textproduct: Charleston

SYNOPSIS

A frontal system will maintain unsettled weather into Monday, then a cold and dry high pressure will build into the region. A reinforcing cold front will move through Friday.

NEAR TERM /UNTIL 6 AM MONDAY MORNING/

Tonight: The mid-levels will consist of a trough over the Lower MS Valley in the evening. It'll shift eastward, stretching from the Great Lakes Region into the Deep South late tonight. This will lead to WSW flow overhead. At the surface, areas of weak low pressure will develop off the East Coast of FL and in the northeast Gulf during the evening, with a stationary front connecting each. They'll shift to the ENE through the night. Meanwhile, a weakening cold front will quickly cross through our area late overnight, followed by troughing behind it. This complex synoptic pattern will keep the highest moisture just off the coast. However, light rain/showers will be possible along coastal areas, before shifting offshore mid- late evening. Though, there could be remnant showers through the night. QPF will likely remain below 0.25" around McIntosh County and vicinity, with event lighter amounts further north and inland. There will be plenty of moisture and low stratus, so fog development is possible overnight. However, guidance indicates 1000 mb geostrophic flow to remain at least 10-15 kt through the night, suggesting a low stratus deck to be the most likely outcome through daybreak Monday. Low temperature will generally be in the lower to middle 40s, warmer at/near the beaches.

SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/

Monday and Tuesday: As a broad upper-lvl trough gradually shears eastward across southeastern Canada, a reinforcing shortwave will march through the region on Monday. At the surface, a front shall reside over portions of northern Florida and extend into the Atlantic adjacent to the South Carolina coastline. This pattern will yield north-northwesterly flow with PWAT values ranging between 0.8 to 1.0". Expect light scattered showers through Monday morning, and then likely taper off by the afternoon with rainfall totals less than 0.10 inches. With limited mid-lvl lapse rates and no appreciable CAPE, convection remains negligible. Thereafter, a dry, cold front should push through the region on Monday night and high pressure to build in behind it. Expect lows to drop into the upper 20s across inland southeast South Carolina and low to mid 30s elsewhere. This pattern will result in quiet weather on Tuesday as skies gradually clear in the morning. Despite the sun returning to the sky, strong CAA will keep temperatures slightly below average with highs in the low to mid 50s. It'll be a couple degrees colder than the previous night, with temperatures dropping into the upper 20s across the interior counties and low to mid 30s near the coastline.

Wednesday: As mid-lvl ridge shifts eastward into the Southeast, strong subsidence will promote a quiet and rain-free forecast. Also, increasing WAA will support a noticeable warm-up and yield temperatures into the low to mid 60s. Expect winds to shift to the southwest as high pressure situates itself across central Florida. This will promote anticyclonic flow across the region and allow overnight lows to be a tad warmer than the previous nights.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

At the surface, high pressure will continue to dominate the forecast on Thursday and allow for another rain-free day. Clear skies and s southwesterly flow will yield temperatures in the mid to upper 60s on Thursday. However, this quiet and warm weather only lasts momentarily, as a reinforcing cold front is expected to sweep across the region on Friday afternoon. This will promote light rain showers on Friday ahead of the approaching front. There's moderate uncertainty pertaining to this weekend as ensemble spread remains large. Cooler temperatures will likely return this weekend following the passage of the front.

AVIATION /00Z MONDAY THROUGH FRIDAY/

IFR or lower cigs will prevail at CHS/JZI/SAV terminals this evening and overnight with ample low-lvl moisture and light rain occurring. Light rain could also reduce vsbys to around 1-3 miles at times, lowest at CHS/JZI terminals this evening. Even with light rains departing late evening IFR or lower cigs will continue through the night as a strong low-lvl inversion holds in place. However, 10-15 kt low-lvl wind fields suggest a low stratus event rather than fog (or at least dense fog) tonight and/or early morning Monday. Drier air will begin to shift into the area post daybreak Monday and sfc winds will be start to increase by late morning (around 15Z). Expect cigs to improve to high-end IFR by noon, but persist Monday afternoon.

Extended Aviation Outlook: Lingering periods of MVFR cigs with occasional IFR cigs expected to persist through Monday night. Expect improving conditions thereafter.

MARINE

Tonight: A frontal system will move through the waters. Expect NE winds sustained around 10-15 kt this evening, becoming N and increasing to 10-15 kt with gusts to 20 kt by daybreak Monday. Seas should average 2-3 ft withing 20 nm, and 3-4 ft for the GA waters beyond 20 nm. Showers and low clouds could bring occasional reductions in visibility. But dense sea fog is not expected.

Monday through Thursday: As a broad upper-lvl trough dominates the forecast aloft, a reinforcing shortwave will march through the region on Monday. At the surface, northwesterly flow will persist as a cold front approaches the local waters. Expect wind speeds to increase to 15-20 kts with periodic gusts of 24-25 kts on Monday night. Thereafter, winds will taper back and remain light through mid-week, before a reinforcing cold front approaches on Thursday night. Winds will shift to southwest as high pressure situates itself across central Florida. Seas will range from 3 to 5 ft with some 6 footers reaching into the the nearshore Charleston and outer Georgia waters on Monday afternoon. Therefore, a brief period of Small Craft Advisories will be possible on Monday evening. Afterwards, the swell looks to ease back as high pressure returns to the Atlantic waters on Wednesday and conditions rapidly improve.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...None.