textproduct: Charleston

WHAT HAS CHANGED

The aviation section was updated to reflect the 00z TAFs.

KEY MESSAGES

- 1) Dangerous heat and humidity will impact southeast Georgia and southeast South Carolina today. Extreme Heat Warnings and Heat Advisories are in effect for portions of the forecast area.

- 2) Isolated to scattered thunderstorms are expected to develop across southeast Georgia and up along the southeast South Carolina coast this afternoon and evening. There will be a risk of a few strong to severe storms capable of producing damaging wind gusts, primarily along and south of Interstate 16.

DISCUSSION

KEY MESSAGE 1: Dangerous heat and humidity will impact southeast Georgia and southeast South Carolina today. Extreme Heat Warnings and Heat Advisories are in effect for portions of the forecast area.

While there is some weak troughing overhead, the region remains on the eastern periphery of a strong ridge aloft with a weak front lingering across the forecast area. As the warm and moist air remains parked across the region, temperatures are expected to reach up into the mid 90s to lower 100s, warmest along/south of the front. For the same area, dewpoints will surge up into the mid to upper 70s, yielding heat index values in the 110-115 range east of I-95 and 105-110 just inland of I-95. An Extreme Heat Warning has been issued for areas east of I-95 and south of Beaufort County, SC, with a Heat Advisory in effect north of Beaufort and just west of I-95. For areas north of the front, inland portions of southeast South Carolina and southeast Georgia, heat index values will top out around 103 this afternoon.

While the front remains near the region into the weekend, heat and humidity will drop to near normal values.

KEY MESSAGE 2: Isolated to scattered thunderstorms are expected to develop across southeast Georgia and up along the southeast South Carolina coast this afternoon and evening. There will be a risk of a few strong to severe storms capable of producing damaging wind gusts, primarily along and south of Interstate 16.

A front is expected to gradually push southward today as weak troughing overhead continues, becoming aligned across portions of southeast GA and up along the southeast SC coast by the afternoon and evening. Along and south of the front, scattered thunderstorms are expected to develop, with the 12Z HREF and REFS indicating probabilities have expanded northwards while remaining south of the I-16 corridor, formerly thinking they would remain largely south of the Altamaha River Valley. The environment in this area is progged to have MLCAPE values upwards of 2,000 J/kg and DCAPE values of 1,000 J/kg or higher, with low-level lapse rates approaching 7 deg C/km. While an isolated risk for hail can't be ruled out, the greatest risk will be for strong-damaging wind gusts, with mid-level flow of around 25-30 knots keeping storms moving thus limiting the heavy rainfall risk. Highest values are found along/south of the Altamaha River Valley, where SPC maintains their slight risk (level 2 out of 5) for severe weather, though portions of the region along/south of the I-16 corridor continues to show a marginal risk (level 1 out of 5). The main time period of concern is roughly from 4-10pm.

AVIATION /00Z THURSDAY THROUGH MONDAY/

00Z TAFs - Mostly VFR conditions will prevail across the area this evening and into the overnight. A couple isolated showers associated with a weak front have developed along the SC/GA boarder but impacts to aviation will be minimal if any as these storms slowly diminish. Winds will turn northwesterly overnight and persist into the early afternoon tomorrow. A late afternoon seabreeze could bring light southerly winds to JZI and SAV by 19 to 20Z tomorrow.

Extended Aviation Outlook: Primarily VFR, with lesser coverage of showers and thunderstorms Thursday and Friday.

MARINE

Through tonight: West winds this morning will turn more southwest and even southerly through the evening. Wind speeds should mostly top out in the 10-15 knot range with gusts up to around 20 knots. Late tonight, A wind shift will work across the waters, turning winds more northerly or even northeasterly by sunrise Thursday. Seas will average 2-4 feet today, followed by 2-3 feet overnight.

Thursday through Monday: Southeasterly flow will dominate across the marine waters through the weekend, with gusts topping out around 10 to 15 knots through Friday. Gusts are forecast to shift to the SW and increase to 15 to 20 knots early this weekend ahead of the arrival of a cold front. The cold front is forecast to push through the region on Sunday, bringing an additional surge in winds and seas. Small Craft Advisories could be needed for portions of the marine waters for 25 knot wind gusts Sunday into Monday.

CLIMATE

Record High Minimum Temperatures:

July 29: KCHS: 80/2016 KCXM: 85/1999 KSAV: 82/1878

August 1: KCHS: 81/1999 KCXM: 86/1999 KSAV: 79/2020

August 2: KCHS: 79/2022 KCXM: 84/1999 KSAV: 80/1886

CHS WATCHES/WARNINGS/ADVISORIES

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