textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated

KEY MESSAGES

- 1) Unsettled weather will return today and linger through Monday.

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

- 3) Coastal flooding is likely next week.

DISCUSSION

KEY MESSAGE 1: Unsettled weather will return today and linger through Monday.

A more unsettled pattern has begun to setup this afternoon as high pressure begins to east in response to our next upper trough. Broader southwesterly flow has begun to overspread the southeast resulting in steady moisture advection northward. This plume of moisture has been noted by increased showers and storms across eastern Georgia and starting to develop along a slowly advancing seabreeze across southeastern South Carolina. Storms should subside this evening. Rain is expected to return on Saturday as coverage increases across South Carolina. PWATS are expected to climb above 2.1 to 2.2 inches by Saturday morning. Storms will likely develop by mid-morning across the South Carolina low lands and slowly drift north with time. Given PWATS in the 98th percentile for this time of year; some locally heavy rainfall cannot be ruled out with the stronger storms. However, storms should move northward with some pace and without a true focus for heavier rainfall and storm development a more focused heavy rain threat does not seem likely on Saturday. Nonetheless, expect to be dodging showers and storms mainly across SC for most of the day Saturday.

By Sunday and into Sunday night, our real rainmaker shall arrive as a upper trough swings through the deep south and a surface low moves across Southern GA and off the Carolina coastline. A backdoor cold front is expected to stall somewhere across South Carolina on Sunday as the surface low moves through. PWATS will continue to be in the 2.25 inch range and could possibly climb to 2.3 inches by Sunday night. With increasing upper level ascent and presence of low level focus with the stalled boundary and attached surface low, rain chances will quickly increase throughout the afternoon and into the overnight hours. The afternoon should start off with scattered to numerous showers and thunderstorms likely confined to the afternoon sea breeze; however, as we go into the overnight hours storms should transition more into widespread moderate rain. Rainfall totals of 1 to 3 inches will be possible across much of the area Sunday into Sunday night with locally higher amounts depending on where the heaviest storms develop during the afternoon. Rainfall may be drug out over several hours which may limit flooding concerns; however, with near record PWATS it will not take much to get stronger rain rates that could result in localized flash flooding. This is noted within some of the 95th percentile rainfall totals approaching 5 to 7 inches for the Sunday through Monday timeframe. While these totals likely won't materialize over the majority of the area they do depict the upper end potential that could occur in localized swaths if storms train over the same area.

Rain will likely continue into Monday as the surface cold front is expected to take its sweet time pushing offshore. Scattered to possibly numerous showers and storms will likely remain a threat through the day on Monday for most of the coastal areas before drier air finally moves in by Monday night. PWATS will remain high and depending on how Sunday goes some localized flooding threat could persist into Monday as grounds become more saturated.

KEY MESSAGE 2: Cooler temperatures early next week along with northeasterly breezy winds.

As rainfall chances increase over the weekend, a cold front will slide through the region on Monday morning. Expect strong high pressure will build into the region behind it. This will yield afternoon temperatures in the mid to high 70s on Monday with northeasterly winds ramping up through the afternoon and evening. Additionally, a cold air damming (CAD) event will setup across the region in the middle of the week. This will support increasing cloud cover, stronger northeasterly winds, and cooler temperatures on Tuesday and Wednesday. Expect afternoon temperatures to only reach into the upper 60s to low 70s on Tuesday and Wednesday. Inland areas will likely see wind gusts up to 30 mph with areas along the coastline experiencing up to 40 mph. Therefore, a Lake Wind Advisory for Lake Moultrie may be warranted on Tuesday and again on Wednesday.

KEY MESSAGE 3: Coastal flooding is likely next week.

Breezy northeasterly winds (thanks to the strong cold air damming) combined with high astronomical tidal levels next week will likely result in coastal flooding issues next week. Minor to moderate flooding is likely with the possibility of reaching major levels. Coastal Flood Watches, Warnings and Advisories could be needed.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

18Z TAFs: VFR conditions prevail at most TAF sites this afternoon as scattered showers have developed across the area. Some brief restrictions will be possible with any passing showers likely leading to MVFR visibilities. The best chance for restrictions look to be near SAV and across eastern GA this afternoon. Showers should subside this evening leading to VFR conditions overnight and into tomorrow morning. Winds will remain light out of east-southeast this afternoon becoming light and variable overnight. Scattered showers and storms will once again be possible after roughly 15z across South Carolina mainly east of I-95.

Extended Aviation Outlook: Flight restrictions are possible with increasing showers and thunderstorms over the weekend into early next week. Breezy northeasterly winds are likely on Tuesday and Wednesday.

MARINE

Rest of Today through Sunday: Winds and seas will remain 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. Increasing showers and thunderstorms are expected over the weekend with Sunday featuring the highest rain chances.

Monday through Thursday: A cold front will cross the coastal waters Monday morning, accompanied by widespread showers and isolated thunderstorms. Northerly winds around 10-15 kts will strengthen and turn more northeasterly on Monday afternoon as strong high pressure builds in behind the cold front. Conditions will deteriorate rapidly Monday night, with northeast winds increasing to 20-30 kts and seas building 4-6 ft. Hazardous marine conditions are expected Tuesday and Wednesday as the pressure gradient strengthens. Northeast winds of 25-25 kts with frequent gale-force gusts of 35-45 kts are possible. Seas will likely build to 6-9 ft in the nearshore waters and 9-12 ft beyond 20 nautical miles. Showers will remain possible, especially across the Georgia waters on Tuesday. Strong northeast flow will likely persist into Thursday, although winds could begin to gradually ease. Elevated seas will be slower to subside and hazardous conditions could continue across much of the coastal waters. Small Craft Advisories, Gale Watches, and Gale Warnings will likely be needed. The prolonged northeast flow, combined with high astronomical tides, could also produce coastal flooding, high surf, and dangerous rip currents.

CHS WATCHES/WARNINGS/ADVISORIES

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