Scientific Forecaster Discussion
fxus62 kchs 180737
Area forecast discussion
National Weather Service Charleston SC
337 am EDT Wed Oct 18 2017
strong high pressure will build over the area through Saturday,
then shift off the coast. A low pressure system will affect the
area early next week.
Near term /through tonight/...
as of 330 am: the center of 1028 mb sfc high pressure is
expected to track from middle Virginia/NC at sunrise to offshore of
the Delmarva Peninsula by sunset. A sfc ridge should remain
across the foothills and Piedmont of the Carolinas through
today. The pressure pattern should support steady northeast
winds across the forecast area. Morning temperatures are
forecast to range from the mid 40s inland to the upper 50s
across the beaches. Sunny conditions and weak 500 mb height rises
should result in high temperatures to reach the mid 70s across
the SC lowcountry to the upper 70s across southeast GA, which is 1 to 2
degrees below normal. Forecast soundings indicate that mixing
will likely peak around 3 kft by mid afternoon. Given the NE
flow and shallow mixing, I will forecast dewpoints to remain in
the upper 40s inland to the mid 50s near the coast. Offshore,
expect partly sunny conditions with isolated to scattered
showers 20 nm and beyond offshore.
Tonight, near term guidance indicates that a secondary high center
will develop along the east facing slopes of the southern
Appalachians. Steady northeast winds and partly cloudy conditions
should allow temperatures to cool into the low 50s inland to the low
60s across the beaches. Low level winds are forecast to remain nearly
parallel to the coast line, keeping isolate to scattered showers
over the warmer waters. I will keep the pops over the land zones in
the single digits.
Short term /Thursday through Saturday/...
a deep layered ridge will maintain dry conditions and gradually
warming temperatures Thursday through Saturday. The only
potential for a few rain showers will be across coastal Georgia
where moisture will increase Saturday afternoon as the surface
high to the north shifts to the east. Away from the immediate
coast, highs will climb through the low/mid 80s with lows in the
Long term /Saturday night through Tuesday/...
an upper trough is expected to dig into the central United
States Sunday and Monday, bringing a cold front and potentially
a low pressure system through the area Monday through Tuesday.
Model disagreements are large but confidence is increasing in at
least scattered showers and thunderstorms during the period.
Aviation /08z Wednesday through Sunday/...
kchs and ksav should observe steady NE winds and unrestricted
flight conditions through the 6z taf period.
Extended aviation outlook: VFR conditions are expected at both chs
and sav terminals through late week.
ridging across the western Carolinas will remain through today
and tonight. The pressure gradient across the marine area will
remain around 3 mbs through the next two periods. Winds outside
the chs Harbor should generally gust around 25 kts, especially
beyond 15 nm. Seas are forecast to range between 6 to 8 ft
today from 15 nm and beyond, settling to 5 to 7 ft tonight.
Small craft advisories will remain across the near and outer
Winds/seas will gradually relax on Thursday as the surface high
continues to build east. We expect seas to be below 6 ft across
the nearshore waters by late Thursday afternoon and by late
Friday night across the offshore Georgia waters. A southerly flow
will develop early next week as a low pressure system approaches
from the southwest.
guidance indicates that minor tidal flooding will occur along
the SC and Georgia coast during high tide this morning. Coastal
flood advisories have been posted until 9 am this morning.
Strong/persistent northeast winds will maintain a risk for minor
coastal flooding with the high tides through Friday. Coastal
flood advisories will likely be needed.
Georgia...coastal flood advisory until 9 am EDT this morning for gaz117-
SC...coastal flood advisory until 9 am EDT this morning for
Marine...Small Craft Advisory until 5 PM EDT Thursday for amz350-352-
Small Craft Advisory until 2 am EDT Saturday for amz374.