Charleston Harbor Marine Forecast
|Today...Sw Winds 10 Kt, Increasing To 15 Kt This Afternoon. A Slight Chance Of Showers And Tstms This Afternoon.|
|Tonight...Sw Winds 10 To 15 Kt, Becoming W 5 To 10 Kt After Midnight. A Slight Chance Of Tstms In The Evening. A Chance Of Showers.|
|Tue...N Winds 10 To 15 Kt, Becoming Ne 15 To 20 Kt In The Afternoon. Waves 1 To 2 Ft. A Chance Of Showers.|
|Tue Night...Ne Winds 15 To 20 Kt With Gusts To 25 Kt. Waves 1 To 2 Ft.|
|Wed...Ne Winds 20 To 25 Kt. Waves 2 To 3 Ft.|
|Wed Night...Ne Winds 15 To 20 Kt With Gusts To 25 Kt. Waves 1 To 2 Ft.|
|Thu...Ne Winds 10 To 15 Kt.|
|Thu Night...Ne Winds 10 To 15 Kt.|
|Fri...Ne Winds 10 Kt.|
|Fri Night...Se Winds 5 To 10 Kt. Mariners Are Reminded That Winds And Waves Higher In And Near Tstms. Unless Otherwise Noted, Waves 1 Foot Or Less. Charleston Harbor Water Temperature 60 Degrees.|
|Area Forecast Discussion|
National Weather Service Charleston SC
1020am EDT Monday Mar 25 2019
Synopsis: Low pressure will cross the region tonight followed by a strong cold front Tuesday. High pressure will then build in from the north and persist into Saturday. A cold front may affect the area late next weekend.
Near Term - Through Tonight
Late morning update: Mid level clouds had expanded across Southeast GA since daybreak in a region of theta-e convergence atop 850 MB. These clouds appear to be in the region where the GFS developed some light Quantitative Precipitation Forecast at 15Z and we believe this model may still be overdone with POPs given a dry solution of both the latest NAM and latest CAMs. We kept the low afternoon POPs but backed off on their extent/coverage. Temps were warming quickly but we no significant changes to highs for now, Plenty of sunshine across GA zones, readings will be pushing 80 many areas in a few hours. The bulk of the convection from the west is expected to move into our forecast area during the evening hours as as well defined mid-level shortwave drops out of the Upper Midwest and moves toward the central/southern Appalachians.
Tonight: The primary trough will cross the Appalachians late this evening and drive the cold front into the forecast area from the northwest late this evening and the early morning hours. Thanks to the time of day that the front is arriving and the impact of its downslope approach, the showers/thunderstorms along the frontal zone should be on a diminishing trend once they enter the forecast area. It is interesting to note that the 25/00z NAM is virtually dry with the frontal passage, perhaps taking into account the downslope approach. The forecast times the arrival of showers and isolated thunderstorms into our inland zones around or just after 00z. We continue to carry a slight chance of thunderstorms till midnight, then showers thereafter. Instability will be hard to come by thanks to the unfavorable time period, and the overall severe threat will be very low. The main period of precipitation should come to an end around midnight, as the low moves offshore. Then late tonight a strong backdoor cold front will begin moving in from the north. There could be showers along the leading edge of the backdoor front, and we maintain 20-30 percent chances closer to the Santee River through sunrise Tuesday. Cold advection will likely take place beyond the tonight period, and lows should range in the mid to upper 50s.
Short Term - Tuesday Through Thursday
A strong backdoor cold front will drop through the area on Tuesday. Models have been trending drier for this feature though there still looks to be enough isentropic ascent to produce at least a couple showers as the front moves south. Considerably cooler air will filter in from the north, keeping highs in the low 60s to the north to mid/upper 60s farther south.
The cool airmass will persist into Wednesday with highs ranging from the low to mid 60s. Temps will rebound on Thursday once the high begins to shift offshore and the cold air advection abates. Highs on Thursday should reach the upper 60s to lower 70s
Long Term - Thursday Night Through Sunday
Unseasonably warm and mostly dry through the period. A cold front may move through late Sunday or Sunday night though it is currently unclear how much precipitation will accompany it.
Through tonight: Southwest flow will prevail across the local waters, with speeds generally in the 10-15 knot range. A solid 15 knots will be possible in the Charleston Harbor and the Charleston County waters. Seas are forecast to range 1-3 feet. Overnight, an area of low pressure will push offshore. Southwest winds will turn more westerly, and then begin to veer around to northerly across the South Carolina waters as a strong backdoor cold front approaches from the north. The best surge of flow associated with the front will take place after sunrise Tuesday, so wind speeds should remain in the 10-15 knot range.
Strong northeast winds will develop over the waters late Tuesday behind the backdoor cold front. Solid Small Craft Advisory conditions will affect all waters by later Tuesday afternoon, then the strongest winds will occur Tuesday night and Wednesday as low pressure develops off the GA coast. Frequent Gale force gusts are possible over all Atlantic waters during this period though the best chance will be over the outer portions of the Charleston nearshore and GA offshore waters. Given that Tuesday night is the fourth period, we held off on the issuance of a Gale Watch for these areas.
Winds will begin to abate Wednesday night though will continue out of the northeast through Friday. A southerly flow will setup next weekend as the surface high to our north moves offshore.
Rip Currents: There will be enhanced risk for rip currents beginning Tuesday as elevated northeast winds and swell impact the beaches
Tides / Coastal Flooding
Between strong high pressure building from the north and low pressure developing off the coast, strong northeast winds will create elevated tide levels along the coast Tuesday through Thursday. While astronomical factors do not favor tidal flooding, probabilistic guidance depicts a low chance for minor salt water flooding, especially Wednesday. We will continue to assess this scenario during the next several days
The KCLX radar remains out of service. Technicians are currently on-site this morning with replacement hardware
NOAA Charleston SC Office: Watches - Warnings - Advisories
GA...None. SC...None. MARINE...None