Sunrise 6:15 AM   Sunset 8:18 PM Moonrise 5:45 PM   Moonset 3:51 AM

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AMZ330 Charleston Harbor- 708 Pm Edt Tue May 21 2024
Tonight - E winds 10 kt, diminishing to 5 to 10 kt this evening.Wed - NE winds 5 kt, becoming E 10 kt in the afternoon. Wed night - S winds 5 to 10 kt. Thu - S winds 5 kt, increasing to 10 to 15 kt with gusts to 20 kt in the afternoon. Thu night - S winds 10 to 15 kt, diminishing to 5 to 10 kt after midnight. Fri - SW winds 10 to 15 kt. Fri night - SW winds 10 to 15 kt. Sat - SW winds 10 to 15 kt. A slight chance of showers and tstms. Sat night - SW winds 10 to 15 kt. A slight chance of showers and tstms.
winds and waves higher in and near tstms.
unless otherwise noted, waves 1 foot or less.
charleston harbor water temperature 76 degrees.

AMZ300 708 Pm Edt Tue May 21 2024
Synopsis for the coastal waters of south coastal south carolina and north coastal georgia - High pressure will persist into late week. Diurnal convection is expected during the weekend. A cold front might approach early next week.

FXUS62 KCHS 211957 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 357 PM EDT Tue May 21 2024

SYNOPSIS
High pressure will persist into late week. Diurnal convection is expected during the weekend. A cold front might approach early next week.

NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
Rest of today: Surface high pressure remains centered across the Piedmont of North Carolina this afternoon with a mid-level ridge located overhead. This persistent seasonably cool and dry weather is thanks to a quasi-stationary mid-level wave off of the southeast coast of the United States. Temperatures have warmed into the mid 80s today across most of the area with dewpoints falling to the 60 degree mark.

Tonight: Surface high pressure will remain overhead with winds quickly falling off as the PBL decouples. Temperatures will decrease rather quickly into the mid 60s and then slowly fall towards the 60 degree mark (especially across the rural zones).
The main question overnight remains the possibility of fog.
Crossover temperatures are right around 60 degrees, which isn't completely supported across the urban zones. Over the rural areas, this is quasi- supported (at least patchy fog).

SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/
Wednesday: A cut off low about halfway between Florida and Bermuda lifts northeast, as a ridge extending from an anticyclone in the western Gulf of Mexico stretches across the local area. While there could be the formation of a weak lee side trough, high pressure at the surface off the coast will be the main feature. The lack of moisture and a continued subsidence inversion will maintain its hold, so even though a weak short wave could brush nearby late, no risk of any convection. 850 mb temperatures reach 15-16C, and that along with an expansion of the low level thickness will support max temperatures in the mid and upper 80s away from the beaches.

Wednesday night: Winds decouple in the evening, leading to another night with good radiational cooling. We leaned toward the cooler side of guidance as a result. Although there is another day of drying in the boundary layer, guidance insists that fog can again develop within a southerly synoptic flow. We added mention of patchy fog to the forecast.

Thursday: The axis of the ridge aloft pulls east and gives way to more of a zonal flow, while at the surface the gradient does tighten some between Atlantic high pressure and a lee side trough. TRhere's another short wave that could move through, and with less subsidence and a much greater supply of moisture (Pwat up near 1.5 inches), it's possible the sea breeze could try and initiate some showers and t-storms. For now we keep it rainfree. 850 mb temperatures climb another degree C, so we added a couple of degrees to max values, which will hit 90F most places away from the shoreline. A warmer night with higher dew points.

Friday: The flow aloft will be mainly zonal, with a decent short wave moving through the Ohio Valley. At the surface, Atlantic high pressure is again the main feature, with a lee side trough possible.
The sea breeze again looks to be the main mechanism for any convection that might occur, as well as the upstream trough. So perhaps a few t-storms pop in the afternoon. Both the low level thickness and the 850 mb temperatures climb even more, so we added highs another 1-2F.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
A weak trough should pass to our north Friday night into early Saturday, followed by zonal flow over the Southeast through Monday, with indications of a trough moving closer by on Tuesday. Surface high pressure will remain in the western Atlantic while fronts are forecasted to pass to our north. Expect convection along/near the sea breeze each afternoon/evening, decreasing during the overnight hours, maybe increasing in coverage Tuesday, dependent upon how far south the cold front can get. Temperatures will remain a few degrees above normal each day and night.

