Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 281757
Area Forecast Discussion
National Weather Service Charleston SC
157 PM EDT Tue Mar 28 2017
A weak cold front will stall over or near the area on Wednesday
before moving back north Thursday night into Friday as a warm
front. Another cold front will move through Friday night into
Saturday followed by drier high pressure Sunday. Unsettled
weather could return as soon as next Monday.
.NEAR TERM /THROUGH TONIGHT/...
A toasty day is in store given low-level warm air advection, a
developing downslope flow aloft, and boundary layer compression
ahead of a weak back door cold front. Mostly sunny skies this
morning have allowed temps to quickly rise into the mid to upper
70s. The tail end of a weak upper vort will move through this
afternoon, bringing a bit more cloud cover and perhaps an
isolated shower or tstm, mainly inland where a lee trough
develops. Despite approaching low and mid level cloudiness, we
expect some of this to dissolve during the afternoon as the
subsidence increases with the downslope flow. Areas closer to
the coast should reach the highest temps. We nudged highs up 1-2
degrees based on current trends and RAP13 thickness progs, which
gives 86-88F in most spots. This could tie or break the record
high at KCHS today.
Tonight, debris clouds should dissipate across the CWA during
the evening hours. The cold front is forecast to slowly drop in
from the north. The approach and passage of the front will likely
keep winds steady from the west. Using a blend of guidance, min
temperatures are forecast to range from the upper 50s inland to
the low 60s across SE GA.
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
Atlantic high pressure will give way to a cold front Wednesday which
should make it into southeast GA as high pressure builds from the
north. Drier air and minimal synoptic forcing will yield dry
conditions Wednesday, although cannot rule out a few showers and/or
storms near the Altamaha River which will be closer to the stalled
front. It should remain rain-free until later Thursday when deeper
moisture returns and isentropic ascent increases across the area
north of the stalled front which will be starting to move back north
as a warm front. Thus, showers and possibly a few thunderstorms
(mainly across GA) are expected. Rain chances will increase further
Thursday night into Friday as the warm front lifts north through the
area and moisture/forcing increase. Although wind fields will be
strengthening, instability appears minimal Friday and thus the
threat for severe weather is low at this time. Either way it should
be a breezy day with gusts up to around 25 mph.
Temperatures should push into the lower to mid 80s most inland
locales Wednesday, with some upper 80s possible given the offshore
flow and frontal compression. On Thursday, high pressure building
from the north will keep it a bit cooler, especially across SC where
it should stay below 80 degrees except close to the Savannah River.
Once again wouldn`t be surprised if upper 80s occurred Thursday
toward inland portions of the Altamaha River closer to the stalled
front. Temperatures Friday will be moderated by the clouds/rain,
likely only reaching close to 80 inland. Prevailing onshore winds
will keep coastal locations much cooler during the daytime through
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A cold front will push through Friday night into Saturday followed
by drier high pressure Sunday. Unsettled weather could return early
next week as a storm system moves across the Deep South, although
there remains significant uncertainty regarding the timing of best
rain chances. Highest confidence in rain will be the first part of
Friday night when showers, and possibly some thunderstorms, are
expected. Temperatures should remain above normal through the
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Extended Aviation Outlook: Restrictions possible Wed night/Thu
morning due to low clouds and/or fog, then likely due to
showers/thunderstorms/low clouds, mainly Thu night into early
The region will remain between a cold front across the Carolina
Piedmont and high pressure off the FL coast. This pattern
should result in a 2-3 mb pressure gradient across the forecast
area. South winds should gradually strengthen across the marine
zones, becoming gusty this afternoon. The highest wind gusts are
forecast to occur across AMZ350 in the low 20 kts. Swells
should remain between 3-4 feet today, portions of AMZ350 and
all of 374 will see 5 feet. Tonight, winds will shift from the
west and weaken as a backdoor cold front slides over the
Lowcountry. Wave heights may decrease around 1 foot with the
weaker offshore winds.
Wednesday through Sunday: A weak cold front will move into the area
Wednesday and Wednesday night as high pressure builds to the north.
The front will return back north through the area as a warm front
Thursday night/Friday. A cold front will then move through Friday
night/early Saturday. At some point prior to the cold frontal
passage Saturday sea fog could develop across the cooler near shore
waters and lead to low visibilities.
Expect a high chance for Advisories Thursday night across the outer
waters, expanding northward into the SC waters through Friday night
as strengthening winds build seas to 6-8 feet, highest beyond
Rip Currents: High risk for rip currents along the SC coast and
Moderate for GA today. Gusty winds and long period 3 foot swells
will likely produce rip currents. The combination of higher than
normal tides, onshore winds and swells in the surf zone will
support an enhanced risk for rip currents through mid week,
possibly lasting into Friday.
High tides could reach Advisory levels, mainly late Wed/Thu, due
to strengthening onshore winds and swells impacting the coast.
This could cause shallow to moderate saltwater inundation in
vulnerable coastal areas, possibly even reaching major levels
Thursday night. Thus, Coastal Flood Advisories are expected with
a potential for Watches/Warnings as well.
RECORDS FOR TODAY
KCHS 85 2007
KSAV 89 1907
KCXM 91 1907
SC...High Risk for Rip Currents until 8 PM EDT this evening for