FXUS62 KCHS 301821 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 221 PM EDT Mon Jun 30 2025
.SYNOPSIS...
A front is expected to move into the area by Wednesday and could then linger in the vicinity into the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
The region will remain on the backside of surface high pressure centered offshore tonight, while a broad trough resides inland. Aloft, a weak upper level wave will shift westwards towards the Southeast coast. Concurrently, a larger scale trough will be moving into the Ohio and Tennessee Valleys. Diurnal showers and thunderstorms will continue to pop-up through the afternoon and into this evening with SPC mesoanalysis indicating 1500-2000 J/kg of MLCAPE. Highest coverage should be focused over southeast Georgia where PoPs peak in the 60-70% range. Further north into South Carolina, PoPs remain 20-30%. The threat for severe weather is low. Convection will largely diminish later this evening and overnight with loss of heating. Low temperatures will be near normal, mainly in the low to mid 70s, except a bit higher at the beaches and immediate coast.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Tuesday through Thursday: Aloft, we begin Tuesday with a baggy upper trough that steadily becomes more well defined and sharper into Wednesday as a shortwave passes by to the north. At the surface, Tuesday will see the area situated between the subtropical high to the east and a front to the west that stretches from the eastern Great Lakes into the lower MS Valley. This front is expected to gradually shift closer to the area through Wednesday and perhaps remain in the vicinity through Thursday. Also of note, precipitable water values are expected to surge for Wednesday with the entire forecast area within an area of 2.25" or higher values. Concerning the coverage of convection, the overall trend is expected to be increasing especially for Wednesday when we anticipate seeing the best combination of forcing and moisture. Slow moving storms and the overall expected increased coverage for Wednesday will also likely yield the greatest potential for locally heavy rainfall across the area. Overall, there is no notable severe threat, though there could always be a strong to marginally severe storm as outflow boundaries interact. Temperatures are expected to be near normal for Tuesday, then perhaps a bit below normal on Wednesday thanks to the increased shower and thunderstorm coverage. Thursday should be back to near or slightly above normal.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
The pattern for Friday through the weekend and into early next week looks to be pretty typically of summer. The one thing to keep an eye on is that some model guidance keeps the mid/late week front lingering along the coast and attempts to develop an area of low pressure along it. As such, the northeast Gulf Coast and Southeast coast are currently highlighted in NHC's Tropical Weather Outlook with a low chance of tropical development over the next 7 days. But for now, the forecast highlights low 90s for highs each day with scattered diurnal convection.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
KCHS and KJZI: Prevailing VFR is expected through the 18z TAF period as the threat for convection is too low to include in the TAF.
KSAV: There could be brief restrictions in ceilings and visibilities this afternoon if any showers or thunderstorms make a direct impact at the terminal. Outside of convection, there are some indications a period of sub-VFR ceilings could develop late tonight towards morning, but opted for a SCT layer at this time until trends are better defined.
Extended Aviation Outlook: Mostly VFR. There is potential for brief impacts from thunderstorms each afternoon and evening with the best chances coming during the mid week time period as a front moves into the region.
&&
.MARINE...
Tonight: Southerly flow is expected to prevail through tonight on the backside of surface high pressure. Speeds average 10-15 kt with seas 2-4 feet.
Tuesday through Saturday: The local waters are expected to be situated between high pressure to the east and an inland front Tuesday and Wednesday, which should lead to the highest period of winds and seas. In fact, Tuesday should produce solid 15 knot winds with frequent gusts to 20 knots across all local waters. The strongest winds are expected for Charleston Harbor and the Charleston County waters where there is some potential for gusts up to 25 knots. Confidence isn't high enough to go with a Small Craft Advisory at this point, but it will need to be considered with future forecast updates. After another period of some enhanced winds Wednesday, speeds should be much lower from Thursday onward. Seas should peak in the 3-4 ft range Tuesday, then diminish back to be 2- 3 ft thereafter.
Rip Currents: The presence of some swell energy and enhanced flow along the Charleston County coast will yield an elevated risk of rip currents for Tuesday. There is a Moderate Risk for the Charleston County beaches and a Low Risk elsewhere.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
&&
$$
NEAR TERM...ETM SHORT TERM...BSH LONG TERM...BSH AVIATION...BSH/ETM MARINE...BSH/ETM