Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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527 FXUS62 KCHS 032025 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 425 PM EDT Wed Jul 3 2024 .SYNOPSIS... A weak front will linger near the area tonight. Through the rest of the week, a hot and humid air mass will build over the region. A weak cold front could approach the region by early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Late this afternoon, KCLX detected a cluster of showers and isolated thunderstorms across portions of Long and Tattnall Counties. This activity should continue to drift south, crossing the Altamaha River between 5 to 6 PM. Isolated coverage may linger across SE GA into the early evening. However, conditions should rapidly stabilize after sunset, resulting in the lingering convection to dissipate. Overnight, forecast soundings indicate that moisture will remain trapped below a llvl inversion. Below the inversion, patches of stratus may develop and gradually build down to the sfc. This process appears most likely over areas that received rainfall this afternoon across SE GA. The forecast will mention patchy fog over areas of wet soil. Using a blend of MOS, min temperatures are forecast to range from the low 70s inland to the mid 70s across the coastal counties. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... A mid level ridge across the southern CONUS will remain in place through the period. The surface pattern feature high pressure offshore and trough of low pressure inland. A weak front will approach the region on Saturday but will stay west of the local area. The weather should be fairly quiet for Independence Day with influence of the ridge helping to limit convection. We keep the forecast area mostly dry, with the exception of an isolated shower or thunderstorm across our extreme southeastern Georgia counties as the deeper moisture resides just to our south. Temperatures will peak in the upper 80s along the beaches and Downtown Charleston and the low to mid 90s elsewhere. Overnight lows will reach down into the upper 70s along the beaches/Downtown Charleston and the low to mid 70s inland. Friday and Saturday should be a bit more convectively active, especially inland. There could be development with the sea breeze, but it appears most will trigger via llvl convergence near the inland trough and then move into the local area from the west. The forecast reflects POPs around 30-45% far inland on Friday, and increasing to 50-65% Saturday as mid-level moisture advection ramps up. High temps on Friday will reach the mid to upper 90s Friday and around the middle 90s Saturday. It will feel even hotter with heat indices approaching the local Heat Advisory criteria of 108 degrees in spots. Friday looks marginal, with Saturday having the better chance for excessive heat headlines. Low temperatures will remain in the mid to upper 70s. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Ridging aloft will prevail through the middle of next week with a broad trough to the northwest and a weakening closed low nearing the Southeast US coast. The surface pattern maintains high pressure offshore and troughing inland. Guidance indicates PWats exceeding 2 inches through much of the period. We are anticipating a slightly more active period with at least scattered showers and thunderstorms possible each day. The greatest coverage is expected in the afternoon and evenings. Max temperatures are forecast to stay slightly above normal, in the low to mid 90s through next week, with lows in the 70s. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... Prior to the 18z TAFs, KCLX detected isolated and scattered showers with one, or two thunderstorms in the vicinity of KSAV. With the passage of the seabreeze later this afternoon, a thunderstorm could pass over KSAV between 18-20z. The potential for this thunderstorm has been highlighted in the KSAV TAF with TEMPO. For KCHS and KJZI, the potential for an afternoon shower is too low to mention in the TAFs. KCHS and KJZI is expected VFR with a steady SE wind around 10 kts till sunset. The concern for late tonight is the potential for fog and possible low ceiling. Forecast soundings indicate some potential for IFR stratus between 09z and daybreak, however MOS guidance does not indicate low ceilings. Given narrow dewpoint depressions and light calm winds, each TAF will feature a mention of either ground fog, or light patchy fog during the pre-dawn hours. After sunrise, conditions will remain VFR with a light E wind. There appears to be little to no chance of deep convection at the terminals on Independence Day. Extended Aviation Outlook: Brief flight restrictions are possible in showers and thunderstorms, mainly in the afternoon and evenings, Friday through early next week. && .MARINE... Late this afternoon, KCLX detected a cluster of showers and isolated thunderstorms across portions of Long and Tattnall Counties. This activity should continue to drift south, crossing the Altamaha River between 5 to 6 PM. Isolated coverage may linger across SE GA into the early evening. However, conditions should rapidly stabilize after sunset, resulting in the lingering convection to dissipate. Overnight, forecast soundings indicate that moisture will remain trapped below a llvl inversion. Below the inversion, patches of stratus may develop and gradually build down to the sfc. This process appears most likely over areas that received rainfall this afternoon across SE GA. The forecast will mention patchy fog over areas of wet soil. Using a blend of MOS, min temperatures are forecast to range from the low 70s inland to the mid 70s across the coastal counties. && .TIDES/COASTAL FLOODING... So far this afternoon, tidal departures within the CHS Harbor have ranged around 1 ft. Given light winds it is expected that the departure will gradually reduce as high tide approaches. However, it appears that water levels will slightly exceed flood stage, around 7 ft MLLW. A Coastal Flood Advisory has been issued until 8 PM. Onshore winds and the approach of the new moon will lead to elevated tides on Independence Day along the Charleston and Colleton county coasts. Tides levels could approach minor coastal flooding criteria of 7 ft MLLW in the Charleston Harbor with the evening high tide Thursday. Further south, no tide issues are expected.&& .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...Coastal Flood Advisory until 8 PM EDT this evening for SCZ049- 050. MARINE...None. && $$ NEAR TERM...ACD/NED SHORT TERM...BRM LONG TERM...BRM AVIATION...ACD/BRM/NED MARINE...ACD/BRM/NED