Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 290008
Area Forecast Discussion
National Weather Service Charleston SC
808 PM EDT SAT MAY 28 2016
Tropical Storm Bonnie over the southwest Atlantic will move
onshore in southern South Carolina Sunday morning, then move
slowly northeast through Tuesday while weakening. A cold front
will then approach the region late next week.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
TD 2 has strengthened into TS Bonnie this afternoon though the
forecast path of the system is quite similar to previously. The
latest forecast brings the system onshore between Beaufort and
Charleston Sunday morning as a marginal tropical storm, then moves
it north and then northeast as it quickly weakens. Some gusty
winds will likely develop along the coast overnight with the
strongest winds late tonight into Sunday morning.
A potentially greater concern is the the heavy rainfall. The first
wave of moderate to heavy rain has been centered over the
Charleston metro area with verified rainfall reports ranging from
1 to 1.4" between Kiawah Island and Mount Pleasant. A weak jet
streak was noted earlier this afternoon across central SC/NC which
was enhancing the upper level ascent over southern SC. As this
feature moves north, we may see a slight decrease in rainfall
intensity. Nevertheless, with Precipitable Water values now
approaching 2" along the SC coast and considerable low and mid
level ascent on the north and west periphery of the storm,
widespread rainfall is anticipated over most of southern SC
overnight. Our latest storm total precipitation shows widespread 1
to 3" in southern SC with the highest totals 3-4" over inland
Dorchester and Berkeley counties. Most areas should be able to
handle this amount of rainfall due to fairly dry antecedent
conditions and the fact that the rain will occur over a fairly
long interval. However some localized flooding is possible
especially if heavy rain occurs early Sun morning coincident with
the 2 am high tide in Charleston.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
TS Bonnie will be near the SC coast Sunday with the latest NHC
forecast taking the system slowly northeast along/near the upper
SC/lower NC coast coast through Tue. The deeper moisture will
shift northeast of the area with time which will translate to
lowering rain chances and warming temperatures with time. However,
heavy rainfall will be possible at times, especially Sunday, and
this could lead to some localized flooding of mainly low-lying and
poorly- drained areas. Isolated tornadoes possible as well, mainly
along the central SC coast into Sunday night.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Models are in fairly good agreement for the long term period. Weak
pressure pattern will be in place for the latter half of the work
week as whatever remnants of the tropical system meanders off the
mid-Atlantic coast and eventually dissipates. A cold front is then
forecast to approach the region Friday into Saturday, resulting in
an increase in precipitation chances. Temperatures will be near to
slightly above normal as heights aloft build.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
KCHS: Periods of rain, heavy at times, rotating onshore tonight.
IFR visibility continuing, eventually lifting to MVFR later
tonight as the rain decreases in intensity somewhat. However IFR
ceilings will likely develop later this evening and persist until
daybreak Sun. Slight improvement expected on Sun though at least
MVFR likely to persist into the afternoon.
KSAV: MVFR ceilings expected overnight with a period of IFR closer
to daybreak Sun. Some rain may skirt past the terminal this
evening and overnight but the heaviest rain will remain east of
the terminal. Improving conditions on Sunday from late morning on.
EXTENDED AVIATION OUTLOOK...Periodic flight restrictions into
Monday, especially at KCHS, as TS Bonnie moves across southeast
SC with occasionally heavy/gusty showers and possibly
TS Bonnie will bring increasing winds/seas to coastal waters
through tonight. Dangerous conditions anticipated over most of the
marine area as the storm moves into the area. The one zone without
a Tropical Storm Warning...nearshore GA waters...now has a Small
Craft Advisory due to tightening gradient on the western periphery
of the storm.
Sunday through Thursday...TS Bonnie expected to move through the
SC coastal waters Sunday morning before pushing ashore. Expect
improving conditions later Sunday as the system moves ashore and
weakens. We issued a SCA for the near shore GA waters into early
Sunday based on the latest NHC forecast track of Bonnie. SCA
conditions will persist into Sun night across the SC waters.
Rip Currents: A high risk of rip currents is expected at all
beaches into early next week.
GA...HIGH RISK FOR RIP CURRENTS through Sunday evening for GAZ117-
SC...Tropical Storm Warning for SCZ045-047>052.
HIGH RISK FOR RIP CURRENTS through Sunday evening for
MARINE...Tropical Storm Warning for AMZ330-350-352-374.
Small Craft Advisory until noon EDT Sunday for AMZ354.