Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 220745
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
345 AM EDT Tue May 22 2018

.SYNOPSIS...
The region will remain in a warm and muggy air mass between
Atlantic high pressure to the east and low pressure to the west
into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 345 AM: High pressure will remain centered over the western
Atlantic today as broad low pressure remains across the Deep South.
This pattern should support steady SSE winds across the forecast
area. Simulate GFS WV indicates that deeper moisture will drift over
the region from SW to NE. As a result, sfc dewpoints are expected to
remain steady or rise into the 70-73 range. The combination of highs
in the mid 80s and dewpoints at 70 or above should yield weak to
moderate CAPE during the mid to late afternoon. In addition, a weak
sea breeze may develop during the early afternoon, drifting inland
through the rest of the afternoon and early evening. I will forecast
CHC PoPs across the coastal zones with likely PoPs across inland GA.

Tonight: Diurnal showers and isolated thunderstorms are forecast to
gradually dissipate through the evening and overnight hours. I will
forecast SCHC PoPs for most areas, slightly greater over the marine
areas. Using a blend of MOS, I will forecast low temps from low 70s
across the beaches to the upper 60s inland.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
The area will remain between Atlantic high pressure to the east and
low pressure to the west. A cold front will approach from the north
Wednesday night before stalling out just north of the area. This
pattern will maintain the tropical air mass in place and lead to
higher than normal rain chances, especially each afternoon and
evening. In general we think the highest chances will be inland near
the better moisture, instability and forcing. Some spots could pick
up over an inch through the period. No significant flooding or
severe weather is anticipated at this time. Temperatures will
generally be near to above normal, especially lows.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
Not much pattern change late this week into early next week with
high pressure remaining to the east and and low pressure to the
west. Will be watching for potential tropical cyclone development in
the south-central Gulf of Mexico. Models have been fairly agreeable
lately that the low will track toward the north-central Gulf Coast
region this weekend. This pattern will continue to maintain a
tropical air mass across southeast SC/GA and lead to higher than
normal rain chances. Temperatures should stay near to above
normal.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR conditions expected at KCHS and KSAV through the 6Z TAF
period. Much like Monday morning, brief ground fog is possible
during the pre-dawn hours. Otherwise, steady south winds will
develop during the daylight hours. A round or two of showers are
possible at KSAV later this morning into the afternoon,
highlighted with a PROB30.

Extended Aviation Outlook: A persistent tropical air mass will lead
to higher than normal rain chances through the weekend, mainly each
afternoon. Thunder chances will be low however given the limited
instability. Some restrictions will also be possible from morning
low clouds and/or fog as well.

&&

.MARINE...
Large high pressure centered over Bermuda will remain over the
region through tonight. Southeast winds will continue through today
and tonight, speeds remaining between 10-13 kts. Wave heights are
forecast to range from 2-3 ft within 20 NM to 4-5 ft beyond 20 NM.

Wednesday through Sunday: The area will remain between low pressure
to the west and high pressure to the east. A tropical cyclone may
develop in the central Gulf of Mexico later this week but models are
in good agreement it will remain far enough away to not have really
significant impacts locally. However, do expect an increase in winds
and seas later this week and we could see Advisory conditions this
weekend.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$
NEAR TERM...NED
SHORT TERM...RJB
LONG TERM...RJB
AVIATION...NED/RJB
MARINE...NED/RJB


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