Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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817 FXUS62 KCHS 110225 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1025 PM EDT Wed Jul 10 2024 .SYNOPSIS... A weak front will meander across the area through Saturday. Atlantic high pressure will then rebuild across the area while a surface trough exists inland early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Elongated upper level ridging remains from the central Atlantic down through the southeast region, downstream from troughing moving through the Great Lakes region. Surface boundary lingers through the SC Midlands and down into eastern Georgia but still expected to slip off the coast overnight into Thursday, while some semblance of a coastal low feature further develops off the southeast coast. Despite the presence of the boundary, quiet weather is looking to dominate across our region through the rest of the night while modestly lower surface dewpoint air edges down through the region. Only minor tweaks were made to the forecast for the mid evening update. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... Thursday: A weak cold front should stall just off the Georgia coast, bringing drier air to the region from the northwest in its wake for a brief period. Aloft, weak ridging will prevail, but show signs of weakening, while a weak sfc trough/wave advects a moist onshore flow across coastal South Carolina counties (mainly the Tri-County) late day and into the overnight period. Convective coverage will therefore remain more focused across the Tri-County Area, with isolated to scattered showers/thunderstorms possible mid-late afternoon into evening hours. Temps will be quite warm, approaching the mid 90s away from the beaches, but considerable mixing out of sfc dewpts should limit heat indices to below Heat Advisory criteria. However, heat indices around 105 are possible across the Tri-County Area as moisture pools along a seabreeze circulation before convection/clouds limit the overall concern. Overnight, temps will remain mild, with lows generally in the mid 70s inland to upper 70s/around 80 near the coast. Additional showers/thunderstorms will also be possible with a weak sfc trough/wave nearby overnight, mainly across coastal South Carolina. Friday and Saturday: Weak low pressure progged across southeast Georgia will be slow to shift north-northwest this weekend, eventually pulling a weak sfc front further inland and/or north of the area late weekend. A moist onshore flow will bring PWATs in excess of 2 inches across the local area, creating greater chances of showers/thunderstorms across the region as mid-upper lvl vort energy drifts north along the Southeast Coast Friday afternoon into early Saturday. Scattered to potentially numerous showers and thunderstorms are possible during this time frame, with greatest coverage occurring during peak heating each afternoon when a seabreeze interacts with the stalled/slow moving front. There is even some potential for warm and humid conditions on Saturday that produce heat indices near 108 degrees across the South Carolina coastal corridor, but much will depend on convective trends heading into peak heating hours. Regardless, afternoon highs should range in the low-mid 90s, warmest across southeast Georgia. Overnight lows will also remain mild, generally in the mid 70s inland to upper 70s/lower 80s along the beaches. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A weak upper trough will exist over the eastern United States Saturday night through Monday, then a broad upper ridge will gradually build across the region from the west heading into the middle of next week. Convective coverage could be slightly greater than a typical summertime pattern would display, especially through Monday as a weak sfc trough lingers. Temps will gradually climb/warm early next week, with heat indices peaking near 108 across portions of the local area Monday and Tuesday afternoons. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... Prevailing VFR through 00z Friday. Isolated showers/thunder will again be possible Thursday afternoon. Precip chances are too low to included in the terminal forecasts for now. Extended Aviation Outlook: Scattered afternoon showers/thunderstorms could produce tempo flight restrictions at CHS/JZI/SAV terminals each afternoon, especially during the weekend. && .MARINE... Some gustier SW winds have remained persistent through the evening in the coastal waters with gusts to around 20 knots at times. Winds will be veering around to the northwest later tonight and weakening, but recent forecast updates reflect some gustier winds through midnight, diminishing thereafter. Thursday through Monday: Weak low pressure developing near the Southeast Coast will be the primary driver in overall wind speed and direction across local waters this weekend. In general, conditions are expected to remain well below Small Craft Advisory levels across local waters with onshore winds around 10-15 kt across SC waters, but offshore and slightly weaker across GA waters Thursday into Friday. The pressure gradient should gradually tighten across local waters during the weekend as low pressure nudges further inland while a weak wave shifts to the north, but wind speeds should remain around 15 kt or less. Seas should range between 1-3 ft Thursday, then gradually build to 2-4 ft during the weekend. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...Adam SHORT TERM...DPB LONG TERM...JRL AVIATION...Adam/DPB MARINE...DPB/Adam