textproduct: NWS Wilmington

WHAT HAS CHANGED

The Heat Advisory continues for Wednesday. Updated 00Z TAF discussion.

KEY MESSAGES

1)Dangerous heat to continue for several days.

DISCUSSION

KEY MESSAGE 1... Dangerous heat to continue for several days.

An area of low pressure off of the northeastern US coast which aided in downslope heating will push off to the north and east on Wednesday. The elimination of the downslope component will allow low level thicknesses to increase. Surface temperatures decrease by a few degrees as a result. More importantly, coastal areas should see a marginal benefit from the afternoon sea breeze. Cooling from the sea breeze will compete with increase dew points, so heat indices will only be marginally improved; down from the Extreme Heat Warning threshold in previous days. Mixing for inland areas should allow dew points to push heat indices below heat headline criteria. A Heat Advisory has been issued for coastal northeastern SC and areas east of I-95 in southeastern NC.

A weak frontal boundary along the NC and SC coast will assist the afternoon sea breeze and provide a more focused area for weak ascent on Wednesday afternoon. Areas west of I-95 will be limited by dry air aloft, but pooling PWs east of I-95, along with a progressing sea breeze and surface thermal low should produce isolated to widely scattered showers and thunderstorms.

By late this week, heights will start to rise in the west and some weak troughiness will develop in the east but not of sufficient strength for any heat-breaking frontal passages. Highs in the mid to upper 90s are expected to continue until Friday. These readings paired with dewpoints in the mid to upper 70s and occasionally low 80s will necessitate heat-related headlines each day. The only nuance will be which days will bring lower dewpoints down over inland zones where an advisory will be sufficient (HI values of 105- 109) and how much of the eastern CWA will requite a warning (HI values of 110 or higher).

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Predominant VFR. Question will be for MVFR fog tonight. Highest chances if any will be at KLBT and perhaps KILM, but formation shouldn't be until late (06-09Z) so additional confidence might come with the 06Z issuance. Even if VSBYs dip to MVFR restrictions may be brief/on and off. Then into Wednesday PROB30s have been included for afternoon convection at terminals with highest confidence.

Extended Forecast... VFR conditions are expected much of the week outside of any convection. Rain chances increase on Friday with afternoon convection possible through the weekend.

MARINE

Benign conditions expected for most of the period. Weak surface flow turns SW to light and variable overnight. Expect a period of light onshore flow Wednesday. Thereafter a more typical SW flow returns as the boundary washes out but wind speeds will remain very tame even by late summer standards. The approach of a front could lead to a slight inc in winds and seas Saturday. A SE swell will be coincident with the wind waves through the duration.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Heat Advisory from 11 AM to 8 PM EDT Wednesday for NCZ096-099- 105>110. SC...Heat Advisory from 11 AM to 8 PM EDT Wednesday for SCZ054>056- 058-059. MARINE...None.