Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 200545 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 145 AM EDT Tue Mar 20 2018 .SYNOPSIS... Low pressure will move east toward the Carolinas on Tuesday, dragging a cold front through Tuesday night as it tracks northeast and deepens off the North Carolina coast. Possible strong to severe thunderstorms will occur ahead of the low on Tuesday with potential for a few flurries in the mix as colder air moves in on the back end on Wednesday. Cold and dry high pressure will extend down into the Carolinas Thursday and Friday. The weekend may become unsettled and remain cooler, with clouds and periods of rain possibly through early next week. && .NEAR TERM /THROUGH TODAY/... As of 930 PM Monday...01Z surface analysis show low pressure centered over middle TN and north-central AL, with a warm front extending to just south of Charleston, SC. The low will track east-northeast through the remainder of the overnight, as the warm front lifts north. Showers and thunderstorms associated with the surface low will track across the forecast area between 09Z-12Z, and although they should be weakening with diminishing upper support, the presence of shear along the warm front will necessitate a close watch for potential rotation. After a lull in activity in the 12Z-18Z window, a vigorous mid- level trough and associated surface cold front will approach from the west in the afternoon and evening hours Tuesday. This will give the atmosphere an opportunity to destabilize, with surface-based CAPE values reaching 1500-2000 j/kg. SPC has included the CWA in an slight to enhanced risk of severe storms for Tuesday afternoon, noting the possibility of a few tornadoes considering the amount of low-level wind shear. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...Complex storm system will be exiting the area albeit slowly through the period. The latest guidance has shown a considerable drying trend with precipiation through the period. It appears the mid level cyclone will just be pulling in too much dry air to allow any significant showers to develop. Overall I have trended pops down through the period. Temperature guidance continues to show some differences but in general maintained a blend. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 300 PM Sunday...Although I would not discount a few flurries as potent shortwave swings through the back end of the upper trough early Thurs, the moisture will be very limited. Therefore will not include any pcp in forecast early Thurs morning as upper trough swings off the coast. CAA continues through Thurs into Friday in strong NW flow as high pressure builds in from the north. The 850 temps drop down around -4c and do not return above 0c until Sat. Temps will drop into the 30s most places with some frost or freeze potential in spots again early Fri morning. Temps both Thurs and Fri may not reach above 60. Low pressure system will brush the Carolinas Fri night into Sat as it moves toward the Mid Atlantic coast. This will produce increase in clouds and greater chc of rain across the area late Fri into early Sat. The latest model runs show a possible wedge type scenario setting up for the weekend with clouds and periods of rain possible. Overall, the weather may turn out to be cooler and more unsettled than originally forecast. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... As of 06Z...Active period on tap with a couple rounds of convection expected during the next 24 hours. First will arrive during the next few hours with a mid-level disturbance pushing a line of showers and thunderstorms west to east across the area. This line should move off the coast around 12Z, followed by a period of drying. Strong southerly flow today increases instability and an approaching cold front/low pressure combo this afternoon will set off another round of showers and thunderstorms. There is an enhanced potential for severe weather in the afternoon with wind and large hail being the biggest threats. Second batch of convection should exit the coast by 00Z but low clouds may linger through the end of the TAF period. Have high confidence that IFR conditions will be experienced at all terminals, but the convective nature means duration will be limited and timing will be difficult to pin down. Extended outlook...Periods of MVFR/IFR through Wednesday. && .MARINE... NEAR TERM /THROUGH TUESDAY/... As of 930 PM Monday...A weak pressure gradient is in place across the waters this evening on the north side of a warm front, which will progress north overnight. Winds will remain light, generally 10 knots or less, and mainly east-southeast until the front lifts through after midnight. At that point, winds will become south to southwest and increase to 15 knots, and shower and thunderstorm activity is expected to be moving off the coast in the few hours before sunrise. Conditions will deteriorate Tuesday, as SW winds pick-up ahead of a cold front. An advisory may not be needed but a few lines of showers, and even strong TSTMS could impact the 0-20 NM waters Tuesday morning, and again in the afternoon. Mariners can expect SW gusts near 20 kt Tuesday, outside of showers and TSTMS. Seas will build to 3-5 ft Tuesday afternoon, and an `Exercise Caution` headline may be needed. A radar update is recommended before venturing out, as some storms may become capable of gusts in excess of 35 kt Tuesday morning and again in the afternoon. SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...Expect a rough and tumble period for the marine community. A complex storm system will be exiting the area with initially gusty southwest winds. The winds will shift to northwest by Wednesday evening but the speeds will remain elevated in a 20-25 knot range. Some guidance is showing higher winds and subsequent shifts may need to increase the wind forecast with gales a possibility. Not surprisingly considering the winds, seas are expected to be high from 4-8 feet with the higher values across the outer waters. LONG TERM /THURSDAY THROUGH SATURDAY/... As of 300 PM Monday...Cold and dry high pressure will extend down over the local waters Thurs through Saturday. Strong off shore flow up to 15 to 20 kts early Thurs will weaken and become more northerly through the period down to 10 kt or less by Sat. This will allow seas to subside from close to 3 to 5 ft early Thursday down less than 3 ft by Fri aftn into Sat. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...MJC/CRM SHORT TERM...SHK LONG TERM...RGZ AVIATION...III is the U.S. government's official web portal to all federal, state and local government web resources and services.