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Show Area Forecast Discussion - Charleston, SC (Charleston, SC Area) Selection: |
| #1279238 (Received by flhurricane at: 6:21 PM 18.Sep.2026) AFDCHS Area Forecast Discussion National Weather Service Charleston SC 614 PM EDT Fri Sep 18 2026 .WHAT HAS CHANGED... Key Message 1 and the Aviation section was updated. && .KEY MESSAGES... - 1) Rain chances will then gradually increase this weekend and especially by early next week. && .DISCUSSION... KEY MESSAGE 1: Rain chances will then gradually increase this weekend and especially by early next week. Tonight: Aloft, the forecast area will continue to sit between prominent ridging and an anticyclone to the west and an upper low across the FL peninsula. This will drive northeast flow aloft and also support a similar storm motion. At the surface, a surface trough positioned to the north will be the primary feature of interest. Convection firing over North Carolina should continue to weaken as it pushes should with only remnant shower activity expected as its enters the Lowcountry. Slight chance pops were maintained for parts of the Charleston Tri- County with non-mentionable pops (10% or less) elsewhere across southern South Carolina into Southeast Georgia. Saturday and Sunday: Aloft, a mid-upper lvl low will pass south of the local area, shifting across the Florida Peninsula and to the Northeast Gulf. At the sfc, a weak front will approach from the north this weekend, potentially reaching the local area late Saturday into early Sunday before stalling/dissipating early week. The setup will favor deep moisture transport across the Southeast United States within a southerly flow with PWATs approaching 2.25 inches locally, and likely support unsettled weather conditions in the form of showers/thunderstorms given sufficient forcing and abundant sfc heating (highs in low-mid 90s Saturday, then upper 80s/lower 90s Sunday). Given a moisture rich airmass, rounds of afternoon/evening convection and a front nearby, there could be a low-end threat for locally heavy rainfall and minor flooding issues. However, minimal shear and modest instability will limit the severe weather threat. Monday through mid-week: The previously mentioned mid-upper low feature is anticipated to drift north across the Southeast United States early week, eventually phasing with a longwave trough passing across the Midwest and Northeast United States through mid-week. The passing low along with the arrival of a stronger cold front from the north should lead to a slightly more active weather period in regards to shower and thunderstorm coverage, and could lead to a greater risk for a few strong and/or marginally severe thunderstorms during peak heating hours heading into the middle of the week. Additionally, moisture levels remain high (PWATS 2+ inches), suggesting at least some minor flooding concerns while the front is nearby. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... 19/00z TAFs: KCHS/KJZI/KSAV: VFR through 20/00z. A few remnant showers from convection dropping south out of North Carolina could approach KCHS and KJZI overnight, but impacts are expected. Extended Aviation Outlook: Shower/thunderstorm chances are expected to increase late weekend and into early next week with the approach of multiple fronts and increasing moisture levels. Periodic flight restrictions are possible. && .MARINE... Tonight: Very quiet conditions will prevail across the local waters. Winds will be strongest this afternoon and through the evening along the land/sea interface with the sea breeze, though winds should peak in the 10-15 knot range. Then overnight, winds will diminish to be 5 knots or less. Seas will average 1-2 ft, except 2-3 ft early for the Georgia offshore leg. Saturday through Wednesday: There are no marine concerns this weekend into early next week as winds/seas are expected to remain well below Small Craft Advisory levels. In general, winds will remain around 10 kt or less with seas in the 2-3 ft range. However, a cold front is anticipated to reach the area by the middle of next week, which should produce an uptick in winds (15-20 kt) and build seas (3-5 ft). Trends will need to be monitored for potential Small Craft Advisory level conditions around mid week. Additionally, shower/thunderstorm coverage is expected to increase next week ahead/along the approaching front. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ |
| #1279231 (Received by flhurricane at: 2:27 PM 18.Sep.2026) AFDCHS Area Forecast Discussion National Weather Service Charleston SC 222 PM EDT Fri Sep 18 2026 .WHAT HAS CHANGED... All sections have been updated. && .KEY MESSAGES... - 1) Rain chances will then gradually increase this weekend and especially by early next week. && .DISCUSSION... KEY MESSAGE 1: Rain chances will then gradually increase this weekend and especially by early next week. This afternoon and tonight: Aloft, the forecast area will continue to sit between prominent ridging and an anticyclone to the west and an upper low across the FL peninsula. This will drive northeast flow aloft and also support a similar storm motion. At the surface, a surface trough positioned to the north will be the primary feature of interest. For the afternoon, there is virtually no support for development across the area due to the lack of any real initiation features. A few showers could push through from upstream within the deep northeast flow, but otherwise we should remain convection-free through sunset. Of more interest is the potential for upstream activity to develop along the aforementioned surface trough and make a run for the forecast area late this evening or in the early morning hours. The good news is that we will be long past peak heating and the environment this upstream convection will be moving into will not be