AVIATION /19Z TUESDAY THROUGH SUNDAY/
KCHS/KJZI: The Charleston terminals are all VFR this afternoon with only some diurnal CU. Winds are currently out of the northeast 5 to 10 kt with a sea breeze expected to move inland this afternoon into evening. As this occurs, winds will veer around from the southeast and increase in speed to around 10 kt.
Overnight, winds will quickly go calm as the PBL decouples with temperatures falling towards the crossover temperature (upper 50s to lower 60s). Another round of patchy fog will again be possible, but will likely hold to only KJZI and surrounding areas outside of Charleston.

KSAV: Savannah is currently MVFR this afternoon, but will likely go VFR very soon. Winds are currently out of the northeast around 5 kts with a sea breeze expected to move inland this afternoon. As this occurs, winds will veer around from the southeast and increase in speed to around 10 kt. Overnight, winds will quickly go calm as the PBL decouples with temperatures falling towards the crossover temperature (upper 50s to lower 60s). Another round of patchy fog will again be possible, but will likely hold outside the city and KSAV.

Extended Aviation Outlook: Mainly VFR. Brief flight restrictions are possible late Wednesday night/early Thursday due to fog, and again in SHRA/TSRA Saturday and Sunday afternoon.

MARINE
Today and tonight: Surface high pressure will persist over the Piedmont of North Carolina allowing for northeast flow over the waters. The elevated pressure gradient has allowed for 2 to 4 ft seas and wind gusts approaching 20 kt as times. Tonight, seas and winds will start to diminish as high pressure slowly moves east, or away from the region.

Extended Marine: High pressure remains the main synoptic feature through the weekend, with the likely formation of a lee side trough. Otherwise, expect a typical summerlike wind pattern beginning Thursday. That's when each day the winds will back and be stronger along the land/sea interface with the formation of the afternoon breeze. Gusts could approach 20 kt in the Charleston Harbor with the passage of the sea breeze. Each night, winds should veer as the low level jet sets up along the coast. But no Small Craft Advisories are anticipated. Eventually convection should return, especially this weekend.

Rip Currents: Given the astronomical influences of the Full Moon, it won't take more than a small swell to lead to an enhanced risk of rip currents at the local beaches. Both the in-house Rip Current Calculator and the Rip Current MOS point to a Low Risk Wednesday.
But if the swell is higher than anticipated, then the risk will need to be raised. Conditions look better for an elevated risk on Thursday with a little more wind and swell energy.

TIDES/COASTAL FLOODING
A coastal flood advisory is in effect for Coastal Colleton and Charleston Counties this evening as another round of minor coastal flooding is forecast. The current tidal anomaly is lower than it was last night (1.6 ft vs 1.3 ft), but the astronomical is higher (5.56 vs 5.79 ft). This will likely create a very similar high tide this evening as compared to yesterday/ Monday evening (7.2 ft at Charleston Harbor).

Minor flooding is possible with the evening high tides Wednesday and Thursday along coastal Charleston and coastal Colleton Counties. There are no concerns at this time along the remainder of our coast.

CHS WATCHES/WARNINGS/ADVISORIES
GA...None.
SC...Coastal Flood Advisory until 10 PM EDT this evening for SCZ049- 050.
MARINE...None.

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Clouter Creek
Click for Map
Tue -- 01:50 AM EDT     0.54 feet Low Tide
Tue -- 04:50 AM EDT     Moonset
Tue -- 06:16 AM EDT     Sunrise
Tue -- 07:54 AM EDT     4.86 feet High Tide
Tue -- 01:49 PM EDT     0.33 feet Low Tide
Tue -- 06:44 PM EDT     Moonrise
Tue -- 08:16 PM EDT     Sunset
Tue -- 08:28 PM EDT     6.01 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Clouter Creek, north entrance, Cooper River, South Carolina, Tide feet

Charleston Harbor Entrance
Click for Map
Tue -- 01:56 AM EDT     0.00 knots Slack
Tue -- 04:01 AM EDT     1.36 knots Max Flood
Tue -- 04:50 AM EDT     Moonset
Tue -- 06:16 AM EDT     Sunrise
Tue -- 07:26 AM EDT     -0.00 knots Slack
Tue -- 10:48 AM EDT     -1.90 knots Max Ebb
Tue -- 01:51 PM EDT     0.00 knots Slack
Tue -- 04:27 PM EDT     1.63 knots Max Flood
Tue -- 06:44 PM EDT     Moonrise
Tue -- 08:14 PM EDT     -0.00 knots Slack
Tue -- 08:16 PM EDT     Sunset
Tue -- 11:30 PM EDT     -2.47 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION

Charleston Harbor Entrance, South Carolina Current, knots

Full Color Weather Map

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