454 FXUS62 KCHS 122212 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 612 PM EDT Wed Sep 12 2018 ...DANGEROUS HURRICANE FLORENCE COULD IMPACT SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA... .SYNOPSIS... Hurricane Florence is expected to impact the Carolinas through the weekend. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... No major changes were made for the sunset update. Convection has been considerably less and weaker than this time yesterday. This is likely due to increasing subsidence aloft spreading west on the edge of Hurricane Florence. Any lingering afternoon convection should dissipate by sunset and expect mostly dry conditions to prevail through the night. Lows will range from the lower 70s well inland to the upper 70s/near 80 at the beaches. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... Large-scale subsidence on the outskirts of Hurricane Florence will likely yield calm conditions on Thursday with little to no precipitation. An increasing layer of cirrus associated with the storm's outflow will be spreading across southeast SC. Additionally, scattered to broken fair weather cumulus will develop after daybreak. We only show isolated showers and tstms over far eastern areas where a stray outer rain band could approach. Highs will reach the low 90s in southeast GA and upper 80s to near 90 in southern SC. Friday looks to be a continuation of Thursday's conditions across southeast GA but with deteriorating conditions over southern SC by afternoon as Florence drifts slowly southwest along the northeast SC coast. More of the outer rain bands will be spreading in from the east on Friday, while the outer wind fields begin to affect far eastern areas. The latest forecast for Florence takes the center into Myrtle Beach, SC late Friday night, then slowly west toward Lake Marion/Moultrie by late Saturday afternoon. Our latest wind forecast shows potentially 40-50 kt winds over portions of Berkeley and Charleston County late Saturday as the center of the storm passes nearby. We expect moderate to heavy rain to expand south and west into southern SC on Saturday. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Although considerable forecast uncertainty remains with Florence, confidence is increasing that we will be dealing with some heavy rainfall over parts of southern SC Saturday night into Sunday. We are now showing storm total QPF of 4-8" over southern SC, highest over Berkeley and Charleston County. The worst conditions are expected to impact the area Saturday night and Sunday, then conditions will slowly improve Sunday night into Monday. && .AVIATION /22Z WEDNESDAY THROUGH MONDAY/... VFR. Extended Aviation Outlook: Mainly VFR conditions through Thursday night. Flight restrictions increasingly likely at KCHS Friday afternoon through at least Sunday, mainly due to restricted visibility in heavy rainfall though occasional MVFR ceilings also possible. Gusty winds expected to impact KCHS Friday night through Sunday night. Sustained winds of 30-40 kt possible Saturday night and Sunday. && .MARINE... Tonight: Northeast winds winds will tip north overnight with winds remaining in the 10-15 kt range. Seas will steadily build through the night, reaching 5-9 ft nearshore and as high as 8-11 ft offshore. Small Craft Advisories remain in effect for all legs outside of the Hurricane Watch area. Thursday through Monday: Small Craft Advisories remain in effect for the coastal waters south of the Hurricane Watch area. We may eventually require tropical headlines farther south based on at least Tropical Storm force winds spreading in late Saturday or Saturday night. Conditions should gradually improve by Sunday night. Refer to the latest Coastal Waters Forecast for details on expected marine conditions. Rip Currents: Large breaking waves combined with building easterly swell will support a high risk for rip currents for all beaches. High Surf: Breaking wave data from both NWPS and WW4 output show breaking waves in the surf zone increasing to greater than 5 ft overnight as seas continue to build over the coastal waters. A High Surf Advisory for maximum breaking waves of 5-7 ft will be issued for all the Georgia coastal zones as well as Coastal Jasper and Beaufort Counties in South Carolina through Thursday afternoon. The advisory exclude Charleston and Coastal Colleton counties where Hurricane and Storm Surge Watches are in place. The combination of building surf and high astronomical tide cycles will produce significant erosion of the beaches through at least Thursday. && .TIDES/COASTAL FLOODING... Tides are expected to peak 7.0-7.2 ft MLLW in Charleston Harbor with the next high tide cycle. These levels will produce shallow coastal flooding across parts of the lower South Carolina coast. A Coastal Flood Advisory will be issued for Beaufort County to cover the midnight tide. Note: Charleston and Coastal Colleton Counties will not be included since they are currently under a Storm Surge Watch. Tides look to remain above 9.2 ft MLLW at Fort Pulaski so no flooding problems are expected along the Georgia coast nor coastal Jasper County, SC. Could actually see blow out tides ahead of Florence as strengthening offshore winds help push water out only the replaced with possible surge as Florence draws closer. && .EQUIPMENT... The Downtown Charleston/Waterfront Park (KCXM) sensor has stopped reporting. Technicians have been notified, but it is unknown when the flow of data will return. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...High Rip Current Risk through Thursday evening for GAZ117-119- 139-141. High Surf Advisory from 10 PM this evening to 2 PM EDT Thursday for GAZ117-119-139-141. SC...High Rip Current Risk through Thursday evening for SCZ048>051. High Surf Advisory from 10 PM this evening to 2 PM EDT Thursday for SCZ048-051. Hurricane Watch for SCZ045-050-052. Storm Surge Watch for SCZ049-050-052. Coastal Flood Advisory from 10 PM this evening to 2 AM EDT Thursday for SCZ048. MARINE...Small Craft Advisory until 10 PM EDT Thursday for AMZ352-354. Hurricane Watch for AMZ330-350. Small Craft Advisory until noon EDT Friday for AMZ374. && $$