particularly supportive of maintenance or continued development. So, it seems reasonable that the hi-res models and the 18/12z HREF show minimal coverage with no support for thunder and little (if any) rainfall. Saturday and Sunday: Aloft, a mid-upper lvl low will pass south of the local area, shifting across the Florida Peninsula and to the Northeast Gulf. At the sfc, a weak front will approach from the north this weekend, potentially reaching the local area late Saturday into early Sunday before stalling/dissipating early week. The setup will favor deep moisture transport across the Southeast United States within a southerly flow with PWATs approaching 2.25 inches locally, and likely support unsettled weather conditions in the form of showers/thunderstorms given sufficient forcing and abundant sfc heating (highs in low-mid 90s Saturday, then upper 80s/lower 90s Sunday). Given a moisture rich airmass, rounds of afternoon/evening convection and a front nearby, there could be a low-end threat for locally heavy rainfall and minor flooding issues. However, minimal shear and modest instability will limit the severe weather threat. Monday through mid-week: The previously mentioned mid-upper low feature is anticipated to drift north across the Southeast United States early week, eventually phasing with a longwave trough passing across the Midwest and Northeast United States through mid-week. The passing low along with the arrival of a stronger cold front from the north should lead to a slightly more active weather period in regards to shower and thunderstorm coverage, and could lead to a greater risk for a few strong and/or marginally severe thunderstorms during peak heating hours heading into the middle of the week. Additionally, moisture levels remain high (PWATS 2+ inches), suggesting at least some minor flooding concerns while the front is nearby. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... The 18z TAF period begins with VFR conditions at KCHS, KJZI, and KSAV. A few showers could pass by KCHS and KJZI early this afternoon, but otherwise conditions should remain free of showers and thunderstorms through sunset. Late this evening and into the early morning hours, we could see isolated to scattered showers move into the vicinity of the terminals, but no significant impacts are expected. Winds will turn onshore out of the south or southeast in the next couple of hours, then will be light and variable overnight. Extended Aviation Outlook: Shower/thunderstorm chances are expected to increase late weekend and into early next week with the approach of multiple fronts and increasing moisture levels. Periodic flight restrictions are possible daily at CHS/JZI/SAV terminals as a result through early next week. && .MARINE... Through tonight: Very quiet conditions will prevail across the local waters. Winds will be strongest this afternoon and through the evening along the land/sea interface with the sea breeze, though winds should peak in the 10-15 knot range. Then overnight, winds will diminish to be 5 knots or less. Seas will start off 2-3 feet, then diminish to just be 2 feet late. Saturday through Wednesday: There are no marine concerns this weekend into early next week as winds/seas are expected to remain well below Small Craft Advisory levels. In general, winds will remain around 10 kt or less with seas in the 2-3 ft range. However, a cold front is anticipated to reach the area by the middle of next week, which should produce an uptick in winds (15-20 kt) and build seas (3-5 ft). Trends will need to be monitored for potential Small Craft Advisory level conditions around mid week. Additionally, shower/thunderstorm coverage is expected to increase next week ahead/along the approaching front. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ |
| #1279202 (Received by flhurricane at: 7:00 AM 18.Sep.2026) AFDCHS Area Forecast Discussion National Weather Service Charleston SC 655 AM EDT Fri Sep 18 2026 .WHAT HAS CHANGED... Aviation section updated for the 12Z TAFs and fog section of key message 1. && .KEY MESSAGES... - 1) Warming temperatures and mostly dry conditions today. Rain chances will then gradually increase this weekend and especially by early next week. && .DISCUSSION... KEY MESSAGE 1: Warming temperatures and mostly dry conditions today. Rain chances will then gradually increase this weekend and especially by early next week. Recent runs of the HRRR indicated that sfc condensation pressure deficits are forecast to lower below 3 mbs across the I-26 corridor during the pre-dawn hours. The forecast has been updated to add a mention of patchy fog for portions Dorchester, Berkeley, and Charleston Counties early this morning. Any fog that develops should dissipate during the first hour or two of sunshine. Today, the forecast area will remain between a closed low over central FL and a H5 ridge axis running west to east across NC. Forecast soundings indicate a dry mixed layer with weak lapse rates between 800-500 mb through this afternoon. The forecast will remain dry today. High temperatures are forecast to range in the low to mid 90s this afternoon. Convection-allowing models show a band of thunderstorms developing from the Midlands east across the Pee Dee region late this afternoon into this evening ahead of a sfc trough. These storms should push south, but should weaken as they reach an increasingly stable environment across SE GA and the Lowcountry. The forecast will feature a tier of SCHC PoPs across inland SC for showers and thunderstorms this evening. Any deep convection should dissipate before midnight. Low temperatures should range between 70-75 degrees. The overall pattern will change this weekend as a weak cold front approaches from the north. Transport of deep moisture will drive precipitable water values up to 2.1-2.3 inches by Saturday evening. This set up will favor unsettled conditions and increased rain chances this weekend. Given the moisture-rich airmass and the presence of rounds of convection (primarily in the afternoon and evenings), there will be at least a low end threat for locally heavy rainfall. However, minimal shear and modest instability will limit the severe weather threat. An unsettled pattern could continue into the middle of next week as a stronger cold front advances across the area. