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Area Forecast Discussion
Issued by NWS Wilmington, NC
Issued by NWS Wilmington, NC
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281 FXUS62 KILM 221706 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 106 PM EDT Mon Jul 22 2024 .SYNOPSIS... Occasional showers and thunderstorms, some with heavy rain, will continue through the remainder of the week as southerly winds bring tropical moisture northward. A weak front could stall near the area this weekend. && .UPDATE... Morning sounding showing a moist (~PW 2.15") and unstable atmosphere. The storm motion is a bit stronger today with motion from the southwest at 15 to 20 kt). Convection along the coast is expect to wane this morning and transition to areas inland. The HREF is showing the axis of heavy rain is expected along the I-95 corridor. && .NEAR TERM /THROUGH TONIGHT/... Showers and thunderstorms likely again today as deep SW flow maintains a moisture rich environment. Slight perturbations in the flow aloft and vorticity maxima centered over the central Carolinas should be more than sufficient for widespread lift this afternoon. A weak sea breeze will likely spark the initial development of showers along the coast, progressing inland with some development possible along the Piedmont trough. Cooler today with early debris clouds and better rain chances by early afternoon; highs in the upper 80s. Hi-res model guidance is showing the bulk of this convection will take shape during the late afternoon and early evening. As we have seen with previous days, elevated instability has been the biggest driver of sustained convection and no reason to expect a large deviation today. It is worth noting that the scale of convection earlier this morning likely will delay surface heating and could hinder convective initiation. Still, the ingredients in place suggest that widespread showers and storms are likely, but still difficult to focus on a particular area. While instability decreases this evening, mid level forcing will continue. This lift is expected to extract all available instability with showers continuing into the late evening and overnight. Persistence forecast for coastal areas as onshore flow could push a few marine showers and storms toward the coast after midnight. Humid with lows in the mid and upper 70s. && .SHORT TERM /TUESDAY THROUGH FRIDAY/... The subtropical ridge will remain anchored near Bermuda through Friday while a series of upper troughs move from the Great Lakes into New England. Over the Carolinas, this should ensure a southwesterly upper level flow advecting in deep Gulf moisture plus a series of subtle upper impulses with attendant convective enhancement. The low level flow should remain southerly which will maintain a solid link to Atlantic moisture by way of the Bahamas. Precipitable water values should remain 2 inches or higher with surface dewpoints remaining in the 70s. From a pattern recognition standpoint this setup favors a very tropical weather pattern with good convective coverage over the coastal waters during the mornings spreading onshore after sunrise, then redeveloping inland during the afternoon hours. Traditional GFS MOS PoPs are 20-30 percent lower than newer NBM guidance through the period. Splitting the difference yields 50-70 percent coverage each day, perhaps peaking on Thursday. This is a good pattern to help alleviate this summer`s drought which was ranked "extreme" (D3) from Florence to Marion and Whiteville on last week`s U.S Drought Monitor update. Due to increased clouds and precipitation coverage, diurnal temperature ranges will remain constricted in this monsoon-like pattern. Highs around 90 Tuesday and Wednesday should remain in the mid-upper 80s Thursday and Friday. Overnight lows should generally fall into the mid 70s with upper 70s near the beaches. && .LONG TERM /FRIDAY NIGHT THROUGH SUNDAY/... GFS, Canadian, and ECMWF models show a front sneaking southward into the Carolinas late Friday night or Saturday morning. This feature likely won`t make it too far south and may stall across South Carolina for the weekend. Yesterday`s 12z ECMWF was the closest model we`ve got showing an airmass change. A more likely scenario is post-frontal easterly flow off the Atlantic maintains a sticky humid low level airmass. In the upper levels the subtropical ridge should begin to redevelop over the Southeast states as the upper trough that drove the front south moves out toward Bermuda. This should reduce convective coverage some, but with the stalled front we`re maintaining "chance" PoPs for showers and thunderstorms through the period. Highs both Saturday and Sunday are forecast to reach the upper 80s with lows 70-75. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... The current state of the atmosphere has not change much from the past few days and is expected to continue through the week. This is very moist, moderately unstable, and weak synoptic and mesoscale lift with a good chance of thunderstorms this forecast period. This morning convection is waning and developing inland, and thunderstorms with MVFR/IFR visibilities/ceilings are likely at the inland TAF sites at KLBT and KCRE. The thunderstorms are possible through 03 UTC. Overnight showers are expected to develop off the coast and KILM TAF is most likely to be impacted by the convection. KCRE and KMYR chance for the overnight convection is slightly lower than KILM. Winds are expected to be south to southwester at less than 10 knots through the period along the coast. Wind speeds will be less than 4 knots overnight. MVFR vsby and ceiling is possible at KLBT and KFLO after 08 UTC. Extended Outlook...Potential for IFR/MVFR with showers and thunderstorms each day. && .MARINE... Through Tonight...No changes from the previous forecast. South winds at 10-15 knots during the day weaken slightly and become southwesterly overnight. Gusts up to 20 knots during the day as a weak sea breeze develops. SE swell continues at 2-3 feet at 9 seconds. Tuesday through Friday Night...A warm and humid weather pattern will continue across the Carolinas with Bermuda High Pressure remaining well offshore. South-southwest winds (strongest Tuesday afternoon through Wednesday at a solid 15 knots) are expected through the period. Tropical moisture lifted north out of the Bahamas will maintain scattered showers and thunderstorms across the coastal waters with the most extensive coverage anticipated during the morning hours. We`re not expecting a washout on any particular day, but convection should be widespread enough to present a marine weather challenge. Confidence is not particularly high yet, but by late Friday a cold front could advance far enough south to begin impacting wind directions, potentially turning them west to northwest. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...Coastal Flood Advisory from 10 PM this evening to 1 AM EDT Tuesday for NCZ107. SC...None. MARINE...None. && $$ SYNOPSIS...TRA UPDATE...RH NEAR TERM...21 SHORT TERM...TRA LONG TERM...TRA AVIATION...21 MARINE...TRA/21