textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Typical summertime storm activity will continue through mid-week. Some storms may produce strong to severe wind gusts.

- 2) Hot and humid conditions will return Tuesday and persist into the weekend. Heat Advisories will likely be required and Extreme Heat Watches/Warnings cannot be ruled out, especially towards the end of the week.

DISCUSSION

KEY MESSAGE 1: Typical summertime storm activity will continue through mid-week. Some storms may produce strong to severe wind gusts.

Rest of today: Radar imagery early this afternoon showed increasing coverage of showers and thunderstorms, particularly across the Midlands and into our South Carolina counties. Models have largely been underdone with this activity. We should continue to see additional development through the afternoon into the early evening. SPC Mesoanalysis currently indicates MLCAPE of around 2500-3000 J/kg with DCAPEs of 700-1000 J/kg. A few strong to severe thunderstorms will be possible with damaging wind gusts as the main hazard. In addition, locally heavy rainfall will be possible in any storm that develops. Flood threat is low, but non-zero especially in locations where storms move over repeatedly.

The chance for isolated to scattered convection will continue for much of the remainder of the week with daytime heating and occasional weak perturbations aloft. Upper ridge centered to the south is expected to build over the area on Thursday, which would act to keep coverage more limited than on other days. While the pattern favors more pulse-type convection, a stronger to severe storm will be possible each day. Damaging wind gusts would be the primary threat. This potential also jives with some of the latest AI guidance.

KEY MESSAGE 2: Hot and humid conditions will return Tuesday and persist into the weekend. Heat Advisories will likely be required and Extreme Heat Watches/Warnings cannot be ruled out, especially towards the end of the week.

Heat headlines are likely Tuesday and into the weekend as heat index values soar into the 105-110 range each afternoon through mid-week and upwards of 115 late in the week. The daily record highs and record high minimum temperatures will likely be challenged at our three climate sites (see Climate Section for more details). Given the very mild overnight periods and minimal coverage of precipitation, there will be few instances of relief from the heat this week and into the weekend.

Tuesday: Upper ridging will gradually shift west across the area and into the deep south with mainly westerly flow aloft. This will allow for temperatures to quickly increase into the mainly the mid 90s with some upper 90s in some locations on Tuesday. These high temperatures will combine with rather high dewpoints in the mid to upper 70s mainly behind the advancing seabreeze each afternoon. This will result in heat indices mainly along the coastal interface of 108 to 110 with some isolated locations possibly increasing to around 112. Further inland, some drier air aloft should be able to mix into the area leading to some lower 70s dewpoints keeping heat indices in and around the 104 to 108 range. As a result, we have gone ahead and issued a heat advisory for all of coastal South Carolina tomorrow and depending on observations may need to expand further south into coastal Georgia.

Wednesday through Saturday: The ridging aloft will gradually amplify towards the end of the week, likely bringing the warmest temperatures of the heat wave. Highs on each day will likely reach into the upper 90s, with a brief moment of touching 100 not out of the question. Conditions will likely follow Tuesday with inland areas mainly west of I-95 mixing into the upper 60s to low 70s dewpoints leading to heat indices in the 104 to 108 range. East of I-95 things will be significantly more oppressive as rather rich upper 70s to low 80s dewpoints should surge further inland each day resulting in heat indices reaching the 108 to 112 range across a large portion of the area Wednesday, Thursday, and Friday. Areas along the highway 17 corridor to the coast including metro Charleston and Savannah could reach heat indices approaching 115+ Thursday and Friday. This couples with ECMWF Extreme Forecast Index and shift of tails that support a rather high confidence impactful heat wave. Probabilistic heat risk also supports nearly 80-90% exceeding HIGH heat risk for most of the area Wednesday through Saturday and nearly 40% of exceeding extreme heat risk on Thursday and Friday which overall jives with the potential worst of the heat wave. Expect several days of heat advisories and possibly extreme heat watches/warnings to come later this week.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Predominantly VFR through 18z Tuesday. Radar early this afternoon showed increasing coverage of showers and thunderstorms. There is potential for brief reductions in ceilings and visibilities within any storm that directly impacts the terminals. Coverage will wane later this evening with loss of heating. Another round of thunderstorms will be possible on Tuesday afternoon, however any potential impacts would likely occur at the very end or beyond the valid TAF cycle.

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

CLIMATE

Record High Temperatures:

August 11: KCHS: 98/1968 KCXM: 97/1954

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

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

August 14: KCHS: 102/1995 KSAV: 102/1925

August 15: KCHS: 96/2023 KSAV: 100/1918

Record High Minimum Temperatures:

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

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

August 12: KCHS: 79/1999 KSAV: 80/1878

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

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

August 15: KCHS: 78/1995 KCXM: 83/2021 KSAV: 80/1995

August 16: KCHS: 78/2019 KSAV: 78/2019

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Heat Advisory from 11 AM to 8 PM EDT Tuesday for SCZ148>150- 152. MARINE...None.