textproduct: NWS Wilmington

WHAT HAS CHANGED

Discussions updated. Abnormally hot conditions are increasingly likely this week, particularly from Wednesday through Friday, when Heat Advisories may be needed for parts of the area. Confidence is increasing in a cold front bringing unsettled weather and cooler temperatures over next weekend.

KEY MESSAGES

1) Unsettled weather is expected through this afternoon with scattered showers and thunderstorms bringing heavy rainfall at times.

2) Heat and humidity will return during the upcoming week.

DISCUSSION

KEY MESSAGE 1...Unsettled weather is expected through this afternoon with scattered showers and thunderstorms bringing heavy rainfall at times.

A weakness in the height field to the east of upper-level high pressure will keep scattered showers and storms in the picture, mainly along the sea breeze, through this afternoon into early this evening. Near the surface, a stalled front remains over the area, but will wash out tonight as surface high pressure takes over from the north. With precipitable water values around 2 inches, rainfall rates of 1-2"/hr can easily occur in a slow-moving thunderstorm. Thus, heavy rainfall capable of producing localized flooding is the primary concern, especially if storms end up backbuilding over the same area.

KEY MESSAGE 2...Heat and humidity will return during the upcoming week.

As upper-level high pressure builds eastward early this week, temperatures will rise above normal and shower/thunderstorm chances will decrease to below seasonal norms. With the core of the high pressure center shifting overhead by midweek, expect well-above normal highs in the middle to potentially upper 90s. Heat Advisory criteria may be reached in some areas between Wednesday and Friday, although enough dry air in the lower atmosphere may be able to keep heat indices from reaching 105F or greater across much of the area. Regardless of whether a Heat Advisory is needed, a period of mostly sunny, dry, and abnormally hot conditions (with heat indices of 100F or higher) is expected.

With regard to this heat extending beyond the work week, guidance tools are coming into better agreement regarding a cold front sliding down from the north next weekend, bringing increased shower and thunderstorm coverage, greater cloud cover, and considerably lower high temperatures. Although the timing of this front and its associated precip carries low confidence, confidence in the heat being cut off this weekend and replaced by unsettled weather is increasing.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

VFR conditions are expected to prevail at least through the first half of tonight outside of any passing showers or thunderstorms. These should continue to be focused along the sea breeze and track inland with time, bringing a risk for transient restrictions to the inland terminals later this afternoon. Overnight, calm winds and clearing skies from west to east are likely to yield extensive LIFR to VLIFR fog and/or stratus at least at KFLO and KLBT, with less confidence near the coast as dense high cirrus may hang on through the entire night. Depending on the extent of stratus and fog, it may take until 14Z or so for restrictions to clear at the inland sites, with a more rapid clearing likely for any restrictions that manage to develop near the coast. Otherwise, brief MVFR cigs may develop as cumulus starts developing by late morning and isolated sea breeze showers become a possibility as well.

Extended Forecast...There is moderate potential for MVFR to IFR conditions in low clouds and fog each morning through the middle of this week. As drier air moves in aloft, the coverage of showers and storms is expected to be isolated on Monday and little to none from Tuesday through Thursday.

MARINE

Through Thursday...Light east to southeast flow is in place as high pressure establishes itself north of the area. As the surface high pressure moves offshore into midweek, a return of south to southwesterly winds at 5-10 kts is expected. On Wednesday and Thursday afternoons, abnormally hot temperatures on land are expected to lead to a nearshore enhancement of the winds due to a stronger sea breeze, increasing speeds into the 10-15 kt range. Seas will run 1-2 ft in the 0-20nmi zones and 2-3 ft in the 20-60nmi zones, primarily driven by southeasterly 8-9 sec swells. Wind waves of 1 ft or less will continue in tandem with the daytime increase in winds. A longer period swell of 11 sec should reach the Southeast coast over Tuesday night into Wednesday, bringing seas into the 2-3 ft range in the 0-20nmi zones and 3-4 ft in the 20-60nmi zones. The period is expected to decrease to around 9 sec over Wednesday night while wave heights remain steady.

CLIMATE

Wilmington, NC is currently just below its hottest summer on record. The average temperature (the simple average of each day's high and low temps) is currently 0.1F below 2011 and 2010 as of the official daily climate report from August 29.

#1 2011 81.8 deg F #2 2010 81.8 deg F #3 2026 81.7 deg F (with two days to go) #4 2016 81.4 deg F #5 2022 81.1 deg F

Continuous temperature records began in Wilmington in 1874.

ILM WATCHES/WARNINGS/ADVISORIES

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