Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 191300 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 900 AM EDT Sat Aug 19 2017 .SYNOPSIS...
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Hot and humid weather will prevail this weekend with a few thunderstorms capable of torrential rainfall, as a front stalls and weakens along the coast. High pressure will expand across the western Atlantic in the upcoming week, maintaining summer like conditions across the region. followed by an approaching front from the NW Wednesday through Thursday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 9 AM Saturday...GOES-16 `differential water vapor` channel shows an axis of enhanced mid-level moisture that extends ENE-WSW across Cape Fear, and over the coastal interior of South Carolina. Convergence will increase near the coast today, as an upper wave helps spawn a surface trough over the eastern half of NE SC and SE NC. Precipitable water content sensed from SSM/I and AMSU polar orbiters show values of around 2 inches along the coast and coastal interior. These factors will result in scattered TSTMS along and near the coast as soon as late morning, gradually moving toward the NNE. Torrential rain may require isolated issuances of localized flood alerts. Diurnal cooling will bring a diminishing trend of the convection after 900 PM. Heat Advisory continues for the coastal zones due to high dewpoints and apparent temps >104 this afternoon. As of 330 AM Saturday...A weak mid level trough, currently over the Tennessee Valley, will push a cold front near the coast later today. This will be the focus for showers and thunderstorms. Both the NAM and GFS have convection firing around mid to late morning and lingering through the late afternoon hours. Once again with precipitable water values near two inches, heavy rainfall will be the biggest threat. Tonight should be relatively quiet with guidance painting a mostly convection free scenario. As for temperatures, there will be a very slight cooling inland with regards to actual temperatures and dewpoints. The coast however still remains very humid with dewpoints in the upper 70s and I will hoist an advisory for these areas.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 330 AM Saturday...The westerlies aloft will pull back slightly to the north this period. With rising 5H heights, mid- level ridging from off the Atlantic will extend westward, across the FA, across the Gulf Coast States, and reaching Texas and northern Mexico. The upper low or if it opens up, an inverted upper trof, will make it`s way across the Gulf of Mexico this period. At the sfc, a stalled frontal boundary will lie NE to SW along the immediate Carolina Coasts or just offshore on Sun. This proximity will allow for convection to develop especially across the coastal counties with low chance category for POPs. Further inland, drier air aloft and subsidence will keep convection to isolated at best during Sun. On Mon, as mentioned earlier, the upper trof aloft will push westward over the Gulf of Mexico, with it`s upper trof axis extending and pushing across the FA during Mon. What ever is left of the frontal boundary will combine with dynamics aloft to producing a low to modest chance for convection Mon into Mon evening. POPs will be hiest across the coastal counties and the southern portions of the ILM SC CWA. This may jeopardize the solar eclipse viewing across portions of the FA. Stay Tuned. Stayed close to a consensus amongst the various model mos guidance. The trend will be for max temps hier Sun, slightly lower for Mon when compared to Sun. Min temps, widespread mid to upper 70s, with a few low 70s well inland, ie. west of the I-95 Corridor, depending on sky conditions. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 300 PM Friday...A flat mid-level ridge will extend from the Atlantic across the Carolinas Tuesday, then get suppressed south as a trough carves out across the Eastern seaboard for the latter half of the week. With no real airmass change evident in guidance until perhaps Thursday, precipitable water values will hover around 2 inches until then. Scattered pulse showers and thunderstorms are expected each afternoon and evening Tuesday through Wednesday, with the highest chances Wednesday night through Thursday when convection becomes organized along and ahead of a frontal boundary. As usual in the extended period, and especially in August, there is a great deal of uncertainty with timing the front and determining how far south it will push. Will hang on to higher PoPs across the southern CWA on Friday to account for that. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/... As of 12Z...Expect VFR conditions thruout this period with 2 exceptions. The 1st mainly affects the coastal terminals from mid-morning thru mid-afternoon at which time MVFR/IFR conditions will be possible from convection due to the sea breeze and the approaching cool front. The other exception will be for all terminals during the pre-dawn Sun hours at which time winds will basically go calm allowing for ground fog to develop. Have indicated possible MVFR conditions from the fog. Wind directions may become variable once the cool front pushes to and stalls nearly overhead. The coastal terminals will see winds back to the South at 10 to possibly 15 kt depending on the strength of the sea breeze. Extended Outlook...Expect flight restrictions from isolated to widely scattered TSTMs Sun, increasing in coverage by Tue through Wed. Flight restrictions will also be possible each early morning due to stratus/fog Wed. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 9 Am SAturday...Little to no E-SE wave energy presently and seas are dominated by S waves 2-3 feet every 6 seconds and up to 4 feet outer waters. Isolated TSTMS will impact the waters today and tonight and radar updates are encouraged. As of 330 AM Saturday...Winds remain fairly brisk this morning due to enhanced low level jetting. Speeds are currently in a 10-15 knot range down a few knots from earlier reports. Speeds will decrease another knot or two then settle into this range through early morning Sunday. Seas are currently just over four feet and shouldn`t rise much if any more. Overall a range of 2-4 feet will continue through Sunday morning as well. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 330 AM Saturday...A meandering but basically stalled sfc frontal boundary in proximity of the local waters, may initially result in changing predominate wind directions. Overall, wind directions will basically be onshore this period. The sfc pg will however remain relaxed thru the period, with speeds basically around 10 kt or less. Significant seas will be dominated by a lazy 1 to 2 foot ESE-SE ground swell with periods 8 to 9 seconds Sunday and approaching 10 seconds during Monday. Wavewatch3 does show a slight increase, up to an additional 1 foot, to the ESE-SE ground swell Mon night into Tue. Sun and MON afternoons/evenings will see some short period wind chop due to the sea breeze and it`s inland progression. Of the 2 days, convection will be more active during Mon, especially across the ILM SC waters. LONG TERM /TUESDAY THROUGH WEDNESDAY/... As of 300 PM Friday...A benign pressure field across the waters will keep winds 10 knots or less Tuesday, as a weak Bermuda high pressure remains in place off the coast. Winds will begin to pick up out of the southwest by Tuesday afternoon as a surface trough takes shape across the Carolina piedmont. Shower and thunderstorm activity is expected to remain isolated to widely scattered over the waters in a general southerly flow through the period.
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&& .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...Heat Advisory until 6 PM EDT this evening for SCZ053>056. NC...Heat Advisory until 6 PM EDT this evening for NCZ099-105>110. MARINE...None.
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&& $$ SYNOPSIS...8 NEAR TERM...SHK/8 SHORT TERM...DCH LONG TERM...CRM AVIATION...DCH/RAN

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