textproduct: Charleston

WHAT HAS CHANGED

All Key Messages and Sections were updated.

KEY MESSAGES

- 1) Hot and humid conditions continue across southeast Georgia and the South Carolina Lowcountry. A couple of strong to severe thunderstorms are possible near the sea breeze this afternoon into the early evening.

- 2) Hot and humid conditions will persist through much of the week.

- 3) Typical summertime convection returns this week.

DISCUSSION

KEY MESSAGE 1: Hot and humid conditions continue across southeast Georgia and the South Carolina Lowcountry. A couple of strong to severe thunderstorms are possible near the sea breeze this afternoon into the early evening.

Dangerous heat continues across the region, with latest observations showing temperatures in the mid to upper 90s under mostly sunny skies. This coupled with dewpoints in the low to mid 70s has resulted in heat index values up to 110 degrees - with the highest values noted along the South Carolina coast. Thus, believe the current Heat Advisory (which remains valid until 7 PM this evening) remains in good shape.

Similar to yesterday, hot and humid conditions will result in chances for scattered showers and storms this afternoon, especially along the advancing sea breeze. While there is ample SBCAPE (up to 2500 J/kg), overall shear is rather meager - suggesting that storms will remain more pulse based rather than organized or linear. Nonetheless, with DCAPE values up to 1000 J/kg, and low level lapse rate between 7.5 to 8 degC/km, can't rule out seeing some isolated damaging wind gusts and small hail with any storm that becomes strong to severe. Brief heavy downpours will also be possible, as soundings show PWATs between 1.5 to 2 inches. Fortunately, any rain will be a welcomed reprieve, with flooding concerning expected to remain minimal given the on-going drought in place. Otherwise, look for convection to gradually wane through the evening, especially after sunset.

KEY MESSAGE 2: Hot and humid conditions will persist through much of the week.

Upper ridging will maintain control over the region through much of the week, leading to a continued stretch of above normal temperatures. Highs are forecast to peak in the mid to upper 90s each day, with heat indices of 100+. Areas east of I-95 and closer to the coast will see the highest heat indices, generally averaging in the 107-112F range as dewpoints surge into the upper 70s/near 80 with the sea breeze. A Heat Advisory has been posted for the coastal corridor, including much of the Savannah and Charleston Metro Areas, for Tuesday and additional advisories could be needed each afternoon through the weekend. Little relief is expected overnight with lows only falling to the upper 70s/lower 80s over most locations. See climate section below for potential records in jeopardy. NWS HeatRisk currently shows a Major (level 3/4) HeatRisk each day, so regardless of heat product issuance, this extended stretch of hot and humid conditions will bring a risk of heat-related impacts, especially to those more vulnerable to heat or those without adequate cooling/hydration.

KEY MESSAGE 3: Typical summertime convection returns this week.

The region will be situated between high pressure offshore and a trough of low pressure inland through much of the week, with ridging the primary feature aloft. Larger scale forcing is lacking, but isolated to perhaps scattered showers and thunderstorms will be possible each day largely due to daytime heating and mesoscale boundaries like the sea breeze. Coverage will be highest in the afternoon and early evenings, before dwindling after sunset with loss of insolation. While the environment favors mainly pulse-type convection, a couple strong to severe storms with damaging wind gusts cannot be ruled out. Locally heavy rainfall is also possible with any storms, but flooding risk is low especially given the hot and dry conditions of late.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Aviation: Scattered thunderstorms are forecast to develop along the sea breeze this afternoon, near or over the KCHS and KSAV terminals between 20-24Z. A TEMPO group has been added to account for this. Otherwise, expect convection to quickly dissipate this evening, with winds becoming light and southwesterly overnight.

Extended Aviation Outlook: There will be a risk for tstm impacts at the terminals each afternoon/evening, especially at KCHS and KSAV.

MARINE

Through Tonight: High pressure will support southerly winds between 10 to 15 kts, with occasional gusts up to 25 kts. Wave heights are forecast to favor 3 ft, increasing to 3-4 ft overnight.

Tuesday through Saturday: Not much change in the pattern this week, with southwest winds in the morning backing more to the south for the afternoon and evenings. Gusts will largely top out in the low 20 kt range, but later in the week, there is a better chance at seeing some 25 knot gusts. Seas will average 2-5 feet.

CLIMATE

Record High Temperatures:

July 7: KCHS: 99/1954

July 8: KCHS: 100/2016 KCXM: 100/1907 KSAV: 101/2010

July 9: KCXM: 99/1986

July 10: KCHS: 100/1986 KCXM: 99/1986 KSAV: 102/1879

July 11: KCHS: 102/1986 KCXM: 100/2001

July 12: KCXM: 97/1966

Record High Minimum Temperatures:

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

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

July 8: KCHS: 82/2016 KCXM: 83/2016 KSAV: 80/1990

July 9: KCHS: 80/1998 KCXM: 85/1998 KSAV: 80/1883

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

July 11: KCHS: 80/2016 KCXM: 82/2016

July 12: KCHS: 79/2020 KCXM: 82/1998

CHS WATCHES/WARNINGS/ADVISORIES

GA...Heat Advisory from 11 AM to 7 PM EDT Tuesday for GAZ217>219- 239-241. SC...Heat Advisory from 11 AM to 7 PM EDT Tuesday for SCZ045- 148>152. Heat Advisory until 7 PM EDT this evening for SCZ045-148>152. MARINE...None.