Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 221651 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1251 PM EDT Wed May 22 2019 .SYNOPSIS... Just slightly warmer than normal afternoon today will give way to an extended heat wave with well above normal temperatures. There are no appreciable rain chances over the course of the next seven days as high pressure dominates the weather. && .NEAR TERM /THROUGH THURSDAY/... As of 1000 AM Wednesday...Fairly decent cloud layer over area, but overall thinning and still expect this trend to continue to lead to partly to mostly sunny skies this afternoon. Forecast on track for a relatively cooler day with NE to E on shore flow and temps closer to 80 near the coast and mid to upper 80s inland. Previous discussion: A surge of easterly winds early this morning is moving across the area, spreading low clouds inland from the coast. Models have a surprisingly good handle on this almost mesoscale event and show clouds thinning from east to west later this morning. It may take until afternoon to get cloud ceilings to break across the interior Pee Dee region where cloud depth near 2000 feet will resist the strong May sun for a few additional hours. In the mid and upper levels strong high pressure is building across Georgia and South Carolina. Forecast 500 mb heights exceeding 591 dam this afternoon and 593 dam Thursday should be at least 100 meters above average and among the highest values observed in May according to the SPC sounding climatology website using CHS data. The maritime boundary layer moving onshore is relatively cool and should keep high temps in the upper 70s and lower 80s near the coast today. Inland temps should still reach the mid to upper 80s. Slightly drier air should make significant inroads across North Carolina where dewpoints will probably dip into the 50s this morning. If we get popup showers this afternoon the best potential should be across Darlington and westward into central South Carolina where higher dewpoints will exist along with modest surface-based instability. Forecast PoPs near Darlington are only 20 percent. High pressure across the Mid-Atlantic states will move offshore Thursday. This should veer our surface winds from east to south. Despite an increase in temperatures and dewpoints, a stronger subsidence inversion aloft will probably cap off any potential for showers. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 300 AM Wednesday...Thursday night ends the slightly cooler conditions as the near term front lifts back to the north and West Atlantic high pressure/return flow resume. Only low level flow will turn to the south however so the moisture will not grow very deep. Dewpoints will be creeping up but will not quite reach the muggy levels seen earlier in the week. So even as Friday highs soar into the low 90s the apparent temperatures will only run a few degrees higher and stay well short of any Heat Advisory. A backdoor cold front drops into the area on Friday night bringing little more than a windshift over northern zones. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 300 AM Wednesday...At the surface, backdoor front washes out over the area on Saturday. Mid level ridge over the Gulf States on Saturday to bring very unseasonably warm conditions locally. Sunday and Monday then grow even hotter, less due to thermal advection and more due to warmer starts and building low level warmth (GFS forecast soundings show a 7kft boundary layer by Monday afternoon). Record highs appear to be in jeopardy, some dating back to the 1950s. The low level ridge above the BL never makes it offshore, still precluding moisture deep enough for surface dewpoints that will push the area into Heat Advisory realm. Some guidance has been suggesting that the ridging aloft should start to weaken early next week leading to a very gradual abating trend in the heat. Given the common model bias of breaking down such hot ridges too quickly have opted to keep the forecast rain-free at this time and will show a continuation of the heat wave. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... As of 18Z...Predominately VFR throughout the period. A cold front has pushed south of the area and stalled. Behind the front, morning stratus is continuing to erode with dry air advection from the east. Expect VFR conditions to return to all terminals over the next few hours. Winds will continue to be from the east at 10-15 knots today until this evening when the front weakens along with the associated pressure gradient. A few areas of stratus are possible after 03Z tonight, but will keep VFR for now. Extended Outlook...Continued VFR through the weekend as high pressure dominates. Hot. Slight chance of brief MVFR conditions each morning from low stratus and/or fog and afternoon TS. && .MARINE... As of 1000 AM Wednesday...1026 mb high pressure centered across the Mid-Atlantic states has pushed a reinforcing surge of east- northeast winds across the area. Sustained wind speeds have increased to 15-20 kt north of Cape Fear, and should increase to around 15 kt south of Cape Fear. These winds should continue through most of the day, gradually diminishing and veering southeasterly tonight, then becoming southerly on Thursday afternoon as the high moves off the Mid-Atlantic coastline. All models are in agreement with this scenario and this is a high- confidence forecast. Seas should build to 3-4 feet this morning (highest near and north of Cape Fear) in a 4-second wind chop. Beneath this, a smaller 9- second southeast swell will continue. As winds diminish overnight into Thursday seas should fall to around 2 feet. Thursday night through Friday night: Southerly flow generally expected through the period. A backdoor cold front will sink into the area Friday night possibly turning flow very briefly E or even NE, mainly over northern waters. Seas generally 2-3 ft. Backswell from a system off New England coast largely gets wave shadowed by OBX and largely stays east of the forecast zones. Saturday through Sunday: Boundary both lifts out to the north and falls apart over the weekend. This leaves Atlantic high pressure to reassert itself albeit weakly. Light southerly winds and 2 to possibly 3 ft seas to continue. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...TRA/RGZ SHORT TERM...MBB LONG TERM...MBB AVIATION...21 is the U.S. government's official web portal to all federal, state and local government web resources and services.