textproduct: Charleston

WHAT HAS CHANGED

A Coastal Flood Advisory has been issued for Charleston and Coastal Colleton Counties for this evening's 11 PM high tide. The Aviation Section was updated to reflect the 18Z TAFs.

KEY MESSAGES

- 1) Hot and humid conditions will linger through the remainder of this afternoon, returning again tomorrow and persisting through early next week. Heat Advisories could be needed.

- 2) A Coastal Flood Advisory has been issued for Charleston and Coastal Colleton Counties for minor flooding with this evening's high tide.

DISCUSSION

KEY MESSAGE 1: Hot and humid conditions will linger through the remainder of this afternoon, returning again tomorrow and persisting through early next week. Heat Advisories could be needed.

Rest of Today: Weak ridging aloft and at the surface will dominate the synoptic pattern through the remainder of today. Temperatures have reached into the low to mid 90s with heat index values topping out around 99-103 across the region. Isolated showers and thunderstorms have begun to develop, with boundary interactions being the main driving force. With a PWAT of 1.9" with this morning's 12Z KCHS RAOB Sounding heavy rainfall is a threat for this afternoon. The CAMs today are not overly impressive with the coverage of showers/storms, mainly in the isolated to scattered category. DCAPE values are only around 500 J/kg according to SPC mesoanalysis.

Sfc high pressure will become more established across the western Atlantic heading into this weekend, favoring a southwest/south flow that brings slightly higher dewpts across the local area. The combination of temps in the mid-upper 90s along with elevated dewpts will yield widespread heat index values above 100 degrees across Southeast South Carolina and Southeast Georgia, and likely a swath of 108-112 heat index values for areas along and east of the I-95 corridor this weekend. At this juncture conditions on Friday afternoon appear too marginal for a Heat Advisory, however this will be reevaluated with the next forecast update. Next week looks to be warm and humid as well with conditions approaching Heat Advisory level conditions each day, but convective coverage could be more numerous with an inland trough nearby Sunday into Monday, followed by the approach of a front from the northwest heading to the middle of next week.

KEY MESSAGE 2: A Coastal Flood Advisory has been issued for Charleston and Coastal Colleton Counties for minor flooding with this evening's high tide.

The astronomical tide at the Charleston Harbor this evening will be 6.2 ft MLLW. While this value is lower than the previous nights which saw coastal flooding, guidance is showing that departure values could approach 0.8 ft which would yield a tide value right around 7.0 ft MLLW (minor coastal flooding). A Coastal Flood Advisory has been issued for Charleston and Coastal Colleton Counties for this evening's high tide, with the tide forecast to reach 6.9 to 7.1 ft MLLW.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

VFR conditions will prevail at KCHS/KJZI through the 18Z TAF period. Isolated showers/tstorms could impact KSAV this afternoon, as denoted by the TEMPO group from 18 to 20Z. VFR thereafter.

Extended Aviation Outlook: Mostly VFR. Low chances of direct impacts from afternoon and evening showers and thunderstorms each day.

MARINE

Today - Friday: South-southwesterly surface flow will continue this afternoon and continue into Friday as a subtropical high develops, with winds and seas expected to remain below Small Craft Advisory criteria.

Saturday - Sunday: Over the weekend, the surface pressure gradient is expected to strengthen between an inland trough and the aforementioned high to the east. This will produce stronger southwest to south flow, with speeds getting more into the 15-20 knot range and an increasing chance of gusts up to 25 knots, mainly for the SC coast and Charleston Harbor. We could even need some short duration Small Craft Advisories over the weekend. 3 feet waves are expected to develop along the coast, with 5 to 6 foot waves in our outer offshore zones (highest in the zones 20-60nm out from South Santee, SC to Savannah, GA).

Monday: The previously mentioned inland trough is expected to move into the coastal corridor, continuing elevated winds with potential for additional Small Craft Advisories. There is a low chance (20%) for a low pressure system to develop/move into the region, which would bring additional wind and wave concerns.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Coastal Flood Advisory from 9 PM this evening to 1 AM EDT Friday for SCZ149-150. MARINE...None.