textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 and 2 were updated due to an earlier error.

KEY MESSAGES

- 1) Above normal temperatures expected to impact the area through the upcoming week. Humidity will increase on Sunday and remain elevated into next week, especially along the coast. Heat Advisories could be needed each afternoon through much of next week.

- 2) Typical summertime convection returns Sunday and will persist into next week.

DISCUSSION

KEY MESSAGE 1: Above normal temperatures expected to impact the area through the upcoming week. Humidity will increase on Sunday and remain elevated into next week, especially along the coast. Heat Advisories could be needed each afternoon through much of next week.

Upper ridging will remain entrenched across the Southeast despite the center shifting offshore over the western Atlantic on Sunday. This pattern will support above normal temperatures through the remainder of the weekend and much of next week. Overnight low temperatures could remain near record-high minimum values through much of the week (see Climate Section below), providing little relief from the daytime heat. Shower and thunderstorm coverage is expected to increase by early next week, which could provide some relief from the heat.

High temperatures Sunday afternoon are forecast to reach the upper 90s inland and the mid 90s along the coast. Following the sea breeze, dewpoints along the coast could rise into the upper 70s, with mid 70s common elsewhere. As a result, peak heat index values are forecast to reach 106 to 107 degrees along the coast, approaching Heat Advisory criteria. Some isolated spots could peak around 108 or 109 degrees, but should be brief. HREF guidance indicates a 20-30% probability of apparent temperatures reaching 108 degrees or higher across the coastal counties on Sunday. Thus, no Heat Advisories are planned at this time. A similar pattern will emerge each day through much of the upcoming week with peak heat indices nearing or reaching Heat Advisory criteria each afternoon. Forecast trends will continue to be monitored to determine where Heat Advisories could become necessary on a day-to-day basis.

KEY MESSAGE 2: Typical summertime convection returns Sunday and will persist into next week.

Despite persistent upper ridging, PWATs are forecast to increase to 2 inches or greater, supporting the return of a more typical summertime convective pattern. Scattered showers and thunderstorms will be possible each day, with the greatest coverage during the afternoon and early evening as instability peaks. Environmental conditions will favor mainly pulse-type convection, although a few storms could become strong to severe each day with damaging wind gusts as the primary hazard.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

05/00z TAF Discussion: KCHS/KJZI/KSAV: VFR for much of the period. Would not be surprised to see a brief period of smoke reduce vsbys at KCHS later this evening with a large fireworks display scheduled to occur not too far from the terminal. This has occurred in previous Independence Day celebrations. Risk for showers/tstms will increase Sunday afternoon. Best chances for impacts are at KCHS and KSAV ahead of the sea breeze. PROB30 groups for TSRA were included 18-21z at KCHS and 19-22z at KSAV.

Extended Aviation Outlook: Brief flight restrictions are possible in afternoon showers/thunderstorms late weekend into next week.

MARINE

Through Tonight: Tranquil conditions continue under sfc high pressure, with south/southwesterly winds up to 15 kts, and seas between 2 to 3 feet.

Sunday through Thursday: The coastal waters will be positioned between high pressure offshore and a trough of low pressure inland through the period. Wind speeds are forecast to stay below Small Craft Advisory criteria through the period, however gusts in the low 20 kt range are possible, especially in the afternoon and evenings. Seas will average 2-4 feet.

CLIMATE

Record High Temperatures:

July 5: KSAV: 100/1902

July 7: KCHS: 99/1954

Record High Minimum Temperatures:

July 5: KCHS: 78/2017 KCXM: 82/2016 KSAV: 78/2016

July 6: KCHS: 79/1990 KCXM: 82/2024 KSAV: 78/2024

July 7: KCHS: 80/2017 KCXM: 82/2022 KSAV: 80/1883

July 8: KCXM: 83/2016 KSAV: 80/1990

July 9: KCHS: 80/1998 KSAV: 80/1883

July 10: KCHS: 81/1986 KCXM: 82/1986

CHS WATCHES/WARNINGS/ADVISORIES

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