textproduct: Charleston

WHAT HAS CHANGED

Fog has diminished, removed mention from the discussion.

KEY MESSAGES

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

DISCUSSION

KEY MESSAGE 1: Rain chances likely to increase late in the week, though no hazardous weather is anticipated at this time.

The area will remain along the western flanks of Atlantic high pressure centered well offshore. Early morning water vapor imagery shows a well defined Tropical Upper Tropospheric Trough (TUTT) low positioned near 29N/75W at 20/06z. Broad subsidence aloft along the western flanks of the TUTT will continue to reside over the area through tonight with subtropical ridging progged to hold aloft across much of the Southeast States. The TUTT is forecast to slowly weaken and remain well offshore as the it propagates west/northwest along the backside of the Subtropical Anticyclone meandering near Bermuda. The net result will be a continuation of warm, rain-free conditions with some high clouds spreading in at times.

Low-level thicknesses are progged to max out about 10-30 meters higher than Tuesday as subsidence aloft builds. Highs are poised to warm into the lower-mid 90s inland with upper 70s/near 80 at the beaches. Temperatures across the coastal counties will remain what somewhat tempered as another robust, pure sea breeze circulation propagates steadily inland through the afternoon. Similar to the past few nights, it will take until the early morning hours Thursday before the boundary fully decouples and influences from the afternoon sea breeze wane. Lows will range from the mid 60s inland to the lower 70s at the beaches. Low- level moisture profiles and 1000 hPa condensation pressure deficits do not look as favorable for fog development compared to this morning, but some shallow ground fog appears likely, especially away from the immediate coast.

Upper level ridging lingers across the southeastern CONUS Thursday, as a sfc cold front stalls out along the Tennessee River Valley. As such, should see largely dry conditions prevail across our area, with highs forecast to rise into the lower 90s under mostly sunny skies.

Will see the aforementioned cold front sag southward over the Carolinas by Friday, causing the upper level ridge to shift over the Atlantic. While the exact position of the front and how far south it progresses will be the key factor in determining rainfall coverage and amounts, current trends continue to favor a strong Atlantic ridge. This would keep the front displaced just to our west and north, and thus limit our chances for seeing meaningful rainfall. Ensemble guidance continues to follow this trend as well, with probabilities for seeing rainfall greater than an inch through Saturday remaining less than 25%. So, while trends currently favor a drier, less impactful event, still encourage folks to monitor the latest forecast as subtle shifts in track may still occur. Otherwise, expect the severe potential with any shower/storm to remain low, given the lack of forcing and moisture in place.

AVIATION /14Z WEDNESDAY THROUGH SUNDAY/

20/12z TAF Discussion: KCHS/KJZI/KSAV: Fog will quickly mix out after daybreak with VFR conditions. Shallow ground of will be possible at all three terminals again early Thursday morning.

Extended Aviation Outlook: There are no high confidence concerns.

MARINE

Through Tonight: Quiet conditions will persist with the region positioned along the western flanks of Atlantic high pressure centered well offshore. East/southeast winds will prevail with speeds less than 15 kt, although some local enhancement along the land/sea interface and Charleston Harbor will likely occur with the sea breeze. Seas will average 2-4 ft.

Thursday through Sunday: 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 will average 2-4 feet through the period.

Rip Currents: A lingering 9 sec, 2-3 ft swell will keep a moderate rip current risk in place for all beaches through this evening.

CHS WATCHES/WARNINGS/ADVISORIES

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