278 FXUS62 KCHS 050902 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 402 AM EST Tue Nov 5 2019 .SYNOPSIS... High pressure will prevail far inland today, while a coastal trough lingers offshore. A cold front will then pass through tonight. High pressure will return Wednesday, before a stronger cold front crosses the area late week. High pressure will build in over the weekend and prevail into early next week. && .NEAR TERM /THROUGH TONIGHT/... Early this morning: We're off to a much warmer start than we were Monday morning, with temps on average about 15-20F higher than 24 hours ago. A mid level short wave and a sharpening trough just off the coast will generate isolated to scattered showers between now and daybreak. Any t-storms look to stay over the ocean. Today: A broad cyclonic flow aloft will encompass much of the eastern half of the country, including the local forecast zones, keeping the sub-tropical ridge suppressed to the south across FL. A strengthening short wave within the west-southwest flow aloft will quickly pass through the region this morning, allowing for a coastal trough to sharpen not far off the local coast this morning. Both the surface trough and mid level short wave will pull away this afternoon, followed by an upstream cold front that arrives by late afternoon. There is plenty of low level moisture in place with PWat far above early November normals across our eastern sections, and it is here where we have our highest PoP in the 30-50% range. Total QPF will average 1/10 to 1/3 inch near and east of I-95, with less amounts further inland. There is adequate instability with MUCAPE as great as 1000-1500 J/kg, plus 40-50 kt of bulk shear, which suggests at least some chance for t-storms, mainly during the late morning and afternoon. However, the updraft strength is relatively weak, so the main weather hazard looks to be lightning rather than wind. Despite plenty of cloudiness throughout the day, there is sufficient warm advection in advance of the cold front to boost max temps into the mid and upper 70s away from the "cooler" immediate coast. Tonight: There is still a 20/30% chance of showers this evening until the cold front moves into the Atlantic by midnight, and it'll remain rather warm out ahead of the front. But with the passage of the front will come drier air, especially in the mid and upper layers of the atmosphere, as strong high pressure builds out of the upper Midwest. Strengthening cool advection will ensure during the overnight hours, allowing for min temps to bottom out in the middle-upper 50s most places as cloud cover diminishes from the northwest to southeast through the night. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... High pressure will build into the area on Wednesday. The center of the high will shift over the Mid-Atlantic states through the day and then off the coast overnight. It will be a dry, seasonable day with some clouds around, especially along the coast. On Thursday, high pressure will weaken considerably as a strong cold front moves into the Southeast. Weak low level convergence could spur a couple showers over the waters that drift toward near the coast, but overall rain chances are pretty low. The cold front is expected to pass through the local area late Thursday into early Friday. Large scale forcing in the form of shortwave energy and upper divergence will support rain with frontal passage. Given the better agreement between models in coverage, PoPs have been increased to 60-70%. Most locations should be able to pick up a quarter of an inch of rainfall. Cool high pressure will build in wake of the front on Friday. Some rain chances will linger near the coast and over the waters in the morning, but the precip should be quick to exit. It will be the start of an unseasonably cool stretch, with highs expected to top out in the 60s. Lake Winds: Favorable mixing profiles behind the cold front on Friday will result in gusty north/northeast winds over Lake Moultrie. A Lake Wind Advisory could be needed. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... A cool and dry fall weekend on tap. Models are in good agreement that high pressure will dominate the surface weather pattern over the weekend into early next week. Aloft, large scale troughing will persist. Plenty of sun is expected with minimal rain chances. Late in the period and beyond (Monday night into Tuesday), another strong cold front is progged to cross the area. Temperatures will generally be below normal, although will be moderating through the period. The coolest nights of the season thus far are expected Friday and Saturday night. We will need to watch for frost/freeze concerns. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... 06Z TAFs: A coastal trough will remain just offshore through Tuesday afternoon, before pulling away Tuesday night. This will produce periods of SHRA/-SHRA and MVFR ceilings into this afternoon. There could even be a TSRA at one or both terminals late this morning and afternoon, but not enough probabilities just yet to include mention in the latest TAFs. Lower rain chances will occur late today and tonight as a cold front moves through and VFR should return as a result. Extended Aviation Outlook: Flight restrictions are possible Thursday in low clouds. Additional restrictions possible Thursday night into Friday due to showers with a passing cold front. && .MARINE... Today: An inverted trough will remain anchored over the nearshore waters this morning, before pulling away further offshore during the afternoon. Dependent upon where the exact axis of this feature aligns itself will determine the exact trichina of winds, but on average they look to be NE or E at no more than 10 or 15 kt. Seas will remain mainly around 2 or 3 ft within 20 nm and 4 or perhaps 5 ft further out. Mariners can expect scattered to numerous showers and a few t-storms into early afternoon, with coverage diminishing later in the day. Some of this activity will result in gusty winds, frequent lightning and reduced visibilities in heavy rains. A few Marine Weather Statements and/or Special Marine Warnings could be required. Tonight: Strong continental high pressure will build out of the upper Midwest and Ohio Valley in wake of a cold front that moves through around 03-06Z. Cool advection and steady isallobaric pressure rises behind the front will allow for winds to increase overnight, leading to the issuance of a Small Craft Advisory on both the AMZ350 and AMZ370 waters starting at 4 am. Wednesday through Sunday: Strong pressure rises on Wednesday will result in elevated winds and seas through much of the day. A Small Craft Advisory will be in effect for the Charleston county waters and outer Georgia waters, however it may need to be expanded to include the remaining nearshore waters. It appeared too marginal to hoist an advisory for those zones at this time. Improvement will occur on Thursday, however it will be short-lived as a strong cold front passes through Thursday night, and marine conditions rapidly deteriorate in its wake. Small Craft Advisories will likely be needed for all waters, including the Charleston Harbor, Friday into Saturday. There is a small chance for gale-force gusts, mainly beyond 20 nm, but at this time it appears to stay below that threshold. Trends will continue to be monitored. Winds and seas will subside Saturday night into Sunday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory from 4 AM Wednesday to 4 AM EST Thursday for AMZ374. Small Craft Advisory from 4 AM Wednesday to midnight EST Wednesday night for AMZ350. && $$ NEAR TERM... SHORT TERM... LONG TERM...ETM AVIATION... MARINE...