Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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368 FXUS62 KCHS 181458 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1058 AM EDT Thu Jul 18 2024 .SYNOPSIS... High pressure will persist offshore, while a weak trough resides inland. A cold front will approach the region Friday and likely stall nearby, before high pressure returns next week. && .NEAR TERM /THROUGH TONIGHT/... Today: The forecast area will remain between a mid-level ridge just east of Bermuda and a trough axis across the Great Lakes. At the surface, a cold front was analyzed just southwest of Nashville and is forecast to sag south into northwestern GA this afternoon. Widespread cloud cover this morning will likely keep temperatures a degree or two cooler compared to yesterday, but widespread 90 to 95 degrees is still expected. This afternoon, a sea breeze is forecast to slowly move inland with MLCAPE values around 2000 - 3000 J/kg. Isolated to scattered showers and thunderstorms will develop near the sea breeze and outflow boundaries this afternoon and evening. It is possible that one or two storms could produce damaging wind gusts. Tonight: Showers and thunderstorms that initiated across the Upstate of SC this afternoon will be slowly moving southeast and approaching the Lowcountry of SC tonight. The most likely scenario is that this cluster of storms will weaken as they approach the TriCounty of SC. Low temperatures are forecast to range from the low 70s inland to the upper 70s across the coastal counties. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... Aloft, broad troughing will prevail over the eastern half of the CONUS on Friday. Then high pressure will build into the region from the east over the weekend. At the surface, a cold front will approach the region on Friday. The front will likely stall in the vicinity of the Carolinas through the weekend. Deep moisture will be present over the forecast area through the weekend, with PWATs over 2 inches. High temperatures on Friday will likely reach into the low to mid 90s, which combined with humid conditions will yield plentiful instability for afternoon convection. Numerous to widespread showers and thunderstorms are forecast on Friday afternoon. A strong to marginally severe thunderstorm is possible, with the main hazard of damaging wind gusts. Additionally, heavy rainfall is possible, however some steering flow aloft may help push storms along and prevent significant training. Similar conditions are expected through the weekend, though PoPs are slightly lower across the region. Heat Index values will continue to reach triple digits each day, peaking around 101-105F. However, afternoon convection may prevent temperatures from reaching their full potential. Overnight lows will be in the 70s. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... High pressure aloft and at the surface will build into the forecast area from the east through the middle of the week. PWATs are forecast to remain elevated along with plentiful instability. Scattered to numerous showers and thunderstorms will be possible each afternoon, generally focused along boundary interactions and the afternoon sea breeze. The current forecast maintains chance to likely PoPs. With precipitation and increased cloud cover through the period, temperatures are forecast to return to near normal or even slightly below normal through the period. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... VFR conditions with SW winds around 10 kts during the morning hours. SW winds at KCHS and KJZI are forecast to strengthen, with gusts near 20kts during the afternoon hours. Thunderstorm activity late this afternoon will be highlighted in each TAF with a TEMPO from 22-2Z. High resolution guidance indicates that a band of showers and thunderstorms may pass near KCHS and KJZI later this evening, highlighted with a mention of VCSH. Extended Aviation Outlook: Scattered afternoon showers/tstorms could produce brief flight restrictions at all terminals through the weekend and into early next week. && .MARINE... Early this morning, sfc wind observations and KCLX indicated that a land breeze was developing 10-15 nm from shore. Winds along the land breeze remained too strong to favor the development of waterspouts. We will continue to monitor conditions for the waterspout potential this morning. Today and tonight, the sfc pattern will support SSW winds generally between 10-15 kts with gusts in the low 20s during the afternoon. Conditions will approach Small Craft Advisory criteria across the Charleston County nearshore waters late this afternoon. Seas are forecast to generally range between 3-4 ft, with some 5 ft across beyond 15 nm from the mouth of the Santee River. A band of thunderstorms may sweep across the SC nearshore waters this evening into late tonight. Some of these storms may bring strong wind gusts, Special Marine Warnings may be needed. Friday through Monday: High pressure will prevail across the marine zones while a cold front approaches the inland zones on Friday and lingers in the vicinity of the Carolinas through the weekend. Conditions are expected to remain below Small Craft Advisory criteria through period, with southerly winds 10-15 knots forecast. Slightly stronger wind speeds are possible along the direct coastline in association with the afternoon sea breeze. Seas should average 3 to 4 ft. Rip Currents: Today: The combination of a 2 ft swell every 8-9 seconds and gusty onshore winds will support a Moderate Risk for rip currents at all of our beaches. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...CPM/Haines/NED SHORT TERM...CPM LONG TERM...CPM AVIATION...CPM/NED MARINE...CPM/NED