Area Forecast Discussion
Issued by NWS Wilmington, NC
Issued by NWS Wilmington, NC
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280 FXUS62 KILM 150615 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 200 AM EDT Mon Jul 15 2024 .SYNOPSIS... Above-normal heat and humidity will persist into midweek. Afternoon showers and storms will remain isolated to widely scattered through midweek until a front reaches down into the Carolinas and stalls late in the week. The front should lift back northward over the weekend and bring a return to more typical summertime pattern. && .UPDATE... Convection continues to hang on inland with elevated instability. Expect this to gradually come to an end over the next couple of hours and provide some beneficial rain to portions of Dillon County. Warm and humid overnight with many areas already seeing dew points hit the 80 degree mark. && .NEAR TERM /THROUGH MONDAY/... Atlantic high pressure will edge in from the east while a trough lingers inland. The upper high pressure system will weaken a bit as it slides more to the southeast. However, we are still expecting above normal temps to continue through the period with lows mainly in the mid to upper 70s inland tonight and highs Monday in the mid to upper 90s away from the immediate coast. Dewpoints should mix out/lower inland during the day Monday prior to the sea breeze passage but still should see peak heat indices up to around 110 degrees most locales. Some spots could more temporarily spike above 110 degrees but we don`t think it`s enough to justify an Excessive Heat Watch/Warning at this time. Thus, another Heat Advisory will likely be issued later today once the ongoing Heat Advisory ends. Otherwise, expect mainly isolated to widely scattered showers/storms into this evening due to the sea breeze, inland trough and some weak shortwave energy aloft, then again Monday afternoon. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... Mid-level ridging will remain in place through the period with heights remaining generally steady. Surface high pressure east of Bermuda will maintain a south to southwest flow as well, which will bring a return of moisture back into the area in the form of PWATS in the 2-2.25" range. Despite this, vertical mixing on Tuesday and Wednesday should act to bring dew points down into the lower 70s, with perhaps some upper 60s inland, during the early to mid-afternoon. Most model guidance has been over-forecasting dew points lately, and have opted to scale these back in the short term by leaning on the GFS for this period. In light of this, while Heat Advisory-level heat indices remain possible, widespread heat indices exceeding 105F for much of the day appear less likely in the short term. Otherwise, diurnal pop-up convection looks to increase in overall coverage on Tuesday and Wednesday as PWATs slowly rise and modest capping diminishes. Nevertheless, with no notable forcing mechanism besides the sea breeze and Piedmont trough, no more than widely scattered development is expected, with perhaps some focus near these two features. Otherwise, scattered fair- weather cumulus can be expected. High temps are expected to reach the middle 90s on Tuesday and low-mid 90s on Wednesday, with greater low-level cloud cover and possibly more high-level debris clouds expected to limit temps somewhat on Wednesday. Low temps in the mid- upper 70s are expected each night. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A significant shortwave trough is expected to pivot through the Great Lakes on Wednesday into Thursday and continue across New England over Thursday night and Friday. This will send a cold front towards our region and bring decreasing mid-level heights from Wednesday night into early Friday. With PWATs rising into the 2.2-2.4" range ahead of this front, showers and thunderstorms will be capable of producing very heavy rainfall and localized flash flooding. Expect overall coverage of showers and storms to increase with the approach of this front and the lowering of heights, with Thursday and Friday seeming like the best two days for scattered to potentially numerous storms across the area. The ECMWF Extreme Forecast Index is showing some signal for excessive rainfall across at least the northern half of the area on Friday in association with this front, particularly if it stalls near or over the CWA. The shortwave driving this front lifts away and ridging noses back in from the southeast after Friday, causing the front to stall out across the Piedmont and lift back northward. Thus, have opted to cap PoPs in the high chance range for the Saturday and Sunday timeframe, but these may end up being too high if the front indeed lifts well to our north over the weekend. Temperatures will depend on the coverage of shower and storm activity as well as their debris clouds which can limit or stop heating during the mid-late afternoon. Thus, highs were held at around 90F on Thursday and in the mid-upper 80s on Friday. High temps on Saturday and Sunday are less certain as the coverage of convection may be much more isolated while ridging builds back in at the same time. So, the mid-upper 80s currently reflected may be adjusted upward in future forecasts. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR to dominate this period. The exception will be possible periodic restricted vsby from BR and low stratus ceilings, mainly across the inland terminals. Boundary layer winds to remain active, keeping the fog from worsening. Isolated/Widely scattered afternoon/evening tstorms warrants atleast VCTS across all terminals, forcing from the sea breeze and an inland sfc trof will be enough for this activity to occur. Too soon to include specifics in regards to include PROB30 or TEMPO tstorm groups. Flow generqally SW to W around 5 kt this morning, increasing to 10-15 kt at the coastal terminals once the sea breeze develops and progresses inland midday thru this evening. Extended Outlook... Atlantic high pressure will bring the return of a more typical summertime pattern with diurnally-driven convection with brief restrictions possible daily. VFR should otherwise dominate outside of any early morning fog/low cigs. By Thu, a cold front will drop into the Carolinas accompanied by an increase in shower/storm coverage thru Fri. && .MARINE... Through Monday...Atlantic high pressure will edge in from the east while a trough lingers inland. This will lead to fairly typical summertime conditions with periods of higher winds, mainly from the afternoon/evening sea breeze and nocturnal surging. However, winds should mostly stay below 20 kt with seas 4 ft or less so we are not expecting to need a Small Craft Advisory. Monday night through Thursday... Bermuda high pressure dominates the low-level flow through the period, even with the approach of a cold front on Thursday. South to southwest winds in the 10-20 kt range prevail with gusts expected to mainly stay below SCA criteria. Waves will remain elevated in the 3-4 ft range due to a combination of decreasing southeasterly swell at 8-9 sec and increasing southerly wind waves. The southeast swell is expected to diminish through Thursday with heights of 2-3 ft on Monday night decreasing to 1 ft or less by Thursday. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...Heat Advisory from 10 AM to 8 PM EDT Monday for NCZ087-096-099- 105>110. SC...Heat Advisory from 10 AM to 8 PM EDT Monday for SCZ017-023-024- 032-033-039-054>056-058-059. MARINE...None. && $$ SYNOPSIS...ILM UPDATE...21 NEAR TERM...RJB SHORT TERM...ABW LONG TERM...ABW AVIATION...DCH MARINE...RJB/ABW