textproduct: Charleston

WHAT HAS CHANGED

Updated the Marine section to address the waterspout potential this morning. In addition, the Aviation section was updated for the 12Z TAFs.

KEY MESSAGES

- 1) Typical summertime storm activity will continue through early this week.

- 2) Hot and humid conditions will return this week.

DISCUSSION

KEY MESSAGE 1: Typical summertime storm activity will continue through early this week.

The Bermuda high will remain in control of our forecast for the next day or so as it slowly flattens out across Florida. This will continue to bring a more summerlike pattern to the area as we remain on the northwestern periphery of the ridge. Expect the seabreeze to be the main surface driver for afternoon showers and thunderstorms. Isolated to scattered storms should develop by mid-afternoon Monday with the progression of the seabreeze. PWATS will remain around 2 inches and with slightly increased moisture throughout the column Monday we could see a little better coverage than today. As always a strong to severe storm cannot be ruled out with damaging winds the primary threat as well as some locally heavy rainfall. However, conditions are not necessarily favorable for a more widespread concern at this time.

Tuesday through Thursday, the upper ridge will shift westward and build over the deep south. A series of shortwaves are expected to progress through the northwesterly flow Tuesday through Thursday leading to slightly increased showers and storms during the afternoon. This will be especially true for inland areas Wednesday and Thursday. Given the increased coverage, warmer temperatures and maybe some drier air in the midlevels advecting in some increased potential for a strong to severe storm looks likely Wednesday and Thursday. This has even been noted in some of the longer range machine learning guidance highlighting increased potential for damaging wind gusts across interior South Carolina on Wednesday. Just something to watch as things may get a little more active later in the week.

KEY MESSAGE 2: Hot and humid conditions will return this week.

Despite having a decent cu field in place, expect highs to warm into the low 90s for most locations this afternoon, with perhaps a few areas flirting with the mid 90s. Dewpoints during this time look to remain in the mid to upper 70s, which should result in heat indices up to 105 degrees. Similar conditions look to prevail Monday as a coastal trough enhances WAA across the region, with a more pronounced heat wave expected to arrive mid week.

High temperatures each day are expected to peak in the lower to mid 90s, with chances for upper 90s by the end of the week, putting a few of our daily record highs and record minimum highs at jeopardy (more in the climate section below). Inland areas (especially those well west of the I-95 corridor) will likely see enough surface mixing to limit dew points to the mid 70s, while those along the coast could see dew points linger in the upper 70s to lower 80s. Combined with the aforementioned temperatures in the mid to upper 90s, expect heat index values between 105-112 degrees to be common along the coast through Wednesday. These values look to further increase by the end of the week as upper level ridging amplifies overhead - which could yield heat index values up to 115 degrees. Thus, expect some Heat Advisories to be issued during the upcoming week, though some Extreme Heat Warnings may also not be out of the question.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

18Z TAFs: Mostly VFR conditions prevail across the forecast area with some isolated to scattered showers and storms developing in and around SAV. Impacts to aviation look to be temporary with the best chances at SAV as we approach 00z tonight and as a result have added a PROB30 group to account for thunderstorm activity this evening. Elsewhere, storms should remain inland of CHS and JZI leaving the area to VFR conditions and light southerly winds behind the seabreeze. Winds will diminish to light out of the southwest overnight.

Extended Aviation Outlook: Periodic flight restrictions are expected in showers and thunderstorms through next week.

MARINE

Monday through Thursday: Atlantic high pressure will be the dominant synoptic feature into next week, keeping winds out of the south- southwest. Light to moderate winds prevail on Monday, though gusty winds are expected along the land/sea interface during the afternoon hours as the sea breeze moves ashore. Coastal troughing sets up overnight into Tuesday and continues throughout the week, keeping winds breezy with gusts into the teens to lower 20s. Seas look to remain largely in the 2-3 ft range, though 4 foot waves will be possible at times in the South Carolina waters from 20-60nm offshore. Small Craft Advisories currently look unlikely, but will be something to monitor.

Coastal Flooding: While elevated tidal cycles are expected next week due to the upcoming perigee and new moon, the south-southwesterly surface flow should keep tidal departures low, limiting the overall coastal flood threat.

CLIMATE

Record High Temperatures:

August 11: KCHS: 98/1968 KCXM: 97/1954 KSAV: 100/2011

August 12: KCHS: 98/1957 KCXM: 98/1998 KSAV: 100/1999

August 13: KCHS: 100/1995 KCXM: 98/1913 KSAV: 98/2010

Record High Minimum Temperatures:

August 10: KCHS: 80/2007 KCXM: 83/2007 KSAV: 79/2024

August 11: KCHS: 79/1983 KCXM: 82/2021 KSAV: 78/1878

August 12: KCHS: 79/1999 KCXM: 83/2021 KSAV: 80/1878

August 13: KCHS: 81/2023 KCXM: 83/2023 KSAV: 81/2023

August 14: KCHS: 80/2023 KCXM: 83/2023 KSAV: 80/2023

CHS WATCHES/WARNINGS/ADVISORIES

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