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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 221957
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
357 PM EDT Fri Mar 22 2019

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

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
This Evening and Tonight: West-northwest flow will persist across 
the Southeast United States along the southern periphery of a large 
mid/upper lvl trough of low pressure centered along the Northeast
Coast. At the sfc, high pressure centered over the Mississippi 
River Valley will gradually shift east as low pressure deepens 
off the Northeast coast. Given the setup, a west sfc wind will 
continue to advect dry air into the region and maintain clear 
skies through the evening. Dry and breezy westerly winds topping
out in the 20-25 mph will continue to produce an elevated fire 
weather risk into early evening hours (see fire weather section
below). Overnight, high pressure over the Midwest will shift 
south, helping push a dry front into the area starting after 
midnight. Clear skies and a dry conditions will prevail through 
the night, but the most noticeable change will be a wind shift 
from westerly flow to northerly flow post fropa. Given the 
setup, temps should dip into the low/mid 40s away from the 
beaches tonight. 

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Surface high pressure will build over the region on Saturday and 
will slide of the Carolina coast on Sunday. Saturday and Sunday, 
daytime temperatures will peak around 70 with morning lows in the 
40s. The center of low pressure will track rapidly east across the 
Ohio River Valley and mid Appalachians on Monday. A cold front 
associated with the low is expected to slide across the foothills 
and Piedmont of the Carolinas by Monday afternoon. Temperatures on 
Monday in advance of the front are forecast to warm into the upper 
70s with dewpoints in the mid to upper 50s. GFS CAPE values may 
surge to around 500 J/kg Monday afternoon and evening. I will keep a 
mention of SCHC for thunderstorms.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions will prevail at both KCHS and KSAV through 18Z 
Saturday. Westerly winds will remain gusty into early evening 
with frequent gusts around 20 kt. 

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

&&

.MARINE...
This Evening through Tonight: West winds should gradually turn west-
southwest this evening as dry high pressure extends over the waters. 
In general, winds should top out in the 15-20 kt range while seas 
are no higher than 3-4 ft. A dry cold front is then expected to 
approach from the northwest, then shift over the coastal waters 
after midnight. Winds are expected to remain elevated (15-20 kt) 
post fropa, but will likely turn northwest after midnight, then 
north across South Carolina waters approaching daybreak Saturday.

Extended Marine: High pressure will build over the marine zones on 
Saturday and will slide east on Sunday, yielding winds generally 
below 15 kts. Seas are expected to range between 1 to 3 ft. A cold 
front will approach the region on Monday, sliding across the region 
Monday night into Tuesday morning. In the wake of the front, gusty 
NE winds are expected across the marine zones. Small Craft Advisory 
conditions may begin on Tuesday and remain through Wednesday. High 
pressure is expected to build across the region on Thursday, 
resulting in decreasing winds. Seas on Thursday may remain at or 
above Small Craft Advisory criteria.

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

&&

.FIRE WEATHER...
Late Afternoon/Evening: High pressure will build into the area as 
low pressure off the New England coast deepens. Dry air across the 
region will allow relative humidity values to remain ion the 20-25 
percent range for the next couple hours. Westerly winds will 
also be breezy into the evening, with frequent gusts into the 
20-25 mph range. Given the conditions, a Fire Danger Statement 
remains in place for all of Southeast Georgia and Southeast 
South Carolina until 8 PM. 

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

&&

.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...DPB
SHORT TERM...NED
LONG TERM...JRL
AVIATION...DPB/NED
MARINE...DPB/NED
FIRE WEATHER...
EQUIPMENT...