop over the area Wednesday, followed by a cold
front approaching from the west on Thursday.

&&

.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
KCHS: VFR rest of today. Morning fog has mixed out into a
scattered to broken deck of strato-cu, and these conditions
should persist through the afternoon. Good chances for fog
again late tonight, with possibly more significant coverage
toward sunrise than this morning. For now have continued MVFR
visibilities in fog late tonight.

KSAV: VFR rest of today. Patchy dense fog has burned off and
will become a scattered to broken strato-cu deck through this
afternoon. Still good chances for fog tonight, with possibly IFR
visibilities and ceilings late tonight and toward sunrise
Saturday.

Extended Aviation Outlook: Flight restrictions are possible with low
stratus and/or fog each night/morning.

&&

.MARINE...
Through tonight: No highlights expected. Have not made any
significant changes to winds/seas through tonight. In general,
south-southeast winds of 8-12 knots most areas, highest near the
coast this afternoon with the combination of a seabreeze. Seas
generally 2-3 ft near shore and up to 4-5 ft our near the Gulf
Stream. There is a potential for sea fog, mainly the near shore
waters south of the Savannah River later tonight as winds veer
to southerly.

Saturday through Tuesday: Atlantic high pressure will prevail
Saturday. A cold front will approach the region from the west late
Sunday, then move through the area Monday. The pressure gradient may
intensify Monday night, causing a brief increase in winds/seas. High
pressure will pass to the north on Tuesday.

Sea fog could be an issue tonight through the weekend and until
a cold front arrives on Monday. Marine Dense Fog Advisories
will be possible at times.

&&

.CLIMATE...
Record highs for February 23:
KCHS: 81/2012 and previous
KSAV: 84/2012
KCXM: 78/1980

Record highs for February 24:
KCHS: 81/2017
KSAV: 86/2012
KCXM: 81/1930

Record high minimums for February 25:
KCHS: 62/1992
KSAV: 63/1992
KCXM: 61/2017

Record highs for February 25:
KCHS: 81/2017
KSAV: 82/1985
KCXM: 80/1930

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$
NEAR TERM...RFM
SHORT TERM...MS
LONG TERM...MS
AVIATION...
MARINE...
CLIMATE...


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