textproduct: NWS Wilmington

WHAT HAS CHANGED

Updated aviation discussion for 00Z.

KEY MESSAGES

1) The best rain chances in weeks will develop tonight into Sunday as a cold front moves through the eastern Carolinas.

2) Rain chances will increase Tuesday lingering through the weekend. Overall rainfall amounts look to remain low with minimal impacts to drought conditions expected.

DISCUSSION

KEY MESSAGE 1...The best rain chances in weeks will develop tonight into Sunday as a cold front moves through the eastern Carolinas.

A weak cold front will move through the eastern Carolinas tonight. Cooler mid and upper level temperatures associated with an accompanying upper disturbance will erode the subsidence inversion sufficiently for convection to accompany the front. Forecast PoPs are as high as 60-80 percent across the Pee Dee and Lumberton region late this evening, with 40-60 percent rain chances developing along the coast late tonight into Sunday morning. This is based mainly on NBM blends with local enhancement from the HREF through 10z Sunday.

Storm total QPF through Sunday evening should average 0.2 to 0.4 inches for most areas, and potentially as high as an inch in the Wilmington area as several high res models suggest a second cluster of showers and storms will develop Sunday morning/early afternoon in advance of a stronger surge of northeast winds that will work its way across the area Sunday afternoon. This surge is the real front which will be followed by an airmass change and cooler temperatures building in Sunday night.

In terms of drought relief, this weekend's system is not likely to significantly improve the D2-D3 drought currently in place across the eastern Carolinas. Six-month rainfall deficits are in the 6-10 inch range, so even a solid inch of rain would only erode a small portion of that accumulated water deficit. Aside from isolated showers in the Wrightsville Beach and Conway areas yesterday, it's been 18-19 days since measurable precipitation fell across most of our forecast area.

KEY MESSAGE 2...Rain chances will increase Tuesday lingering through the weekend. Overall rainfall amounts look to remain low with minimal impacts to drought conditions expected.

Compared to the previous forecast, rain chances have decreased for Tuesday as drier air is tough to erode with the shortwave ahead of the cold front. Moisture will continue to increase into Wednesday with more appreciable rain chances, the cold front moving through into Thursday. Unsettled weather lingers through the end of the period as waves of PVA move through aloft with localized low pressure at the surface. Best rain chances for the period will be Wednesday with the frontal passage, but rainfall amounts greater than 0.5" are unlikely. The subsequent disturbances also don't look to bring much rainfall, though there is the added uncertainty towards the end of the work week. Embedded thunderstorms could also produce slightly higher rainfall amounts Wednesday and Thursday, with severe weather not expected at this time.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Showers and isolated thunderstorms are moving into the forecast area from the west this evening as a weak cold front pushes eastward. This will bring passing light showers to the terminals overnight with vis predominantly remaining above MVFR levels. Support for thunder is meager over most of the area expect just off the coast, so expect coverage to remain isolated at worst, with any vis restrictions being brief. Ceilings carry lower than typical confidence in this scenario as guidance tools tend to overexaggerate how low cig heights get during the passage of a weak frontal system. While cigs may slip below 1000 feet tonight, have opted to reserve these mainly to PROB30 and TEMPO groups as they should be transient in nature. Otherwise, expect at least MVFR cigs to persist through much of tomorrow with passing showers and isolated thunderstorms at times until a surge of gusty north-northeast winds arrive later in the afternoon, which may feature a narrow band of heavy showers and perhaps a thunderstorm along it. Behind this feature, skies should scatter out inland while greater moisture near the coast should keep restrictions in place through 00Z.

Extended Forecast...Lingering MVFR cigs remain possible through Sunday night into Monday, mainly for the coastal terminals. There is a low potential for low stratus or ground fog Tuesday and Wednesday nights, along with impacts possible from showers or thunderstorms on Wednesday.

MARINE

Through Sunday...Today is the last day we're experiencing the summerlike weather pattern of south to southwest winds due to Bermuda high pressure offshore. A weak cold front should make it down to the beaches late tonight with light and variable winds expected to develop behind the boundary Sunday morning. Waves of showers and embedded thunderstorms are possible late tonight up until the arrival of a stronger surge of northeasterly winds Sunday afternoon into Sunday evening. Small Craft Advisory conditions may develop as early as late Sunday afternoon north of Cape Fear as wind speeds are expected to 20-25 knots by late in the day.

Sunday Night through Thursday...The cold front will be through with a strong NE surge moving across the coastal waters. Small Craft Advisory conditions will be met as NE winds gust ~25 kts within 20 NM and then ~30 kts 20-60 NM out. Gale Force gusts may be possible for the offshore waters of SE NC but for now it looks very brief. Seas 3-6 ft within 20 NM and 6-9 ft beyond. High pressure will lead to improving conditions late Monday through Wednesday with 2-3 ft seas and lighter NE winds becoming SW as the high moves away Tuesday night. Wind speeds will increase to 15-20 kts through Wednesday ahead of another cold front, seas near 4 ft. The front will move through sometime Thursday with winds turning to the NW.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...Small Craft Advisory from 5 PM Sunday to 2 PM EDT Monday for AMZ250. Small Craft Advisory from 8 PM Sunday to 2 PM EDT Monday for AMZ252-254-256.