Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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962 FXUS62 KCHS 251748 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 148 PM EDT Sat May 25 2024 .SYNOPSIS... A weak disturbance will move through the area this evening. Hot conditions expected for Sunday and Memorial Day. A cold front could bring impacts to the region Monday night into Tuesday. && .NEAR TERM /THROUGH TONIGHT/... As of 145 PM, KCLX was detecting isolated showers across SE GA/SC. By mid-afternoon, the coverage of showers and thunderstorms should be focus along and west of the sea breeze and with the outflow associated with a passing MCS over SE GA. The update forecast will adjust PoPs and WX to recent radar trends. Temperatures are on pace to peak around 90 degrees for most areas over the next hour. Modifying the 12Z KCHS sounding, the environment across the forecast area this afternoon should feature MLCAPE around 2000 J/kg or normalized CAPE of 0.15-0.2. DCAPE values may range between 1000-1200 J/kg, especially across SE GA. The thermal profile combined with effective bulk shear of 30-35 kts may support strong to severe thunderstorms across SE GA/SC this afternoon and evening. The first round of severe weather could be associated with the arrival of the MCS over northern GA. Recent runs of the HRRR indicate that the leading cells may arrive over SE GA around 3 PM. SPC has issued a mesoscale discussion for this activity, indicating a 40 percent chance for a Watch. At the same time, sea breeze showers and thunderstorms should initiate over portions of Charleston and Berkeley Counties. Some of these storms may pulse and become quite tall, yielding some potential for damaging wind gusts. By late this afternoon, the two modes of convection, MCS over SE GA and sea breeze for the coastal counties, will produce numerous outflow boundaries with the moderate DCAPE. These boundaries will largely determine the overall timing, placement, and duration of convection heading into the early evening. The environment will feature deep moisture, PW values between 1.5-1.7 inches. HREF indicates that some thunderstorm clusters will have the potential of producing 1.5-2 inches in a 3-hr period this afternoon and evening. Overnight: A mostly dry night will prevail once evening convection dies off and the mid-level impulses propagates offshore. It will remain warm and fairly humid with lows ranging from the upper 60s well inland to the mid 70s at the beaches. There is a chance that little fog could develop early Sunday morning, especially where rain falls today. However, the fog could remain fairly light with no significant impacts. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... Ridging builds overhead on Sunday which will aid in limiting convection. Rain chances are no higher than 20%. Main story will be the unseasonably hot temperatures. Highs peak in the low to mid 90s across most locations. Lows Sunday night only fall to the low/mid 70s. Mid level ridge axis shifts offshore on Monday/Memorial Day as a broad trough moves into the eastern U.S. At the surface, a cold front will approach the region from the west. Little convection is expected through at least mid-afternoon then upstream showers and thunderstorms could move into the area later in the day into the evening. There is potential that this activity is more organized and pose a risk for stronger storms with gusty winds. Highest rain chances shift offshore late Monday night/early Tuesday morning. Lows will mainly be in the upper 60s to lower 70s. The front should push offshore on Tuesday. Deepest moisture also exits the area, and the weather looks fairly quiet with just isolated showers/thunderstorms are still possible. High temperatures again above seasonal normals in the lower 90s. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... High pressure builds into the region for late week behind a secondary cold front that passes through later Wednesday night or early Thursday. Rain-free forecast in tact, essentially disregarding the outlier/wetter GFS. Temperatures should return back to more seasonable levels. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... 18Z TAF Discussion: KCHS/KJZI/KSAV: Prior to the 18Z TAFs, KCLX was detecting an increasing number of showers across SE GA and SC. A couple of updrafts were located within the KCHS terminal. Showers and thunderstorms should develop at least in the vicinity of the terminals at the onset or an hour into the 18Z TAF period. Thunderstorm coverage should peak late this afternoon into early this evening, each TAF will feature a TEMPO for TSRA, generally between 20-01Z. Convection should gradually dissipate or track over the Atlantic waters this evening. The rest of the night should remain VFR with light SW winds. Extended Aviation Outlook: Brief flight restrictions are possible due to showers/thunderstorms each afternoon/evening. && .MARINE... Through Tonight: A southerly flow regime will prevail through tonight. Winds will remain less than 15 kt with seas 1-2 ft. A cluster of tstms could move off the Georgia coast later this evening which could produce convective winds >34 kt. Sunday through Thursday: South to southwest winds persist through early next week. A cold front will then pass through the waters before high pressure builds for late week. Conditions stay below Small Craft Advisory through the period. Winds speeds average 15 knots or less with seas 2-3 feet on average. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM... LONG TERM... AVIATION...NED MARINE...