textproduct: NWS Wilmington

WHAT HAS CHANGED

Heat Advisory remains in effect for most of the area until 8 PM EDT this evening. Another Heat Advisory will go into effect for all of northeast SC and southeast NC from 11 AM to 8 PM EDT Friday.

Elsewhere, aviation discussion updated below for the 18Z TAFs.

KEY MESSAGES

- 1) Well above normal temperatures and humidity will bring triple digit heat indices through Saturday. Heat Advisory in effect Friday.

- 2) A cold front will result in increased chances for showers and thunderstorms this weekend, followed by cooler temperatures early next week.

KEY MESSAGE 2

A cold front will result in increased chances for showers and thunderstorms this weekend, followed by cooler temperatures early next week.

An upper low currently spinning over Quebec will gradually move to the southeast towards New Brunswick/Nova Scotia/Prince Edward Island over the weekend, ejecting into the Atlantic by early next week. Its associated trough will deepen and drop through the mid-Atlantic states, allowing this summer ridge to retrograde and exit stage left towards the Plains. Between these features and the upper low over the PNW, this creates an Omega blocking pattern. Haven't seen one of those in awhile.

The oppressive summer heat gets one more punch in Saturday, before the heights aloft finally start to come down late in the day. A surface cold front pushes in from north to south, allowed for showers and storms to kick up sometime late Saturday afternoon through the evening. Bulk shear continues to tease 25 kts, aided by increased northwesterly flow aloft. SPC now has the area in a "Slight Risk" (threat level 2/5) for severe weather, with the main threat being damaging winds.

Still have healthy rain chances in place Sunday. Think the front should ultimately clear the area and head well south, but some guidance still has it lingering through parts of SC, while others have strengthening low pressure form along the front and spread moisture back into the area.

Drier weather in store Monday and Tuesday, with high temperatures in the upper 80s.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Mostly VFR through the 18Z TAF period. SE breeze at 8-10 kts has picked up at the coastal terminals due to the seabreeze, but winds go calm again late tonight. Seeing more of an increased signal for fog before sunrise Friday morning. May have more minor MVFR visibilities near KILM, but there are more significant concerns near KFLO, which may drop down into IFR by 09-10Z. Fog should mix out by 13Z or so. Gradient winds pick up slightly out of the SW later Friday morning, before the seabreeze starts building back in towards the end of the period.

Extended Outlook...Showers and thunderstorms should become numerous across the area late Saturday afternoon through Sunday as a cold front arrives from the north. The highest potential for IFR conditions in convection is expected Saturday evening. Prevailing VFR conditions should return by Monday and Tuesday.

MARINE

Through Tuesday...Light S to SE winds continue tonight. On Friday, the high will begin to retreat offshore as pressures lower to our north in advance of an approaching cold front. This tightened pressure gradient should lead to increasing south to southwest winds Friday afternoon, likely exceeding 15 knots north of Cape Fear.

Moderate west to southwest winds are expected Saturday up until the cold front arrives during the evening. This front should be accompanied by gusty thunderstorms that may sweep rapidly offshore Saturday night. There are still questions as to how far south the front moves on Sunday, but it appears to remain near enough to the area for good chances for showers or thunderstorms to continue, especially south of Cape Fear. Drier weather should arrive on Monday and Tuesday.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Heat Advisory until 8 PM EDT this evening for NCZ087-096-099- 105-107-109. Heat Advisory from 11 AM to 8 PM EDT Friday for NCZ087-096-099- 105>110. SC...Heat Advisory until 8 PM EDT this evening for SCZ017-023-024- 032-033-058-059. Heat Advisory from 11 AM to 8 PM EDT Friday for SCZ017-023-024- 032-033-039-054>056-058-059. MARINE...None.