Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 230210 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1010 PM EDT Sat Sep 22 2018 .SYNOPSIS... High pressure will prevail through early next week. An upper trough approaching from the west, will gradually push a cold front this way, reaching our coast Friday. Drier and slightly cooler high pressure is expected build in next weekend. && .NEAR TERM /THROUGH SUNDAY/... As of 1000 PM Saturday...The 00z sounding from MHX indicated a subsidence inversion between 6000-14000 feet AGL. Clouds have recently developed beneath the base of this inversion across the Cape Fear area, advecting slowly westward. I`ve adjusted sky cover forecasts overnight to increase cloudiness a bit early on, but still anticipated mostly clear skies overall. Showers developing farther offshore may approach the coast late tonight but should remain mainly a maritime nuisance. Discussion from 300 PM follows... The flat nature of the cumulus this afternoon are indicative of the convection-suppressing mid level ridge overhead. Even without this feature the area would likely stay rain- free with such low available moisture especially aloft. Forecast soundings show a fog signal once again tonight though not as strong as last night so will relegate to patchy and leave out dense.The main impact will likely only be to aviation save for perhaps in the LBT vicinity. The mid level ridge moves off the coast on Sunday but will still keep enough dry air in the mid levels to preclude meaningful rain chances. A moistening of the low levels in easterly flow makes non- measurable tropical showers seemingly more likely than measurable rainfall. Similarly with the capping inversion precluding deep convection will leave out thunder. A cold front drops into just north of the area by evening, too moisture starved to represent much more than a wind shift. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 320 PM Saturday...High pressure pushes in from the NE on Sunday night behind moisture-starved frontal boundary. Models are spitting out some light rainfall across parts of the area but with a continued light SW flow borne of the western periphery of the offshore mid level ridge this may be asking a lot of the continued dry air in forecast soundings. Despite the continued NE flow temperatures and dewpoints don`t really change heading into Monday night. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 320 PM Saturday...Bermuda to Bahama upper ridge will be holding on Tuesday and Wednesday before shifting east, as an upstream and broad upper trough, and associated its axis, edge eastward across the Mississippi Valley. It appears the trough is of sufficient latitudinal amplification to bring a moderate degree of 925-700mb Gulf moisture pluming NE ahead of a slowly approaching cold front. As such, rain chances ramp up a bit Thursday and Friday. The cold front to cross the coast Friday night. The front may be slowly clearing the SC coast into Saturday, and overall, drier and slightly cooler air should filter in Saturday. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 00Z...High pressure will stay in control through the forecast period. A stationary frontal boundary will remain north and west of the region. Dry air just above the stable boundary layer overnight should help with dispersion of moisture which will make fog development difficult. Will likely have some minor restrictions to show the possibility where more surface moisture is present. VFR again on Sunday with clear skies and some afternoon Cu possible. Extended Outlook...Mostly VFR through this period. However, flight restrictions are possible in late night/early morning fog/stratus each day. And brief flight restrictions are possible within showers/thunderstorms Sunday through Tuesday, especially during the afternoon/evening hours. && .MARINE... NEAR TERM /THROUGH SUNDAY/... As of 1000 PM Saturday...Light southeasterly winds will turn more northerly nearshore late tonight with a landbreeze. With such light wind speeds there should be no impact to mariners. Seas are only 1-2 feet almost exclusively in 11 second easterly swell. Changes with this forecast update were all minor. Discussion from 300 PM follows... Conditions remain minimal with such a light gradient in place only a minor SE swell. As pressures rise over the NE U.S. the SE winds locally could turn more easterly on Sunday. Little change in seas expected. SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 320 PM Saturday...Cold front sags through from the south SUnday night turning winds to NE and increasing speed by about a category in addition to adding a little gustiness. Seas should open up to 3-4 on Monday and possibly a few 5 footers Monday night offshore, but only across NC waters. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 320 PM Saturday...Weak tropical low pressure, or possibly just a surface trough will approach the Carolina coasts late Tuesday night, dissipating as it lifts to the north across the NC Outer Banks Wednesday. Well established SW wind flow will follow in wake of this feature Thursday. As the low nears Tuesday, we may see gusty NE winds and elevated seas, so an SCA or SCEC possible at this time Tuesday. TUesday onward, isolated TSTMs can be expected to impact the 0-20nm waters. && .TIDES/COASTAL FLOODING... As of 320 PM Saturday...Still anticipate warning level (6.7+ft MLLW) during high tides for the next few days, likely through the full moon on 24th/25th as the astronomical tides add to the flood wave coming down the river. The current ETSS has consistently been overdone and it`s forecast of 8.2 ft shall be no exception. Have tempered these values with guidance from our Service Hydrologist and currently forecasting 7.3 ft this evening. Values slightly exceeding 8 ft certainly possible as the moon waxes to the full Harvest Moon. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...Coastal Flood Warning until midnight EDT tonight for NCZ107. MARINE...None. && $$ SYNOPSIS...MJC NEAR TERM...TRA/MBB SHORT TERM...MBB LONG TERM...MJC AVIATION...MBB MARINE... TIDES/COASTAL FLOODING...

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