textproduct: NWS Wilmington

WHAT HAS CHANGED

Discussions updated. Precip chances have been lowered for Sunday and high temperatures increased.

KEY MESSAGES

1) Temperatures well above normal Thursday through Sunday with heat indices over 100 degrees.

2) Limited rain chances until the arrival of a cold front this weekend.

DISCUSSION

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

KEY MESSAGE 1 DESCRIPTION... Mid-upper ridging will remain in control through this weekend while high pressure remains in place offshore. As the ridge strengthens on Thursday and shifts towards the area on Friday, temperatures are expected to rise well-above normal, with low-mid 90s expected away from the coast on Thursday and mid-upper 90s on Friday. The sea breeze will offer relief closer to the coast. However, as the flow aloft becomes more westerly on Friday, downslope flow and a pinned sea breeze will allow for even coastal areas to reach the low 90s. Heat index values inland should reach the upper 90s to low 100s on Thursday and at least into the low 100s on Friday, although whether dew points stay high enough to support 105F or greater for 2+ hours during the afternoon is questionable as model guidance this time of year tends to overestimate dew points.

With a weak cold front shifting into the Piedmont region on Saturday and the ridge axis overhead, another hot day is expected with heat indices reaching or exceeding 100F, but increased cloudiness and scattered precip along the sea breeze should result in slightly lower daytime highs than on Friday. With the front lifting back north on Sunday and the ridge axis nearby, pop- up convection should be more isolated than on Saturday, allowing for yet another day of heat and humidity where heat indices could reach around 105F.

KEY MESSAGE 2... Limited rain chances until the arrival of a cold front this weekend.

KEY MESSAGE 2 DESCRIPTION... With a mid-upper ridge axis west of the area, the coverage of showers and storms should remain very isolated through the end of the week. Although increasing amounts of instability will be present for thunderstorms as temperatures rise, forecast soundings depict a considerable amount of subsidence and dry air in the mid-upper troposphere, which will inhibit development and keep coverage limited. Something to watch is the low chance for an isolated strong to severe storm on Friday due to the heat helping to produce moderate instability and large DCAPE (>1000 J/kg) overlapping with around 20 kts of effective shear. While most of the area will remain dry, if a pop-up storm can get going despite the dry air, it may produce strong wind gusts. In addition, if a storm from the Piedmont can propagate into the area, a strong wind gust threat could also exist.

Over the weekend, the mid-upper ridge axis will shift eastward as a surface cold front pushes southeast. This front will slow down as it moves east of the Appalachians into the ridge, but its presence should increase the coverage of afternoon showers and storms somewhat for Saturday, although continued dry air in the middle troposphere will continue to limit development and coverage. As is typical for fronts this time of year, it should stall near or over the area before lifting back northward on Sunday. Thus, expect more in the way of isolated convection on Sunday as the front moves away. Thereafter, guidance tools generally suggest more substantial troughing will affect the eastern US, bringing increased chances for showers and storms ahead of a stronger cold front, but the specifics on when and where remain murky at this time.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

High confidence in prevailing VFR conditions persisting through the TAF period as steady southwest flow holds firmly in place. Transient MVFR cigs due to cumulus may affect the terminals during mid-late morning before lifting above MVFR levels by around noon.

Extended Forecast...Restrictions from isolated afternoon/evening storms possible Thursday, Friday, and Sunday, mainly inland. Increased daytime coverage of storms on Saturday will increase potential for restrictions at all sites. Otherwise, VFR.

MARINE

High pressure near Bermuda today will continue moving eastward through this weekend into the central Atlantic. As a result, expect southerly winds into tonight to veer to southwesterly winds by early Thursday with speeds between 10-20 kts through Friday night as a Piedmont trough sets up and tightens the pressure gradient against the high. With very warm temperatures on land, expect a healthy sea breeze to develop as well, and result in gusty south to SSE winds near the coast which can top out around 20-25 kts during the afternoon. As a cold front shifts in from the northwest and the high moves further away, winds slacken over the weekend, but a healthy sea breeze will continue to bring enhanced winds near the coast each afternoon.

Seas will run generally 1-3 ft in the 0-20nmi zone and 2-4 ft in the 20-60nmi zone. An easterly 8 sec swell will predominantly contribute to the wave spectrum through Wednesday with waves of 2-3 ft before subsiding to 1-2 ft on Thursday and 1 ft or less from Friday onward. Enhanced winds over Thursday and Friday will lead to wind waves contributing 2-3 ft (3-4 ft) waves in the 0-20nmi (20-60nmi) zones during those days. Lingering southerly wind waves of 1-3 ft will continue through Sunday with a 1 ft or less easterly swell.

CLIMATE

Hot temperatures are expected this weekend which may reach record highs. The hottest day is expected to be Friday, 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...None. SC...None. MARINE...None.