textproduct: NWS Wilmington

WHAT HAS CHANGED

Made a small update to introduce small PoPs along the northern areas for later this afternoon and early this evening. Currently the cap is still holding, but if anything can develop the projected CAPE suggests there could be an isolated strong t-storm or two. Currently SPC highlights a Marginal Risk across much of the forecast area.

Previous update: Confidence in major to extreme HeatRisk today through Sunday is increasing. Confidence in development of showers and thunderstorms this weekend is increasing.

Updated 12Z aviation discussion.

KEY MESSAGES

1) Temperatures well above normal through Sunday with heat indices over 100 degrees expected each day.

2) Low rain chances today before a cold front brings increased rain chances for the weekend and start of next week.

DISCUSSION

KEY MESSAGE 1...Temperatures well above normal through Sunday with heat indices over 100 degrees expected each day.

KEY MESSAGE 1 DESCRIPTION...Mid-level ridge peaks in strength today, bringing the hottest temperatures so far this year. The combination of subsidence and westerly downslope flow will increase temperatures several degrees from Thu. Both 850 temps and partial thickness indicate an area along and west of I-95 where triple digit heat will be possible. Expect only a few areas to realize 100F, but widespread 98-99F is likely. Temperatures well above normal will even extend to the coast today with flow at 925mb keeping the sea breeze pinned near the coast for much of the day. Still a fair amount of low level dry air, which will limit dewpoints. However, the extreme nature of the heat means much of the area will flirt with heat advisory criteria and have no plans to alter the current heat advisory. Although the ridge starts to weaken Sat and more so Sun, temperatures well above normal continue. Highs will drop a bit from Fri, but there will also be a slight increase in boundary layer moisture. A slight increase in dewpoints would more than offset the slightly cooler temperatures thus additional heat advisories may be needed. Cloud cover and storm coverage this weekend will also play a role in the need for additional heat products.

KEY MESSAGE 2...Low rain chances today before a cold front brings increased rain chances for the weekend and start of next week.

KEY MESSAGE 2 DESCRIPTION...Ridging aloft peaks today, leading to a hostile convective environment. Despite precipitable water approaching 2" and SBCAPE pushing 3000 J/kg, mid-level dry air and subsidence will really work against deep convection. Similar to Thu it will take enhanced low level convergence, either with the sea breeze or the Piedmont trough, to get deeper convection going. Any storms that do develop are likely to be short lived and moving northwest to southeast. Perhaps the best chance for storms will be late evening as waning convection along the Piedmont trough moves into far western counties.

On Sat a subtle weakness develops in the 5h ridge with 2 weak 5h high centers developing later Sat into Sun. One is to the southwest and the other to the southeast. While forecast soundings do show the environment becoming more favorable for storm development, the main factor in greater storm coverage will be enhanced convergence along the weak cold front moving into the area. especially where the sea breeze and the cold front come together. However, dry air remains an issue and will have an impact on storm coverage and duration. Front drifts north of the area Sun with rain chances trending lower. Rain potential will be higher than the last few days with the 5h pattern shifting from ridging to broad troughing. Shortwaves moving through the flow aloft and a reduction in mid-level dry air will keep rain chances elevated into the middle of next week.

AVIATION /13Z FRIDAY THROUGH TUESDAY/

VFR expected. The only exception would be isolated storms near coastal terminals in the afternoon and near inland terminals in the evening. Brief MVFR/IFR CIGs and VSBYs are possible in storms. WSW winds ~10 kt with the sea breeze bringing S winds ~15 kt. Higher gusts are possible through the day, more frequent along the coast. Winds will turn northerly late tonight with the passage of a weak cold front and perhaps some lower CIGs.

Extended Forecast...MVFR/IFR from afternoon and evening storms possible this weekend and early next week. Otherwise VFR.

MARINE

Offshore high pressure will maintain southwest winds across the waters through the middle of next week. For the bulk of the forecast the gradient will support 15-20 kt within 20 nm and a solid 20 with 25 kt at times beyond 20 nm. The only day in the forecast where this will not be the case is Sat. A weak front moves in from the northwest, stalling before reaching the waters. The front will weaken the gradient, resulting in speeds around 10 kt inside 20 nm and 10-15 kt beyond 20 nm. Seas 2-3 ft this morning with widespread 3 ft in the afternoon and evening. Seas drop closer to 2 ft Sat and Sat night with the decrease in wind speeds. Winds return on Sun, ramping up seas with 2-4 ft in the morning becoming widespread 4 ft for the afternoon, a pattern that will repeat Mon and Tue. Near 20 nm and beyond 5 ft seas are likely to develop late Sun and linger into Sun night.

CLIMATE

Hot temperatures are expected this weekend which may reach record highs. The hottest day is expected to be today, but Sunday may reach similar levels. The high temp records for each climate site are provided below for these dates (June 12 and 14).

Location Jun 12 Jun 14 Wilmington, NC: 98 (1920) 99 (1958) Lumberton, NC: 103 (1911) 101 (2015) N. Myrtle Beach, SC: 96 (2016) 98 (2010) Florence, SC: 97 (2022) 102 (1958)

ILM WATCHES/WARNINGS/ADVISORIES

NC...Heat Advisory until 8 PM EDT this evening for NCZ087-096-099- 105-107-109. SC...Heat Advisory until 8 PM EDT this evening for SCZ017-023-024- 032-033-039-055-058-059. MARINE...None.