National Weather Service Raw Text Product

411 
FXUS62 KCHS 080413
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1213 AM EDT Sat Oct 8 2016

...HURRICANE CONDITIONS WILL REACH THE COAST OVERNIGHT AND
SATURDAY MORNING...
...LIFE THREATENING SURGE AND DANGEROUS FLOODING OVERNIGHT...

.SYNOPSIS...
Hurricane Matthew will move north along just offshore of the coast
of Southeast Georgia and Southeast South Carolina late tonight
and Saturday. The hurricane will move away from the forecast area
Saturday night and high pressure will begin building in
thereafter.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
We have updated the forecast to allow the Tornado watch to expire.
Still, we have seen a few weak couplets moving rapidly west
through the Charleston quad-county area, and it is here that there
may still be a non-zero risk for a brief, isolated tornado.
However, this is not enough to justify a new watch.

It will be very interesting to see what kind of winds occur at
Gray's Reef (Buoy 41008) at 12 am as the western eye wall will
pass very close to that site. This will add in determining what
kind of winds coastal sections of Charleston County will
experience Saturday morning when the center of Matthew makes it's
closest approach to our area.

Nonetheless, the hurricane is forecast to move north tonight and
northeast Saturday making its closest approach to Tybee Island
shortly after midnight and Folly Beach around sunrise. The track
guidance from NHC has not changed too much with the outer envelop
of hurricane force winds brushing the Georgia coast and making a
farther inland push along the lower South Carolina coast due to
its orientation. Matthew's eye is forecast to come uncomfortably
close to the Charleston Metro area with the potential for the
western eye wall to brush areas such as Kiawah Island, Folly
Beach, Downtown Charleston, Mount Pleasant, Isle of Palms and
Sullivan's Island with gusts in excess of 100 mph.

The worst conditions will occur overnight into Saturday. Solid
tropical storm conditions are expected with hurricane conditions,
particularly in frequent gusts, expected along the Georgia and
far Southern South Carolina coasts. For Edisto Beach up across
Charleston County, the risk for sustained hurricane force winds is
still increasing, especially along/east of Highway 17, including
Downtown Charleston. Frequent gusts to hurricane force could occur
as far inland as Summerville.

IT IS IMPORTANT TO STRESS...any slight deviation to the right or
left of this track could significantly alter what level of
impacts are realized.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Matthew will be well off the coast Sunday and starting to loop
around to the south by Monday. Meanwhile, broad high pressure to our
north will be building into the area, bringing drier conditions and
tranquil weather. Aloft, heights will rise as a ridge moves over the
east coast late Monday. The result of this pattern will be a rain-
free forecast across our entire area Sunday. Some showers may form
far offshore on Monday, but no rain is expected over land.
Temperatures will be in the 70s each day and the 50s Sunday Night.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Virtually no change in the forecast thinking for the long term
period. Matthew is still forecast by many long term models to loop
around off the southeast coast as high pressure prevails inland
across the forecast area. The inland high pressure and prevailing
north to northeast flow will continue through Thursday with just
slight chance to chance PoP's across the coastal waters at times.
Through the period, temperatures will gradually warm, reaching near
normal values by Thursday.

&&

.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
Tropical storm conditions will impact the terminals through the
night with improving conditions during the day Saturday. 

Extended Aviation Outlook: Improving conditions late Saturday as
Hurricane Matthew moves away from the coast. Gusty northerly winds
may continue Sunday and Monday, especially along the coast.

&&

.MARINE...
Tonight: Tropical Storm conditions will continue early tonight,
before hurricane conditions overspread the local marine area after
midnight and continues into early Saturday. A Hurricane Warning
remains in effect for all legs. Seas could reach in excess of 30
ft along and east of the Matthew's eye.

Sunday through Wednesday: Matthew will be well offshore Sunday while
high pressure builds in from the north. The interaction between
these two features will create a strong pressure gradient across the
coastal waters. Winds and seas will be high enough to warrant Small
Craft Advisories through at least Tuesday. Conditions will start to
improve on Wednesday as the gradient weakens.

Rip Currents: High risk of rip currents into the weekend due to
Hurricane Matthew.

&&

.HYDROLOGY...
The risk for flash flooding will continue into Saturday as
Hurricane Matthew makes its closest approach to the area.
Additional rainfall amounts will range from 8 to 14 inches, except
3 to 7 inches across interior Southeast Georgia.

It is highly likely that the combination of very heavy rainfall and
high surge will lead to a widespread flooding event for low-lying
coastal areas, especially downtown Charleston and possibly
downtown Savannah. Excessive fresh water flooding with high surge
could make for a dangerous situation for the coastal counties.
Flooding in Downtown Charleston could be worse than what was
observed during the October floods of last year.

&&

.TIDES/COASTAL FLOODING...
**Worst timing in regards to the approach of Matthew in sync with
 high tide overnight.**

Tidal departures are continuing to raise tide levels along the
coast into major flooding, where we actually saw a rise of almost
1/4 foot in tide levels in just a mere 6 minutes at Ft. Pulaski
prior to midnight.

Although the forecast high tide occurs around 1 to 2 am, given the
large volume of water being pushed into harbors, inlets, etc. we
will experience highest tide levels occurring some 30-60 minutes.
Tide levels as such will approach or even surpass flooding levels
that we had during October of 2015, meaning levels could top 8.5
ft MLLW at Charleston and up near 12.0 ft or even higher at Ft.
Pulaski. This would put the level at Ft. Pulaski near the record
crest set by Hurricane David which produced a 12.21 foot crest in
1979. It would also be in the top 3 or 5 crests on record for
Charleston and the highest since Hurricane Hugo in 1989. This is
an extremely dangerous situation for coastal areas and in downtown
Charleston, as well as in and near Tybee Island, which will be cut
of from the mainland.

Many beach communities will see extensive damage to beach front
properties due to a combination of large breaking waves, high
surge and dangerous winds. Homes at Edisto Beach where already
being undermined at a high tide earlier and Tybee Island saw
significant flooding along the beach front. Expect considerably
worse conditions overnight and it can not be stressed enough that
how dangerous this scenario is.

The forecasted inundation continues to be 4-8 ft for South Carolina
and 7-11 ft for Georgia. Some coastal locations could experience the
worst storm surge since Hurricane Hugo with devastating impacts.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Flash Flood Watch through late Saturday night for GAZ087-088-
     099>101-114>119-137>141.
     Tropical Storm Warning for GAZ087-088-099>101-114-115-137. 
     Hurricane Warning for GAZ116>119-138>141. 
     High Risk for Rip Currents through Saturday evening for GAZ117-
     119-139-141.
SC...Flash Flood Watch through late Saturday night for SCZ040-
     042>045-047>052.
     Tropical Storm Warning for SCZ040-042-043. 
     Hurricane Warning for SCZ044-045-047>052. 
     High Risk for Rip Currents through Saturday evening for 
     SCZ048>051.
MARINE...Hurricane Warning for AMZ330-350-352-354-374. 
&&

$$
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
HYDROLOGY...
TIDES/COASTAL FLOODING...