textproduct: NWS Wilmington

WHAT HAS CHANGED

Aviation discussion updated for 12Z TAFs.

Several new coastal and beach hazards have been raised due to high tides and dangerous surf. Forecast highs today have been nudged down by several degrees west of the Cape Fear area due to clouds. Forecast shower chances today have been increased slightly across the Pee Dee region. Most other changes were minor.

KEY MESSAGES

1) Minor coastal flooding and beach erosion are possible during each of the next several high tides.

2) After scattered showers end today, the coolest airmass since early June will build across the Carolinas.

3) Strengthening offshore low pressure will bring significant beach hazards.

DISCUSSION

KEY MESSAGE 1...Minor coastal flooding and beach erosion are possible during each of the next several high tides.

Strong northeast wind is banking water up against the east- facing beaches. At the time of this writing, tidal anomalies at Wrightsville Beach were measured at +1.5 feet and +1.3 feet at Myrtle Beach. This morning's 6 AM high tide should have enough storm surge associated with it to reach minor coastal flood levels north of Cape Fear where a Coastal Flood Advisory has been issued. The Cape Fear River will also likely reach minor flood stage at the downtown Wilmington gauge during its 8:30 AM high tide this morning.

As considerable storminess continues for the next few days offshore, models suggest there will be a +1.5 to +2.2 foot storm surge present through at least Saturday.

This means each high tide will have the potential to cause minor flooding. We're most concerned with this evening's and Friday evening's high tides at the New Hanover and Pender county beaches which could exceed flood stage by up to 1 foot. The surge will be somewhat lower along the Brunswick County and South Carolina beaches where flood stage could still be reached during high tides this evening and Friday evening. Objective beach erosion guidance indicates that may be sand loss experienced during high tides through Saturday mainly on the Pender and New Hanover county beaches.

KEY MESSAGE 2...After scattered showers end today, the coolest airmass since early June will build across the Carolinas.

Despite rather cool conditions today with temperatures stuck in the 60s (lower 70s along portions of the coast) an approaching upper level disturbance should ignite scattered elevated convective showers. Forecast soundings from both the GFS and NAM show small positive instability resulting when parcels between 875-800 mb are lifted.

The best PVA and implied ascent should develop late this afternoon into early this afternoon across the Pee Dee region where showers are most likely to occur. Scattered showers should make their way down to the South Carolina coast during the afternoon. Thunder chances are not zero, but remain quite low given the meager CAPE values noted on forecast soundings.

Once the upper disturbance pushes off the coast tonight, 850-925 mb winds that have been easterly should back northerly, shutting off moist Atlantic inflow and allowing cool and dry Canadian air to spread across the area. Lows tonight should dip into the 50s each night through Sunday or Monday night. Both Friday night and Saturday night should have good radiational cooling conditions from clear skies and light winds and I wouldn't be surprised to see lows in the 40s across inland cold spots. Highs Friday through the weekend should remain the 70s with dewpoints in the very comfortable 40s and lower 50s.

KEY MESSAGE 3...Strengthening offshore low pressure will bring significant beach hazards.

A thousand-mile long band of gale force winds extending from off Nova Scotia to the North Carolina coast is producing a wide swath of large and growing waves across the western Atlantic. The northeasterly wind trajectory means some portions of the coast are being shielded from the worst effects by the shallow water on Lookout Shoals and Frying Pan Shoals. The New Hanover County beaches, particularly the south end of the county including Carolina Beach, Kure Beach, and Fort Fisher have no such shielding and should see the direct impact from 11 second northeasterly swell today. Breaking waves should build to 5-7 feet and a High Surf Advisory has been issued for this area.

All beaches north of Cape Fear will experience a high risk of rip currents today. The South Carolina beaches should have a moderate risk of rip currents. East-facing beaches will also experience a strong left-to-right longshore current produced by northerly winds. Similar conditions should continue Friday.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Widespread MVFR is expected to continue through today before gradually scattering out from north to south tonight. Scattered showers will affect the terminals at times through today, bringing brief MVFR vis restrictions in the heavier showers. While thunder is not expected, a few rumbles cannot be ruled out. Breezy north winds will continue with gusts as high as 25kts likely at all sites and up to 30 kts at coastal terminals.

Extended Outlook...VFR conditions should continue for the next several days.

MARINE

A long period of hazardous marine weather conditions should peak in severity along the coast this evening. Gale force gusts are likely occurring now across the 20-60 mile offshore waters and may continue through late tonight.

1008 mb low pressure east of the North Carolina coastline should deepen to 994 mb over the next 36-48 hours as it moves northward off the Mid Atlantic coast. The tightest portion of the pressure gradient should set up across our marine area this afternoon through this evening when gusts to gale force are expected inside the 0-20 mile waters of the Cape Fear coast. A Gale Warning remains in in effect there with a Small Craft Advisory along for the South Carolina coastal waters.

A long fetch of gale-force northeasterly winds pointed at the North Carolina coast should generate seas building to 8-14 feet for the 20-60 mile offshore forecast zones. Closer to the coast, 6 to 9 foot seas are expected north and east of Frying Pan Shoals with 5-7 foot seas west of Frying Pan Shoals including the Grand Strand coastal waters. Conditions will slowly improve Friday, but residual 6 foot seas could linger inside 20 miles of shore north of Cape Fear through early Saturday.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Coastal Flood Advisory until 8 AM EDT this morning for NCZ106- 108. High Risk for Rip Currents through this evening for NCZ106-108. Coastal Flood Advisory until 11 AM EDT this morning for NCZ107. High Surf Advisory until 8 PM EDT this evening for NCZ108. SC...Beach Hazards Statement through this evening for SCZ054-056. MARINE...Gale Warning until 6 AM EDT Friday for AMZ250-252-280-284. Small Craft Advisory until 7 AM EDT Friday for AMZ254-256.