Scientific Forecaster Discussion
fxus62 kchs 210435
Area forecast discussion
National Weather Service Charleston SC
1235 am EDT Wed Mar 21 2018
a strong cold front will move offshore this evening, then high
pressure will build in through Friday. Another cold front could
impact the area this weekend.
Near term /until 6 am this morning/...
the cold front has cleared all of the forecast area. Breezy
conditions will persist for much of the night with the onset of
strong cold air advection and associated isallobaric rises. Only
minor adjustments were made for the midnight update.
Lake winds: strong cold air advection behind a departing cold front
will support low-level mixing has already begun with Pinopolis
showing 20 kt sustained at midnight. A lake Wind Advisory is in
Short term /6 am this morning through Friday/...
a powerful upper low will rotate through the mid-Atlantic region
on Wednesday, with cool surface high pressure building over the
southeast. Some wrap around moisture may bring some
stratocumulus to the tri-County area Wednesday afternoon,
otherwise sunny skies are expected. Strong cold air advection
will be somewhat offset by downslope flow though highs will only
reach the upper 50s to lower 60s. Deep mixing to 5-6 kft in
concert with 30-40 kt boundary layer winds will result in breezy
conditions across the area. 20-30 mph with gusts to 35 mph are
Wednesday night temps will drop into the middle to upper 30s
across the area under cold air advection, however with surface
winds remaining above 5 kt the chance for frost is greatly
High temps will begin a gradual rise Thursday into Friday as the
surface high shifts southeast and begins to modify. Temps will
reach the mid/upper 60s by Friday. Thursday morning we again
expect lows to dip into the mid 30s inland due to cold advection
and radiational cooling. Wind speeds expected to be a bit
lighter so we could be looking at frost concerns in some rural
Long term /Friday night through Tuesday/...
high pressure is expected to prevail through much of the weekend.
There are some model discrepancies on Sunday, but general consensus
is that a cold front will approach from the north and will then drop
through the forecast area Sunday night. A wedge-like setup looks to
develop on Monday. Rain chances will accompany the front, although
it looks that rainfall totals will not amount to too much.
Temperatures will be near normal.
Aviation /06z Wednesday through Sunday/...
VFR. Gusty west-northwest winds will impact the terminals into the late
afternoon Wednesday. Gusts will likely top 30 kt at times during
the mid/late afternoon hours.
Extended aviation outlook: VFR through Saturday. MVFR ceilings
possible Sunday as a front drops into the area. Breezy
conditions expected on Wednesday.
initialized with gale warnings all zones outside of the
Charleston Harbor now that gales are expected within the first
This evening and tonight: a cold front will shift offshore this
evening with strong cold air advection in it's wake. Expect conditions
to deteriorate over all coastal waters tonight as mixing taps
into fairly strong low-lvl wind fields. Given the setup, all
gale watches have been upgraded to gale warnings overnight,
beginning in offshore Georgia waters at 10 PM and the remainder
nearshore waters outside the chs Harbor at 2 am. Seas will also
build through the overnight period, becoming as high as 4-6 ft
in nearshore waters and 6-9 ft in offshore Georgia waters.
Strong cold air advection will continue Wednesday into
Wednesday night as high pressure builds southeast over the
waters. Frequent gusts to gale force are expected over the
coastal waters beyond approximately 15 nm from shore where water
temperatures are a bit warmer, mainly Wednesday into Wednesday
evening before low-level winds drop off considerably. A short
period of Small Craft Advisory winds is possible late Wednesday
night into Thursday morning before conditions drop below
advisory thresholds. We show a Gale Warning for all but
Charleston Harbor running through Wednesday evening/overnight.
SC...lake Wind Advisory until 6 PM EDT this evening for scz045.
Marine...Gale Warning until midnight EDT tonight for amz350-352-354.
Gale Warning until 4 am EDT Thursday for amz374.
Small Craft Advisory until midnight EDT tonight for amz330.