Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 310513
Area Forecast Discussion
National Weather Service Charleston SC
113 AM EDT TUE MAY 31 2016
The remnants of once Tropical Storm Bonnie will continue to
meander over or just off the coast of Charleston County
overnight, before gradually moving off to the northeast Tuesday
through the middle of the week. A cold front could then approach
the region late in the week and become stationary this weekend.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Recent satellite trends showing partial clearing working into our
northwest tier overnight as the surface low slides further into
the Atlantic. If so, given the wet grounds there will be a risk
for fog. We have opted to add patchy fog mentions on the midnight
The remnants of Bonnie still in the local area. The circulation
is easily identified by radar and surface observations, and it`s
position won`t vary too much even by morning.
Given precipitable water in excess of 1.7 to 1.8 inches we have
maintained shower chances through the night generally along
coastal Charleston County.
A sharp delineation will be found north of I-16 in Georgia
between the extensive clouds associated with low pressure near the
Charleston County coast and mostly clear skies across se Georgia.
The saturated conditions and widespread clouds will equate to
little temperature fall over the South Carolina zones, while in
Georgia the better radiational cooling exists. On average mid and
upper 60s will be good for lows.
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
Tuesday and Tuesday night: Other than the presence of the remnants
of Bonnie slowly pushing off to the northeast, the overall pattern
looks to be quite nebulous. The models are a bit at odds with the
track of the remnant center of circulation of Bonnie, but regardless
it will have no real impact on the forecast other than the
prevailing northwest to west flow across the area. Overall
convective activity on Tuesday is expected to be focused mainly
across southeast South Carolina which is where the modestly better
moisture will reside. Regardless, the forecast still only features
slight chance to chance pops mainly for afternoon and evening
showers and storms. Any lingering activity will diminish in the
evening and the overnight will see the best chance for development
shift to the coastal waters. Cloud cover will likely be less than
Monday, though still concentrated closer to the center of Bonnie. As
such, temperatures will be warmer and we will see highs in the
mid/upper 80s for southeast South Carolina and upper 80s to low 90s
in southeast Georgia. Overnight lows will be mild, only falling to
Wednesday through Thursday: The transition to a pattern much more
typical of summer will take hold with subtle riding well south of
the main belt of westerlies across the northern CONUS. The weakly
forced surface pattern will yield what should be typical summer
diurnal convection each afternoon. Pops feature 30-40 percent
chances each afternoon and evening. The threat for organized severe
thunderstorms is quite low, but we can`t totally count out a couple
of strong to severe storms where boundary interactions occur. Highs
will be in the upper 80s to around 90 with lows around 70.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Models are in fairly good agreement through the long term period.
Weak high pressure will give way to a cold front approaching from
the west Friday into Saturday. The front will then likely stall over
or near the area through weekend, before eventually dissipating.
Rain chances will stay in the forecast each day, peaking in the
afternoon when instability is greatest. Temperatures will be near
or slightly above normal.
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
KCHS: MVFR/IFR cigs look likely overnight into mid morning as
enough of an inversion in the boundary layer will likely exist
to trap moisture in the low level moist cyclone area across the
immediate area. Radar trends suggest dry weather is likely
overnight but showers may redevelop late morning and this
afternoon. Outside of convective rains pockets...conditions
should become VFR this afternoon and evening.
KSAV: We are currently forecasting VFR conditions through 06z
Wednesday, although there is a low end risk for some fog/stratus
around 10-14z this morning and isolated SHRA/TSRA late this
EXTENDED AVIATION OUTLOOK...Mainly VFR. Low risk for flight
restrictions from mainly afternoon showers/thunderstorms and
early morning fog/stratus.
Overnight: The remains of Bonnie will spiral near the coast of
Charleston County, resulting in mostly west or northwest winds at
or below 15 kt. The exception will be for some south and southwest
winds at less speeds across the Georgia waters where they are
further removed from the circulation of the low to the north. Seas
will be a mix of wind waves and swells, no more than 2-4 ft. The
potential exists for a flare-up of convection out near the Gulf
Stream overnight and a few of these storms could be strong with
gusty winds, heavy rains and frequent lightning strikes.
Tuesday through Saturday: The remnant circulation of Bonnie will
continue to move away to the northeast through Tuesday, leaving a
rather benign pattern in place into the weekend. Winds will continue
to be west to northwest Tuesday and Tuesday night, before shifting
to light onshore through the end of the period. Wind speeds are
expected to be less than 15 knots through the week with seas
generally 1-3 feet, up to 4 feet at times in the outer waters.