Area Forecast Discussion
Issued by NWS Wilmington, NC

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516 FXUS62 KILM 152327 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 727 PM EDT Thu Mar 15 2018 .SYNOPSIS... High pressure will remain to our south over the weekend. A weak cold front will push through from the north Friday and lift north Saturday. Another boundary will move through on Sunday. A moderately strong storm system will affect the area late Monday into Tuesday. && .NEAR TERM /THROUGH FRIDAY/... AS OF 300 PM THURSDAY...A final shortwave trough rotating around the back side of the big East Coast trough is moving across Virginia this afternoon and should exit the coast this evening. A surface trough associated with this feature is compressing the pressure gradient across the Carolinas leading to strong southwesterly winds gusting as high as 35 mph. These impressive gusts should die away after sunset, however sustained surface winds of 10-20 mph may linger through midnight before subsiding late. Skies should remain generally clear overnight with only a patch or two of cirrus expected. Lows in the mid 40s, perhaps a little cooler in spots if winds diminish more quickly. Warm advection should turn neutral Friday as a backdoor front approaches from the north. An upper ridge will move toward the Carolinas from the west, but a shortwave propagating through the ridge position may still allow some increase in clouds during the afternoon. There is surprising spread in the models with temperatures depending on how much cooling occurs near the backdoor front. I`ve raised our forecast highs by several degrees into the lower to middle 70s away from the ocean. but later shifts may still need to add another 1-2 degrees given how models sometimes under- estimate how reluctant cold air is to move in with a front during a sunny day. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 3 PM Thursday...By 8 pm Friday night, a weak cold front may be decelerating, or already stalled somewhere between Cape Fear and the Myrtle Beaches, lying east to west. This feature, or its remnants. will lift north in quick fashion Saturday morning, as surface low pressure moves east into Kentucky. This low is presently a deepening `lee-side` entity over the high plains of eastern Colorado. Moisture profiles associated with this weak boundary are primarily dry, with enough layered moisture present however, to bring a broken deck of H8 clouds. As soon as the dissipating boundary is whisked NNE, clouds will lower and thicken from the W-SW Saturday morning, as the low migrates into the Appalachians, and off the NC Outer Banks Saturday night. Soon after the low reaches the sea, it will pull a cold front across SE NC and NE SC into early Sunday. As a result, the best chances of rain reside here Saturday afternoon and night. Drying high pressure sets in daybreak Sunday. Overall QPF is low, because only a brief period of relatively deep moisture prevails, Saturday afternoon to early evening, as PWAT values temporarily spike to just over an inch. Tenth of an inch average SE NC, and just a few hundredths over NE SC for the rain buckets this period. Mild SW flow Saturday despite clouds and a few showers, could bring many spots above 70, with the milder air to reside over the interior of NE SC, and points NE either side of a line from Whiteville to Burgaw. Lows both Sat/Sun morning, either side of 50 degrees. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM Thursday...High pressure building in Sunday behind backdoor cold front while mid level flow is a downsloping WNW direction favoring a fair amount of sunshine. This sunshine will be short-lived however as moisture comes flooding back Sunday night into Monday according to model soundings (GFS has entire column saturating). This is in response to warm advection developing aloft yet some surface ridging holding and serving as a surface to be overrun. Rain should break out area-wide on Monday. Initially QPF should be fairly light due to the surface wedge and zonal mid level flow. Rain prospects look better and heavier Monday night and early Tuesday as the warm front lifts through accompanied by a developing surface low. Drying trend begins later Tuesday though it may be gradual at first. The late period will trend towards cooler weather as a deep trough returns in the east. Shortwave energy rotating through this trough could bring clouds and even light showers on Thursday. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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As of 00Z...VFR with scattered clouds. Gusty winds slowly decrease this evening with LLWS likely overnight all terminals. Westerly winds Friday except becoming southwest at KCRE/KMYR in the afternoon. Winds KLBT/KILM become light and variable late afternoon. Extended outlook...VFR. Slight chance MVFR Sat night/Sun. MVFR/SHRA likely Mon/Tue.
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&& .MARINE... NEAR TERM /THROUGH FRIDAY/... AS OF 300 PM THURSDAY...The pressure difference between high pressure over Florida and a low pressure trough moving off the Mid- Atlantic coast is sustaining strong southwest winds across the Carolinas. These winds will continue to worsen through this evening and veer more westerly, peaking before midnight at 25-30 knots with gusts of 35 knots possible. All models are in agreement with this scenario and this is a high confidence forecast. As the trough moves farther away from the East Coast late tonight winds should quickly diminish Friday morning, with seas only taking a few hours to settle down given the short offshore trajectories. A Small Craft Advisory will remain posted through the night and into Friday morning. Seas building to 4-6 feet this evening could grow as large as 7-8 feet across the waters 20 miles S/SE of Cape Fear given the effective fetch on a west-southwesterly wind. SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 3 PM Thursday...Initially, a welcoming marine platform, but by the afternoon Saturday, gusty SW winds between 20-25 KT should become common, as seas approach 6 ft offshore, as low pressure moving toward the sea. approaches the coastline between Cape Lookout and Cape Hatteras. As a result, SCA flags may be needed for late Saturday in gusty SW winds and highly chopped seas. Light showers can be expected Saturday afternoon and night. Soon after the low reaches the sea, it will pull a cold front across SE NC and NE SC into early Sunday morning. Winds Friday night although not strong, may become NE-E or waver a bit, as a weak front drops south and stalls near or just south of Cape Fear. LONG TERM /SUNDAY THROUGH TUESDAY/... As of 300 PM Thursday...Flow will be turning onshore early in the period as a wedge of high pressure weakens to our north. A southerly component will become established on Tuesday as a warm front lifts through the area. Winds and seas in the warm sector could increase as surface low pressure approaches to the point where an advisory is needed. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 6 AM EDT Friday for AMZ254-256. Small Craft Advisory until 10 AM EDT Friday for AMZ250-252. && $$ SYNOPSIS...MBB NEAR TERM...TRA/JDW SHORT TERM...MJC LONG TERM...MBB AVIATION...MRR is the U.S. government's official web portal to all federal, state and local government web resources and services.