textproduct: Charleston

WHAT HAS CHANGED

Update to allow the Lake Wind Advisory to expire as well as the Small Craft Advisory for Charleston Harbor and the southern SC coastal waters.

KEY MESSAGES

- 1) Breezy conditions with summer-like temperatures today across the South Carolina Lowcountry and Southeast Georgia.

- 2) Above-normal temperatures and below-normal rain chances are expected through the upcoming weekend. Temperatures could approach the triple digits this weekend.

DISCUSSION

KEY MESSAGE 1: Breezy conditions with summer-like temperatures today across the South Carolina Lowcountry and Southeast Georgia.

Ahead of an approaching "cold" front, the increased surface pressure gradient along with low-level warm air advection will continue the hot and breezy conditions throughout the rest of the afternoon hours. High temperatures in the lower to mid 90s remain expected today, and with drying in the lower/mid levels, dew points should mix out into the mid to upper 60s for majority of the area keeping heat indices in the mid 90s to lower 100s. The exception is for areas in Liberty/Long/McIntosh counties, where lingering surface moisture may bring heat indices into the 105-108 deg F range. Isolated spots in that region may briefly reach 108-109 deg F, though the forecast continues to look too marginal for a Heat Advisory. Given the strong westerly wind component throughout the column, the sea breeze is expected to remain just off-shore, keeping chances for showers and thunderstorms low across the area. The aforementioned portions of southeast Georgia are again the exception giving the marginally higher surface/low-level moisture, where an isolated shower/storm may develop or move through, with probabilities near 20%.

The weak front moves through overnight into Wednesday morning. The record high minimum temperature tied this morning at the Charleston airport will likely stand, though temperatures dipped below the records at both Downtown Charleston and Savannah.

KEY MESSAGE 2: Above-normal temperatures build with below- normal rain chances expected through the upcoming weekend. Temperatures could approach the triple digits this weekend.

The weak front will push offshore Wednesday as Atlantic high pressure extends westward across the forecast area. Aloft, broad troughing will transition to a building ridge and increasing subsidence, limiting convection into and through the weekend. Additionally, relatively dry low and mid-level air will persist through most of the week, further suppressing convection, with no more than isolated shower or thunderstorm activity expected.

Expect near-normal temperatures behind the front on Wednesday, with a weak surface high pressure moving into the southeast before dissipating, bringing varying winds throughout the day. A gradual warming trend is forecast through the remainder of the week and into the weekend. High temperatures are expected to reach the mid to upper 90s Friday, with upper 90s becoming common across much of the area Saturday and Sunday. A few locations could even exceed 100 degrees this weekend. Combined with dew points in the 70s, heat index values could reach 108-112F, especially across the coastal counties. Additionally, since convection is forecast to be isolated, we do not expect much relief from showers/storms. While confidence in the magnitude of the heat remains limited given the forecast range, the combination of extreme heat, high humidity, and limited cooling could necessitate Heat Advisories where heat indices meet or exceed our local criteria of 108F degrees. Forecast trends will continue to be monitored over the coming days.

AVIATION /20Z TUESDAY THROUGH SUNDAY/

23/18z TAF: VFR through the period. Westerly winds will remain gusty throughout the afternoon hours, weakening into the evening. A cold front will bring gradual shift towards northerly winds by daybreak, and then northeast through the rest of the morning.

Extended Aviation Outlook: No high confidence concerns.

MARINE

Through Tonight: Breezy southwesterly winds with gusts into the mid/upper 20s will continue across the Charleston County waters into the evening and a Small Craft Advisory remains in effect there. Winds are weaker, albeit still breezy, across the near and offshore zones from Savannah down to Altamaha Sound. Winds weaken throughout the evening and overnight hours, with a weak front pushing through during the overnight hours, bringing a switch to northeasterly winds throughout the morning hours.

Wednesday through Sunday: Favorable marine conditions are expected across the local waters through the weekend. A weak front located offshore Wednesday will dissipate by Thursday as Atlantic high pressure extends westward over the region. Expect an increase in winds along the coast during the afternoon and evening periods associated with the daily sea breeze circulation. Otherwise, no marine hazards are anticipated through the forecast period.

Rip Currents: Breezy southwest winds along the Charleston County beaches will continue to support a moderate risk for rip currents through this evening. Conditions look to remain in the low risk category for all remaining beaches today, and through Thursday.

CLIMATE

Record High Temperatures:

June 28: KCHS: 99/1998 KCXM: 100/1959 KSAV: 100/1998

Record High Minimum Temperatures:

June 23: KCHS: 78/2024 <--- record tied as of 6 AM.

June 27: KCHS: 77/2015 KSAV: 79/1952

June 28: KCHS: 78/2013 KCXM: 81/1998 KSAV: 80/1880

June 29: KCHS: 79/1977 KCXM: 83/1998 KSAV: 80/1885

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for AMZ360.