Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston SC
1034 am EDT Monday Jul 25 2016
Atlantic high pressure will prevail through much of the week while
a weak trough persists inland.
Near term /until 6 PM this evening/...
opted to drop all mention of mentionable pops across the forecast
area for this afternoon. None of the high resolution models are
spitting out anything meaningful through sunset and with mid-
level heights rising through the day this scenario seems
plausible. Nudged highs up a degree or so well inland. Hot and
humid conditions will continue with heat indices ranging 102-106;
highest along the lower South Carolina coast where localized
pooling of dewpoints will occur behind the resultant.
Short term /6 PM this evening through Thursday/...
tonight: tonight will be mostly clear most areas with lows again in the mid
70s many areas.
Tuesday through thursday: impressive and persistent mid/upper-
level ridging extending across the Carolinas and Georgia will
remain in place into the second half of the week. Model guidance
is consistence with showing below- normal precip through this
period, due largely to the lack of substantial deep layer moisture
and cape values mainly 1500 j/kg or less through peak afternoon
heating each day. Have removed mentionable pops from the forecast
for the Charleston Metro for Tuesday, with only slight chance
maintained across most of southeast Georgia where models indicated
that convection across northern Florida could creep a bit north
Tuesday afternoon. Slight chance pops will remain in the forecast
mainly along the sea breeze corridor and inland Wednesday and
Thursday as confidence is lower in convective personality at this
point. Early morning land- breeze formation will likely result in
some convergence along and off the coast each morning, but and
storms forming along this boundary should remain isolated and weak
with a couple of waterspouts the primary concern.
Temps will remain above normal through the period given the warm
airmass already in place, west-southwest flow through the low/mid levels and
subsidence aloft allowing for plenty of sunshine through midday each
day. Heat indices will top out in the mid to upper 100s each day,
with a few areas possibly near the 110 briefly in the afternoons,
though not likely long or widespread enough to solicit a heat
Long term /Thursday night through Sunday/...
hot and humid conditions will continue through the weekend as
ridging persists overhead and Atlantic high pressure remains at the
surface. A weak cold front may approach from the north Friday or
Saturday, but will likely dissipate before reaching the area.
Afternoon thunder chances across land areas, and morning thunder
chances over the waters, trend closer to climo in the long range,
with dry air/subsidence aloft gradually moderating through the
weekend. High temps will continue to reach the mid-to- upper 90s
away from the immediate coast through the weekend assuming minimal
debris clouds and convection abates until mid-to- late afternoon
A pattern change could come as early as Monday as weak upper level
troughing begins working into the eastern U.S.
Aviation /15z Monday through Friday/...
VFR conditions expected to prevail at kchs/ksav through 12z Tue.
Very low chances for isolated convection this afternoon along the
Extended aviation outlook: VFR will prevail at both sites. Brief
flight restrictions possible with isolated afternoon
showers/thunderstorms mainly late week.
the waterspout index was 56 on the 25/12z chs raob, which is in
the high category. Satellite shows cloud lines developing
offshore of Folly Beach south to Tybee Island and with favorable
atmospheric conditions in place a few waterspouts can't be ruled
out. A marine weather statement has been issued to address this.
Today: persistence forecast through tonight as the pattern holds
with the Atlantic ridge axis. Wind speeds will increase later
today as the sea breeze rolls inland and reach 15 kt tonight as
the nocturnal boundary layer jet peaks and then veers more
westerly nearing daybreak on Tuesday. Seas will average 2 to 3 ft
much of the time.
Tuesday through saturday: Atlantic high pressure will prevail
through the period with south-southwest winds through Thursday.
Expect winds mainly 10 to 15 knots and seas generally 2 to 3 feet,
with gusts to 20 kt and seas to 4 feet across the outer Georgia
waters during the early morning hours. Any early morning showers and
thunderstorms will remain isolated.