427
FXUS62 KCHS 101026
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
626 AM EDT Thu Oct 10 2024

...COASTAL FLOOD WARNING ISSUED FOR CHARLESTON AND COASTAL
COLLETON COUNTIES...

.SYNOPSIS...
Hurricane Milton will track into the western Atlantic through
tonight. High pressure will build across the region Friday and
extend through the weekend. A strong cold front could push
through the area early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Rain is quickly ending. Near term pops have been updated to
lower coastal pops. Hourly temperatures were also adjusted
slightly based on current trends. The rest of the forecast is on
track.

GOES-E satellite imagery and radar data from KMLB show the
center of Hurricane Milton will emerge out in the Atlantic later
this morning. A Predecessor Rain Event (PRE)-type feature
extending to the north and northeast of Milton`s center is
producing light to locally moderate shower activity in the
vicinity of a subtle coastal front noted just offshore. Rain
across coastal Georgia into south coastal South Carolina has
remained very light so far with much of the rain likely falling
in the form of virga and/or sprinkles given the amount of dry
air noted below the sub-cloud layer. The only exception is right
along the Georgia coast where deeper moisture, characterized by
dewpoints near 70 and PWATs just over 2 inches per latest RAP
analysis, is found. Coastal rain chances should peak just before
daybreak (highest Georgia coast) with rain chances steadily
diminishing through the morning as Milton begins to pull away
from the Florida Space Coast. No rain is expected beyond the
coastal counties this morning.

Attention shifts to the potential for tropical storm force winds
at the coast with an elevated wind gust potential across the
interior. At the coast, the north and northwest portions of the
tropical storm force wind field will brush coastal Georgia into
far south coastal South Carolina later this morning with the
highest risk for sustained winds of 39 mph (tropical storm
force) occurring along the beaches such as Sapelo Island, Tybee
Island, Hilton Head and Edisto Beach. Wind gusts as high as
45-50 mph will be possible as diurnal mixing initiates after
sunrise. A Tropical Storm Warning continues from Edisto Beach
south to the Altamaha Sound. Farther inland and across the
Charleston Tri-County, there are persistent signals in the
high-res ensemble guidance supporting an elevate wind gust
potential where diurnal mixing will begin to tap into the
elevated wind field aloft. The latest Grand Ensemble areal and
point-probabilities highlight a 60-80% chance for wind gusts
reaching 40-45 mph away from the coast and across the Charleston
Metro Area, not directly associated with Milton`s expanding
wind field. Gusts of this magnitude can down trees and powerlines,
but the risk for wind damage is more elevated than usual given
many areas across the interior observed extensive tree damage
with Tropical Storm Helene just two weeks ago. A Wind Advisory
continues for all areas outside of the Tropical Storm Warning
area through 8 PM, although 40 mph gusts should subside prior
this.

Another cool day is expected, but temperatures will be a warmer
than Wednesday as cloud cover steadily decreases as Milton
pulls farther away from the region. Highs will warm into the
mid-upper 70s with a few spots taking a run for 80 across
interior Southeast Georgia.

Tonight: Quiet and cool conditions will prevail overnight as
high pressure prevails. Lows tonight will range from the upper
40s well inland to the upper 50s at the beaches.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Hurricane Milton will progress further away from the southeast
coast into the Atlantic Ocean on Friday while high pressure
builds into the local area into the weekend. Aloft broad
troughing will prevail across the southeastern states.
Conditions will improve on Friday, with any lingering
precipitation confined to the marine zones. Noticeably cooler
temperatures will be present on Friday, with temperatures in the
50s around daybreak only warming into the low to mid 70s.
Friday night could be the coldest the region has seen in a
while, our first real shot of fall-like temperatures, with 50s
across most of the forecast area and upper 40s far inland. If
winds are able to go light to calm temperatures may need to be
adjusted downward a degree or two, with favorable radiational
cooling conditions. Saturday and Sunday should see plentiful
sunshine with high temperatures in the upper 70s Saturday and
low 80s Sunday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
High pressure will prevail at the surface on Monday with an
almost zonal pattern aloft. Global models are in fairly good
agreement through the long term period. Monday night into
Tuesday an anomalously deep trough is forecast to swing across
the eastern CONUS, with a strong cold front at the surface.
While FROPA is currently forecast to remain dry, the cold front
could to bring the region our first relatively "cold" airmass.
Temperatures at the beginning of the week will be a few degrees
above normal, with highs on Monday in the mid 80s and overnight
lows in the mid to upper 50s. However, post-FROPA on Tuesday
high temperatures will only be in the upper 60s to low 70s.
Overnight temperatures Tuesday night onward are forecast to dip
into the upper 40s inland with low 50s along the coastal
counties. These temperatures post-FROPA are more akin to early
November than mid October.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
10/12z TAF Discussion:
VFR will prevail through 12/12z. Gusty winds associated with
Milton will impact the terminals for much of the day with the
highest winds occurring this morning where gusts near 30 kt will
be possible. Despite the elevated winds, there is a risk for
low-level wind shear with speeds around 2 kft peaking around 50
kt.

