Area Forecast Discussion Issued by NWS Charleston, SC
000
FXUS62 KCHS 120106
AFDCHS
Area Forecast Discussion
National Weather Service Charleston SC
906 PM EDT Thu Apr 11 2024
.SYNOPSIS...
A cold front will move through the area tonight. High pressure
will gradually build across the region late this week and
persist through next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Deep, negatively tilted upper trough axis is in the process of
swinging through the Carolinas this evening with attending
surface low tracking through Lake Erie. Primary cold front/dewpoint
boundary is advancing through southeast/eastern South Carolina
with drier air advecting into the region from the W/SW.
Secondary boundary is still upstream and there is a tongue of
moisture/cloud cover rotating through Georgia on the southern
flank of the upper trough, along with some spotty shower
activity that is just about to move into the far southwest
counties of the forecast area. Moisture axis and spotty showers
are looking to swing east/northeastward through the region
through around midnight or so, with decreasing clouds overnight.
Meanwhile, southwest winds remain gusty and will be veering
westward overnight and remaining gusty, although winds may tend
to subside some toward sunrise before increasing again during
the day Friday. Wind Advisory has been allowed to expire at 8
pm, but replaced with a Lake Wind Advisory that runs through the
day Friday.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Friday: A broad trough will exist both surface and aloft, with a
weak short wave to pass through midday, and another and stronger one
to brush by to the north late. With so much dry air in place, this
will produce no more than a few stratocumulus or flat cumulus. Full
insolation and a deep downslope flow will result in max temperatures
in the lower and middle 70s, in line with the low level thickness
forecast blended with the MOS and NBM guidance. Deep mixing and a
packed pressure gradient will result in breezy to windy conditions.
Highest winds will peak at 25-35 mph, or even a little higher on
elevated bridges. Not quite enough for a Wind Advisory, but
certainly enough for a Lake Wind Advisory on Lake Moultrie.
Friday night: Gusty winds will fade during the early evening, but
never fully decouple. High pressure gradually builds in from the
west, and with clear skies and weak cold advection, we`ll see lows
getting down to mid and upper 40s inland, 50-55F degrees closer to
the Atlantic. Any Lake Wind Advisory on Lake Moultrie that is issued
will come down early at night.
Saturday: High pressure will be situated along the northern Gulf of
Mexico coast, with a trough near the Appalachians. The trough aloft
edges into the ocean, as ridging to the west is working its way
eastward. There`s still some gustiness to the winds, but much less
than recently; peaking around 20 or maybe 25 mph. Full sunshine and
another day with a downslope flow will equate to max temperatures
very similar or a tad warmer than Friday.
Sunday: Zonal flow will prevail aloft, with an upstream short to
approach late. However, it doesn`t have any moisture to work with,
so no impacts. Higher heights aloft, 805 mb temperatures climbing to
12-13C, and the low level thickness as much as 1390-1395 meters will
support an even warmer day. We have lower 80s just about everywhere
away from the coast, where local sea breeze influences will hold
temperatures down in the 70s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A 5910-5920 meter anticyclone in the Gulf of Mexico will expand
across the local counties early to mid week, with heights across our
area climbing near or even above the 90th percentile. That along
with 850 mb temperatures that are also near or greater than the 90th
percentile, and Atlantic high pressure at the surface to dominate,
will support temperatures far into the 80s each afternoon away from
the beaches. No records, but about 5-10F degrees above normal. With
more of a southerly synoptic flow to develop, night time lows will
also be some 5-10F degrees above climo.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Deep upper level trough axis and an associated tongue of better
moisture will be swinging through the region over the next
several hours. This may bring another period of sct-bkn MVFR
cloud cover through the region late this evening and into the
overnight hours at the terminals. Cloud cover will clear out in
earnest thereafter with conditions trending solidly VFR
thereafter.
Winds will remain on the gusty side through much of the night,
veering from southwest to west overnight. Gusts of 20 to 30
knots will be common although gusts may tend to diminish toward
Friday morning. Gustiness redevelops/continues through the day
Friday.
Extended Aviation Outlook: Prevailing VFR. Gusty W winds will peak
near 25 or 30 kt at the terminals Friday afternoon, before
diminishing considerably by sunset.
&&
.MARINE...
Tonight: Buoys and ship reports observed marginal Gale Warning
conditions across the marine zones late this afternoon. These
conditions will likely remain through early this evening. A cold
front is timed to sweep across the marine zones late this evening.
In the wake of the front, winds will veer from the WSW and
strengthen with gusts between 35-40 kts. The gusty conditions should
continue across the marine zones until the pre-dawn hours Friday.
The Gale Warnings were extended later into tonight to highlight the
post-frontal wind surge. Seas this evening should range between 6-10
ft, decreasing to 4 to 8 ft late tonight.
Friday: Solid Small Craft Advisory conditions will exist across all
waters, with a pinched gradient in place due to a broad surface
trough across the immediate waters. Wind gusts will reach close to
30 kt at times, but with the offshore trajectories, seas that are
initially as high as 5-7 feet, will slowly start coming down through
the day. Waves will be at least near 2 feet in Charleston Harbor.
Friday night and Saturday: There is still enough of a gradient
between a broad trough to the north and northeast, and high pressure
to the southwest, that we still might require Small Craft
Advisories, especially on the Charleston County Atlantic waters, and
the Georgia waters beyond 20 nm offshore.
Saturday night through Monday night: Finally much better marine
conditions, with high pressure stretching over or to the south of
the area from the Gulf of Mexico into the Atlantic. Although there
could be some locally higher winds due to the sea breeze, on average
the wind speeds will be 15 kt or less, and seas no greater than 2 to
4 feet.
High Surf: Large breaking waves are expected to develop at the
beaches today, highest along the Charleston county coast. A High
Surf Advisory is in effect until 8 AM Friday.
Rip Currents: There might be just enough swell energy to produce a
Moderate Risk of Rip Currents at area beaches on Friday.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Lake Wind Advisory until 7 PM EDT Friday for SCZ045.
High Surf Advisory until 8 AM EDT Friday for SCZ050.
MARINE...Gale Warning until 6 AM EDT Friday for AMZ330-352-354-374.
Gale Warning until 8 AM EDT Friday for AMZ350.
&&
$$
NEAR TERM...Adam
AVIATION...Adam
MARINE...NED