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... 12Z TAFs: Any ground fog this morning should dissipate during the first hour or two of daylight this morning. VFR conditions with light northwest winds this morning. A weak sea breeze should advance across the terminals between 19-20Z, turning winds from the southeast. Recent runs of the HRRR indicates that isolated showers and thunderstorms this evening, greatest chance across KCHS and KJZI. The coverage appears too limited to mention in the TAFs at this time. Extended Aviation Outlook: Rain chances are expected to increase late this weekend and into early next week which could result in periodic flight restrictions. && .MARINE... Today and tonight: Light northeast winds this morning should turn from the southeast this afternoon following the sea breeze. Winds may veer from the southwest tonight, speeds less than 10 kts. Wave heights should continue to diminish today, settling to around 2 ft tonight. Saturday through Wednesday: Winds and seas are expected to remain well below Small Craft Advisory thresholds through the period. Winds will be 10 knots or less for much of this period, with seas generally in the 2-3 ft range. The main forecast concern will be increasing coverage of showers and thunderstorms across the local waters, especially early next week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ |
| #1279188 (Received by flhurricane at: 2:57 AM 18.Sep.2026) AFDCHS Area Forecast Discussion National Weather Service Charleston SC 242 AM EDT Fri Sep 18 2026 .WHAT HAS CHANGED... All sections have been updated. && .KEY MESSAGES... - 1) Warming temperatures and mostly dry conditions today. Rain chances will then gradually increase this weekend and especially by early next week. && .DISCUSSION... KEY MESSAGE 1: Warming temperatures and mostly dry conditions today. Rain chances will then gradually increase this weekend and especially by early next week. Recent runs of the HRRR indicated that sfc condensation pressure deficits are forecast to lower below 3 mbs across the I-26 corridor during the pre-dawn hours. We will continue to monitor IR satellite and observations for any indication of fog formation. It is possible some patchy fog or ground may develop across Dorchester, Berkeley, and Charleston Counties this morning. Any fog that develops should dissipate during the first hour or two of daylight. Today, the forecast area will remain between a closed low over central FL and a H5 ridge axis running west to east across NC. Forecast soundings indicate a dry mixed layer with weak lapse rates between 800-500 mb through this afternoon. The forecast will remain dry today. High temperatures are forecast to range in the low to mid 90s this afternoon. Convection-allowing models show a band of thunderstorms developing from the Midlands east across the Pee Dee region late this afternoon into this evening ahead of a sfc trough. These storms should push south, but should weaken as they reach an increasingly stable environment across SE GA and the Lowcountry. The forecast will feature a tier of SCHC PoPs across inland SC for showers and thunderstorms this evening. Any deep convection should dissipate before midnight. Low temperatures should range between 70-75 degrees. The overall pattern will change this weekend as a weak cold front approaches from the north. Transport of deep moisture will drive precipitable water values up to 2.1-2.3 inches by Saturday evening. This set up will favor unsettled conditions and increased rain chances this weekend. Given the moisture-rich airmass and the presence of rounds of convection (primarily in the afternoon and evenings), there will be at least a low end threat for locally heavy rainfall. However, minimal shear and modest instability will limit the severe weather threat. An unsettled pattern could continue into the middle of next week as a stronger cold front advances across the area. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... 6Z TAFs: Recent runs of the HRRR indicated that sfc condensation pressure deficits are forecast to lower below 3 mbs across KCHS and KJZI during the pre-dawn hours. However, LAMP guidance indicates some fog potential at KSAV between 10-12Z. We will monitor observations overnight, the addition of fog in the TAFs is possible given clear sky and light to calm winds. After daybreak, VFR conditions with light northwest winds this morning. A weak sea breeze should advance across the terminals between 19-20Z, turning winds from the southeast. Extended Aviation Outlook: Rain chances are expected to increase late this weekend and into early next week which could result in periodic flight restrictions. && .MARINE... Today and tonight: Light northeast winds this morning should turn from the southeast this afternoon following the sea breeze. Winds may veer from the southwest tonight, speeds less than 10 kts. Wave heights should continue to diminish today, settling to around 2 ft tonight. Saturday through Wednesday: Winds and seas are expected to remain well below Small Craft Advisory thresholds through the period. Winds will be 10 knots or less for much of this period, with seas generally in the 2-3 ft range. The main forecast concern will be increasing coverage of showers and thunderstorms across the local waters, especially early next week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ |
