488 
FXUS62 KCHS 060015
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
815 PM EDT Fri Jul 5 2019

.SYNOPSIS...
A trough of low pressure will linger across the region into the
weekend. A weak front will stall over the area during the early
to middle part of next week. Atlantic high pressure will
rebuild late next week. 

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 810 PM: A line of thunderstorms along an old outflow 
boundary remains across SE GA to the offshore SC waters. These
storms are moving fairly slow, producing areas of 2-3 inches of
rainfall within a 2 hour period. I will update the forecast to
increase the mention of thunderstorms across SE GA through the
rest of this evening.

Previous discussion:
Until Sunset: A large area of showers and thunderstorms will
continue across the area. SPC Mesoscale Analysis shows MLCAPEs
approaching 3,000 J/kg in areas where the storms are moving, so
their intensity should maintain. The severe threat will 
persist into the evening, with the main concern being damaging 
wind gusts. But the most noticeable impact may be the rainfall.
Plenty of moisture is in place with PWATs >2". Along with slow
storm movements, heavy rainfall amounts are being observed.
Localized flooding is happening in some locations and this
hazard should continue with the storms into the evening. Any 
strong storms will dissipate around sunset as the atmosphere 
stabilizes.

Tonight: A weak trough will be over our area. Models are in
decent agreement showing scattered showers persisting through
the first part of the night, then trending downward with
intensity and areal coverage in the second half. Towards
daybreak they should increase along the coastal counties. Lows 
will be in the 70s for most areas.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Only minor adjustments were made to the previous short term of the 
forecast. Current thinking has changed little. Previous discussion 
follows.

A surface trough will linger over the area on Saturday while a 
series of weak upper disturbances rotate through. A very moist 
airmass will reside over the Southeast with Precipitable Water 
values at or above 2.2 inches. The moist atmosphere coupled with 
moderate instability and ample forcing for ascent should support 
numerous showers and tstms during the day Saturday. Convection will 
likely linger into Saturday evening before trending offshore late 
night as the boundary layer stabilizes over land. Isolated severe 
thunderstorms will be possible Saturday afternoon, primarily due to 
wet microbursts.

Sunday looks a bit drier than on Saturday due to shortwave 
ridging and fairly pronounced NVA across the area. However, 
fairly strong instability will develop during the day and 
prevailing southerly flow supports an early afternoon sea breeze
development. We thus have scattered showers and tstms in the 
forecast with likely PoPs along the sea breeze corridor in the 
afternoon.

Numerous showers and tstms are expected to develop on Monday as
an upper shortwave approaches from the west and a weak surface 
front drops into the area and stalls. Precipitable Water values 
could surge as high as 2.5" across southeast GA during the 
afternoon. Such deep moisture combined with BL winds below 10 kt
could lead to localized flooding problems where heavy rainfall 
moves repeatedly over the same areas.&&

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A weak upper ridge will build over the area mid to late next 
week though the surface front will linger in the area at least 
into Wednesday before shifting farther south. Somewhat better 
coverage of convection is anticipated Tuesday and Wednesday.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Prior to the 0Z TAFs, a line of thunderstorms was passing over
KSAV with light showers around KCHS. The thunderstorms should
continue over KSAV until 2Z. Once the thunderstorms dissipate
this evening, showers are expected to linger in the KSAV area
until midnight. The rest of the night should feature light south
winds with VFR condition. Another round of thunderstorms should
develop near KSAV Sat afternoon, highlighted with a TEMPO from
18-22Z. The chance for thunderstorms appears a bit less around
KCHS, I will highlight the greatest potential with a PROB30 from
21-24Z.

Extended Aviation Outlook: Flight restrictions will remain 
possible due to showers and thunderstorms, mainly during the 
daytime hours.

&&

.MARINE...
Tonight: Under the influence of subtropical high pressure to 
the east, winds will primarily be out of the south or southwest 
through the period. Speeds should be in the 10-15 kt range. 
Seas will average 2-3 feet.

A somewhat enhanced southerly gradient will develop over the 
weekend and persist into early next week due to an inland 
surface trough and approaching front. Winds/seas currently 
forecast to remain just below SCA criteria. Weaker flow then 
expected for much of next week as a front stalls over the area.

&&

.TIDES/COASTAL FLOODING...
The risk for coastal flooding will continue with this evenings 
high tide due to the moon's perigee and onshore winds. A 
Coastal Flood Advisory has been issued for the southeast South 
Carolina coast for late this evening.

&&

.EQUIPMENT...
The KCLX radar has experienced a hardware failure. The radar
will be down until further notice.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Coastal Flood Advisory until midnight EDT tonight for SCZ049-
     050.
MARINE...None.

&&

$$
NEAR TERM...NED
SHORT TERM...
LONG TERM...JRL
AVIATION...NED
MARINE...
TIDES/COASTAL FLOODING...
EQUIPMENT...