textproduct: NWS Wilmington

WHAT HAS CHANGED

Several coastal products have been issued this evening for Saturday. A Coastal Flood Advisory has been issued for all local beaches for minor coastal flooding during Saturday morning's high tide. A High Surf Advisory has been issued for New Hanover and Pender county beaches for Saturday afternoon and night for breaking wave heights up to 6 feet. A High Rip Current Risk is in effect for east-facing beaches, with a Strong Longshore Current (and moderate rip risk) for S-facing beaches.

Aviation discussion updated for 0z TAFs.

KEY MESSAGES

1) Heavy rain will develop during Saturday and persist at times into Sunday morning. A few areas could see flash flooding as a result, especially across coastal areas. Isolated tornadoes are possible Saturday night into early Sunday.

2) Hazardous surf conditions and minor coastal flooding are likely this weekend.

3) Hazardous marine conditions are likely this weekend.

DISCUSSION

KEY MESSAGE 1...Heavy rain will develop during Saturday and persist at times into Sunday morning. A few areas could see flash flooding as a result, especially across coastal areas. Isolated tornadoes are possible Saturday night into early Sunday. Isaias is expected to make landfall along Gulf this evening and will remain far west of the forecast area. Even though it remains far to the west deep tropical moisture will overspread the area. As UVVs increase during Saturday with divergent flow expanding overhead the potential for heavy rainfall will exist especially Saturday afternoon into early Sunday morning. In fact, there are some scenarios that depict PWATs approaching 2.4 to 2.5 inches during Saturday which would rival the highest PWATs at the CHS RAOB for this time in October. While most guidance suggest a broad area of 2 to 4 inches, especially along coastal areas the HREF is showing a couple max areas greater than 10" just off the coast. Given the environment and proximity of some of the higher end rainfall amounts feel it is best to issue a Flood Watch for the coastal counties and Columbus County to start with. Additionally, there will be an opportunity with an environment supportive of tornadoes. This potential is similar across all of northeast SC and southeast NC highlighted by a Marginal (1 of 5) Risk Saturday night into early Sunday morning. A Marginal Risk is also highlighted across the forecast area during the remainder of the day Sunday but is more conditional at that time. Deeper drying during Sunday will impact the areal extent of any convection and the threat of flooding.

KEY MESSAGE 2... Hazardous surf conditions and tidal flooding are likely this weekend.

No changes to the previous thinking regarding coastal impacts this weekend. The increased onshore will yield rough surf and strong rip currents. A High Surf Advisory may be needed for Saturday due to breakers exceeding 5 ft in the surf zone, along with elevated rip current risks. Wave-runup may also cause minor to moderate beach erosion, especially those beaches with a weakened shoreline structure with high tide Saturday evening. Rough surf may linger into Monday but should improve as the winds become more favorable.

The winds coupled with the high astronomical tides during the next several high tide cycles will lead to minor coastal flooding along all area beaches and the lower Cape Fear River including downtown Wilmington. A Coastal Flood Advisory will likely be needed for high tide starting Saturday morning.

KEY MESSAGE 3... Hazardous marine conditions are likely this weekend.

See marine section.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

VFR conditions with abundant high clouds will continue through tonight, with MVFR cigs moving into NE SC as early as 10-11z. These cigs will continue expanding northward Saturday morning, potentially lowering to IFR by late morning for inland terminals. 0z TAFs carry predominant sub-VFR cigs around 800-1200 ft for most of the day Saturday. However, it is likely these low cigs will be more patchy in nature, versus widespread, and could see bouncing of cigs between VFR and MVFR/IFR during the day. This may be handled with the addition of TEMPOs during later TAFs.

Rain chances will also be increasing during the night, with high chances during the day Saturday into Saturday night. Showers are expected to be heavy at times, and therefore have included lower vsbys in the TAFs. Best chance for occasional thunder will be at coastal terminals during the day, though can't rule out isolated thunder for I-95 terminals. Northeasterly winds will be increasing into Saturday morning, turning easterly by Saturday afternoon, with gusts near 30 kts at coastal terminals and around 25 kts inland Saturday.

Extended Outlook...IFR conditions are likely inland Saturday night, with lower confidence at coastal terminals. Heavy rain and thunderstorms are expected Saturday night into Sunday, higher confidence at coastal terminals. VFR should return as dry air filters in late Sunday and Monday.

MARINE

Northeast to easterly winds will increase Saturday as the pressure gradient tightens between high pressure north of the area and Isaias which will be moving farther inland after landfall along the Gulf this evening. The flow will continue to veer to the southeast and south during Saturday evening and wind speeds will likely be aided by areas of convection. While sustained winds may be marginally at or below Gale Force frequent gusts to Gale Force support replacing the Gale Watch with a Gale Warning. Seas will become steeper and increase to 7 to 10 ft, especially offshore. The flow will finally veer to an offshore direction Sunday night with speeds decreasing with improving maritime conditions during Monday. At some point the Gale Warning will need to be lowered in favor of a Small Craft Advisory, possibly during Sunday.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Flood Watch from Saturday morning through late Saturday night for NCZ099-105>110. Coastal Flood Advisory from 6 AM to 10 AM EDT Saturday for NCZ106-108-110. High Risk for Rip Currents from 6 AM EDT Saturday through Saturday evening for NCZ106-108. High Surf Advisory from 2 PM Saturday to 8 AM EDT Sunday for NCZ106-108. Beach Hazards Statement from 6 AM EDT Saturday through Saturday evening for NCZ110. SC...Flood Watch from Saturday morning through late Saturday night for SCZ054>056-058-059. Coastal Flood Advisory from 6 AM to 10 AM EDT Saturday for SCZ054-056. High Risk for Rip Currents from 6 AM EDT Saturday through Saturday evening for SCZ054-056. MARINE...Gale Warning from 8 AM Saturday to 6 AM EDT Sunday for AMZ250- 252-254-256-280-284.