Sunrise 6:42 AM   Sunset 7:54 PM Moonrise 4:08 PM   Moonset 4:09 AM

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AMZ330 Charleston Harbor- 1000 Am Edt Sat Apr 20 2024
Today - W winds 5 to 10 kt, becoming sw late. A slight chance of showers and tstms late. Tonight - SW winds 5 to 10 kt, becoming nw after midnight. A chance of showers and tstms in the evening, then showers and tstms likely after midnight. Sun - NE winds 5 to 10 kt, becoming N 10 to 15 kt with gusts to 20 kt in the afternoon. A chance of showers and tstms in the morning, then showers with a slight chance of tstms in the afternoon. Sun night - N winds 15 kt with gusts to 20 kt. Showers with a slight chance of tstms in the evening, then showers likely after midnight. Mon - NE winds 10 to 15 kt with gusts to 20 kt. A chance of showers, mainly in the morning. Mon night - NE winds 10 kt. A slight chance of showers. Tue - NE winds 10 kt. Tue night - SE winds 10 kt. Wed - SW winds 10 kt. Wed night - SW winds 10 kt.
winds and waves higher in and near tstms.
unless otherwise noted, waves 1 foot or less.
charleston harbor water temperature 69 degrees.

AMZ300 1000 Am Edt Sat Apr 20 2024
Synopsis for the coastal waters of south coastal south carolina and north coastal georgia - A slow moving front will bring unsettled weather to the region this weekend. High pressure will then return and prevail into the middle of next week.

FXUS62 KCHS 201419 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 1019 AM EDT Sat Apr 20 2024

SYNOPSIS
A slow moving front will bring unsettled weather to the region this weekend. High pressure will then return and prevail into the middle of next week.

NEAR TERM /THROUGH TONIGHT/
Today: Zonal flow aloft continues across the southeastern United States this morning as the mid-level ridge has been suppressed south towards southern Mexico with a potent long wave trough across eastern Canada. In between the two features, a cold front remains stalled with several rounds of convection forecast to move east along the boundary. Current surface analysis has a cold front stalled across the Upstate of SC arching back east across southern NC. Latest observed sounding from KCHS shows a thin PBL with an impressive 850 mb temperature of 16 degrees C (or at the 75th percentile for this time of year). This will easily support high temperatures around 90 degrees for most locations (except right at the beaches were highs in the mid 80s are forecast). Through the morning into early afternoon hours, no precipitation is expected. The deep westerly flow will keep the sea breeze pinned pretty close to the coast this afternoon.
Forecast soundings suggest dewpoints will mix out into the upper 50s/lower 60s, but dewpoints should hold/pool into the upper 60s in the vicinity of the sea breeze during peak heating.
Modified soundings support modest mixed-layered instability (MLCAPE 1000-1500 J/kg) in the vicinity of the sea breeze, so a few showers/tstms could pop along or even just behind the circulation in the absence of any large scale forcing mechanisms aloft. Pops near 20% were continued across the coastal counties this afternoon to account for this possibility. However, dry air in the mid-levels remain, so some modification will need to occur before multiple deep moist updrafts can sustain themselves.

Tonight: Southern stream shortwave energy moving along the north-central Gulf Coast this morning will traverse the area this evening and overnight as the surface front meanders south into Southeast South Carolina and Southeast Georgia. Models are inconsistent with both the depth and intensify of the forcing with this shortwave. However, with some degree of residual instability and a surface boundary lurking about, expect a healthy coverage of showers/tstms to work from southwest to northeast across the area into early morning hours Sunday. Pops 50-70% were utilized to account for tonight's convection with convection first increasing over interior Southeast Georgia early this evening and exiting off the middle South Carolina coast early Sunday morning as the aforementioned shortwave pushes through and eventually offshore.

0-6km bulk shear looks to only average 20-25 kt and with both the depth and intensity of forcing for ascent ahead of the shortwave still unclear, expect any convective organization to be largely driven by mesoscale processes, such as possible outflow collisions and boundary interactions with the slow moving surface front and the remnants of the pinned sea breeze circulation near the coast. Despite the loss of insolation after sunset, elevated DCAPE values 800-1000 J/kg will support a risk for damaging winds with a few of the stronger tstms this evening with the possibility of brief convective organization/enhancement near boundary interactions. Lows will range from the upper 50s/lower 60s near the CSRA and Southern Midlands (north of the front) to the upper 60s/near 70 south of I-16 into far southern South Carolina (south of the front).

SHORT TERM /SUNDAY THROUGH TUESDAY/
A cold front will likely be positioned off the South Carolina coast and extending back into southeast Georgia Sunday morning.
The front will shift away from the area later in the day and overnight. Better forcing for ascent with shortwave energy passing across the region will lead to increasing coverage of showers through the day. Focus looks to be oriented over inland areas initially with activity progressing more towards the coast in the afternoon. Given positioning of the front, instability and thunder chances should primarily be over the eastern half of the forecast area. Temperatures will be tricky as there will be a notable gradient with highs ranging from the mid 60s across inland and northern zones to upper 70s/near 80 near the far southeast Georgia coast. Rain chances will decrease Sunday night as precip activity moves offshore. Lows will mainly be in the upper 40s to lower/mid 50s.

