Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 251941
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
341 PM EDT Thu May 25 2017

.SYNOPSIS...
High pressure will linger over the region through this weekend. A
weak cold front is expected to slowly slide over the Coastal Plain
early next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
Sfc high pressure centered over Gulf of Mexico / FL will gradually
ridge north across GA/SC tonight. Deep dry air will increase across
the region, yielding clear to mostly clear conditions and near zero
PoPs. Pressure gradient across the forecast area should range around
2 mbs, keeping winds steady from the WSW. Using a blend of
temperature guidance, low temperatures will range from the upper 50s
to the low 60s.

Friday, mid levels should begin the day zonal with slight rises from
the west during the afternoon hours. LLVL flow will remain from the
WSW through the day. The combination of full insolation and WSW
winds should yield increasing low level thicknesses. High
temperatures are forecast to range in the mid 80s inland to the low
80s across the beaches.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Weak ridging aloft will build slowly through the period. At the
surface, elongated high pressure stretching from the Gulf of Mexico
into the Atlantic Basin will remain in control. Though boundary
layer flow will be mainly southwesterly, low-to-mid-level flow will
be westerly, resulting in drier downsloping conditions precluding
mentionable POPs for most. The exception is areas near and north of
Lake Moultrie, where some modest destabilization and moisture
pooling associated with a disturbance north of the area may allow
some showers/thunderstorms to scrape the area.

Low level thickness values suggest highs in the mid-90s Saturday and
Sunday, but with some mid level cloud cover and afternoon cumulus
possible, have moderated the forecast both days. Still, with the
seabreeze trapped near the coast, lower-90s can be expected
everywhere except the beaches both days. Afternoon dew points in the
lower 70s Sunday will contribute to heat index values approaching
100 for some areas along the HWY 17 corridor.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The surface cold front will approach the area through the first
half of the week as the trough aloft slides east, bringing the
potential for another period of unsettled weather Monday through
Wednesday.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
VFR flight conditions will remain through the TAF period. West
winds should continue to gust between 25-30 kts until 23z. Winds
will decrease with the passage of the mid level trough and
sunset, however, winds will remain steady from the WSW through
tonight. Forecast soundings indicate that the mixed layer will
deepen to 5 kft by mid day Friday. KCHS is expected to develop
gusts between 15-20 kts by 16z.

Extended Aviation Outlook: VFR.

&&

.MARINE...
The marine area will remain between low pressure over New England
and high pressure over central Florida. Winds should continue to
gusts above 25kts across the harbor through early this evening.
Gusty conditions may continue across the offshore zones through the
rest of the evening. Small Craft Advisories are scheduled to expire
during the evening hours. On Friday, southwest winds are forecast to
remain gusty, but less than advisory levels. Wave heights are
expected to range between 1-2 feet within 10 nm and 2-3 feet beyond
10 nm.

Friday night through Monday: High pressure will prevail across
the coastal waters into early next week. Moderate breezes will
persist across the waters through the period, with winds
approaching advisory criteria at times mainly for the Charleston
County nearshore waters, where the gradient will be tighter
thanks to a weak disturbance north of the area. Seas will be 2
to 3 feet, with higher seas possible beyond 40 nm at times.

&&

.TIDES/COASTAL FLOODING...
Tide levels will trend higher each day as we approach the new moon
and perigee this Friday. Despite the unfavorable wind direction,
minor coastal flooding is possible along mainly the South Carolina
coast with the evening high tide cycles through the weekend.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for AMZ330-
     352-354.
     Small Craft Advisory until midnight EDT tonight for AMZ350-374.

&&

$$
NEAR TERM...NED
SHORT TERM...CEB
LONG TERM...JMC
AVIATION...CEB/JMC
MARINE...CEB/NED
TIDES/COASTAL FLOODING...CEB


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