FXUS62 KCHS 030246 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1046 PM EDT Fri May 2 2025 .SYNOPSIS... High pressure will prevail through tonight. A cold front will affect the area this weekend, then potentially linger nearby into early next week before high pressure builds in again from the west. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Tonight: High pressure centered across the Atlantic and extending to the Southeast Coast will gradually give way late while a large trough digs south toward the ArkLaTex region. The trough will nudge a cold front east with time, reaching the Southeast United States after daybreak Saturday. Expect a slight uptick in southerly flow well ahead of this feature, allowing for a slightly more mild night under high clouds. Most areas are expected to remain dry, but there is one exception well inland. Convection continues to occur along a boundary across Central Georgia and the South Carolina Upstate. While this activity could cool pool southeastward with time, drier air depicted on soundings and weak instability locally will likely limit activity from reaching far western zones. However, should activity reach the area it would be in a weaker state, mainly showers, with an arrival time around 2-3 AM. At this time, a precip- free forecast remains, but the approaching boundary will need to be monitored for he potential of including showers for a brief period across inland zones overnight. In general, low temps should range in the low-mid 60s inland to upper 60s/around 70 near the coast. A few spots could dip into the upper 50s across the Francis Marion Forest late night. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Saturday a closed low in the mid-levels will be positioned over the Middle Mississippi Valley will set up an omega block pattern over the CONUS, with ridging building into the Southern Plains and another mid-level closed low over the west coast. This omega block pattern will dominate the upper levels into early next week. At the surface a cold front will slowly push into the local forecast area Saturday evening and into Sunday before stalling in the vicinity of the coastline. Saturday will see the region's first widespread shot at rain in a while, however, despite forecast PWAT values of upwards of 1.5", both the HRRR and the HREF are not overly impressive with the coverage of showers and thunderstorms. The forecast features PoPs generally 60-80% across the region Saturday night into Sunday at this juncture, but these values will likely need to be adjusted as additional short term guidance comes in. There is a low end potential for a strong to severe thunderstorm, with shear values around 30 to 40 knots. The limiting factor for severe storms will be the lack of instability, with CAPE values only around 1000 J/kg. The greatest chance for a strong to severe thunderstorm will be across inland SC/inland GA where there are better instability values. Showers and thunderstorms could linger into Sunday, with PoPs around 60% Sunday afternoon. While there is a chance for a strong to severe thunderstorm again on Sunday, the chance is lower than on Saturday due to even lower instability values. High temperatures on Saturday will reach into the mid to upper 80s, with around 80 at the direct coastline. Conditions will remain mild overnight Saturday into Sunday due to cloud cover and possible precipitation, only dropping into the 60s with around 70 at the beaches. Slightly cooler conditions are expected on Sunday as the cold front begins to push through, with upper 70s to low 80s forecast. Overnight Sunday into Monday a cooler airmass will be ushered in by the cold front, with lows in the 50s to mid 60s along the beaches. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... The omega block pattern begins to break down mid week as the closed low over the Middle Mississippi Valley pushes eastward and exits the CONUS off the New England coastline. The forecast through mid-week will remain dry, with slight chance to chance PoPs returning through the end of the week, as another cold front approaches the region. Temperatures will return to near normal through the week. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are expected at CHS/JZI/SAV terminals through 00Z Saturday. However, gusty south to southeast winds are expected to develop at all terminals Friday afternoon, topping out near the 20- 25 kt range. Cloud cover and precip chances increase late in the TAF period, but probabilities remain too low to include in the latest TAF issuance. Extended Aviation Outlook: Showers and thunderstorms are expected to impact CHS/JZI/SAV Saturday afternoon into Monday morning as an approaching cold front passes through the region. && .MARINE... Tonight: High pressure centered across the Atlantic will extend to the Southeast Coast while a trough approaches the region late night. A slight tightening of the gradient is possible, holding a southeast/south wind across local waters in the 10-15 kt range through much of the night. Seas will range between 1-3 ft, but should gradually build to the 2-4 ft prior to daybreak (largest across outer Georgia waters). Saturday through Wednesday: Southerly winds could surge slightly Saturday afternoon into Sunday as a cold front pushes through, however conditions are expected to remain below Small Craft Advisory criteria. East-southeasterly swell begins to mix in on Saturday and into Sunday, expect seas to be from 3 to 5 ft over the weekend, and then decrease to 2 to 3 ft for the rest of the period. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...DPB SHORT TERM...CPM LONG TERM...CPM AVIATION...CPM/DPB MARINE...CPM/DPB