Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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583 FXUS62 KCHS 021307 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 907 AM EDT Thu May 2 2024 .SYNOPSIS... Atlantic high pressure will remain across the Southeast through much of next week. && .NEAR TERM /THROUGH TONIGHT/... Conditions have improved greatly across Southeast Georgia per satellite, surface observations and regional webcams. The Dense Fog Advisory has been cancelled for that area, including Allendale County, SC. Current trends suggest most of the dense fog lingering over Southeast South Carolina should lift by 10 AM where a Dense Fog Advisory continues. Today: Strong ridging will prevail aloft, while the local zones are situated near the western periphery of the Bermuda- Azores High. Unlike yesterday, the sea breeze boundary is not expected to be active, given the subsidence aloft and minimal instability. Even though we lose about 2-3 hours of insolation due to the morning fog, the ridging aloft and 850 mb temperatures reaching near 15C will support another warm day. The low level thickness has done very well the past few days, but with an east-southeast synoptic flow we didn`t go quite as high as thew 1000-850 mb thickness implies. Even so, a blend of the MOS, NBM, and NBM50 was used to produce highs in the mid and upper 80s away from the beaches. A few places could hit 90F degrees across interior southeast Georgia. 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 /13Z 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 kt. Seas are just around 2 feet. 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...Dense Fog Advisory until 10 AM EDT this morning for SCZ042>045- 047>052. MARINE...None. && $$