A tropical wave moved off the coast of Africa on August 19th.
A disturbance formed along the
wave to become Hurricane Bonnie; the description of Bonnie is at the link to the left. The wave
moved westward after spawning the storm, moving through the western Caribbean on the 24th
and into Central America on the 25th. It moved into a region of broad cyclonic circulation in the
eastern Pacific, leading to the formation of a large area of disturbed weather between the 90th and
110th meridians from the 26th through the 29th. A definite center appeared on the 29th, and
drifted west to the south of Cabo San Lucas.
Beginning a drift to the north, the disturbance became a tropical
on the night of the
30th, only 300 miles south of Cabo San Lucas. Strengthening at a modest pace, the cyclone
became a tropical storm on the 1st, before brushing the southeast tip of Baja California. Heavy
rains fell across southern portions of Baja California, with nearly 13 inches accumulated at Los
Cabos, 8.86" at Sinaloa, and 4.72" at Sonora. As it emerged into the very warm waters of the
Gulf of California, Isis gained hurricane strength. It moved ashore at Topolobampo on the night
of September 2nd, and subsequently weakened.
Turning to the northwest, the center entered southern Arizona by the
morning of the 4th, and
became absorbed by an upper level low later that day. Below is a track of the cyclone, prepared
by the National Hurricane Center.
Below are the storm total graphics for Isis. The absolute
maximum on land fell near the center in
the southern tip of Baja California, with secondary maxima along the west coast of mainland Mexico.
Data for the maps was obtained from the Comision del Agua, the parent agency of Mexico's National
Below is the calendar for Daily Precipitation Maps. Note that
the 24-hour periods end
at 12z that morning.