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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

FXUS62 KCHS 220809

Area Forecast Discussion
National Weather Service Charleston SC
409 AM EDT Fri Mar 22 2019

High pressure will build over the region through the weekend. 
Low pressure may move across the region on Monday night through 
Tuesday night. High pressure will then rebuild. 


Today: Aloft, the forecast area will remain under the influence
of west-northwest flow around the large upper low situated over
New England. At the surface, high pressure stretching along the
Mississippi Valley will gradually shift eastward as a low 
deepens off the New England coast. This will result in low level
northwesterly flow across the region in the morning, becoming 
westerly in the afternoon. Deep dry air will prevail, yielding a
dry forecast. Temperatures are forecast to top out around 70 in
most areas, with some low 70s expected in southeast Georgia. 
Westerly winds will be breezy at times, with gusts topping out 
in the 20-25 mph range. 

Tonight: High pressure over the Upper Midwest will become the 
dominant feature, veering winds around to more northerly late 
tonight. Clear skies and a dry forecast will prevail. Lows are 
forecast to reach the low to mid 40s in most areas away from the


High pressure over the area on Saturday will slide off the 
Carolina coast on Sunday. Dry weather with warming temperatures 
are expected. Highs Sunday will be in the mid to upper 70s.

An upper shortwave will approach the area on Monday, pushing a 
surface low pressure system into central and eastern SC during 
the afternoon. 0-6 km flow will be predominantly westerly so 
moisture return ahead of the low will be somewhat limited. 
Isolated to scattered showers should move into the area late 
Monday afternoon. There may be enough instability to support a 
few thunderstorms as well. Strong warm advection will result in 
another warm day with highs in the upper 70s.


A series of shortwaves will move through the area Monday night 
through Tuesday night while a backdoor cold front slowly sinks 
south through the area. We currently have the highest rain 
chances on Tuesday as this coincides with the front dropping 
through the area and the strongest PVA aloft. Cool high pressure
will affect the area through Wednesday before weakening and 
shifting east, allowing for a warming trend late next week.


VFR conditions will prevail at both KCHS and KSAV through 06Z 
Saturday. Westerly winds will become gusty late this morning and
this afternoon, with frequent gusts into the 20-25 knot range. 

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


Today through tonight: Northwest winds topping out in the 15-20
knot range will prevail this morning and any lingering Small 
Craft Advisories are expected to come down by noon. Winds will 
see a brief west-southwesterly surge this afternoon, and could 
be near advisory thresholds for Charleston Harbor and the 
Charleston County waters. Overall, winds should top out in the 
15-20 knot range with seas 2-4 feet out to 20 nm and 4-5 feet 
beyond. Overnight, winds will veer around to northerly after 
midnight. Winds will remain elevated in the 15-20 knot range and
just below advisory thresholds. 

High pressure will maintain relatively benign marine conditions
Saturday through Sunday night. Stronger southwest flow will 
setup on Monday ahead of a low pressure system, though the 
current forecast keeps conditions just below advisory levels.

A strong northeast gradient will develop next Tuesday through 
Thursday behind the backdoor cold front. Small Craft Advisories 
are likely across most of the marine area.

Rip Currents: Breezy westerly winds and moderate swell energy
will combine to produce a moderate risk of rip currents at all
beaches through this evening. 


Today: High pressure will build in to the area as an area of low
pressure off the New England coast deepens. Dry air across the 
region will result in relative humidity values falling into the 
20-25 percent range this afternoon. Westerly winds will be 
breezy this afternoon, with frequent gusts into the 20-25 mph 
range. A Fire Danger Statement has been issued for all of 
southeast Georgia. A Fire Danger Statement could also be needed 
for southeast South Carolina following coordination with users 
and surrounding NWS offices later this morning. 

Saturday through Sunday: Critical or near-critical relative
humidity values are likely to persist.


The KCLX radar has failed. Technicians will look into the issue
this morning.


MARINE...Small Craft Advisory until noon EDT today for AMZ374.
     Small Craft Advisory until 6 AM EDT early this morning for