542
FXUS62 KCHS 110705
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
305 AM EDT Thu Jul 11 2024

.SYNOPSIS...
A weak front will meander across the area through Saturday.
Atlantic high pressure will then rebuild across the area while
a surface trough exists inland Sunday through the middle of
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Satellite water vapor indicated a longwave trough advancing across
the Mid West, a broad ridge across the Southeast U.S., and a closed
low northeast of the Bahamas. The closed low over the western
Atlantic was drifting west towards the Southeast U.S. coast. At the
sfc, a cold front is timed to reach the coast early this morning,
becoming nearly stationary this morning. A broad area of weak sfc
low pressure is expected to develop off the Southeast U.S. coast
today. In fact, NHC has highlighted the Atlantic waters between the
Carolinas and FL with a 10 percent for cyclone formation through
this weekend.

The circulation around the broad area of sfc low pressure over the
western Atlantic is expected to push the stalled front westward as a
weak warm front this afternoon and tonight. As a result, winds
across the SC Lowcountry and coastal GA should turn from the SE late
this afternoon and tonight. Beginning late this afternoon, sfc
dewpoints across the SC Lowcountry should gradually increase from
the Atlantic, reaching the mid to upper 70s by this evening. As a
result, MLCAPE is expected to increase across the Santee River basin
late this afternoon through tonight, possibly exceeding 3000 J/kg.
High resolution guidance indicates that isolated to scattered
showers and thunderstorms will develop near and east of the warm
front this afternoon through tonight. HRRR, RRFS, and HREF indicates
the greatest coverage along the Santee River basin and areas north.

High temperatures are forecast to generally range in the mid 90s
this afternoon inland from the beaches. Coastal temperatures should
peak in the upper 80s to low 90s. Heat index values are forecast to
range between 100-105 degrees along and east of I-95. Tonight, low
temperatures are forecast to range from the low 70s inland to the
upper 70s across the coastal counties.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A weak surface low will be over southeast GA Friday morning,
drifting slowly west while dissipating during the day. A subtle
boundary associated with the low may remain draped across
southern SC for much of the day. A decent moisture gradient will
persist across the area, with somewhat drier air remaining over
southeast GA while >2" PWATs spread into southern SC. There
should also be a solid afternoon sea breeze pushing inland.
Scattered convection possible anywhere, though better coverage
is expected over southern SC. Convection may persist well into
Friday night, particularly over southern SC.

Upper ridging will occur Saturday into Sunday, though some
models show shortwave energy moving into the area later Sunday
afternoon. A weak surface boundary is expected to linger across
southern SC on Saturday before dissipating, potentially aiding
convective development. Despite the relative lack of pronounced
weather features, there should be ample moisture and forcing
for at least scattered showers and thunderstorms both days. We
still show slightly greater coverage over southern SC on
Saturday.

The upper ridging will result in gradually warming temperatures
during the period. Surface dewpoints will remain in the upper
70s across the southeastern half of the forecast area for much
of the period. Heat indices are progged to climb above 108
degrees in this area both Saturday and Sunday. Heat Advisories
are relatively likely both days.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Broad upper ridging will persist early next week, though a few
shortwaves will ripple through at times. Atlantic high pressure
will build to the east while a surface trough persists just
inland. At least scattered mainly diurnal convection expected.
High temps warming into the upper 90s next week, combined with
juicy dewpoints, will likely result in heat indices above 108 in
parts of the area. We could even be approaching Excessive Heat
Warning criteria (113F) Tuesday and Wednesday.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
Prior to the 6Z TAFs, a weak cold front was just inland of the
terminals. The cold front should slide across the terminals
before dawn, resulting in light winds to turn from the NW and
dewpoints to decrease. The front should become nearly stationary
along the coast during the daylight hours this morning. An area
of low pressure is expected to develop off the Southeast U.S.
coast today. The circulation around the is expected to push a
warm front inland from the coast, better defined north of the
Santee River. Scattered showers and thunderstorms should develop
near the warm front this afternoon into this evening.
Confidence is too low to mention SHRA/TSRA at KCHS/KJZI this PM.
However, TAFs will indicate that winds will turn from the
southeast by mid to late afternoon.

Extended Aviation Outlook: Scattered showers and thunderstorms
could produce brief flight restrictions each afternoon.

&&

.MARINE...
Today: A cold front is expected to reach the coast early this
morning, then becoming nearly stationary through the rest of the
morning. Morning winds should favor a direction from the northwest
between 5 to 10 kts. The circulation around an area of broad low
pressure over the western Atlantic is expected to push the stalled
front inland as a weak warm front this afternoon. Winds across the
marine zones should shift from the SE between 5 to 10 kts this
afternoon. Seas are forecast to range between 1 to 3 ft today.

Friday through Monday, southerly flow will persist with no
headlines expected. The gradient will tighten slightly early
next week as Atlantic high pressure strengthens to our east
while a potent trough exists inland. Sustained winds could
occasionally be close to 15 kt as opposed to the typical 10-15
kt of flow. Seas will range from 2-4 ft through the period.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$

NEAR TERM...NED
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...JRL/NED
MARINE...JRL/NED