328 FXUS62 KCHS 061733 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1233 PM EST Sun Nov 6 2022 .SYNOPSIS... High pressure will prevail into the early part of the week. Low pressure that develops in the Atlantic could impact the area during the middle and latter portion of this week. && .NEAR TERM /THROUGH TONIGHT/... Moist onshore flow will continue today with unseasonably muggy dewpoints for early November. Pockets of sunshine will allow for strong insolation and boundary layer heating. We already see some low 80s in spots. 500-1000 Joules of CAPE are anticipated across southeast GA and far western SC where numerous showers and isolated thunderstorms are expected to develop. Elsewhere, slightly drier air will minimize rain chances. Overnight: The onshore flow will come to a quick end tonight as the low-level wind pattern backs to the northeast in response to strengthening low pressure over the southwest Atlantic. As skies clear and the boundary layer decouples away from the coast, expect modest radiational conditions to occur, especially well inland. Lows were skewed towards the coldest of the 06/00z guidance with some local mesoscale adjustments made to account for water, the Santee-Copper lakes and typical cold spots. Lows will range from the upper 50s/near 60 inland to the upper 60s at the beaches and in Downtown Charleston. Conditions will be favorable for at least patchy fog across the interior. Some of the fog could become locally dense, especially in the Metter- Hampton corridor and points north where the lowest 1000 hPa condensation pressure deficits are progged. Thankfully, 10-15 kt of 1000 hPa geostrophic wind should keep the fog from becoming too widespread. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... Monday: Strong, dry Canadian surface high pressure will build from the northwest on Monday. Meanwhile surface low pressure over/near the Bahamas will organize as it makes it crawl westward. A H5 591 dm ridge will dominate the region and subsidence aloft will maintain a stable atmosphere even with the presence of lingering llvl moisture. Thus, the current forecast features partly sunny skies with abnormally warm temperatures. Highs will reach the low 80s across locations away from the coast and min temps in the low to mid 60s. Tuesday: As deep high pressure shifts eastward toward New England, a wedge pattern will set up along the eastern slopes of the Appalachians. This will strengthen the pressure gradient across the forecast area, as the area of low pressure broadens over the northern Caribbean. Northeast winds will increase during the day with gusts up to 25 mph mainly along the coastal areas. With the advection of a much drier air mass, dew points will plummet throughout the day, around 20 degrees in most locations. The day will remain rain-free thanks to the presence of a strong subsidence cap and incoming dry air. Northeast flow will bring cooler, yet still mild temperatures across the southeast SC counties with highs in the low/mid 70s and mid/upper 70s in the southeast GA counties. Lows will be drastically cooler dipping into the upper 40s inland and lower 50s near the coast. Wednesday: Deep anti-cyclonic flow over the Mid-Atlantic will continue to steer the low pressure system near the Bahamas westward toward the southern Florida Peninsula. As the system nears the region, the pressure gradient will continue to tighten with a surface pressure gradient spanning ~7 mb across the forecast area. Gusty conditions are possible just about everywhere with gusts up to 25 mph inland and 30-35 mph along the coast. Elevated gusts across Lake Moultrie could warrant a Lake Wind Advisory. Deep moisture associated with the low will begin to encapsulate the southern Atlantic. There could be some showers that develop offshore, but a strong ridge and mid-level capping inversion will maintain a mostly rain-free forecast over land. Temperatures will be closer to seasonable values with highs in the upper 60s/near 70F. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The main focus in the long term period remains on the development of a low pressure system in the Atlantic. Much of its track largely depends on the strength and eventual demise of the ridge across the Southeast U.S. A faster eroding ridge will cease the westward movement of the system where it has the potential to then take on a more northeastward track as a trough phases with its upper counterpart. This scenario will likely result in a slightly quicker departure of the low; moving out of the area by early weekend. On the other hand, a more substantial ridge could allow the system to reach the Gulf of Mexico before becoming absorbed by the trough and phasing with a surface cold front, shifting it eastward back into the Atlantic as the front sweeps the area. Regardless, potential impacts are heavy rainfall and gusty conditions across the region through the end of the week. Expect more details on this system in the coming days, as current guidance continues to show vast disagreements and run-to-run inconsistencies. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Numerous showers will impact KSAV early this afternoon, along with possible MVFR ceilings. Conditions should improve by 20 or 21Z. For the remainder of the terminals and 18Z TAF period, VFR anticipated. Some shallow ground fog possible late tonight but the best chance for more widespread and/or dense fog will be far inland. Extended Aviation Outlook: Gusty NE winds possible at the terminals Tuesday through Thursday. && .MARINE... Nearshore seas have subsided below 6 ft based on data from the Charleston wave buoy and Grays Reef buoy, so will allow the Small Craft Advisory for the SC nearshore waters to expire at 1pm. For the Georgia offshore leg, seas 6-7 ft will persist through the afternoon and the advisory remains in force there. It still looks like seas will top out at 5 ft over the Savannah to Altamaha Sound nearshore leg so there are still no plans to issue a Small Craft Advisory for that location. Otherwise, southeast winds will back to the east today with speeds 10-15 kt diminishing to 10 kt later in the afternoon. Tonight: Winds will back to the northeast overnight as low pressure develops east of the Bahamas. Winds will average 10-15 kt with seas 3-5 ft nearshore waters and 5-6 ft offshore waters, still above advisory levels for the Georgia offshore leg. Monday through Friday: A significant marine hazard event is expected through much of the week, with conditions deteriorating late Monday. A low pressure system moving westward across the northern Caribbean will interact with strengthening high pressure to the north, producing a strong northeast gradient over the local waters. Gale conditions will be possible Tuesday through Wednesday night for a majority of the marine zones. Elevated northeast winds are expected to continue throughout the remainder of the period. Seas are expected to build substantially with peak values ranging 5-11 ft across the nearshore waters and 12-16 ft in the outer GA waters from 20-60 nm Tuesday night through Thursday, perhaps even into Friday. High Surf: Low pressure that is expected to form to the south will interact with strong high pressure to the north this week. Gusty northeast winds and increasing swell could lead to breaking waves 5 feet or higher along the beaches as early as Tuesday through late week. As a result, High Surf Advisory could be required. In addition, beach erosion will be possible. && .TIDES/COASTAL FLOODING... Astronomical tide levels are rising as the full moon on November 8th approaches. Additionally, persistent moderate to strong northeast winds will cause tidal anamolies to increase. Through Monday, the morning high tides look to be close enough where there might be minor coastal flooding each day. Starting Tuesday an even stronger northeast flow could produce more substantial anomalies that may result in moderate to perhaps major coastal flooding at the Charleston Harbor tide gauge. The Georgia and far southern South Carolina coast could come into play starting Tuesday when the more significant tide levels begin, continuing through Wednesday or Thursday. A series of Coastal Flood Advisories and possibly Coastal Flood Watches/Warnings may eventually be needed. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 1 PM EST this afternoon for AMZ350- 352. Small Craft Advisory until 5 AM EST Friday for AMZ374. && $$ NEAR TERM...JRL SHORT TERM... LONG TERM... AVIATION...JRL MARINE... TIDES/COASTAL FLOODING...