Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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483 FXUS62 KCHS 021348 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 948 AM EDT Thu May 2 2024 .SYNOPSIS... Atlantic high pressure will remain across the Southeast through much of next week. && .NEAR TERM /THROUGH TONIGHT/... The Dense Fog Advisory has been cancelled for the remainder of Southeast South Carolina. Today: Fog/stratus has mostly dissipated. Expect a healthy cumulus field to develop later this morning as temperatures rise. Cumulus are already starting to form along the upper Charleston County coast near McClellanville. Any cumulus should scour out later this afternoon as the sea breeze moves inland. Forecast soundings are not as capped as what was depicted yesterday, but still expect a rain-free day for most areas. Will need to watch for a few brief pop ups near the sea breeze where dewpoints will pool back into the upper 60s/near 70. Gridded pops were held below mentionable thresholds for now. It should be noted a few of the CAMs do depict isolated showers/tstms, mainly over Southeast South Carolina where convergence along the sea breeze will be a bit stronger. Typically, convergence along a pure sea breeze circulation is not as strong as a resultant sea breeze, so this will be watched carefully. Highs from the upper 80s/near 90 inland with cooler conditions closer to the beaches look on track. Tonight: Very little change to the pattern surface and aloft. Winds will quickly decouple this evening, allowing for good radiational cooling to occur. Actual lows will be similar to what they were early this morning. Subsidence aloft and considerable boundary layer moisture will again lead to fog developing after midnight. For now we show areas of fog all counties, but dense fog is likely, and another Dense Fog Advisory could be required. We included mention in the Hazardous Weather Outlook. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... Shortwave ridging will persist Friday, though the ridge axis will move off the coast during the afternoon. Strong mid-level subsidence is expected to maintain dry conditions over the area, though we can`t rule out a late day shower or thunderstorm far inland if something moves in from the west. Highs will be in the upper 80s except along the coast where prevailing onshore flow enhanced by an afternoon sea breeze keeps temps in the upper 70s to lower 80s. Increasing moisture and a series of shortwaves will move through Saturday through Sunday. Prevailing onshore flow should produce a robust sea breeze that will move inland fairly early in the afternoon both days. Scattered to numerous showers and tstms are expected, especially farther inland where the sea breeze interacts with greater instability. Although activity should wane overnight, the continuation of upper level energy moving through Saturday night could sustain at least isolated nocturnal convection. Highs both days will reach the low/mid 80s except near the coast where a marine layer will reduce temps. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... Monday should again feature scattered diurnal convection given a weak shortwave moving through, coincident with moderate surface based instability. A strong subtropical ridge will build over the area Tuesday through late week, bringing dry weather and unseasonably warm temperatures. Record high temps are not out of the question on Wednesday. Highs Wednesday and Thursday are expected to climb well into the 90s. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... KCHS/KJZI/KSAV: All terminals will experience prevailing flight restrictions in stratus and fog through mid morning, resulting in conditions below alternate minimums, and even near airfield minimums early on. Improvement back to VFR should occur by 1330-1430Z at all sites. There are indications that a few showers will form along the sea breeze this afternoon. But the potential is too low given dry and sinking air in place. Late in the TAF cycle there will likely be another round of fog/stratus that forms. For now we went down to MVFR ceilings and visibilities, although IFR or even LIFR is again possible. Extended Aviation Outlook: Flight restrictions possible in overnight/early morning fog and stratus. Isolated to scattered showers and thunderstorms are possible Saturday through Monday. && .MARINE... Today: The local waters will remain near the western side of Atlantic ridging, resulting in light winds veering around to the NE this morning, then to the E-SE this afternoon. Even with local sea breeze enhancements, speeds will be no more than about 10-15 kt. Seas will hold around 2 ft. Tonight: The synoptic pattern is basically the same, and E-SE winds are again no more than about 10 kt, with seas only 2 feet throughout. As of this time with an onshore flow, fog is likely not a concern. Friday through Tuesday: Atlantic high pressure will maintain benign conditions over the marine area Friday through Tuesday. SE winds early in the period will steadily switch to S and then SW. Wind speeds will generally be less than 15 kt with seas no higher than 4 ft. The pattern will favor a good sea breeze each afternoon along the coast, with winds in Charleston Harbor potentially gusting 15-20 kt at times. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$