Charleston Harbor Marine Forecast
| Today...N Winds 10 To 15 Kt, Becoming Nw 5 To 10 Kt Late. |
| Tonight...Nw Winds 5 To 10 Kt. |
| Tue...N Winds 10 To 15 Kt With Gusts To 20 Kt. |
| Tue Night...N Winds 10 To 15 Kt, Diminishing To 5 To 10 Kt After Midnight. |
| Wed...N Winds 5 Kt, Becoming W In The Afternoon. |
| Wed Night...Sw Winds 10 To 15 Kt With Gusts To 25 Kt. |
| Thu...W Winds 15 To 20 Kt. Waves 1 To 2 Ft. |
| Thu Night...Nw Winds 10 To 15 Kt. |
| Fri...N Winds 10 To 15 Kt. |
| Fri Night...N Winds 10 Kt. Unless Otherwise Noted, Waves 1 Foot Or Less. Charleston Harbor Water Temperature 60 Degrees. |
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Area Forecast Discussion National Weather Service Charleston SC 703am EST Monday Dec 2 2024 Synopsis High pressure will prevail through the middle of the week. A cold front should push across the area near the end of the week. Near Term - Through Tonight Today: A deep and broad trough aloft will persist across much of the country east of the Rockies, including the local counties. This will maintain a supply of cold and very dry air within a west-northwest flow throughout the atmosphere. At the surface, high pressure will bridge across a weak cold front near the South Carolina coast and then extending west near the I-16 corridor in Georgia. There is some change in air mass as a result, as the 850 mb temperatures drop to as cold as -3 to -4C north, and 0 to 1C south. Similarly, the 1000-850 mb thickness is also unseasonably cold; down to 1300-1310 meters north, and 1315-1325 meters south. Despite full sunshine and even some downslope flow developing in the afternoon, we'll be a little cooler than yesterday. Highs will range from 50-55F across most of South Carolina, and mid to upper 50s over Georgia. Tonight: A reinforcing cold front will push through overnight. It might come through in parts, or there could be a southeast to northwest oriented trough that develops in its wake. Either way, cold high pressure in the Great Plains will build southeast into our area. Winds decouple early on, but recouple late as the gradient tightens up and cold advection develops. The 850 mb 0C isotherm drops to near the Georgia-Florida border, and by 12Z Tuesday our 850 mb temperatures are as cold as -5 to -7C north, and -2 to -4C south. In response, minimum temperatures will drop down to the upper 20s well inland, 30-32F near the US-17 corridor, and mid-upper 30s closer to the coast and in downtown Charleston. There's just enough wind to produce wind chills down as low as 20-22F, or close to the Cold Weather Advisory criteria in a few places. Since any such values look too isolated, no advisory is planned. The approach of a short wave could produce few-scattered stratocumulus overnight, especially north and northwest. But it's much too dry to generate any precipitation. Short Term - Tuesday Through Thursday A broad trough will push off the eastern Seaboard Tuesday. Cold, surface high pressure will become centered over the Southeast U.S. behind the departing trough. The center of the high will then slide offshore Wednesday night as a cold front approaches from the west. Conditions will be rain-free and dry through Wednesday, and even Thursday despite the frontal passage. The deeper moisture looks to slide south of the area, with a small chance of an isolated shower brushing southeast Georgia Thursday. Otherwise, a slight uptick in southwesterly winds are expected in association with the FROPA. Breezy conditions are possible late Wednesday night into Thursday. Gusts across Lake Moultrie could reach 25 kt or greater, which would warrant a Lake Wind Advisory during this time frame. Tuesday will feature chilly temperatures with highs only reaching the mid to upper 40s most places, and low 50s south of Savannah, GA. Wednesday's high temps will reach the low/mid 50s. Slightly elevated southwesterly winds across the local area will result in a brief warm-up Thursday. Highs are forecast to warm back into the low to mid 60s. Clear skies and calm winds will favor a strong radiational cooling setup Tuesday night, bringing the coldest temperatures of the week. Expect min temps in the low-mid 20s for most inland counties and low to mid 30s along the immediate coast/beaches. Isolated areas inland could dip down as low as the upper teens, thus Cold Weather Advisories could be needed for some counties. Wednesday night will be warmer with lows remaining above freezing; mid to upper 30s inland and lower 40s along the coast. Long Term - Thursday Night Through Sunday The aforementioned dry cold front should quickly push through early Thursday night, and weak ridging should then build aloft. Another cold front associated with a shortwave could approach late weekend or early next week, with little model consensus in terms of the timing/strength. Its arrival could bring a bout of deep moisture and a solid chance of seeing showers. Confidence remains low with this feature; therefore, we maintain the NBM's output of 20-30% POPs for early next week. Temperatures will be slightly below normal initially, moderating to near normal over the weekend. Marine Today: Continental high pressure bridges across a weak cold front this morning, and the combination of a tighter gradient, modest isallobaric pressure rises, and cold advection will boost winds high enough on the Charleston County ocean waters, where we have hoisted a short-duration Small CRaft Advisory through 10 AM. On the other Atlantic waters, some gusts will peak around 25 kt, but their frequency and coverage is not enough to issue any Small Craft Advisory. As cold advection fades and the gradient slackens this afternoon, winds will back, and drop to 10 or 15 kt. Seas through the day will be limited by the offshore fetch, mainly 2-3 feet within 20 nm, and 3-4 feet further offshore. Tonight: A reinforcing cold front moves into the waters after midnight, with a 1037 mb high to build across in its wake. Similar to conditions from this morning, a tighter gradient, some rise in pressures, and cold advection will occur. This will allow for NW winds again as strong as 15 or 20 kt. But there is greater coverage of 25 kt gusts across the outer Georgia waters, and even some 6 foot seas, to raise a Small Craft Advisory starting at 4am Tuesday. The nearshore waters will be close to advisory thresholds, and we'll continue to monitor. Tuesday through Saturday: Surface high pressure across the Eastern CONUS will prevail through the middle of the week before a cold front pushes offshore Thursday night. Northwesterly winds will increase to around 15-20 kt Tuesday as building high pressure tightens the pressure gradient. A Small Craft Advisory issued for the outer Georgia waters from 20-60nm should be gone by Tuesday afternoon when gusts are forecast to drop below 25 kt. Then, lighter winds around 10 kt will shift out of the southwest Wednesday afternoon with another surge expected later in the evening ahead of the aforementioned cold front. Small Craft Advisories look likely during this period when gusts 25-30 kt are possible. Elevated winds could continue into Friday as high pressure rebuilds, before settling Saturday. Seas will average 3-5 feet Tuesday, with a brief period of improvement Wednesday before returning to 3-5 ft Thursday with the FROPA. NOAA Charleston SC Office: Watches - Warnings - Advisories GA...None. SC...None. Marine Small Craft Advisory until 10am EST this morning for AMZ350. Small Craft Advisory from 4am to 11am EST Tuesday for AMZ374. |
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