textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Dense fog possible tonight across interior Southeast South Carolina and Southeast Georgia. - 2) The coastal flood risk will linger through Friday. Another round of coastal flooding is likely next week.

- 3) Unsettled weather will return Friday through Monday.

- 4) Cooler temperatures along with breezy to windy conditions are likely next week.

DISCUSSION

KEY MESSAGE 1: Dense fog possible tonight across interior Southeast South Carolina and Southeast Georgia.

Broad high pressure over the region tonight has resulted clear skies and calm winds, creating ideal conditions for fog development. As temperatures drop late tonight, fog is expected to form across most locations away from the immediate coast. Guidance continues to indicate the possibility of dense fog (visibilities below 1/4 mi) across far inland zones in GA and the Charleston Tri-County. A Dense Fog Advisory could be needed if these trends continue. Fog should dissipate within 1 to 2 hours after sunrise this morning.

KEY MESSAGE 2: The coastal flood risk will linger through Friday. Another round of coastal flooding is likely next week.

Astronomical tides continue to run higher than normal due to the recent full moon. Combined with the build up of tidal waters across inland waterways, and a possible slowing of the gulf stream, coastal flooding will pose a risk through Friday, especially at the Charleston Harbor. Tide levels at the Charleston Harbor are forecast to reach around 7.0 ft MLLW with the noon high tide today. Have opted to hold off on a Coastal Flood Advisory at this juncture as the departures appear to be trending downward and there is a chance the tide could peak around 6.9 ft MLLW (just below minor flooding). Coastal flooding is not a concern at Fort Pulaski.

Breezy to windy northeast winds induced by strong cold air damming, combined with already high astronomical high tides, will likely result in coastal flooding issues next week. Minor to moderate flooding is likely, with a possibility of reaching major levels. Coastal Flood Watches, Warnings and Advisories could be needed.

KEY MESSAGE 3: Unsettled weather will return Friday through Monday.

The pattern will get more active as we head into late week, and especially over the weekend. Upper ridge will lose influence as a larger scale trough shifts into the eastern U.S. Moisture levels will surge with PWats climbing to around 2.25 inches, which is well above climo for this time of year (near 98th percentile). Showers and thunderstorms are likely each day, with the greatest coverage expected Sunday into Monday with better forcing aloft and the cold front pushing through. Pockets of heavier rainfall will be possible. LREF indicates the chance for rainfall greater than 1" is roughly 65- 75% through Monday evening, with a 25-35% chance for greater than 2". Timing still needs to be refined, but drier air should start to move in Monday afternoon following fropa.

KEY MESSAGE 4: Cooler temperatures along with breezy to windy conditions are likely next week.

Guidance is consistent indicating strong high pressure will wedge south into the Carolinas and Georgia Tuesday into the middle of next week. This will bring notably cooler temperatures and gusty winds to the area. Winds could become supportive of a Lake Wind Advisory for Lake Moultrie, and we will also need to monitor the potential for gusts near 40 mph along the immediate coast/beaches. Otherwise, rain chances will linger, though its unclear how much coverage there will be. Some model solutions hint at a wave of low pressure developing nearby, while others keep any wave and deeper moisture to the south.

AVIATION /06Z THURSDAY THROUGH MONDAY/

06Z TAFs: Mostly clear and light to calm winds are present over the terminals tonight. MIFG has developed at KCHS as of 06Z and is forecast to expand into KJZI and KSAV into the early morning hours. Guidance continues to indicate the risk of dense fog will likely remain inland of the terminals through sunrise. The 06Z TAFs feature MIFG with a TEMPO group to show visibilities getting down to 3SM. A weak sea breeze is expected to shift winds from the southeast beginning in the early afternoon hours. Fog is possible again tonight into Friday morning.

Extended Aviation Outlook: Flight restrictions are possible in early morning fog/stratus late this week and also in showers and thunderstorms over the weekend into early next week. Gusty winds are likely on Tuesday.

MARINE

Through Sunday: Winds and seas will remain well below Small Craft Advisory thresholds across all marine zones. Winds will surge a bit each afternoon and evening, but speeds should mostly top out in the 10-15 knot range and will be strongest along the land/sea interface.

Monday and Tuesday: High pressure will wedge south into the Carolinas and Georgia following the passage of a cold front. Marine conditions are expected to deteriorate, with Small Craft Advisories likely as early as Monday evening. The worst conditions look to occur on Tuesday when guidance indicates a high probability for winds to reach gale-force (NBM showing 60-80% chances for gusts greater than 34 kt, highest in the waters beyond 20 nm). We will also need to be on the lookout for hazardous beach conditions, including dangerous rip currents and high surf.

CHS WATCHES/WARNINGS/ADVISORIES

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