High pressure builds inland Monday with front well to the east.
A few showers could develop as main upper wave passes through, though guidance varies on coverage. Kept PoPs limited to 20% over land. Otherwise it will be unseasonably cool with highs topping out in the mid 60s. Lows Monday night are forecast to be in the mid to upper 40s, except lower 50s closer to the coast.

Ridge of high pressure extends into the area on Tuesday. No weather concerns with temperatures moderating back to the mid 70s.

LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
High pressure continues into Wednesday. A cold front could move into the region Wednesday night or Thursday but most guidance isn't showing as much of a clear cut frontal passage.
Regardless, little if any impact is expected with a dry forecast persisting. Temperatures will within a few degrees of normal.

AVIATION /14Z SATURDAY THROUGH WEDNESDAY/
20/12z TAF Discussion: KCHS/KJZI/KSAV: VFR for much of the period. An isolated shower/tstm could develop along the mid-late afternoon sea breeze circulation, but impact chances are too low to mention at this time at any of the three terminals. Rain chances will increase this evening as a southern stream shortwave moves across the region. Shower/tstms could impact KSAV first, then spread into both Charleston terminals later in the evening. VCTS was highlighted at KSAV by 01z and KCHS and KJZI by 03z to account for this. Confidence in timing/intensity is not high enough to show a TEMPO or prevailing group at either terminal.
These will be reconsidered for the 18z TAF cycle. As the front drops south, expect low clouds to spread in behind it. There is a chance cigs could drop to high-end IFR by sunrise Sunday.
Limited conditions to MVFR for now to trend.

Extended Aviation Outlook: Flight restrictions in low clouds and showers/thunderstorms are possible Saturday night through Sunday with a slow moving front. Low clouds could linger into Monday. Predominant VFR thereafter.

MARINE
Today: Broad south to southwest winds trajectories will dominate the waters today. Some slight enhancement near the land/sea interface could occur later this afternoon as a pinned sea breeze circulation develops, but a significant enhancement to the surface wind field is not expected. Winds will average 10-15 kt with gusts near 20 kt possible at times near the coast and in the Charleston Harbor this afternoon as the sea breeze forms.
Seas will average 2-3 ft. An isolated shower or tstm could pop near the sea breeze late in the afternoon.

Tonight: A cold front will sink south into the South Carolina coastal waters tonight as scattered to numerous showers/tstms push offshore. A few of these tstms could be strong producing wind gusts in excess of 35 kt and cloud-to-water lightning.
Southwest winds will veer to the west this evening all waters, then shift northwest to north behind the front as it drops south to near the Savannah River Entrance by daybreak Sunday. Speeds look to average 5-10 kt, but will surge to 10-15 kt in the South Santee-Edisto Beach nearshore leg a few hours before daybreak Sunday. Waves will average 2-3 ft.

Sunday through Thursday: A cold front draped across the area Sunday morning will push east with time, turning winds around to the north/northeast and increasing in speeds. Seas also build and Small Craft Advisories will be possible for portions of the waters Sunday night into Monday, especially the Charleston county and outer Georgia waters. The other nearshore zones are not out of the question but looks more marginal at this time.
Winds ease on Tuesday with no additional concerns through Thursday.

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

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Abbapoola Creek entrance
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Sat -- 12:21 AM EDT     0.64 feet Low Tide
Sat -- 05:09 AM EDT     Moonset
Sat -- 06:44 AM EDT     5.10 feet High Tide
Sat -- 06:44 AM EDT     Sunrise
Sat -- 12:42 PM EDT     0.52 feet Low Tide
Sat -- 05:07 PM EDT     Moonrise
Sat -- 07:13 PM EDT     5.34 feet High Tide
Sat -- 07:53 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION

Abbapoola Creek entrance, Stono River, South Carolina, Tide feet

Charleston Harbor Entrance
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Sat -- 12:59 AM EDT     0.00 knots Slack
Sat -- 03:06 AM EDT     1.19 knots Max Flood
Sat -- 05:08 AM EDT     Moonset
Sat -- 06:43 AM EDT     Sunrise
Sat -- 06:49 AM EDT     -0.00 knots Slack
Sat -- 10:11 AM EDT     -1.88 knots Max Ebb
Sat -- 01:15 PM EDT     0.00 knots Slack
Sat -- 03:36 PM EDT     1.35 knots Max Flood
Sat -- 05:06 PM EDT     Moonrise
Sat -- 07:23 PM EDT     -0.00 knots Slack
Sat -- 07:53 PM EDT     Sunset
Sat -- 10:39 PM EDT     -2.13 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION

Charleston Harbor Entrance, South Carolina Current, knots

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