Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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960 FXUS62 KCHS 031118 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 718 AM EDT Mon Jun 3 2024 .SYNOPSIS... High pressure will extend across the area through Wednesday. A cold front will slowly move through on Friday, followed by high pressure. && .NEAR TERM /THROUGH TONIGHT/... Today: Aloft, shortwave ridging is expected to gradually shift eastward and become aligned across Georgia and the Carolinas, up into the central Appalachians. At the surface, no real change as subtropical high pressure remains the main feature extending westward into the Southeast. Overall, there aren`t many factors pointing to a very active period of diurnal convection. No triggering or focusing mechanisms are present, and the development of convection will be solely dependent on surface destabilization and potential subsequent boundary interactions. Model guidance generally features MLCAPE values on the order of 1,000-1,500 J/kg with rather meager lapse rates and convective indices. Based on the suite of hi-res model solutions, we favor isolated to scattered convection in the afternoon and early evening hours. Rain chances are held in the 20-30 percent range, highest inland. Model soundings do depict a decent amount of mid-level dry air yielding 800-1,000 J/kg of DCAPE. However, there doesn`t seem to be much support for strong enough updrafts to produce any notable severe threat. Highs should be a few degrees warmer than the weekend, with mid to upper 80s across the forecast area. Tonight: Any ongoing convection should quickly end during the early evening hours with the loss of diurnal heating. The rest of the overnight will be quiet and dry, with no notable fog concerns. Lows are forecast to fall into the mid to upper 60s away from the immediate coast. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... A potent shortwave is forecast to move in from the west Tuesday afternoon. PWATs above 1.8" and moderate instability should be in place during the afternoon. Meanwhile, the seabreeze will eventually shift inland later in the afternoon. Decent convective coverage expected farther inland in the afternoon, with more isolated activity closer to the coast. Slightly higher surface dewpoints on Wednesday are expected to result in considerably greater instability. Southerly prevailing flow should allow for a more progressive sea breeze in the afternoon. A few weak vort maxima expected to move through during the day. Scattered convection expected mainly during the daytime. Model DCAPE values exceed 1000 J/kg over inland areas so we could see some gusty winds in some storms. Thursday could be the most active day this week due to upper levels transitioning to a broad upper trough and a pronounced shortwave moving through in the afternoon. PWATs expected to rise to near 2" during the day, providing plenty of moisture for showers and thunderstorms to develop. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... A cold front drops through the area on Friday, however convective coverage is uncertain since mid-level subsidence seems likely given the quasi-zonal flow. Compressional heating looks to push highs into the low to mid 90s. A noticeable airmass change is expected this weekend as high pressure builds from the northwest. Downslope flow should still keep highs above 90 in most spots, but dewpoints should mix down into the upper 50s to lower 60s. && .AVIATION /11Z MONDAY THROUGH FRIDAY/... VFR conditions will prevail at KCHS, KJZI, and KSAV through 12z Tuesday. Current thinking is that the best chance for showers and thunderstorms will be inland of the terminals in the afternoon and early evening hours. Therefore, we have not included any mention in the TAF`s at this point. Extended Aviation Outlook: Outside of any convection, conditions will be VFR through the period. && .MARINE... Today and tonight: High pressure to the east will remain the primary feature controlling winds and seas across the local waters. Winds are expected to be southerly to south- southeasterly through the period with speeds topping out in the 10-15 knot range. Some enhancement along the land/sea interface can be expected in the afternoon and early evening thanks to the sea breeze. Seas are expected to average 2-3 feet. Tuesday through Saturday: High pressure will remain over the western Atlantic Tuesday through Thursday night, maintaining southerly flow at or below 15 kt, seas at or below 4 ft, and a daily sea breeze circulation along the coast. A cold front will move through on Friday, briefly shifting winds to the NW before they turn back E by Saturday. && .TIDES/COASTAL FLOODING... Astronomical tides are on the rise this week. Although wind direction is not particularly favorable for surge, we continue to see a positive tidal anomaly of 0.5 to 0.7 ft. The evening high tides Tuesday through Thursday could reach 7.0 ft MLLW in Charleston, necessitating Coastal Flood Advisories. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH SHORT TERM...JRL LONG TERM...JRL AVIATION...BSH/JRL MARINE...BSH/JRL