textproduct: Charleston

WHAT HAS CHANGED

Small Craft Advisory issued for Charleston Harbor. Coastal Flood Advisory for Charleston and Coastal Colleton until 3 PM.

KEY MESSAGES

- 1) Minor coastal flooding is possible expected along portions of the South Carolina coast early this afternoon.

- 2) Breezy conditions with somewhat unsettled weather possible today into Monday. Mild temperatures expected through midweek, then a cold front should bring at least scattered showers on Thursday.

DISCUSSION

KEY MESSAGE 1: Minor coastal flooding is possible along portions of the South Carolina coast early this afternoon.

A Coastal Flood Advisory has been issued for Charleston and Colleton Counties until 3 PM EST.

At high tide early this morning, the Charleston Harbor tide gage indicated a tidal departure of 0.95 ft. Gusty northeast winds should continue along the Charleston County coast through the day. The tidal departure headed to the high tide at 1:04 PM should remain at or above 0.87 ft, necessary for minor coastal flooding. The water level is forecast to crest between 7.0 to 7.2 ft MLLW, minor coastal flooding begins at 7.0 ft MLLW.

KEY MESSAGE 2: Breezy conditions with somewhat unsettled weather possible today into Monday. Mild temperatures expected through midweek, then a cold front should bring at least scattered showers on Thursday.

This morning, regional radar composite indicated several large areas of light rain across GA ahead of amplifying H5 shortwave. In addition, another patch of showers over the outer GA/SC waters was tracking toward shore, developing within a inverted sfc trough. Based off of radar trends and HREF and REFS guidance, scattered to numerous showers may develop across SE GA and portions of SC this morning, then gradually decreasing in coverage this afternoon. At the sfc, ridging high pressure will likely maintain a 3-4 mb pressure gradient across the forecast area today. Northeast winds should remain between 10 to 15 mph with gusts between 20 to 25 mph, highest along the coast. Given the rounds of showers, thick mid to high clouds, and northeast winds, high temperatures should favor values in the mid 70s.

Tonight, showers should continue across the nearshore and outer Atlantic waters overnight. BKN to OVC mid and high clouds and steady northeast winds should favor low temperatures in the mid 50s inland to the low to mid 60s along the coast.

Extended: High pressure lingers overhead Monday before drifting eastward over the Atlantic Tuesday into the middle of the week. A coastal trough is expected to develop just off the GA/SC coast and provide sufficient convergence to generate showers. This shower activity will likely favor the GA coast through Monday, with coverage then gradually spreading across the entire coastline Tuesday into Wednesday as the parent high slips to the east and allows the trough to attempt to push onshore. Nonetheless, do not expect to see much in the way of impactful accumulations. Rather, will likely see most places only receive a few hundredths to a tenth of an inch at best.

With a pinched gradient in place, will also see breezy northeasterly winds continue, with gusts between 20 to 25 mph possible each afternoon and evening, especially along the coast. Afternoon highs during this time should remain seasonal, with temperatures in the mid 70s Monday rising into the upper 70s to lower 80s by midweek.

Model certainty wanes heading into the latter half of the week, as guidance differs on how the upper level pattern will evolve. Most showcase a fairly progress trough moving eastward toward the Atlantic, though timing and the location of the moisture axis could still vary a bit in the coming days.

AVIATION /15Z SUNDAY THROUGH THURSDAY/

Prior to the 12Z TAFs, recent observations indicated MVFR ceilings across most of SE GA and the SC Lowcountry. TAFs will feature restrictive ceilings in either FM groups or TEMPOs until 14-15Z. In addition, KCLX detected isolated showers in the vicinity of KSAV at the onset of the TAF, expected to end by 14Z. By mid-morning, northeast winds are forecast to strengthen to 10 to 15 kts with gusts around 20 kts. The most frequent gusts should occur over KJZI, with lesser winds over KSAV and KCHS. Wind gusts should come to an end early this evening, with steady northeast winds around 10 kts remaining through the remainder of the TAF period.

Extended Aviation Outlook: Breezy northeasterly winds continue through Monday, along with rain chances and the potential for periodic flight restrictions.

MARINE

A Small Craft Advisory has been issued for Charleston Harbor through this evening.

Today through Tonight: At the sfc, ridging high pressure will likely maintain a 3-4 mb pressure gradient across the forecast area today and tonight. Northeast winds should generally remain between 15 to 20 kts and gusts between 25 to 30 kts through the near term. As a result, wave heights should remain between 5 to 8 ft. Small Craft Advisories will remain in effect outside the Charleston Harbor.

Monday Onward: Frequent gusts into the 25-30 knot range are expected into Monday, along with seas in the 5-7 ft range. These conditions will support an extended period of Small Craft Advisories. Winds should gradually diminish Tuesday into Wednesday as the gradient relaxes. However, seas will remain elevated enough to keep the advisories going through Tuesday night. By Wednesday night and Thursday, winds will diminish even more as a cold front approaches from the west.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Coastal Flood Advisory until 3 PM EST this afternoon for SCZ149-150. MARINE...Small Craft Advisory until 7 PM EST this evening for AMZ340. Small Craft Advisory until 7 AM EST Wednesday for AMZ360-362- 364. Small Craft Advisory until 7 AM EST Thursday for AMZ384.