Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 280758 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 358 AM EDT Tue Mar 28 2017 .SYNOPSIS... The risk for showers and perhaps an isolated strong thunderstorm will occur today ahead of a cold front which will move through late tonight. Relatively cooler and drier high pressure will build in from the north late Wednesday into Thursday. Showers and thunderstorms are expected as warmer and more humid air returns Friday ahead of a cold front which will move offshore early Saturday. Some of the thunderstorms may be strong to severe Friday and Friday night. The weekend should be dry as high pressure takes hold. Then early next week, a southern stream system will again bring the risk for showers and thunderstorms. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM Tuesday...A healthy warm and moist southerly return flow along with clouds have kept temps up in the 60s most places with dewpoint temps well into the 50s. This juicy air mass ahead of a cold front will set the stage for an increasing chc of shwrs/tstms through today. ML CAPE will reach over a 1000 J/kg as heating of the day occurs with increasing LLJ and dewpoint temps up around 60. Expect increasing coverage through the morning hours from west to east with increasing shear and upper level support mainly over NC. The cloud cover may slow the destabilization process but decent elevated CAPE early on will be aided by heating of the day and upper level support to produce added lift and potential for storms with gusty winds and hail in isolated stronger storms. SPC has most of central and eastern NC in a marginal risk for SVR weather diminishing as the shortwave tracks off shore by late aftn. There may be some lingering shwrs/tstms along the coast into early evening depending on how fast the shortwave traverses the area. Southerly winds will veer slowly to the SW and become gusty through the day before shifting to the W by Tues evening as trough moves through. Expect plenty of clouds through the day but some breaks or brightening will allow temps to reach up toward 80 most places. The increasing SW flow will fight against inland movement of sea breeze and therefore the stable air behind sea breeze will remain pinned closer to the coast. Overall expect increasing westerly flow aloft and drier air to put an end to convection across the area by late aftn with some lingering clouds into the evening. Pcp water values up around 1.4 inches in the aftn will drop under an inch by midnight as winds from the sfc up through the mid levels become westerly and eventually northwest overnight. Clearing should take place overnight although some residual low level moisture will remain into the morning. Temperatures will drop off slowly as the cold front will not actually make it through until the early morning hours on Wed. Low temps should be in the mid 50s most places. Although the official surf zone forecast season has not started yet, local beaches will see an increase in rip current activity today. This a result of a healthy SE ground swell affecting the local waters and increasing the surf. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 AM Tuesday...Cold front will be offshore Wed morning. Strong high pressure centered across eastern Canada will begin to ridge south across the Carolinas later Wed and Wed night. A wedge will develop Wed night and persist into Thu before the ridge begins to weaken and shift offshore Thu night. Dry weather Wed into Thu as partial sunshine returns. A potent southern stream system will approach from the W Thu night. Clouds will be on the increase later Thu and especially Thu night. The system has slowed down some, but will continue to advertise a slight chance/small chance of showers and thunderstorms, mainly overnight Thu with the lowest risk across the Cape Fear area and the highest across the I-95 corridor and westward. The cool air Will be slow to arrive and so highs on Wed should still be well above normal, upper 70s to lower 80s with marine influences keeping the coastal communities in the lower to mid 70s. Highs Thu will be in the upper 60s to lower 70s with perhaps some mid 70s across portions of the Pee Dee. Lows will be mainly in the 50s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 AM Tuesday...Next in series of potent southern stream systems will impact the eastern Carolinas Fri and Fri night with a categorical risk for showers and thunderstorms developing. The combination of significant upper level support and strong and deep moisture return and lift provides at least the opportunity for a more widespread and significant rainfall event. There will be some risk for strong to severe thunderstorms during this time. 0-6 km effective bulk shear parameters are not particularly impressive. However, instability does