Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 230145
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
945 PM EDT Mon Apr 22 2019

.SYNOPSIS...
High pressure will prevail with dry weather through Thursday.
Low pressure and a cold front will then bring unsettled weather
late this week into the weekend. 

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Another quiet night weatherwise will prevail across the local 
region, with high pressure at the surface and a deep and dry 
northwest flow aloft as a short wave ridge approaches from the 
west. Clear skies and light/calm winds will support almost 
optimal radiational cooling. It won't be as cool as the last two
nights with higher dew points, but we're still on track for min
temps 50-55F inland from US-17, with temps closer to 60F along 
the coast and in downtown Charleston. The Hi-Res guidance 
continues to hint at some fog as we approach sunrise. We 
continue to think it'll just be shallow ground fog, so there is 
no mention in the forecast.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Tuesday through Thursday: Subsidence provided by deep layered high 
pressure will support high temperatures in the lower/middle 80s 
Tuesday, then temperatures will warm further into upper 80s/close to 
90F away from the beaches Wednesday and Thursday. Expect low 
temperatures in the mid/upper 50s inland and lower 60s close to the 
coast Tuesday night, followed by low temperatures around 60F inland 
and in the lower/middle 60s closer to the coast Wednesday night. 
Within the westerly flow aloft, patchy high clouds will stream 
across the region at just about anytime through Wednesday. Then, 
thicker cirrus could spread across the region Thursday. Otherwise, 
expect nothing more than scattered diurnal cumulus especially 
Wednesday/Thursday, and the chance for measurable rainfall will 
remain essentially zero through this period.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A storm system with its associated cold front is expected to move 
through the region on Friday, bringing showers and cooler 
temperatures. However, models disagree on the track and timing of 
the main features along with the main bands of rainfall.
Hence, we have chance POPs in the forecast. By the weekend the 
models continue to differ on whether it will be dry or if showers 
will persist. We opted to go with slight chance POPs to account for 
this.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
VFR. Low end chance of some ground fog close to daybreak Tuesday.

Extended Aviation Outlook: VFR through Thursday, with only a low 
probability for ground fog around sunrise each day. Then, low 
pressure, a cold front and showers/thunderstorms could produce 
periodic flight restrictions Friday into Saturday.

&&

.MARINE...
Tonight: A minimal gradient will prevail with high pressure 
overhead. S or SW winds on the South Carolina waters and SE on 
the Georgia waters early on will move to the SW and W overnight
and late with land breeze influences. Speeds will be around 5-10
kt. Seas will average around 2 ft near shore and 2-3 ft on the 
outer Georgia waters.

Tuesday through Saturday: Under high pressure, the sea breeze 
circulation featuring winds of 15 knots or less will dominate local 
winds Tuesday afternoon/early evening. Seas will average 1-3 feet, 
highest beyond 20 nm. Then, a tightening pressure gradient will 
support somewhat stronger southwest synoptic winds especially 
Wednesday through Thursday, and the south/southwest sea breeze could 
locally gust as high as 15-20 knots. Seas will respond and will 
average 2-4 feet. A cold front will then move through the region 
sometime between Friday afternoon and late Friday night, followed by 
a wind shift to the northeast by Saturday. Winds/seas could approach 
SCA levels Saturday.

&&

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

&&

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