194
FXUS62 KCHS 101125
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
725 AM EDT Wed Jul 10 2024

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

&&

.NEAR TERM /THROUGH TONIGHT/...
At daybreak, KCLX detected a band of showers with embedded
thunderstorms near the mouth of the Santee River, pushing east.
Based on radar trends, the forecast will feature greater PoPs
across northern Charleston County and adjacent waters early
this morning.

The forecast area will remain under a broad 590 DM ridge through
this afternoon. At the sfc, a trough will remain off the SC coast.
Recent SPC mesoanalysis indicates a field of deep moisture
convergence with weak sfc vorticity. As a result, a few showers have
developed over Charleston County and the adjacent Atlantic waters
early this morning. This activity should slide to the east through
the pre-dawn hours, time to push outside the forecast area by
sunrise.

Some degree of cloud cover is forecast to linger over the forecast
area today, initial low clouds with high clouds increasing this
afternoon. Near term models indicate that a weak cold front will
approach from the west today. As the front approaches, sfc winds
across the forecast area are forecast to favor a direction from the
west. Temperatures should warm quickly this morning, with many areas
expected to reach 90 degrees by noon. Temperatures should peak
generally in the mid 90s during the mid afternoon. The cold front is
expected to push across the inland counties during the early
afternoon hours, nearing the I-95 corridor by late afternoon.
Dewpoints in the wake of the cold front should fall into the low 70s
to upper 60s this afternoon. However, east of the front, dewpoints
will remain in the mid to upper 70s. The highest dewpoints should
occur across portions of Charleston and Berkeley Counties, resulting
in heat index values in excess of 108 for a few hours this
afternoon. A Heat Advisory has been issued for Charleston and
Berkeley Counties until 8 PM this evening.

The combination of hot temperatures and elevated dewpoints along and
ahead of the front should result in at least moderate instability
this afternoon. Recent runs of the HRRR and RRFS indicate that MLCIN
will remain between 5 to 10 J/kg through the heat of the afternoon.
As a result, both models indicate little to no convection across the
region this afternoon. Favoring the HREF, the forecast will feature
SCHC to CHC PoPs across the coastal counties this afternoon,
greatest coverage across SE GA. Severe weather is not expected.

Tonight, the cold front is expected to slide over most of the
forecast area. Cooler dewpoints should advance across most of SE
GA/SC, with values in the 60s east of I-95. Min temperatures are
forecast to range from the low 70s inland to the upper 70s along the
coast.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
A weak cold front will drift just off the GA coast Thursday,
ushering in a considerably drier airmass, albeit briefly. Aloft,
a relatively weak ridge will persist. Later in the afternoon, a
weak surface wave over south coastal SC will enhance a moist
onshore flow into the Charleston Tri-County Area. The only
chance for convection appears to be over the far eastern zones
and mainly after 2 pm when moisture increases. Temps will be
relatively toasty in the mid 90s, but significantly lower
dewpoints should prevent the need for any Heat Advisories.

A weak surface low over eastern GA will drift northwest on
Friday, taking with it a weak surface front draped across
eastern SC. Moisture will return to the area with PWATs in most
locations back above 2" by midday Friday. Some vorticity may
break off the upper low in northern Florida and lift north
through the area Thursday night and Friday. The sea breeze
should be fairly strong on Friday, pushing well inland during
the afternoon. Scattered convection expected pretty much
everywhere, though better coverage may exist across inland SC
where the sea breeze interacts with the stalled front.

Saturday could be fairly wet as the remnants of the upper low
over Florida lift north into the area. Deep tropical moisture
will stream in from the southeast, pushing PWATs above 2.3". We
will also have the stalled front across the area and a robust
afternoon sea breeze.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
A weak upper trough will exist over the eastern United States
Saturday night through Monday, then a broad upper ridge will
gradually push east. Convective coverage could be slightly
greater than typical summertime, especially through Monday.
Temps will gradually climb, with heat indices getting close to
108 by Tuesday.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
12Z TAFs: Conditions are forecast to remain VFR across the
terminals this morning. A cold front will approach from the west
late this afternoon and evening. It appears that isolated to
scattered showers and thunderstorms will develop along and ahead
of the cold front. Based on the expected environment, the
greatest potential for convection should occur closer to KSAV
compared to KCHS and KJZI. However, confidence is too low to
mention SHRA/TSRA in the KSAV TAF at this time. Winds are
forecast to remain from the WSW through the daylight hours
today. Winds are timed to veer from the NW by 8Z tonight.

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

&&

.MARINE...
Today: The environment could favor the development of a waterspout
across portions of the Charleston County waters early this morning.
Otherwise, the sfc pattern will support southwest winds between 10
to 15 kts. Seas will favor values around 3 ft, with 2 ft see common
within 10 km of shore.

Thursday through Monday, no advisories expected. Winds Thursday
morning may be NW across nearshore waters, then shifting to SW
by afternoon. For the remainder of the period, winds will
generally be southerly at or below 15 kt with seas 2-4 ft.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for SCZ045-050-052.
MARINE...None.

&&

$$

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