textproduct: NWS Wilmington

WHAT HAS CHANGED

Storm chances have increased slightly for Friday. There is a Marginal Risk of severe storms on Saturday and possibly again on Sunday.

KEY MESSAGES

1) Heat and Humidity Will Continue to Build Through the Weekend; Potentially Producing Extreme Heat; Thunderstorm Chances May Provide Localized and Temporary Relief

2) Another Period of Dangerous Heat Possible Next Week.

DISCUSSION

KEY MESSAGE 1...Heat and Humidity Will Continue to Build Through the Weekend; Potentially Producing Extreme Heat; Thunderstorm Chances May Provide Localized and Temporary Relief.

Building heat and humidity between offshore Bermuda high pressure and a front to our west will begin to impact to the area Friday and culminate over the weekend. Afternoon temperatures in the mid to upper 90s combine with dewpoints in the lower to mid 70s will drive an increasing heat risk. While a few inland locations could flirt with Heat Advisory Criteria(apparent temps of 105 to 110 F) on Friday, much of the forecast area is currently expected to reach these levels Saturday and Sunday.

A broad mid/upper level trough with embedded convective complexes currently progressing across the Lower Mississippi Valley will shift eastward into the SE US on Friday. Remnant mesoscale convective complexes(MCVs)and an associated plume of enhanced moisture may support scattered to numerous showers and storms across the area Friday afternoon and evening, mainly inland, with rain chances shifting along the coast overnight. Signals in both the CAMS and coarser deterministic guidance have been more robust over the past several runs, with HREF LPMM output suggesting localized heavier rainfall amounts of 1-3 inches are possible over the Pee Dee and Cape Fear regions. Cannot rule out isolated flash flooding, mainly in urban and poor drainage areas.

On Saturday, convection coverage should be more isolated to scattered in nature, with activity largely driven by the seabreeze through the evening ahead of a weak sfc front. The front is expected to sag into the area late Saturday night into Sunday. Higher rain chances along and ahead of the front could support widespread clouds, potentially providing some localized relief. Although, deep layer shear will remain weak(10-15kts), moderate to strong destabilization within an increasing moist, high PWAT airmass on both Saturday and Sunday may support locally damaging winds through precip loading and wet microburst processes.

KEY MESSAGE 2...Another Period of Dangerous Heat Possible Next Week.

The weak sfc front is forecast to slip slowly south of the area, sometime during the day on Monday, though timing remains somewhat uncertain. In it's wake, sfc high pressure and associated NELY low- level flow may bring a brief reprieve from the heat, primary due to lower BL dewpoints in the upper 60s/near 70 and less oppressive humidity.

However, the onset of SELY low return flow leading and rising humidity, combined with a strong mid-level high (~597 dm) centered over the Tn Valley and mid South, will likely bring increasing chances of extreme heat by the middle part of next week. Heat indices are expected to climb back into the 105-110 F range, setting up what could very well be several days of extreme heat centered around the upcoming 4th of July holiday.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Dry VFR conditions are expected to persist through much of the forecast period. A possible exception is patchy fog that may develop Friday morning around daybreak. Any fog that does develop Friday morning will quickly scour out owing to strong daytime heating. Scattered to possibly numerous showers are storms with associated sub-VFR restrictions are expected Friday afternoon and evening.

Southeasterly 7-10 kt at KILM, KCRE, and KMYR with today's seabreeze circulation, while remaining more southerly inland TAF sites. Winds will increase along the coastal TAF sites Friday afternoon, with gust of 15 to 20kts.

Extended Forecast...Patchy fog is possible Saturday morning, especially near areas that receive heavy rain the day/evening before. Scattered diurnal and sea-breeze driven convection expected Saturday. More organized and widespread shower and storm chances are possible Sunday afternoon as a weak sfc front moves into the area. Dry conditions are expected early next week.

MARINE

Light SELY winds today will become dominated by the sea breeze during the afternoon, before diminishing this evening and tonight. Seas will average 1-2 ft.

The pressure gradient tightens Friday as high pressure offshore and low pressure inland support increasing southerly flow of 12 to 17 kts. Seas will gradually build to 2-3 ft Friday afternoon and 3-4 ft Friday night. Winds increase further Saturday and veer southwesterly as an area of low pressure traverses the Mid-Atlantic. Sustained winds of 17-20kts with occasion gusting near 25 knots are expected, strongest INVOF of Surf City. Seas will build to 3-4 ft out 20 nm, and up to 5 ft out 60 nm.

As the surface low shifts offshore Sunday, winds diminishes to 10-15 knots, while remaining generally southerly to southwesterly. Seas gradually subside but remain elevated at 2-4 ft.

A back door cold front will drop southward through the region late Sunday into Monday. Northeasterly flow behind the front will peak around 15 knots on Monday afternoon. Seas respond by building to 3-4 feet in the nearshore waters, 4-5 feet in offshore NC waters.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...None.