textproduct: Charleston

WHAT HAS CHANGED

The aviation section was updated for the 26/00z TAFs. Key Message 1 was updated to reflect near term trends.

KEY MESSAGES

- 1) Locally heavy rainfall is possible through Sunday as a stalled front remains in the vicinity of the South Carolina Lowcountry.

- 2) Hot and humid conditions return to Southeast South Carolina and Southeast Georgia during the middle of next week.

DISCUSSION

KEY MESSAGE 1: Locally heavy rainfall is possible through Sunday as a stalled front remains in the vicinity of the South Carolina Lowcountry.

Tonight: Earlier convection has dissipated, but regional radars are already showing a secondary wave of showers/tstms developing from the southern Midlands into central Georgia with the approach of another mid-level shortwave. There remains plenty of MLCAPE in the wake of earlier convection and should help sustain this activity for a few more hours as it works east to the coast.

Sunday: Given continued weak shortwaves aloft and the stalled front remaining nearby, Sunday may start off with scattered showers and isolated thunderstorms, especially across portions of southeast South Carolina. By the late morning/early afternoon, a surface high pressure moving in from the north begins to shift the front to the south. As that occurs, some models are developing a weak surface low along the front as it shifts southwards, leading to the continuation of heavy rainfall risks on Sunday. The 12Z HREF has a 70-90% chance for 1"/3hrs over the Charleston tri-county area during the afternoon hours, with a 30-50% chance for 3"/3 hrs, with probabilities decreasing as the front/low moves to the south. In addition to the heavy rainfall threat, steep low-level lapse rates with the high PWATs may enhance downdraft strength, bringing a risk for strong damaging wind gusts of 50 to 60 mph.

KEY MESSAGE 2: Hot and humid conditions return to Southeast South Carolina and Southeast Georgia during the middle of next week.

The mid-levels will consist of a very strong ridge over the Rockies and Plains early to mid next week. Meanwhile, troughing will be along the Eastern Seaboard. We'll generally be on the eastern periphery of the ridge, with NNW flow overhead. At the surface, weak High pressure will prevail over or nearby early to mid next week. Hot and humid conditions are expected to return during the middle of next week. Tuesday and Wednesday look to be the hottest days of the week, with highs in the mid to upper 90s, with some spots possibly reaching the 100 degree mark across far inland GA. Even temperatures at the coast will be in the 90s. Dewpoints are expected to be in the low 70s far inland, but pool into the mid to upper 70s at the coast with the afternoon sea breeze. This will equate to heat indices in the 100-105 degree range inland, and the 108-112 degree range for our coastal counties on Tuesday. Though, the range could increase to 110-115 degrees for our coastal counties on Wednesday. If this pans out, at least our coastal counties would need heat headlines both days. The wild card would be afternoon convection. Tuesday is looking fairly dry. But Wednesday may have scattered convection, which would quickly lower temperatures. It could also lead to strong to marginally severe storms. But those details will get ironed out in later forecasts. The heat and humidity is expected to drop to near normal values on Thursday with the arrival of a front.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

26/00z TAF Discussion: KCHS/KJZI/KSAV: Earlier convection has dissipated, but radar is showing a secondary wave of showers/tstms starting to develop from the southern Midlands into central Georgia. This activity will continue to push east/southeast this evening, possibly impacting all three terminals. Preliminarily, PROB30s were introduced to account for this activity, but TEMPO groups may be considered just before the final TAF package is released. Conditions would be limited to MVFR for now. Quiet conditions overnight. Risk for showers/tstms will once again maximize during the afternoon hours Sunday. PROB30 was introduced 20-23z at KCHS and KJZI given models are hinting at better coverage across the South Carolina Lowcountry. No mention was included at KSAV for now given confidence is a bit lower there.

Extended Aviation Outlook: Brief flight restrictions are possible Wednesday and Thursday due to showers and thunderstorms.

MARINE

Through Thursday: A stationary front nearby will continue southwesterly winds today. Expect modest winds and seas Sunday and Monday. Winds and seas will be much higher late Tuesday into Wednesday, so Small Craft Advisories may be needed for most of our waters.

CLIMATE

Record High Temperatures:

July 28: KCHS: 101/1949 KCXM: 100/1936 KSAV: 102/1949

July 29: KCHS: 100/1993 KCXM: 99/1999 KSAV: 103/1993

Record High Minimum Temperatures:

July 25: KCHS: 80/2011 KCXM: 82/2016 KSAV: 80/1893

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

CHS WATCHES/WARNINGS/ADVISORIES

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