205 FXUS62 KCHS 092114 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 514 PM EDT Tue Oct 9 2018 ...TROPICAL STORM WARNINGS ISSUED FOR SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA INCLUDING THE ADJACENT COASTAL WATERS... .SYNOPSIS... Hurricane Michael will move north across the Gulf of Mexico before making landfall along the Florida Panhandle Wednesday. Michael will then weaken to a tropical storm as it moves northeast across Georgia and South Carolina Wednesday night into Thursday. Cooler high pressure will then build in through early next week. Refer to the latest advisory on Hurricane Michael issued by the National Hurricane Center. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... GOES-E visible imagery shows a ribbon of tropical moisture arcing from Southeast Georgia to offshore of the eastern Bahamas into the central Caribbean Sea. RAP and satellite derived data suggest PWATS of 2.25-2.50 inches are embedded in this tropical connection and is helping to support several large bands of heavy rainfall from southern Georgia and offshore of the Florida east coast. The band will slowly propagate north through the night as Hurricane Michael moves north across the eastern Gulf of Mexico and several mid-level perturbations embedded in the southeast-northwest oriented flow between subtropical high pressure moving farther offshore of the North Carolina Outer Banks of Hurricane Michael cross the area. Southeasterly low-level jetting as high as 35-40 kt will remain in lace through much of the night so any shower activity will have the potential of producing localized wind gusts of 40-50 mph. Otherwise, breezy conditions will continue at the beaches. Overnight pops will range from 70-100% along with a "rain heavy at times" qualifier. The risk for any freshwater flooding will be highest across the coastal counties, especially during the evening high tide. Widespread flash flooding is not expected through sunrise, thus a Flash Flood Watch will not be issued for this time period. It will be a warm and humid night for early October with lows ranging from the mid 70s inland to around 80 at the beaches. The record high minimum temperatures at all three climate sites could be challenged. See the climate section below for additional information on the records. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... On Wednesday the main feature will be the weak inverted trough off to the northeast of Hurricane Michael. The center of this trough will be along the SC/GA coastline at daybreak Wednesday, then move north-northeast through early afternoon. We expect numerous heavy showers with isolated tstms across the area during the morning with the greatest coverage and intensity over southern SC closer to the trough. Unseasonably high PWATs in excess of 2.1" will support torrential rainfall at times. During the afternoon the best convergence associated with the trough are is forecast to move north of the area though we then expect some outer rain bands from Michael to start rotating through the area. A bit of a lull is possible Wednesday evening, then the rain shield associated with Michael is expected to move into interior southeast GA with some outer bands farther to the north and east. The brunt of the torrential rainfall associated with Michael's circulation will move through on Thursday with the greatest effects over our inland zones. Latest storm total QPF shows 2-4 inches across coastal sections and 3-5" inland. The strongest winds will begin in southeast GA late Wed night and affect most of southern SC during the day Thursday. An enhanced tornado threat appears likely from Wednesday afternoon through at least Thursday morning based on model progs for low-level helicity and surface-based instability. Slightly cooler and drier weather expected late Thursday night into Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Late this week, surface high pressure will build back into the region behind departing TC Michael. Precipitation potential is looking rather low Friday and Saturday as a dry column sits overhead, then rain chances will increase with increasing moisture levels ahead of an approaching cold front Sunday into the first part of next week. Temperatures look to remain above normal. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... Conditions will deteriorate across the terminals next 24 hours as Hurricane Michael moves across the eastern Gulf of Mexico. Outer bands will move through the KSAV terminal later this afternoon and across KCHS tonight. These bands will bring reductions to vsbys, possibly as low as IFR at times. Timing of these conditions is proving a bit tricky, but generally followed a blend of the latest high resolution guidance to pin down impact times. First, expect steadier rains to move into KSAV by 22z and KCHS by 03-04z. This band will linger for about 2-4 hours before moving north of each site. Showers will linger after these times, but timing is too uncertain to include prevailing or TEMPO groups. Amendments will be issued as needed. Gusty winds will also linger through the entire period, possibly as high as 30 kt at times. Extended Aviation Outlook: MVFR or lower conditions likely at both terminals Wednesday afternoon through Thursday night as Hurricane Michael moves west of the area. The greatest chance for IFR ceilings and/or vsbys will be late Wednesday night through Thursday afternoon due to moderate to heavy rain. && .MARINE... Tonight: Nasty marine conditions will continue across all waters tonight with winds 20-25 kt with gusts to 30 kt. Shower activity will be capable of producing localized wind gusts to 40-45 kt. Seas will build through the night, reaching 5-8 ft nearshore waters and 9-11 ft offshore waters. Wednesday through Saturday: The impacts of Hurricane Michael are obviously the main concern with this package. Marine conditions will become increasingly treacherous during the day Wednesday with the strongest winds and largest seas Wednesday night into Thursday. Improving conditions Thursday night into the weekend as high pressure builds in. Rip Currents: A high risk for rip currents continues into Wednesday due to persistent, strong onshore wind, some swell and astronomical influences. The rip current risk will remain elevated through the week. && .TIDES/COASTAL FLOODING... Coastal Flooding: The decision was made locally to issue a long-duration Coastal Flood Advisory for all coastal zones, excluding Tidal Berkeley, to cover all high tides through the duration of Michael. Minor to locally moderate coastal flooding is expected through the period. At this time, levels are not expected to reach Coastal Flood Warning criteria for either Fort Pulaski or Charleston Harbor with average inundations above ground level expected to stay 2 feet or less. This will be watched carefully and warnings will be issued if needed. High Surf: Expect breakers of 5 to 8 feet to impact the surf zone before winds turn offshore in the wake of Michael. A High Surf Advisory has been posted for all beaches. && .CLIMATE... Record high minimums for 9 October: KCXM: 77/2017. Record high minimums for 10 October: KCHS: 75/2017. KCXM: 78/2017 and previous. KSAV: 75/2017. Rainfall record for 10 October: KCHS: 1.82/1990. KCXM: 2.13/1990. KSAV: 5.68/1990. Rainfall record for 11 October: KCHS: 4.48/1990. KCXM: 5.46/1990. KSAV: 4.43/1885. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...Tropical Storm Warning for GAZ087-088-099>101-114>119-137>141. High Rip Current Risk through Wednesday evening for GAZ117-119- 139-141. High Surf Advisory until 8 PM EDT Thursday for GAZ117-119-139- 141. Coastal Flood Advisory until 2 PM EDT Thursday for GAZ117-119- 139-141. SC...Tropical Storm Warning for SCZ040-042>045-047>052. High Rip Current Risk through Wednesday evening for SCZ048>051. High Surf Advisory until 8 PM EDT Thursday for SCZ048>051. Coastal Flood Advisory until 2 PM EDT Thursday for SCZ048>051. MARINE...Tropical Storm Warning for AMZ330-350-352-354-374. && $$ ST/JRL