June 2, 2016

Bonnie redevelops into tropical depression, flooding the islands



The remnants of Tropical Storm Bonnie have managed to hang on long enough to be upgraded this morning by the National Hurricane Center to a tropical depression again.

No matter its designation, the persistent tropical low has managed to bring a really soggy week to the Outer Banks and set records for daily and monthly rainfall on southern Hatteras Island.

This morning,  the National Weather Service in Newport/Morehead City said that the post-tropical remnants of Bonnie had strengthened overnight and early this morning as the low pressure area moved offshore of Cape Hatteras over the warmer Gulf Stream waters.

At 11 a.m., the Hurricane Center deemed that it had sufficient tropical characteristics to be upgraded to a tropical depression again and the storm was located 25 miles east-southeast of Cape Hatteras with winds of 30 mph.  The depression was moving northeast at 7 mph.

The local Weather Service forecasters say that the system will move slowly northeast this afternoon.  Precipitation has wrapped mainly around the backside of the depression and moderate to occasionally heavy showers are expected until at least mid-afternoon.

The Weather Service has issued a flood watch for Outer Banks Dare and Hyde counties until 5 p.m.

The ground on Hatteras and Ocracoke islands is already saturated from heavy rainfall since late Sunday night and there is deep standing water on Highway 12, side roads, and in neighborhoods.

Drew Pearson, Dare County's emergency manager says there is standing water everywhere in the county and travelers should use caution  when on the roads.

The wind on southern Hatteras shifted to the northwest behind the depression this morning and has gusted up to about 38 mph.  The Weather Service has posted a small craft advisory.

The storm total -- since the rain started late Sunday into early Monday morning -- at Billy Mitchell airport in Frisco was 9.99 inches at 2 a.m. this morning, and several inches of rain has fallen since then.

Several records at the Frisco airport have been set since the storm started. A record 7.09 inches was recorded on May 30, breaking the previous record was 3.44 inches, set in 1940.

A monthly rainfall record for the month of May at Billy Mitchell also fell. The total for the month was 12.67 inches, breaking the old record of 11.7 inches, set in 2003.  The  normal rainfall for May is 3.57 inches.

The actual tropical cyclone that has brought the wet weather was actually weak and short-lived.

Forecasters at the Hurricane Center had their eyes on an area of disturbed weather north of the Bahamas for most of last week.  However, it wasn't until Friday, May 27, at 5 p.m. that the area of showers and thunderstorms became a tropical depression. At 5 p.m. on Saturday, the depression became weak Tropical Storm Bonnie with winds of 40 mph. 

The storm made landfall Sunday morning in South Carolina and was downgraded to a tropical depression again.  By Monday, the Hurricane Center declared Bonnie post-tropical and stopped issuing advisories on it.

However, the storm's remnants have hung around South and North Carolina all week, bringing rain and an increased threat of rip currents.

This morning, the Hurricane Center said Bonnie is moving along the southern edge of the mid-latitude westerlies, and the cyclone should move generally east-northeastward to eastward with a gradual increase in forward speed during the next couple of days.  The track forecast follows that of the various consensus models, which
are tightly clustered.

According to the Hurricane Center, "The center of Bonnie will be moving over warm Gulf Stream waters for the next 12 to 24 hours while the vertical wind shear is light.
Thus, the intensity forecast calls for modest strengthening during that time.  After that, increasing shear and sea surface temperatures below 24C should cause Bonnie to again degenerate to a remnant low, with the system dissipating by 72 hours."

The weather on the Outer Banks should improve tomorrow.  The forecast for Friday is for temperatures in the low 80s with only a 20 percent chance of showers.  The weekend should be warm with a chance of afternoon showers.  A cold front is forecast to approach from the west on Monday, pushing offshore early Tuesday and bringing drier weather.

For more information on the forecast, go to the local Weather Service website at www.weather.gov/mhx/.  Or check out the local office on Facebook at https://www.facebook.com/NWSMoreheadCity/?fref=ts.

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