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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 170548
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
148 AM EDT Tue Sep 17 2019

.SYNOPSIS...
Hurricane Humberto will continue to move away from the coast 
through mid week. A cold front will advance through the area 
Wednesday, followed by high pressure into early next week. 

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Early this morning: Clear skies will prevail across the forecast
area through sunrise. No changes needed to the going forecast. 

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
Tuesday: As Hurricane Humberto accelerates away from the area, 
the pressure gradient across the area will weaken. Sinking 
motion across the area in the wake of Humberto combined with 
compressional heating ahead of a backdoor cold front will help 
low level temperatures and thickness values to increase. As a 
result, with abundant sunshine it will be rather hot especially 
for mid September. Raised high temperatures a degree or two in 
most areas away from the coast with highs generally in lower to 
mid 90s away from the coast. Heat indices will only reach 95 to 
100 away from the coast as low level dew points mix out a bit 
during the afternoon. Moisture and cloud cover increase Tuesday 
night and there could be a shower or two along the coast during 
the later half of the night. However, will maintain a silent 10 
percent pops in the forecast due to the expected limited 
coverage. 

Wednesday: As the backdoor cold front pushes through the area 
from north to south, there could be a few showers. Cooling 
temperatures aloft support some instability especially during 
the afternoon. As a result, think there could be a few 
thunderstorms along and ahead of the front. Kept it dry in the 
north where the front will move through before any instability 
can develop. Limited moisture and instability should keep rain 
chances in the slight chance category. Cooler and drier air will
advect into the area from the north behind the front. High 
temperatures should range from 80-85 across southeast South 
Carolina to the upper 80s across mainly interior southeast 
Georgia. As the back door cold front pushes south of the area, 
the threat for precipitation will end in the south Wednesday 
evening. It will be much cooler by Thursday morning with lows 
ranging from near 60 in the north away from the coast to near 70
along the coast in southeast Georgia. 

Thursday: Cooler and less humid conditions are expected for all
areas with highs ranging from the upper 70s along the South 
Santee River to the mid 80s to the west of I-95 and south of 
I-16. Breezy conditions are likely near the coast, especially 
for the beaches and barrier islands.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Deep layered ridging will persist over the region late week 
into early next week, bringing near climo temps and dry weather 
for the forecast area.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
VFR conditions will prevail at KCHS and KSAV through 06z
Wednesday.

Extended Aviation Outlook: Patchy fog is possible around the 
terminals around daybreak Wednesday, flight restrictions appear 
unlikely at this time. Otherwise, VFR.

&&

.MARINE...
Tonight: Seas from buoy 41004 dropped another foot from what 
was forecasted earlier. After accounting for this in the updated
forecast, we opted to drop the Small Craft Advisory for AMZ352.
The other zones (AMZ350 and AMZ354) didn't need any changes 
with their advisories. Those zones could have NE winds as high 
as 25 kt this evening with hazardous seas.

TC Humberto will continue to impact the coastal waters on 
Tuesday and Tuesday night with large swells and modest northeast
winds. The swells will begin to decrease by Wednesday, but the 
northeast winds will increase behind the backdoor cold front on 
Wednesday prolonging the small craft advisory conditions for 
AMZ350 and AMZ374. Looks like significant improvement in marine 
conditions is unlikely until late week especially for AMZ350 and
AMZ374. The gradient and overall winds and seas should subside 
this weekend as broad high pressure blankets the southeast 
states.

Rip Currents: Moderate Risk at all beaches Tuesday due mainly 
to earlier rip current reports and continued elevated/long 
period swell emanating from Hurricane Humberto. The rip current 
risk will then remain elevated throughout at least midweek as 
the large swells from Hurricane Humberto continue. The rip 
current risk could remain elevated perhaps through the end of 
the week as northeast winds and the longshore currents 
strengthen behind the backdoor cold front.

&&

.TIDES/COASTAL FLOODING...
Low chances for minor coastal flooding around the times of high
tide through late week, especially along the South Carolina 
coast.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 8 PM EDT Saturday for AMZ374.
     Small Craft Advisory until 6 PM EDT Friday for AMZ350.

&&

$$

NEAR TERM...BSH
SHORT TERM...MTE
LONG TERM...
AVIATION...BSH/MTE
MARINE...SPR/MTE
TIDES/COASTAL FLOODING...