Sunrise 6:15 AM   Sunset 8:17 PM Moonrise 5:45 PM   Moonset 3:52 AM

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AMZ330 Charleston Harbor- 1243 Pm Edt Tue May 21 2024
This afternoon - E winds 10 kt. Tonight - E winds 5 to 10 kt. Wed - NE winds 5 kt, becoming se in the afternoon. Wed night - S winds 5 to 10 kt. Thu - SW winds 5 kt, becoming S 10 to 15 kt in the afternoon. Thu night - S winds 10 kt. Fri - SW winds 10 to 15 kt. Fri night - S 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 1243 Pm Edt Tue May 21 2024
Synopsis for the coastal waters of south coastal south carolina and north coastal georgia - High pressure will persist for most of this week. Diurnal convection is expected during the weekend.

FXUS62 KCHS 211426 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 1026 AM EDT Tue May 21 2024

SYNOPSIS
High pressure will persist for most of this week. Diurnal convection is expected during the weekend.

NEAR TERM /THROUGH TONIGHT/
Today: Latest KCHS observed sounding (21.12z) revealed a very dry air mass in place with a PWAT of 0.90" (or near the 25th percentile according the SPC sounding climatology page). This is thanks to surface high pressure centered right over the Piedmont of NC with the ridge axis extending northeast and southwest.
This morning there was a thin stratus deck that built down to areas of fog. That has since lifted to a strato-cu/ cu deck with partly to mostly cloudy skies forecast. 850 mb temperatures have risen to 14 degrees C this morning (compared to 11/ 12 degrees C this time yesterday morning) with 1000/ 850 mb thicknesses rising to around 1395 m (or around 5 m). High temperatures will likely be 2 - 4 degrees warmer than yesterday or around 84/ 85 degrees.

Tonight: Diurnally driven cloud cover fades quickly this evening leaving mainly clear skies and light winds. Blended guidance fog probabilities as well as MOS guidance suggest some fog potential...which has been added to the forecast for the overnight/early Wednesday morning timeframe.

SHORT TERM /WEDNESDAY THROUGH FRIDAY/
Wednesday: The mid-levels will consist of a cut-off Low off the Southeast coast in the morning. It'll move further offshore as time progresses. Meanwhile, a ridge will prevail over the Southeast U.S.
At the surface, High pressure along the Southeast coast in the morning will shift offshore into the afternoon. A front will slowly approach from the north and northwest during the evening and overnight. Though, it won't make it near our area as the periphery of the High remains the dominant synoptic feature. Ongoing low and mid-level subsidence will bring our area dry conditions with mostly sunny/clear skies. Expect a sea breeze quickly moving inland during the afternoon. Low-level thickness values and 850 mb temperatures support highs in the upper 80s before the passage of the sea breeze, except cooler at the beaches. Lows should range from the lower 60s far inland to the lower 70s along the immediate coast.

Thursday: A mid-level ridge over the Southeast U.S. in the morning will weaken as time progresses, leading to west southwest flow overhead. Surface High pressure just off the Southeast coast in the morning will move further offshore as time progresses. Meanwhile, a front to our north and northwest will continue to approach, especially overnight. However, it's not expected to reach our area.
The periphery of the High will bring another day with dry conditions. Though, subsidence won't be as strong, so expect more cumulus clouds in the afternoon along with a strong sea breeze quickly moving inland. Low-level thickness values and 850 mb temperatures support highs around 90 degrees before the passage of the sea breeze, except cooler at the beaches. Lows will be mild, in the mid 60s far inland to the lower 70s along the immediate coast.

Friday: The mid-levels will consist of west southwest flow overhead.
At the surface, High pressure will be centered in the western Atlantic, with it's periphery trying to extend into the Southeast. A front to our north and northwest during the morning will dissipate into the afternoon, partly due to the High trying to build back into our area. Increased moisture ahead of the front and circling around the High will be in place across our area during the afternoon.
Temperatures peaking in the lower 90s will help to increase instability. Therefore, a few thunderstorms may form around the vicinity of the weakening front and along the sea breeze in the afternoon, especially across our SC counties. But it's not looking like a washout at this time. These details will be ironed out with future forecast updates.

LONG TERM /FRIDAY NIGHT THROUGH MONDAY/
A weak trough should pass to our north Friday night into early Saturday, followed by zonal flow over the Southeast through Monday.
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. Temperatures will remain a few degrees above normal each day and night.

AVIATION /14Z TUESDAY THROUGH SATURDAY/
KCHS/KJZI/KSAV: Satellite data shows some fog and lower cloud cover across the region trying to spread down toward the KSAV terminal. 12Z forecast will have a brief period of sct lower clouds at KSAV. Otherwise, a SCT Cumulus deck will likely develop later this morning hours and into the afternoon across the region. A brief period of BKN cloud cover is possible.

Meanwhile, an uptick in northeasterly winds up to 10 knots will take place during the morning, veering easterly or southeasterly through the afternoon. Winds diminish during the evening.

Extended Aviation Outlook: VFR through Friday. Brief flight restrictions are possible due to showers/thunderstorms later Saturday.

MARINE
Northeasterly winds persist across the coastal waters today with speeds running 10 to 15 knots and seas 2 to 4 feet in the nearshore waters, 3 to 5 feet in the outer waters. Winds and seas diminishing tonight.

Extended Marine: High pressure remains the main synoptic feature through Thursday. A cold front should approach from the north and northwest later Friday, but it's not expected to reach our area.
Otherwise, expect a typical summer wind pattern beginning Thursday.
That's when each day 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. Additionally, convection should return during the weekend.

Rip Currents: With the approaching 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 internal calculations and RCMOS point to a Low Risk through Wednesday. But if the swell is higher than anticipated, then the risk will need to be raised.

TIDES/COASTAL FLOODING
The combination of rising astronomical tides with the upcoming Full Moon and onshore winds will cause tides to be elevated through the middle of this week. Minor flooding is possible with the evening high tides through 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 from 6 PM to 10 PM EDT this evening for SCZ049-050.
MARINE...None.

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Kiawah River Bridge
Click for Map
Tue -- 01:22 AM EDT     0.48 feet Low Tide
Tue -- 04:52 AM EDT     Moonset
Tue -- 06:17 AM EDT     Sunrise
Tue -- 07:22 AM EDT     5.00 feet High Tide
Tue -- 01:22 PM EDT     0.30 feet Low Tide
Tue -- 06:44 PM EDT     Moonrise
Tue -- 07:56 PM EDT     6.18 feet High Tide
Tue -- 08:16 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION

Kiawah River Bridge, 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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