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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 170524
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
124 AM EDT Mon Jun 17 2019

.SYNOPSIS...
Atlantic high pressure will prevail into Tuesday. An inland
surface trough will develop by mid week then persist over the
Southeast into next weekend. 

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Temps running a tad higher than this time last night, and we'll
end up a tad warmer by morning, mainly down in the upper 60s 
and lower 70s, mid 70s along the immediate coast. Skies will be 
mostly clear or partly cloudy (due to some stratocumulus from 
the ocean and cirrus far overhead). However, some late night fog
will form far inland as the nocturnal inversion strengthens.

The main challenge overnight will be the potential for fog.
Condensation pressure deficits are not not as favorable as last
night, and it'll be difficult to the achieve cross-over temps.
We'll leave patchy fog in the forecast, but not show any in the
grids until 4 am across our inland zones.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
Monday through Wednesday: Overall, conditions will gradually become 
more conducive to convective development as we approach mid week. 
Aloft, the ridge will hang on Monday then weaken Tuesday and 
Wednesday as a shortwave ripples through. At the surface, the 
subtropical high will extend into the area Monday, followed by a 
surface trough that moves into the area through Wednesday. Monday 
convection should be isolated to scattered, with the best coverage 
across southeast Georgia. Rain chances on Tuesday and Wednesday 
certainly warrant higher values, but have kept them in the high 
chance range. Model differences are considerable regarding coverage, 
with some depicting virtually no coverage and others having coverage 
that could support 50-60 percent chances. Overall, there aren't any 
obvious features to latch onto for determining possible organization 
and any severe threat. Atmospheric flow is better by Wednesday, so 
perhaps the severe threat is marginally higher then. In general, the 
severe threat looks low each day but there could be an isolated 
stronger storm depending on how mesoscale boundaries interact. 
Temperatures should top out in the low 90s each day, with lows in 
the low to mid 70s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A fairly robust mid level short wave is progged to pass through the 
southeast states Thursday into early Friday. This appears to be the 
most significant period for a potential risk of organized convection 
as 700 MB flow increases greater than 30 kt over much of the area. 
Timing and convective mode look tricky and global models continue to 
show moderate to strong instability at times late week. It still 
remains quite uncertain how convection will play out at this 
juncture. On Friday, the surface trough will mostly move offshore 
and POPs range from slight chance northern SC zones to chance GA. 
Upper ridging is expected to build over the weekend with hot and 
humid weather and at least a slight chance for afternoon/evening 
showers and tstms. Temps on average will run above climo by several 
degrees for highs and lows through most of the medium range.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
The 06Z TAF set has prevailing VFR. However, there could be 2-3
hours of ground fog and marginal MVFR visibilities through 12Z
at either site. Then for the afternoon, as the sea breeze 
shifts inland, scattered-broken cumulus will occur, along with 
isolated to scattered SHRA/TSRA. But any direct impacts are too
uncertain to include at this stage. 

Extended Aviation Outlook: Mainly VFR. Brief flight restrictions 
are possible in afternoon showers/thunderstorms, especially by 
mid week.

&&

.MARINE...
Overnight: Atlantic high pressure will be the main driver of 
the winds, generally from the S or SW as high as 10 or 10-15 kt,
except. Seas will be 2-3 ft.

Monday through Friday: Through the week, south to southwest flow is 
expected to prevail across the local waters as the area sits between 
high pressure to the east and a developing trough inland. Wind 
speeds will mainly top out in the 15-20 knot range, primarily along 
the land/sea interface in the afternoon and in surges during the 
overnight periods. Seas will average 2-4 feet, and could be as high 
as 5 feet at times over the outer waters in the mid to late week 
period.

&&

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

&&

$$
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...