Marine Weather Net

Charleston Harbor Marine Forecast


TONIGHT

W
WINDS
5 - 10
KNOTS

SAT

NW
WINDS
5 - 10
KNOTS

SAT NIGHT

SW
WINDS
10 - 15
KNOTS

SUN

SW
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
AMZ330 Forecast Issued: 528 PM EDT Fri Jul 20 2018

Tonight...W Winds 5 To 10 Kt. A Chance Of Tstms. Showers, Mainly This Evening. Locally Heavy Rainfall Possible This Evening.
Sat...Nw Winds 5 To 10 Kt, Becoming Sw In The Afternoon.
Sat Night...Sw Winds 10 To 15 Kt. A Chance Of Showers And Tstms.
Sun...Sw Winds 10 To 15 Kt. A Chance Of Showers And Tstms.
Sun Night...S Winds 10 To 15 Kt. A Chance Of Showers And Tstms.
Mon...S Winds 10 To 15 Kt. A Chance Of Showers And Tstms.
Mon Night...S Winds 10 To 15 Kt. Showers And Tstms Likely.
Tue...S Winds 15 Kt. Showers And Tstms Likely.
Tue Night...S Winds 10 To 15 Kt. A Chance Of Showers And Tstms.
Wed...S Winds 10 Kt. Showers And Tstms Likely.
Wed Night...S Winds 10 Kt. A Chance Of Showers And Tstms. Mariners Are Reminded That Winds And Waves Higher In And Near Tstms. Unless Otherwise Noted, Waves 1 Foot Or Less. Charleston Harbor Water Temperature 84 Degrees.
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Area Forecast Discussion
National Weather Service Charleston SC
658pm EDT Fri July 20 2018

Synopsis: Low pressure across the area will shift northeast near the coast through tonight while a stationary front lingers nearby this weekend. A trough of low pressure will then generally persist into the middle of next week before Atlantic high pressure starts to rebuild late next week.

Near Term - Until 6am Saturday Morning
Tonight: A weak area of low pressure will continue to meander along/near a stationary front draped across the eastern 1/3 of Southeast South Carolina into parts of Southeast Georgia this evening. Along and east of the low's center, numerous to widespread showers along with embedded thunderstorms will continue to produce episodes of heavy rainfall, with most recent radar trends suggesting the bulk of activity occurring near coastal locations in Southeast Georgia. Expect widespread precipitation to gradually shift offshore in the next couple hours, putting an end to the bulk of a minor flooding threat. Overnight, drier air is anticipated to wrap around the western edge of the surface low as it begins to slowly make a northeast shift late, which should allow most precipitation to taper off over western zones early, followed by coastal areas later tonight. Given the latest rain event, there could be some fog development late tonight as guidance suggests, mainly over inland areas where low temps dip into the low 70s. Closer to the coast, overnight lows should range in the mid/upper 70s.

Short Term - 6am Saturday Morning Through Monday
Saturday: The pesky stationary front will finally push offshore as a frontal waves pushes off to the northeast in response to shortwave energy propagating east. DNVA/subsidence in the wake of the shortwave should suppress convection for much of the morning into the early-mid afternoon hours before forcing begins to increase once again ahead of yet another shortwave rounding the base of the mean longwave trough that is in place across the eastern United States. Expect scattered to numerous showers/tstms to develop across central Georgia into the South Carolina Midlands during the afternoon hours ahead of a cold front, spreading east into Southeast South Carolina and Southeast Georgia by late afternoon and offshore early Sunday morning as as the cold front meanders east and eventually stalls out along the coast. Models show sufficient 0-6km bulk shear and instability to support a few severe tstms, but the degree of post- sunset instability this far east is somewhat unclear. The risk for severe weather, mainly in the form of damaging winds, will be greatest across the interior where the juxtaposition of shear and instability will be the most favorable during the late afternoon/early evening hours, but if upstream convection can organize into a QLCS/squall line or several multi-cell clusters, then the severe risk could spread farther east to the coast. This will have to be carefully monitored. Pops will range from 20-40% Saturday afternoon and 50-60% Saturday Night, highest across the interior. Highs will warm into the lower 90s away from the coast with overnight lows ranging from the lower 70s well inland to around 80 at the beaches.

Sunday and Monday: Stalled front along the coast will serve as a focus for scattered showers/tstms both days as the long-wave trough aloft tries to cut off from the main belt of the westerlies. There is some model disagreement on where the exact placement of the front will be as weak low pressure develops along it, so maintained chance probability of precipitation for most areas Sunday afternoon/evening. Further refinements in the Probability of Precipitation forecast will be needed as additional model runs are received. The risk for showers/tstms will persist through much of the night. Highs will warm into the lower 90s away from the coast with lows ranging from the lower 70s well inland to around 80 at the beaches. The risk for heavy rainfall/flooding as well as isolated wet microbursts will continue

Long Term - Monday Night Through Friday
The upper trough across the eastern United States will gradually weaken through Thursday then a deep layered Atlantic ridge will build from the east. Deep moisture and synoptic scale forcing should support numerous showers and tstms through Wednesday before coverage becomes more scattered late week.

Marine Discussion
Tonight: Weak low pressure over inland will move slowly northeast along a stationary front overnight. This will keep winds elevated a bit higher than normal but below Advisory levels over all coastal waters. However, showers and thunderstorms are likely much of the night, which will produce locally worse conditions. In general, southwest winds will turn west late, remaining as high as 15-20 kt early tonight before decreasing to 10-15 kt. Seas should range between 2-4 ft, highest in northern South Carolina waters and offshore Georgia waters.

Saturday through Wednesday: The gradient will be enhanced for much of the time due to surface low pressure over the Southeast U.S. while weak high pressure remains offshore. South to southwest winds will range from 10-20 kt for much of the period. In addition, numerous showers and thunderstorms will produce locally hazardous conditions. Seas could get close to 6 ft Monday Night into Wednesday and Small Craft Advisories may be needed

NOAA Charleston SC Office: Watches - Warnings - Advisories
GA...None. SC...None. MARINE...None

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