668 FXUS62 KCHS 291714 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 114 PM EDT Sat Jun 29 2019 .SYNOPSIS... A trough of low pressure will dissipate over the area today. A weak front will shift into the area late Sunday into Monday before high pressure prevails through late week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... No major changes were made with the latest update. Expect a coastal trough over the area to dissipate with Atlantic high pressure edging in from the east and an inland trough remaining to the northwest in the lee of the Appalachians. Isolated to scattered showers and thunderstorms near the coast this morning will slowly transition inland as the sea breeze strengthens. Moderate instability and week deep layer shear suggest mainly pulse-type convection with a low severe storm risk as convection will be driven by mesoscale interactions. High temps should be in the lower 90s inland with mid- upper near the coast. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... Tonight: Any lingering convection will quickly dissipate after sunset as convergence shifts back over the Atlantic. Isolated convection is expected to redevelop over the coastal waters by late evening, but any such activity should remain offshore through daybreak Sunday as the low-level flow becomes parallel if not slightly offshore the coast. Lows will range from the upper 60s/lower 70s well inland to the mid-upper 70s at the coast with near 80 at the beaches. Sunday through Tuesday: Atlantic high pressure will retreat further offshore early next week as a large mid/upper lvl trough of low pressure shifts over the Northeast United States. The trough will help drive a weak front into the region from the north late Sunday into early Monday. Although forcing is not particularly strong with the arriving front, PWATs should increase up to 1.75-2.00 inches ahead of it, supporting a few showers and/or thunderstorms during peak diurnal heating Sunday afternoon/evening. Greatest chances of precip appear to be over Southeast Georgia. By daybreak Monday, the bulk of moisture will shift south of the region with the front, leading to dry conditions over the entire area. A ridge of high pressure will then begin to build over the Southeast on Tuesday, resulting in dry and noticeably warmer conditions. High temps should range in the lower 90s on Sunday with overnight lows in the low/mid 70s. Despite weak fropa by daybreak Monday, warm high pressure following the front should support temps in the mid 90s Monday afternoon. Monday night lows should range in the low/mid 70s. Temps will be even warmer on Tuesday as high pressure continues to build across the region. Latest 1000-850mb thickness levels support temps in the mid/upper 90s, warmest along and west of the I- 95 corridor. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... At the sfc, lee troughing will gradually develop inland and become more pronounced through late week while a large mid/upper lvl ridge of high pressure becomes centered over the Southeast United States. The setup will favor warm conditions across the area as light southerly flow at the sfc occurs below a light west/northwest flow aloft. Although high pressure will dominate aloft, substantial heating could produce a few afternoon showers or thunderstorms mid week, especially across inland areas closer to the lee trough. Latest 1000-850mb thickness levels suggest temps approaching the mid/upper 90s Wednesday and Thursday afternoon, before some mid-lvl energy breaks down the ridge and potentially brings greater chances of showers and thunderstorms during the weekend. These temps in combination with sfc dewpts in the lower 70s could produce heat index values up to 105-107 degrees mid week, falling just short of Heat Advisory criteria in July. However, high temps should still approach the mid 90s away from the coast this weekend. Overnight lows will be mild, generally ranging in the mid 70s inland to upper 70s near the coast. && .AVIATION /17Z SATURDAY THROUGH WEDNESDAY/... Mostly VFR at KCHS/KSAV through 18Z Sunday except for some likely shower/tstm impacts, mainly through mid afternoon until the sea breeze strengthens and shifts inland. Extended Aviation Outlook: VFR conditions should prevail at both CHS and SAV terminals. However, brief flight restrictions are possible during an isolated shower or thunderstorms each afternoon/evening. && .MARINE... Through Tonight: A chaotic wind field this morning will become more solidly onshore this afternoon as a weak surface trough dissipates. Winds will max out around 10-15 kt with seas 1-2 ft. Winds will veer more to the southwest overnight with similar wind speeds/sea heights. Sunday through Wednesday: Atlantic high pressure will gradually retreat offshore Sunday, allowing a weak front to shift into the area late Sunday into early Monday. High pressure will then dominate the pattern over coastal waters while a lee trough develops inland and persists through the middle of the week. Given the setup, winds and seas are expected to remain below Small Craft Advisory levels during the period. However, southerly winds should increase up to 15- 20 kt late Sunday into early Monday, then become more northerly following fropa before gradually weakening and quickly returning to southerly winds Tuesday and Wednesday. Seas should build up to 2-4 ft, highest in northern South Carolina waters late Sunday into early Monday, then gradually subside to 1-3 ft Tuesday and Wednesday. && .TIDES/COASTAL FLOODING... There will be a risk for at least shallow coastal flooding across the coastal counties Monday through the middle of next week due to the approaching perigee, new moon and onshore winds. The greatest potential for shallow coastal flooding will occur during the evening/early night high tide. Coastal Flood Advisories could be needed. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...RJB SHORT TERM... LONG TERM... AVIATION...RJB MARINE...RJB TIDES/COASTAL FLOODING...