textproduct: NWS Wilmington

WHAT HAS CHANGED

Coastal Flood Advisories have been issued for this morning's high tide at the beaches and along the river in downtown Wilmington. Forecast lows have been tweaked 1-2 degrees cooler tonight away the Cape Fear Area. The onset of shower chances has been pushed back to Saturday.

12z aviation forecast below.

KEY MESSAGES

1) Minor coastal flooding should continue during most high tides through Wednesday.

2) Canadian air will modify this week with dry weather expected to last through at least Friday.

DISCUSSION

KEY MESSAGE 1...Minor coastal flooding should continue during most high tides through Wednesday.

A check of tide gauges this morning shows water level anomalies ranging from +1.3 feet at Myrtle Beach to +1.7 feet at Wrightsville Beach, a consequence of strong low pressure east of the NJ coast and broad cyclonic flow covering the entire US East Coast. Even after the low weakens and moves away from the East Coast Tuesday and Wednesday, it will take time for this much water to drain away from the coast. The latest PETSS guidance shows even by Wednesday there should still be tidal anomalies around +1.0 feet north of Cape Fear.

The highest water level of this entire event for us may occur this morning. After tweaking guidance for current conditions, we're forecasting Wrightsville Beach to reach 7.0 feet MLLW and Myrtle Beach to reach 7.5 feet MLLW during this morning's 8 AM high tide. Both are one foot above flood stage. Subsequent high tides over the coming days will likely exceed flood stage as well, but should not reach the magnitude of this morning's tide.

On the Cape Fear River at downtown Wilmington our forecast is for 5.9 feet MLLW during the 10:30 am high tide, about 0.4 feet above flood stage.

KEY MESSAGE 2...Canadian air will modify this week with dry weather expected to last through at least Friday.

Cyclonic flow across the East Coast will begin to dissipate Monday and Tuesday as strong low pressure off the Mid Atlantic coast weakens and lifts northeastward. High pressure from the surface through the upper levels should develop over or just east of the Carolina coast. Sinking air within the developing ridge aloft should lead to a pronounced subsidence inversion which should maintain dry weather with above normal temperatures expected Tuesday through Friday.

Model solutions begin to diverge by Saturday and forecast confidence decreases. The ridge could remain across the area, or there is some potential for tropical moisture to begin arriving from the south. Forecast rain chances of 30-40 percent are only about 10 percent above climatology for early October given the large uncertainty.

AVIATION /10Z SUNDAY THROUGH THURSDAY/

VFR with clear skies. Westerly gusts around 15 kt forecasted for KILM and KLBT this afternoon, with potential for infrequent gusts up to 20 kts. Elsewhere, light WNW winds around 10 kts or less through tonight.

Extended Outlook...VFR. There is a low potential for morning ground fog Tuesday through Thursday.

MARINE

Today through Thursday...990 mb low pressure just east of the New Jersey coastline should begin to weaken later today and then will lift out to the northeast Monday into Tuesday. Broad cyclonic flow covering the East Coast will bring light to moderate west to southwest winds across our area today.

East-northeasterly backswell at 12 second period will continue across the area today, decreasing in amplitude tonight into Monday. Within 20 miles of shore, seas should average no higher than 3 feet near Cape Fear and only 2 feet west of Cape Fear. As winds and swell both decrease Tuesday into Wednesday, some truly ideal marine weather conditions are expected with only 1-2 foot seas and winds less than 10 knots under high pressure.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Coastal Flood Advisory until 11 AM EDT this morning for NCZ106- 108-110. Coastal Flood Advisory until 1 PM EDT this afternoon for NCZ107. SC...Coastal Flood Advisory until 11 AM EDT this morning for SCZ054- 056. MARINE...None.