Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 181817 CCA AFDILM Area Forecast Discussion National Weather Service Wilmington NC 217 PM EDT Tue Apr 18 2017 .SYNOPSIS... A cold front will drop south stalling in South Carolina later today before lifting back north as a warm front on Wednesday. The Bermuda High will expand west over the region Thursday through Saturday. Another cold front may reach down into the Carolinas this weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Tuesday...A cold front was progressing southward this morning reaching through our forecast area. By mid morning it was draped just north of the tip of Cape Fear southwest into SC. A moisture rich air mass with fairly deep column of moisture and more stable air mass behind was producing low clouds with northerly winds behind the front. Ahead of the front the winds were still S to SW with some mid clouds mixing with the sunshine. Temps to the north were in the mid 60s while to the south the temps were into the 70s. The heating to the south will produce more unstable conditions this afternoon and therefore included some thunderstorms into northeast SC this aftn. Temps to the north of the front will struggle to reach into the 70s. The main focus for shower activity will be along the front but will also be aided by some differential heating and convergence along the sea breeze. HRRR shows the main focus of showers over coastal NC this morning but over SC this aftn where the greater heating and instability will be. Also focuses some shower activity along the sea breeze boundary in SC. May see a few showers producing a quick shot of heavier rain but overall QPF will be on the low side and will be focused mainly south and west of the local forecast area overnight. Lows tonight will be influenced by the moisture and will fall modestly to within a couple of degree of 60 area wide. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 315 AM Tuesday...Chief feature this period is a weak and meandering frontal boundary over the area, perhaps enough to focus a few showers or a TSTM Wednesday, while interacting with a flimsy inland migrating sea breeze boundary aligned with the synoptic trajectories. This should provide an opportunity for a shower or storm for any local but not all will see fruition of measurable rainfall, as dynamical energy remains mediocre at best. Thursday will be warmer than Wednesday as low-level winds cut off the maritime influence ashore, becoming W-SW. Have opted to remove thunder Thursday since mid-level drying will set in capping the column above 10 thousand feet. Consequently, also expect more clouds Wednesday compared to Thursday. Small POPS were inserted Wednesday night despite diurnal cooling as weak boundary remnants begin to lift north over the area. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 300 PM Monday...A low amplitude upper ridge and Bermuda high pressure will bring unseasonable warmth. The ridge will not be strong enough to suppress isolated sea breeze convection by the looks of it. A very slow moving front will enter the area on Friday and so isolated storms will be possible just about anywhere while temperatures remain elevated above their seasonable norms. Thereafter the details become a bit convoluted but the late weekend trend does seem to be rather unsettled. Strong troughiness will be developing to our west leading to cyclogenesis. The speed at which this brings the front back as a warm front as well as the timing of the system`s trailing cold front are not well agreed upon between various guidance. Right now it appears the former occurs Saturday and the latter on Sunday. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... As of 18Z...A cold front has almost cleared the TAF forecast area as it is making its way south through NE SC early this afternoon. Just to the north of the front was decent coverage of low IFR stratus and spotty pcp and fog bringing vsbys into MVFR. Overall expect IFR to MVFR cigs along and just north of front into early eve as front slows to a halt over SC. To the south of the front expect mainly VFR but scattered showers will erupt producing possible MVFR ceilings in SHRA and iso TSRA with possible IFR in brief heavier rain until this eve, but this activity should remain inland from CRE/MYR. Expect conditions to improve up to MVFR over NC TAFS into this evening but IFR will return in light rain and fog overnight into Wed. Extended outlook...MVFR/IFR conditions possible in showers and TSTMS Wed and Wed night. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Tuesday...A rather weak cold front is dropping slowly south across the waters, but will stall out near or just south over SC waters later today. Winds will be N to NE north of the boundary and S to SW to the south of the south. Most of the coastal waters will see a northerly component to the winds develop through today with the exception of AMZ256 where the front may stall producing more variable winds. Winds will be generally light but will increase and become gusty behind the front later today. The increase in winds with a greater on shore component will push seas up from less than 3 ft up to 3 to 5 ft overnight into Wed morning. SHORT TERM /WEDNESDAY THROUGH THURSDAY/... As of 315 AM Tuesday...Manageable marine conditions to prevail Wed/Thu. Seas in recovery mode Wed with onshore winds so the subsiding trend will be a slow one Wed, but no advisories or caution statements appear to be needed, but it will be a bit bumpy in 3-4 foot seas in 7 second intervals from the E. An improving trend Thu as surface winds turn to WSW-SW and ease up, as weak and broad high pressure over the area unravels the pressure gradient. Thu 2-3 foot seas in a mix of E-SE wave trains. This period do expect a few marine showers and isolated TSTMS. Getting a radar check is recommended before venturing out both Wed/Thu. LONG TERM /FRIDAY THROUGH SATURDAY/... As of 300 PM Monday...The period may start with light W wind but a SW flow should become established at Thursday wears on with a large area of high pressure off the coast. This SW flow will continue through the period and may become a bit more gusty as a cold front approaches from the NW. The appearance of 4 ft seas will be gradual but should increase through the Friday- Saturday timeframe. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RGZ SHORT TERM...MJC LONG TERM...MBB AVIATION...MJC is the U.S. government's official web portal to all federal, state and local government web resources and services.