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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 231131
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
731 AM EDT Sat Mar 23 2019

.SYNOPSIS...
High pressure will build over the region through early Monday.
Low pressure is expected to move across the region Monday night
and Tuesday. High pressure will then rebuild. 

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: The mid/upper level trough across the northeastern US 
will move off the coast and shortwave ridging will steadily move
across the Mississippi Valley. At the surface, high pressure 
will be the primary feature in the wake of a cold front drifting
to the south. Deep dry air will remain in place and a dry 
forecast with clear skies is in place. Highs are forecast to be 
very similar to Friday with temperatures ranging from the upper 
60s across the Tri-County region to the low 70s closer to the 
Altamaha. 

Tonight: The tranquil pattern will persist as high pressure 
remains across the forecast area. A few high clouds could pass 
through at times, but no impact on the forecast. With a weak 
pressure pattern in place for much of the forecast area, good 
radiational cooling conditions will set up. Look for lows to 
range from around 40 inland to the low 50s at the coast.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Warm advection will occur Sunday through Monday as the surface 
high shifts offshore and deep southerly flow strengthens. Upper 
shortwave energy will move into the Carolinas on Monday with a 
surface low shifting from the SC Midlands into the Grand Strand 
Monday evening. The best moisture and forcing will be over far 
northern areas closer to the surface low track. We maintained 
scattered showers, along with isolated thunderstorms Monday 
afternoon/evening. Isentropic ascent may produce a few lingering
showers into Tuesday as a backdoor front drops through the 
area. Considerably cooler air will usher in behind the front on 
Tuesday. Highs in the mid/upper 70s Sunday-Monday will drop to 
the 60s Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Somewhat cooler weather will continue Tuesday night through 
Wednesday night before temperatures moderate with the surface 
high moving offshore. Temps expected to be pushing the upper 70s
to around 80 late next week with mainly dry conditions.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions will prevail at KCHS and KSAV through 12z 
Sunday.

Extended Aviation Outlook: Flight restrictions possible Monday 
night through Tuesday night.

&&

.MARINE...
Today through tonight: Northeast winds will prevail this 
morning behind a southward moving cold front. Wind speeds are 
expected to top out in the 15-20 knot range. Then by the 
afternoon the gradient will relax significantly and winds will 
veer to become onshore. Speeds are forecast to be 10 knots or 
less. Overnight, winds are expected to remain onshore and top 
out around 10 knots. Seas will peak this morning, highest 3-5 
feet in the Charleston County waters. Then overnight seas will 
drop off and become 1-3 feet everywhere.

Gusty southwest winds expected Monday ahead of the surface low 
but conditions are currently forecast just below advisory 
thresholds. However, a persistent strong northeast gradient will
likely yield advisory conditions for most if not all of the 
waters Tuesday through at least Thursday.

&&

.FIRE WEATHER...
Relative humidity values are expected to drop into the 20 to 25
percent range this afternoon. However, winds will be much 
lighter today so no Fire Danger Statements are planned at this 
time.

&&

.EQUIPMENT...
The KCLX radar is inoperative. Parts are on order and repairs 
are expected to occur on Monday.

&&

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

&&

$$

NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...BSH/JRL
MARINE...BSH/JRL
FIRE WEATHER...
EQUIPMENT...