The National Weather Service has started issuing a series of alerts as New Jersey braces for strong gusty winds, heavy downpours, severe thunderstorms and isolated tornadoes from the remnants of Tropical Storm Debby on Friday.

Forecasters say some of the thunderstorms that develop Friday, especially in the afternoon and at night, could generate 60 mph wind gusts, strong enough to knock down trees and power lines. They also say some of the thunderstorm cells could pack large hail, frequent lightning, heavy bursts of rain and possible tornadoes.

The weather service says the heavy rain could spark rapid flooding on roads and highways, and also could cause some rivers and streams to overflow because many areas of the state are already saturated from this week’s heavy rain and lighter rain that fell last week and last weekend.

Shortly before 5 p.m. Thursday, Debby lost some of its wind strength, so it was downgraded from a tropical storm to a tropical depression. The National Hurricane Center said Debby is now moving toward the north-northwest at a speed of about 10 mph.

The storm system’s center was located about 45 miles east of Charlotte, North Carolina and about 95 miles west-southwest of Raleigh, North Carolina.

“A faster northward or north-northeastward motion is expected during the next day or two,” the agency said in its latest public storm advisory. “Maximum sustained winds are near 35 mph, with higher gusts. Little change in strength is forecast during the next couple of days, but Debby is expected to become a post-tropical cyclone on Friday.”

A post-tropical cyclone no longer has tropical characteristics, but it can still pack a big punch with heavy downpours and strong winds.

These are among the weather alerts that the National Weather Service issued for New Jersey as of early Thursday evening. Additional alerts may be issued later tonight or early Friday.

N.J. wind alerts

• Atlantic, Cape May, Cumberland, Monmouth, Ocean, Salem and southeastern Burlington counties are under a wind advisory from 6 a.m. to 11 p.m. Friday, with southerly winds of 15 to 25 mph and gusts up to 50 mph expected.
• Camden, Gloucester, Hunterdon, Mercer, Middlesex, Morris, Somerset and northwestern Burlington counties are under wind advisory from 6 a.m. to 11 p.m. Friday, with forecasters calling for southerly winds of 15 to 25 mph and gusts up to 50 mph.
• Hudson County is under wind advisory from noon to 11 p.m. Friday, with southerly winds of 15 to 25 mph and gusts up to 50 mph expected.
• Sussex and Warren counties are under a wind advisory from 11 a.m. to 8 p.m. Friday, with southeast winds 15 to 25 mph and occasional gusts of 40 to 50 mph expected.

N.J. flood alerts

• Ocean County is under a coastal flood advisory from 6 a.m. Friday to 6 a.m. Saturday, with up to 1 foot of inundation above ground level expected in low-lying areas near back bays and tidal waterways.
• Minor coastal flooding is expected along Barnegat Bay, “especially near Mantoloking, where persistent southerly winds will trap high water from draining at high tide,” the advisory says. “High surf may result in sand dune breaching and beach erosion near the times of high tide.”

N.J. rip current alerts

• Beaches in Atlantic, Monmouth and Ocean counties face a high risk of dangerous rip currents from Friday morning through Friday evening. The weather service notes that “rip currents can sweep even the best swimmers away from shore into deeper water.”

N.J. surf advisories

• Atlantic, Cape May, Monmouth and Ocean counties have high surf advisories in effect from 8 a.m. to 8 p.m. Friday, with large breaking waves of up to 5 to 6 feet expected in the surf zone.

Current weather radar

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Len Melisurgo may be reached at LMelisurgo@njadvancemedia.com or on X at @LensReality.