Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 171114 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 714 AM EDT Thu Aug 17 2017 .SYNOPSIS... High heat and humidity will continue across the area through Friday. Showers and thunderstorms will be on the increase during the weekend ahead of a cold front. This front will get hung up in close proximity early next week and then dissipate, keeping at least scattered showers and thunderstorms in the forecast. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM Thursday...The northwest flow aloft will continue today with little in the way of boundaries or forcing initially at the surface. There is some mid level divergence moving across the area later this morning and afternoon which has been picked up by the models. This should trigger a mid to late morning start to convection which should continue through the afternoon. With weak shear do not anticipate any significant severe threat but with PW`s near 2.20 inches some localized flooding is possible. Convection should diminish with the loss of daytime heating tonight. Temperature guidance has cooled slightly with the 00 UTC cycle however still warm enough to hoist a heat advisory for most areas. As was the case Wednesday, the 105 criteria may be just for an hour or two and if the convection develops as expected, a plethora of outflow boundaries may actually keep numbers below 105. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 300 AM Thursday...Still looks like a hot and humid day Fri with a likelihood for another Heat Advisory. 850 mb temps will be 20-21 deg C. This should result in highs in the mid 90s with lower 90s at the coast. The dewpoints will again be high, mainly mid and upper 70s with a few 80 degree dewpoints for portions of the coast. This will again bring the heat index above 105 and as high as 106 to 108 degrees. High temps should back off a category or so on Sat with more in the way of clouds associated with showers and thunderstorms. Dewpoints will still be high and so heat index values should still climb above 100, but few places should reach 105 degrees. Overnight lows will be mainly in the mid and upper 70s, although if a large thunderstorm outflow develops, lows may drop into the lower 70s for portions of the area Sat night. A deep trough will carve out across the eastern third of the nation during this period. This will help drive a cold front SE. The trough should begin to lift out during Sat. The seabreeze and Piedmont Trough on Fri should allow for isolated to scattered showers and thunderstorms during the heating of the day. Fri night, a strong mid-level shortwave trough will be moving across central NC and the upstate of South Carlina. This feature will lift to the NE overnight. Expect showers and thunderstorms to our NW should at least skirt portions of our Forecast Area during the night. Sat morning, the cold front should be on our door step. However, it does not look like the front will be able to push through as the main driving mechanism aloft will be departing. Another impulse will be moving across Virginia and northern portions of North Carolina Sat night. This should help to keep the front in close proximity, but mainly to our N. We expect the risk for showers and thunderstorms will be significantly higher Sat as compared to Fri. However, it is too early to say it will be a washout. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 300 PM Wednesday...A cold front will show little movement into Sunday, but height rises aloft will be underway. Overall expect a downward trend in storm coverage and a warmer afternoon. Attention to Monday`s forecast continues to increase each day due to the solar eclipse. Unfortunately there isn`t much different in the way of thinking and even less fortunate the news isn`t great. True the front will be weakening but convective signals in the models are still suggesting ample moisture for considerable coverage of thunderstorms that afternoon. The silver lining could be the rising heights aloft, possibly capping thunderstorm formation until after the eclipse or at least its peak. Even so all it takes is one vigorous towering cumulus to ruin the view over a given location. By Tuesday the front no longer appears in the models but a well defined piedmont trough develops. Thunderstorms forming within this boundary and moving east paired with seabreeze activity calls for scattered POPs just about area-wide. By Wednesday some mid level troughiness starts breaking into the area in association with a large trough forming north of the Great Lakes. A continued moist boundary layer paired with energetic NW flow likely means a continuation of the unsettled weather. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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As of 11Z...Some low stratus below 1 kft was around, but not enough to warrant a ceiling. Any visibility restrictions due to BR should be gone by 12z and any patchy stratus will burn off by mid morning. The seabreeze and Piedmont Trough will help to initiate isolated to perhaps scattered showers and thunderstorms. Strong heating should allow cumulus to build by late morning and midday with convection mainly expected this afternoon. As the seabreeze pushes inland, the risk for thunderstorms will move inland of the coastal terminals by late afternoon. The risk for thunderstorms will linger longer at KFLO and KLBT, perhaps to 02z or so. Prevailing conditions will be VFR, however, should a thunderstorm impact the immediate terminal, ceiling and visibility should briefly drop to MVFR or lower. Tonight, low stratus is expected to develop after midnight. Will include sct-bkn deck at or below 1 kft after 06z at all the terminals. If ceilings do develop at or below 1 kft, it will likely be after 09z. Extended Outlook...Flight restrictions due to showers and thunderstorms are likely Sat-Sun. Convection should be less numerous Mon. Early morning low stratus and fog will be possible, especially Sun and Mon.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 AM Thursday...Very light wind fields continue across the coastal waters this morning with buoy reports showing speeds less than five knots. Winds will shape up gradually through Friday morning with a decent southwest flow of 10-15 knots later tonight. For today winds will be mostly driven by the sea breeze. Significant seas will be around two feet at best. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 300 AM Thursday...The Piedmont Trough and seabreeze will be the main driver of winds on Fri. An approaching cold front Fri night and Sat should get hung up N of the waters through the end of the forecast period. SW winds will be in place through the period. The strongest winds are expected late Fri and Fri night, on the order of 15 to 20 kt. Winds should tick down to 10 to 15 kt during Sat and to near 10 kt toward Sun morning. Seas of 2 to 3 ft Fri will build to 3 to 4 ft Fri night and Sat perhaps subsiding about a foot during Sat night. LONG TERM /SUNDAY THROUGH MONDAY/... As of 300 PM Wednesday...A front will be stalled over land Sunday into Monday in a weakening state. This boundary will serve a similar function to the Piedmont Trough normally seen during the warm season and we should still see a fairly typical southwesterly flow. Seas will run 2 to 4 ft for the most part, highest offshore in the coast- parallel flow. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Heat Advisory from noon today to 5 PM EDT this afternoon for SCZ017-023-024-032-033-039-053>056. NC...Heat Advisory from noon today to 5 PM EDT this afternoon for NCZ099-107>110. MARINE...None. && $$ NEAR TERM...SHK SHORT TERM...RJD LONG TERM...MBB AVIATION...RJD is the U.S. government's official web portal to all federal, state and local government web resources and services.