textproduct: Charleston

WHAT HAS CHANGED

Aviation section has been updated.

KEY MESSAGES

- 1) Minor coastal flooding is possible along coastal areas of Charleston and Colleton Counties with high tide this evening and possibly Tuesday evening.

- 2) Rain chances likely to increase late in the week, though no hazardous weather is anticipated at this time.

DISCUSSION

KEY MESSAGE 1: Minor coastal flooding is possible along coastal areas of Charleston and Colleton Counties with high tide this evening and possibly Tuesday evening.

Astronomical influences associated with the recent new moon and lunar perigee along with a modest onshore flow will continue to drive elevated tide levels, potentially leading to minor coastal flooding along parts of the lower South Carolina coast this evening. The latest forecast advertises a peak high tide 7.0-7.2 ft MLLW in the Charleston Harbor this evening and 6.9-7.1 ft MLLW Tuesday evening. A Coastal Flood Advisory for Coastal Colleton and Charleston Counties could be needed for this evening's high tide and possibly again Tuesday evening, although confidence in reaching the 7.0 ft MLLW minor flood stage is much more uncertain by then. Astronomical tide levels then begin to fall and the potential for minor coastal flooding will diminish.

KEY MESSAGE 2: Rain chances likely to increase late in the week, though no hazardous weather is anticipated at this time.

The synoptic pattern is forecast to shift slightly during the latter half of the week, bringing a more unsettled weather regime to the region. While finer details remain uncertain, most guidance indicates shortwave energy rounding the northwestern periphery of an upper ridge Wednesday into Friday. At the surface, a cold front is expected to drop southeastward across the Great Appalachian Valley late Wednesday before potentially stalling across the Carolinas and later lifting into the Northeast U.S. as a warm front by Saturday. The approach of this boundary will promote increasing moisture and rain chances across the region. However, the eventual placement and southward progression of the front will play a key role in determining where and how much precipitation occurs. Notably, the latest ensemble guidance indicates a 20-50% probability of accumulated rainfall exceeding one inch, with the highest probabilities currently focused inland.

In terms of severe weather potential, the latest solutions favor the deeper moisture and thus greater instability to remain to our north. Additionally, weak forcing and shear will keep the potential for severe weather low during this latter portion of the week.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

KCHS/KJZI/KSAV: Generally VFR throughout the 00Z period, though there could be scattered pockets of ground fog for areas inland from the coast as winds weaken. Low-level condensation pressure defecits look to be too high for widespread/thick fog, especially across southeast South Carolina, so any fog that does form will likely be fairly shallow and transient. Southeast winds increase throughout the morning hours, becoming marginally gusty behind an afternoon sea breeze.

Extended Aviation Outlook: There are no high confidence concerns.

MARINE

Through Tonight: The synoptic flow regime will change little through tonight as Atlantic high pressure remains centered well offshore. An easterly flow regime will prevail with east to southeast winds 15 kt or less prevailing. Some local enhancement could occur along the land/sea interface and Charleston Harbor this afternoon with the sea breeze. Seas will average 2-4 ft.

Tuesday through Saturday: No marine concerns are expected. High pressure to the east will drive onshore east-southeasterly flow each day, with wind speeds mostly topping out in the 10-15 knot range. Each afternoon and evening there could be some local enhancement along the land/sea interface with the diurnal sea breeze. Seas should average 2-4 feet through the period.

Rip Currents: Influences from the new moon cycle combined with persistent onshore flow will produce an elevated risk of rip currents. A moderate risk for rip currents is in place for all beaches through Tuesday.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Coastal Flood Advisory until midnight EDT tonight for SCZ149- 150. MARINE...None.