Extended Aviation Outlook: Some gusty NE winds are possible
Friday morning in the wake of Hurricane Milton. Otherwise,
prevailing VFR.

&&

.MARINE...
Today: Dangerous conditions will be found across the waters
today with tropical storm conditions. A Tropical Storm Warning
continues for all waters, including Charleston Harbor.
Conditions will begin to improve this afternoon as Milton
begins to pull away. Elevated winds and seas will persist into
tonight although the diminishing trend will continue.

Friday through Tuesday: Conditions should begin to improve on
Friday as Hurricane Milton progresses further into the Atlantic
and away from the east coast. However, gusty NE winds around 25
knots will still be common Friday. While seas will begin to
diminish Friday as the system moves further away from the
coastline, they are still forecast to be 5 to 7 ft along the
nearshore waters and 8 to 10 ft across the 20 to 60 nm offshore
GA waters as swell associated with Milton continues to impact
the marine zones. Conditions will continue to improve into the
weekend and early next week as high pressure builds into the
region. A strong cold front is forecast to push through the
region early next week, with possible Small Craft Advisory wind
gusts along the Charleston nearshore waters and the 20 to 60 nm
offshore GA waters Monday night into Tuesday.

Rip Currents: A high risk for rip currents continues into
Friday with an elevated risk into Saturday.

High Surf: Latest breaking wave guidance support peak breaking
wave heights of 4-7 ft across the beaches today with spots along
parts of the Charleston County coast possibly seeing breakers as
high as 8 ft. A High Surf Advisory continues into this evening
for all beaches. The combination of powerful high surf and
elevated tides will result in areas of significant beach
erosion.

&&

.TIDES/COASTAL FLOODING...
Tidal departures continue to increase. Updated total water
forecast calls for 8.1 ft (major) in the Charleston Harbor and
10.4 ft (moderate) for Fort Pulaski. The Coastal Flood Watch has
been upgraded to a Coastal Flood Warning and a Coastal Flood
Advisory has been issued for Tidal Berkeley County.

Tides are beginning to feel the influences from Milton as
northeast winds intensify across the nearby Atlantic waters with
atypical tide traces now being observed. Peak departure for the
early morning high tide was about +1.4 ft at Charleston Harbor
and +1.8 ft at Fort Pulaski. Water levels will diminish as low
tide approaches later this morning although departures will
likely grow as onshore winds intensify.

Charleston and Coastal Colleton: There is an increased concern
that tide levels in the Charleston Harbor will make a solid run
for 8.0 ft MLLW/2.24 ft MHHW (major) for the early afternoon
high tide with some of the latest PETS data showing a peak tide
level around 8.1 ft MLLW/2.34 ft MHHW with a similar output
noted on the latest ETSS. Given the increase in tide levels
noted in the various guidance, the decision was made to issue a
Coastal Flood Watch for Charleston and Coastal Colleton Counties
with a large valid time given the atypical tide traces
expected. The decision to upgrade to a Coastal Flood Warning
(major flooding) or a Coastal Flood Advisory (moderate flooding)
will be made later this morning with the next total water
forecast update. If a Coastal Flood Warning issued, a Coastal
Flood Advisory would also be needed for Tidal Berkeley at 8.0 ft
MLLW/2.24 ft MHHW in the Charleston Harbor is the minor flood
threshold for that zone. The risk for minor to possibly moderate
coastal flooding during the afternoon high tide cycles will
persist through Saturday.

Beaufort County south to McIntosh County: Similar tide trends
are being observed this morning. Trends suggest tides will peak
solidly in the moderate flood level for Fort Pulaski with levels
reaching 10.1 ft MLLW/2.6 ft MHHW. A Coastal Flood Advisory has
been issued for this area to cover the early evening high tide.
Minor. The risk for minor coastal flooding during the afternoon
high tide cycles will persist through Saturday.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Tropical Storm Warning for GAZ116>119-138>141.
     Wind Advisory until 8 PM EDT this evening for GAZ087-088-
     099>101-114-115-137.
     High Risk for Rip Currents through this evening for GAZ117-119-139-
     141.
     High Surf Advisory until 8 PM EDT Friday for GAZ117-119-139-
     141.
     Coastal Flood Advisory from 11 AM this morning to 5 PM EDT
     this afternoon for GAZ117-119-139-141.
SC...Tropical Storm Warning for SCZ047>049-051.
     Wind Advisory until 8 PM EDT this evening for SCZ040-042>045-
     050-052.
     High Risk for Rip Currents through this evening for SCZ048>051.
     High Surf Advisory until 8 PM EDT Friday for SCZ048>051.
     Coastal Flood Advisory from 11 AM this morning to 5 PM EDT
     this afternoon for SCZ048-051-052.
     Coastal Flood Warning from 11 AM this morning to 5 PM EDT this
     afternoon for SCZ049-050.
MARINE...Tropical Storm Warning for AMZ330-350-352-354-374.
&&

$$