textproduct: NWS Wilmington

WHAT HAS CHANGED

Aviation discussion updated for 12Z TAFs.

KEY MESSAGES

1) Isolated strong to severe storms possible today and Sunday.

2) Heat and humidity build today and Sunday.

3) Prolonged and dangerous heat expected next week with limited rain chances.

DISCUSSION

KEY MESSAGE 1... Isolated strong to severe storms possible today and Sunday.

Rapid destabilization late this morning is likely to set the stage for sea breeze convection early this afternoon. The introduction of dry air aloft could lead to a strong, albeit isolated, wind gust. Stiff synoptic southerly flow at the coast will dampen the forcing available along the leading edge of the sea breeze, especially once cold pools congest the environment. Inland areas will likely see more isolated convection once convective temps are reached during the early to mid afternoon. Downslope flow will also keep the boundary layer too dry for anything more than isolated surface-based coverage of storms for inland areas this afternoon. Similar to coastal areas, any storms that develop may produce a strong wind gust.

A weak shortwave traversing the southern Appalachians is expected to reach the I-95 corridor this evening. An ongoing cluster of thunderstorms harbored by this shortwave will push eastward through the Carolinas later today, expanding during peak heating over western NC. As the cluster moves eastward, severe weather chances increase due to warm temperatures and increasing shear in portions of NC. The timing of this convection will be a key component of today's forecast with HREF and deterministic solutions bring the storms into our area just before or around sunset. SPC has increased the severe weather threat to Slight (Level 2 of 5) for a few damaging wind gusts along this line. The best chance for severe weather will be central NC.

Isolated storms are expected on Sunday, primarily along the Piedmont trough during the afternoon and ahead of a weak surface front during the evening. The initial round of convection will be assisted by another weak shortwave. Dry air aloft could support a few damaging wind gusts. The best chance for strong wind gusts will be for northern portions of the area.

KEY MESSAGE 2... Heat and humidity build today and Sunday.

Warmer and more humid today than previous days. Stiff south winds will keep coastal communities in the lower 90s, but the addition of humidity promises little relief. Inland areas should climb into the mid 90s. Dew points will be a little lower inland, especially with winds slightly more SW than previous days and drier air aloft to limit clouds and convection. Heat indices should easily reach 100 this afternoon; between 100-104 at the coast. Heat-related stress, illness, and impacts are possible --- especially for anyone without effective cooling and/or adequate hydration.

Sunday will likely be the warmest day of the weekend. Westerly winds will pin the sea breeze to within a few miles of the coast and downslope flow will push temperatures into the mid 90s for most of the forecast area. West winds typically favor better mixing and lower dew points and the 1-2 degree decrease should keep heat indices between 100-105 on Sunday afternoon. Coastal areas may creep a little closer to the heat advisory threshold where compressional heating at the sea breeze combines with locally higher dew points. Regardless of an active headline, heat-related stress, illness, and impacts are possible --- especially for anyone without effective cooling and/or adequate hydration.

KEY MESSAGE 3... Prolonged and dangerous heat expected next week with limited rain chances.

A weak cold front will move south of the region on Monday. This may bring a brief reduction in heat and humidity levels through Tuesday in NE flow. Southeasterly flow develops on Tuesday evening and continues through much of next week with high pressure offshore. A strong ridge will amplify over the eastern US through mid week and persist into the holiday weekend. Air temperatures could approach record highs late next week. Combined heat and humidity will produce prolonged and dangerous heat indices, especially late next week. Extreme heat will be centered around the July 4th holiday. The ridge and dry air aloft will put a lid on rain chances for much of next week.

AVIATION /09Z SATURDAY THROUGH WEDNESDAY/

12Z Sat thru 12Z Sun: High confidence in mainly VFR conditions outside of early morning stratus (and a bit of fog) inland (mainly at KLBT) and showers/storms pretty much anytime thru the period (mainly near the coast this AM and then spreading inland during the day before diminishing from SW to NE tonight. Thus, the SE NC terminals (KILM/KLBT) generally have the best chance of seeing rain restrictions. Otherwise, gusty SW winds during much of the daytime, especially near the coast (KILM/KCRE/KMYR).

Extended Forecast...Storms are likely on Sunday and Sunday night ahead of a cold front. Front lingers Monday with isolated to scattered storms. VFR Tuesday and Wednesday.

MARINE

Winds increase further Saturday and veer southwesterly as an area of low pressure traverses the Mid-Atlantic. Sustained winds up to 20 knots are possible near the coast this afternoon. A few gusts to 25 knots are also possible. Recreational boaters should be cautious in area inlets on Saturday.

As the surface low shifts offshore Sunday, winds diminish to 10-15 knots, while remaining generally southerly to southwesterly. Seas gradually subside to 2-3 ft out to 20 nm, but remain elevated at 3-4 ft out to 60 nm.

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...Beach Hazards Statement through this evening for NCZ106-108. SC...None. MARINE...None.