textproduct: Charleston

WHAT HAS CHANGED

The Aviation section was updated for the 12z TAFs.

KEY MESSAGES

- 1) A fairly typical summertime pattern is forecast with daily shower and thunderstorm chances through the week.

DISCUSSION

KEY MESSAGE 1: A fairly typical summertime pattern is forecast with daily shower and thunderstorm chances through the week.

Through tonight, a classic summertime airmass will prevail with the region positioned along the west side of Atlantic high pressure centered to the southeast of Bermuda. Warm and humid conditions within a weakly forced environment will support isolated to perhaps scattered showers/tstms this afternoon which could linger into the evening hours, especially across Southeast Georgia where some of the high resolution CAMs suggest a more concentrated band of weakening convection could spread north of the Altamaha River along an outflow boundary closer to sunset. Guidance suggests a subtle mid-level shortwave will pass west- east over the Lowcountry and Southeast Georgia during peak heating. No meaningful forcing is noted with various model cross sections highlighting very little, if any, upward vertical velocities (UVVs) with this feature. Convection will likely remain pulsy in nature with updrafts being heavily influenced by mesoscale processes such as boundary collisions. An isolated strong to locally severe tstm will be possible just about anywhere where updrafts can become locally enhanced. Strong/damaging winds, frequent cloud-to-ground lightning and locally heavy rainfall will be the primary hazards. Pops 30-50% were highlighted for today with the highest pops confined to areas near the Altamaha River. Convection will gradually wind down this evening with dry conditions expected to prevail through the overnight hours. Highs today will warm into the upper 80s/lower 90s away from the beaches with a few mid 90s possible across interior Southeast South Carolina where influences from morning stratus over Southeast Georgia and possibly far southern South Carolina will be less. Lows tonight will range from the lower 70s inland to the upper 70s at the beaches and Downtown Charleston.

Monday evening, the forecast area will become positioned between surface high pressure in the Atlantic and an approaching cold front from the northwest. Guidance suggests the front will move into northern Georgia and the South Carolina Midlands Tuesday evening and then stall, remaining through the end of the week. The mid-levels will consist of a series of weak disturbances moving over the Southeast during the week. Isolated showers and thunderstorms are possible Monday, with coverage increasing Tuesday onward, owing to the front in the vicinity. Showers and thunderstorms are expected to peak in the afternoon and evenings when instability is highest. The threat for organized severe weather is low, but cannot rule out a couple of strong to severe storms.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

21/12z TAF Discussion: KCHS/KJZI: VFR. Isolated to scattered showers/tstms could develop just to the west of KCHS by afternoon-mid afternoon. CAMs are mixed on exactly where convection will concentrate which is not unusual in this type of weakly forced environment. PROB30 for TSRA was maintained from 17-20z to account for this. Convection should remain inland of KJZI, thus no mention was included.

KSAV: VFR. Isolated to scattered showers/tstms are expected to develop near the terminal later this afternoon. PROB30 for tstms from 22-01z was maintained.

Extended Aviation Outlook: Brief flight restrictions are possible with any showers and thunderstorms.

MARINE

Through Tonight: A southerly flow regime near 10 kt with seas 1-2 ft will prevail through tonight with the waters positioned along the western flanks of Atlantic high pressure.

Monday through Friday: The coastal waters will become positioned between high pressure centered well offshore and an approaching cold front Monday night, leading to increasing winds and building seas. Gusts could approach 25 knots at times Monday evening into Tuesday evening, but looks fairly marginal for Small Craft Advisories. Conditions should stay below advisory levels through Friday.

CLIMATE

Record High Minimum Temperatures:

June 23: KCHS: 78/2024 KSAV: 77/2017

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...None.