Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 191425 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1025 AM EDT Sun Mar 19 2017 .SYNOPSIS... Canadian high pressure will build across the Carolinas today and tonight, then shift into Florida by Monday night. After a brief warmup on Tuesday the next cold front will bring showers Tuesday night followed by much chillier conditions Wednesday and Thursday. A gradual warming trend is expected late in the week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1030 AM Sunday...No significant changes to the forecast this morning. A few clouds are advecting and developing across the northeast corridor of the CWA and this was expected. Temperature and dewpoint temperatures are on track. Previous discussion follows: Cold front moving across the area will exit stage right early this morning, pushing offshore even Georgetown county in the next hour or so. Thereafter, the front will move east as expansive high pressure across the Great Lakes ridges down the Appalachians and towards the ILM CWA. This ridge axis will likely remain west of the area through today, and as the gradient remains pinched behind the front, gusty NW winds are expected through the day. Forecast profiles show up to 30 kts on RAP/NAM BUFR soundings at the top of the PBL this aftn, so wind gusts of 20-30 mph are forecast through the daylight hours. This NW wind is a downslope direction, which will combine with mostly clear sky conditions to somewhat offset ongoing CAA. The exception to this will be in NE zones, where a mid-level vorticity impulse will drop around the closed low off New England, and off the Outer Banks this aftn. Attm it appears any precip will remain offshore as best PVA is directed east of the CWA, but increased cloudiness is possible and have added some increased sky percentages along and NE of a line from Elizabethtown to Carolina Beach. Still, have highs on the warm end of the guidance envelope, low 60s in the Pee Dee, to upper 50s across Cape Fear. As the surface high drifts SE tonight, winds will ease towards calm and temps will plummet beneath good radiational cooling conditions. A blend of guidance is preferred for mins tonight, which suggests mid 30s most places, but around 40 at the beach, and some lower 30s possible in the typical cold spots. Have continued with patchy frost across a good portion of the area, but will let day shift make a decision on any frost advisory for tonight.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 AM Sunday...Surface high pressure centered over the southern Appalachians Monday morning will sink south into Florida by Monday night. With full sunshine Monday and warm advection (850 mb temps rise from +2C to +8C during the day) highs should reach the upper 60s across the Pee Dee region with 60-63 on the coast. Westerly flow aloft will advect in moisture late Monday night with clouds increasing late. I`m not sold on any precip making it this far east despite the .01 QPF contour on both the ECMWF and GFS very close to Bennettsville and Lumberton before 12z Tuesday. Forecast soundings show cloud bases ~11,000 feet and insufficient lift in my opinion to get measurable precip down to the ground. The airmass really modifies on Tuesday as west-southwest flow continues between the high down over Florida and a cold front dropping south across the central Appalachians and Ohio Valley. Assuming there`s enough sunshine, 850 mb temps up to +12C could allow highs to reach 80 in the SC Pee Dee region, with low to mid 70s along the coast. The approach of a shortwave trough Tuesday evening coupled with weak instability and an increasing depth of moisture should yield a wave of showers and thunderstorms, most concentrated across SE North Carolina like in the Saturday night event we just had. The actual surface cold front has slowed down in the models. (last night`s ECMWF was the first to suggest this) The front may only reach Cape Fear by sunrise Wednesday morning. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 300 AM Sunday...A surface cold front should be traversing the area Wednesday morning, pushing all the way down to Charleston by lunchtime. Shallow cold air surging south behind the front coupled with a moist westerly flow over the top of the frontal surface means Wednesday could remain cloudy with patches of light rain or sprinkles. By Wednesday evening the mid level flow should veer more northerly, dragging in enough dry air to dissipate the post-frontal clouds. Unfortunately this means radiational cooling within the chilly airmass could create headaches with frost or even a mild freeze by Thursday morning. Model ensembles still show enough spread in forecast low-level temperature/moisture for Wednesday night/Thursday morning that I don`t have high confidence, but it definitely bears watching. Surface high pressure moving across the Great Lakes Wednesday night and Thursday will move off the East Coast late Thursday night. Veering low-level winds will modify our airmass Friday and Saturday with rising temperatures and dewpoints. Precip chances may increase Saturday as the next synoptic frontal systems approaches from the west. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... As of 12Z...Clear skies will predominate over the next 24 hours...with the only exception across far-eastern North Carolina including the Wilmington airport (ILM) where scattered to occasionally broken cold-air cumulus with bases as low as 4000 feet should develop. Breezy northwest winds with gusts up to 23-26 knots are expected during the daylight hours, diminishing to less than 10 kt tonight. Extended outlook...VFR expected through the period except for possible MVFR/IFR conditions from low ceilings and pcpn ahead of the next cold front Tuesday night into Wednesday. && .MARINE...
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NEAR TERM /THROUGH SUNDAY/... As of 1030 AM Sunday...No changes to the coastal waters forecast with the mid morning update. Previous discussion follows: Cold front moving off the coast this morning will push through the coastal waters through daybreak, leaving gusty NW winds in its wake. Strongest of these winds are expected through late morning behind the front, with a slow decline in speed forecast by evening as high pressure begins to build towards the area. West winds first thing this morning will quickly become NW in the next few hours, and then increase to 20-25 kts with higher gusts, persisting above SCA thresholds into this evening. The ongoing SCA has been extended through this evening for the winds, even as seas fall from 4-6 ft most of today to 3-4 ft on thee offshore winds this evening. Winds will ease further tonight and veer to the North as elongated high pressure builds down the coast, and by Monday morning North winds of 10-15 kts will be common across the waters, producing seas of 2-4 ft. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 AM Sunday...High pressure centered over the southern Appalachians Monday morning will drop south into Florida by Monday night. With the reorientation of the ridge, our winds will back from northwest to southwest. By Tuesday night, a cold front dropping south through the Ohio Valley and central Appalachians will move into North Carolina. Yesterday`s ECMWF model may have been correct after all as more models are slowing down their depiction of this front as it approaches the area. Our latest forecast now shows the wind shift reaching Cape Fear around sunrise Wednesday morning. LONG TERM /WEDNESDAY THROUGH THURSDAY/... As of 300 AM Sunday...A wave of low pressure moving off the North Carolina coast early Wednesday morning will kick a cold front southward. Latest model projections show the boundary passing by Cape Fear around sunrise and blowing clear through Charleston by noon. Breezy northeast winds behind the front will probably lead to Small Craft Advisory conditions Wednesday through Thursday.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for AMZ250- 252-254-256. && $$ SYNOPSIS...TRA NEAR TERM...JDW/SHK SHORT TERM...TRA LONG TERM...TRA AVIATION...TRA is the U.S. government's official web portal to all federal, state and local government web resources and services.