grow with mixed layer CAPE values on the order of 500 to 1000 J/kg as the warm front should move to our N. Mid-level lapse rates are forecast to be rather modest. The potential is there for an active day/night leading into the weekend, although magnitude is certainly still a question mark. In the wake of this system, dry weather and near to above normal temps are expected for the weekend as mid-level ridging builds across the area and surface high pressure builds from the NW and N. Attention then will turn westward as next southern stream system along the Gulf Coast Sun night lifts to the NE and drags a warm front to the N. This will again bring deep moisture into the Carolinas, and with that, showers and thunderstorms early next week. Given timing differences between long range models and a general slower trend as compared to 24 hours ago, will cap POPs in the chance category until we can gain better resolution as to when the highest risk for showers and thunderstorms will occur. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... As of 06Z...VFR conditions will last until around daybreak as upper disturbance reaches the area. Expect mainly MVFR SHRA but an increasingly unstable air mass will produce isolated IFR TSTMS mainly from 13Z thru 21Z with coastal terminals mainly after 15Z. Winds will veer slowly through the day but may see a slight backing along coastal terminals in the afternoon due to sea breeze. Generally looking at SSW to SW winds 5 kt or less overnight and picking back up to SW 10-15 kt during daylight Tue. A cold front will lag behind the convection and will likely push thru late Tue night into early Wed. Kept fog out of the forecast as winds remain up overnight with plenty of clouds. Extended outlook...MVFR and possibly IFR conditions possible from fog Wed morning. MVFR/IFR conditions due to showers and thunderstorms Fri/Fri night. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 AM Tuesday...SSW winds 10 kt or less will veer and increase through today as gradient tightens a bit between high pressure off shore and an approaching cold front. By this evening winds will become more westerly remaining around 10 to 15 kt. Seas will increase but will remain in the 2 to 4 ft range over SC waters and 3 to 5 ft in NC waters. The greater off shore westerly wind component overnight will push most of the 5 fters beyond our local waters leaving 2 to 4 ft by morning. Winds my spike up a bit as cold front crosses the waters Wed morning. A longer period SE swell will continue to reach our local waters from a rather deep low pressure system well offshore from the SE U.S. Coast forecast to move northeast, further away from the U.S. mainland. Boaters navigating to and from area inlets on Tue could encounter rough wave conditions especially during an outgoing tide combined with the incoming 10+ second period swell. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 AM Tuesday...Cold front should be offshore at the start of the period. Strong high pressure across eastern Canada will build south and eventually wedge across the Carolinas Wed night and Thu. The strong ridge should then move offshore Thu night. N winds Wed morning will veer to NE. NE winds Wed night and Thu will then veer to SE Thu night. Sustained wind speeds will increase to 15 to 20 kt Wed night and remain in that range through the end of the forecast period. Seas will build to 3 to 5 ft by Wed night and then remain in that range for much of Thu before perhaps subsiding about a foot Thu night. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 300 AM Tuesday...A Small Craft Advisory is likely for all waters Fri and Fri night with conditions possibly lingering into Sat. Slow moving area of low pressure will be moving across the Ohio Valley Fri. Its accompanying warm front will move across the waters Fri. As low pressure moves offshore of the Mid-Atlantic states late Fri night and Sat morning, it will strengthen and drag a cold front across the waters. High pressure will slowly build across the area from the N and NW Sat night and Sun. SE winds Fri morning will become S and then SW Fri night. The wind direction will become westerly early Sat morning and then NW by Sat afternoon. N winds Sat night will become NE overnight Sat with NE winds persisting into Sun before veering to easterly during the afternoon. The strongest winds are expected Fri and Fri night, up to 20 to 25 kt. Seas late Fri and Fri night will build to 4 to 7 ft and around 8 ft at frying Pan Shoals. Seas during Sat will only slowly subside as backswell from departing storm system impacts the waters. Seas should drop below advisory levels by late Sat and to 2 to 4 ft on Sun. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RGZ SHORT TERM...RJD LONG TERM...RJD AVIATION...RGZ

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