Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 301416
Area Forecast Discussion
National Weather Service Charleston SC
1016 AM EDT Fri Sep 30 2016
A cold front will linger not too far offshore through the weekend
before moving farther east early next week as high pressure builds
from the north. Meanwhile, tropical cyclone Matthew should be
moving north from the Bahamas, likely staying off the coasts of
Georgia and South Carolina.
.NEAR TERM /THROUGH TONIGHT/...
Late this morning: Morning showers and thunderstorms across
eastern Charleston County have moved off to the north and almost
the entire forecast area is cloud free. Today will be quiet and no
noteworthy changes were made to the going forecast. The region
will sit within cyclonic southwesterly flow aloft around the deep
upper low centered over Kentucky. Much drier air has worked its
way into the column and precipitable water values across inland
areas are well below 1 inch. Model soundings show a considerable
subsidence inversion about 700 mb and the forecast is dry.
Temperatures will be cooler than previous days and highs will
range from the low 80s well inland to the mid 80s along the coast.
Tonight: As the upper low over central Kentucky begins to lift to
the north, the front will drift back to the west slightly. We
kept scattered showers and tstms in the forecast over the SC
coastal waters and added slight chance pops along the outer
Charleston County coast later tonight due to the westward drift of
.SHORT TERM /SATURDAY THROUGH MONDAY/...
No significant weather impacts expected this period. At the surface,
weak high pressure should prevail with a cold front stalling out
just offshore. Aloft, a broad upper low should move north into the
Great Lakes over the weekend and then east into New England Monday.
This pattern will feature temperatures mostly above normal and low
rain chances, mainly near the coast, possibly by Monday extending a
bit farther inland across southeast Georgia as the low-level flow
turns more easterly. Lower dewpoints in the 50s/60s will also make
it feel more comfortable, especially inland.
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Uncertainty higher than normal this period given the model
disagreement regarding tropical cyclone Matthew and thus kept the
forecast close to WPC guidance. The NHC/WPC forecast shows Matthew
moving from near Cuba at the start of the period north to the
Bahamas and then continuing well east of the GA/SC coasts through
mid week. Of course the stronger and closer the storm is to the
coast the stronger the winds and higher the rain chances will be. At
this time the best chance of higher impacts will be along the SC
coast. Refer to the NHC for the latest forecast on Matthew.
Temperatures should remain at or above normal through the period,
especially if Matthew doesn`t significantly impact the area.
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
VFR expected at both terminals through Saturday morning.
Extended Aviation Outlook: Flight restrictions possible due to
early morning fog early next week, then from low clouds/rain toward
the middle of next week. Breezy conditions also possible Wed
depending on the track of tropical cyclone Matthew.
With the front stalled over the waters today into tonight, fairly
weak winds are expected and seas 3 ft or less.
Saturday through Wednesday: No significant concerns regarding
winds/seas through at least Monday night as a cold/stationary front
remains situated over or near the area. Winds will generally be 15
knots or less with seas 4 feet or less.
Conditions thereafter will depend greatly on the track of tropical
cyclone Matthew which is forecast by the NHC to be near the northern
Bahamas Wednesday morning. This will mean increasing winds/seas
across the local waters toward mid week given the tightening
pressure gradient due to high pressure to the north. As for winds we
stayed close to WPC guidance as the GFS seemed too strong and too
far west with the storm. We generally went with the GFS-based
WaveWatch guidance for seas but did lower them a bit toward mid week
given the official NHC forecast on Matthew is farther east.