Area Forecast Discussion
Issued by NWS Wilmington, NC
Issued by NWS Wilmington, NC
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290 FXUS62 KILM 270751 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 351 AM EDT Mon May 27 2024 .SYNOPSIS... An approaching cold front should enhance thunderstorm coverage late Monday into Monday night. Mostly dry weather is expected to commence from Tuesday onward as the front pushes offshore after stalling through mid-week. Relatively cool and dry high pressure should remain in control going into this upcoming weekend. && .NEAR TERM /THROUGH TONIGHT/... Will have an outflow boundary, and a sea breeze by midday today. Combined with instability increasing, expect the 2 boundaries to be a source of forcing with the end result convection outbreak. A cold front accompanied with a pre- frontal trof will approach from the WNW today, pushing across the FA to just off the mainland by daybreak Tue. Convection will be ongoing with these approaching boundaries, likely reaching the western periphery of the CWA by early to mid aftn. SPC continues to outline the entire ILM CWA in DAY1 SLGT (2 of 5) risk for today with damaging wind gusts and hail primary threats. Embedded mid-level southern stream low amplitude s/w trof will also antagonize the convection, keeping the SVR threat ongoing well into tonight. Another 90+ degree day for highs, except 4 to 8 degrees cooler at the beaches. Sfc dewpoints will likely reach widespread 70s except if any mixing from aloft is realized, a few western portions of the ILM CWA may temporarily drop into the 60s. Tonights lows will run in the 70s possibly a few 60s occurring from rain-cooled air. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... The cold front should be stalling out near the coast during the Tuesday morning hours with mainly dry conditions across the area, except for possibly a few showers grazing the coastal zones. Some uncertainty remains regarding how much redevelopment might be seen along the sea breeze during the afternoon as a mid-level dry slot is expected to arrive with much drier air and subsidence during peak heating. The Cape Fear region is favored for any new development, but PoPs have been capped at slight chance due to the increasingly unfavorable conditions. Otherwise, expect decreasing clouds and downslope flow out of the west to yield highs around 90F. Whatever development happens to occur during the afternoon should quickly dissipate with the loss of daytime heating during the evening. In addition, the passage of a mid-level shortwave and weak height falls should help to push the cold front further offshore with light NW winds and a breath of drier air arriving over Tuesday night. This will support lows in the mid-60s inland and upper 60s near the coast. On Wednesday, meager cold advection will help to shave a few degrees off of daytime highs, with mid-upper 80s forecast despite sunny skies. The bigger difference will be felt in the lower humidity, with dewpoints expected to mix down into the mid-50s during the afternoon as very dry air and subsidence aloft dominate. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Yet another mid-level shortwave should bring subtle height falls over Wednesday night, with a dry cold front expected to pass through as a result. This will turn winds to northerly or NNW with another breath of dry air filtering in. Morning lows in the low-mid 60s are expected. One final and particularly potent shortwave is expected to dive southward from around Lake Huron on Thursday morning to North Carolina on Friday morning. Guidance differences persist in the shape and orientation of this wave, which will have an impact on the forecast for Thursday and Friday. At this point, I maintained continuity with a dry and relatively cool forecast for both days. However, the GFS continues to suggest that clouds and light rain may be a concern on Thursday amid weak isentropic upglide on the 300-305 K surfaces, but other model guidance fails to acknowledge this possibility. The differences persist into Friday as the GFS brings a more east-west oriented shortwave down from the north while other guidance shows a positively-tilted wave only grazing our area. The former would bring additional rain chances on Friday while the latter keeps things dry. Similar to the previous forecast, kept silent PoPs in for now with highs around 80F on both days and overnight lows in the mid-upper 50s. Beyond the end-of-week uncertainty, a mid-level ridge is slated to move in while surface high pressure drops from the Great Lakes region on Thursday to the coastal Carolinas by early Sunday. This should make for a dry weekend with sunny skies and slightly-below-seasonable highs. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... VFR to start off the 00Z TAF period, except for possible and brief period of IFR stratus and N thru NE winds 10 kt or less thru 07-08z for the ILM and possibly LBT terminals. Otherwise, looking at VFR there-after with SW winds staying active enough to keep early morning fog limited. Approaching cold front from its parent low located over SE Canada, will result in a tightening sfc pg ahead of it, with SW winds gust to around 20 kt this aftn and evening. Wind directions at the coastal terminals will become S-SSW due to the sea breeze. Convection will break out midday, vcnty of the sea breeze, and where the outflow from last night ended up. Convection upstream will approach and move across the terminals later this aftn and evening, likely ongoing at the end of this 24 hr fcst period. Extended Outlook...Scattered thunderstorms and accompanied periodic short-lived IFR conditions late tonight thru Tue, especially across the SC terminals. Otherwise, mainly dry conditions and VFR thereafter for the remainder of the week. && .MARINE... Through Tonight...Tightening sfc pg well ahead of a sfc cold front approaching from the west will result in SW winds increasing this aftn, except S-SSW near shore due to the sea breeze. Speeds will increase to 15 to 20 kt with few/occasional gusts around 25 kt. Once the pre-frontal sfc trof pushes thru later Tue evening, winds will veer to the WSW-W at reduced speeds especially during the pre-dawn Tue hrs. The cold front will be nearly overhead come daybreak Tue. Seas will build to 2 to 4 ft, with occasional 5 footers possible especially outer waters. Unfortunately, seas will be governed by the low period locally produced waves. V-hull as opposed to a flat bottom boat is preferred today, especially venturing out into the ATl Waters and possibly even the ICW. Tuesday through Friday... A couple of cold fronts will make for changeable wind directions through the period. The first front should be stalling right near the coast at the start of the period with SW winds over the waters and seas subsiding into the 2-3 ft range, mainly driven by southerly wind waves. SW winds continue until the first front is shoved offshore on Tuesday night, with NW winds taking over early Wednesday morning. Seas fall to around 2 ft on Wednesday with a mix of 1-2 ft southerly swell and ESErly swell both with periods of 6-7 seconds while winds back to SW again as the first front washes out. Winds veer to NNW behind a second front pushing through over Wednesday night and the flow then becomes variable as high pressure builds down from the northwest. A low chance exists for low pressure to affect the waters on Thursday and Friday with showers and stronger winds, but confidence is too low to include in the forecast at this time. && .TIDES/COASTAL FLOODING... SW to SSW winds to increase to around 15 mph with occasional gusts over 20 mph as the tightening sfc pg and sea breeze combine. This will develop a strong south to north longshore current, affecting all beaches except Brunswick County (Moderate rip current threat) where a moderate west to east longshore current will occur. The lower Cape Fear River(Wilmington southward) will likely eclipse (barely) 1 more minor coastal flood threshold (5.5 ft MLLW) during late tonights high tide cycle. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...Beach Hazards Statement from 6 AM EDT this morning through this evening for NCZ106-108. SC...Beach Hazards Statement from 6 AM EDT this morning through this evening for SCZ056. MARINE...None. && $$ SYNOPSIS...ILM NEAR TERM...DCH SHORT TERM...ABW LONG TERM...ABW AVIATION...DCH MARINE...DCH/ABW TIDES/COASTAL FLOODING...DCH