Hurricane Dennis - August 28-September 8, 1999

A tropical wave moved off the west coast of Africa on August 17th.  It moved westward with no
signs of development until the 21st, when thunderstorms increased with the wave.  A low level
circulation developed, and a tropical depression formed 190 miles east of Turks Island in the
Bahamas on the evening of the 23rd.  Strengthening continued despite westerly shear, and Dennis
became a tropical storm on the morning of the 24th, and a hurricane early on the 26th.  Once the
unfavorable upper winds lessened late on the 27th, Dennis reached its peak intensity of a category
two hurricane off the northwest Bahamas on the 28th.  An upper level trough allowed the storm to
track northward, but before it could get caught up in the westerlies, the upper trough passed the
system by, leaving Dennis to lose all thunderstorm activity and stall 110 miles east of Cape Hatteras
on August 31st.  It was at this time that cool air enveloped the circulation, its wind field expanded
towards New Jersey, and Dennis took on a subtropical it would keep for a
a couple days.  After days of meandering, a high pressure ridge developed in the eastern United
States, allowing Dennis to move westward and reacquire tropical characteristics, such as
thunderstorms near the center and a warmer core.  It made landfall near Cape Lookout on
the verge of becoming a hurricane during the afternoon of the 4th.  It moved up the spine of the
Appalachians, and became a frontal wave over Lake Ontario on the 7th, before becoming
absorbed by a larger low on the 9th.  The track of Dennis lies below, courtesy of the National
Hurricane Center.

Hurricane Dennis (1999) Tracl

On the graphic below is the storm total rainfall for Dennis.  Note the maximum in southeast
 North Carolina, near and to the right of the point of landfall, and the secondary maxima in the
 mountains of Virginia and central Pennsylvania near its track. Some of the rain in the Mid-
Atlantic occurred along a coastal front which formed ahead of Dennis' circulation.  The map
 below was generated using data provided by the National Climatic Data Center.

Hurricane Dennis (1999) Storm Total Rainfall
Hurricane Dennis (1999) Storm Total Rainfall Hurricane Dennis (1999) Storm Total Rainfall

Below is the calendar for Daily Precipitation Maps.  Note that the 24-hour periods end
at 12z that morning.

Sun Mon Tue Wed Thu Fri Sat
29 30 31 1 2 3 4
5 6 7 8