Boris was a hurricane
that made landfall on the south coast of Mexico with
80-knot winds between Acapulco and Lazaro Cardenas.
The hurricane caused an estimated five deaths.
a. Synoptic History
Boris could have originated from a tropical wave
that moved from Africa to the eastern Atlantic Ocean on 8 June and crossed
Central America on 23 June. This is based on continuity, as the
wave was very poorly defined on satellite imagery for many days.
The first signs of a low-level circulation on satellite imagery
appeared on the 26th, centered about 250 n mi south of the Gulf
of Tehuantepec. The system became a tropical depression
on the 27th when convective banding increased around the center. The
track of Boris begins at this time as indicated in Table 1
and in Fig. 1 (36K GIF).
The tropical cyclone
moved northwestward at 8 to 10 knots for the next two days and strengthened from
25 knots to 80 knots during a 36-hour period, with a ragged
eye appearing on
satellite imagery just before landfall at 1800 UTC on the 29th.
The center crossed the south coast of Mexico midway between
Lazaro Cardenas and Acapulco.
Boris quickly weakened to a depression and turned southwestward
in response to a building ridge to its north. The system was
disrupted by the mountainous terrain of Mexico and dissipated on
the 1 July after moving back over water just south of Puerta
b. Meteorological Statistics
Figures 2 (26K GIF)
and 3 (28K GIF) show
curves, as a function of time, of minimum
sea-level pressure and maximum one-minute surface wind speed,
respectively, as well as the data on which they are based. As is
the case for most eastern Pacific
tropical cyclones, only satellite data was available to estimate the intensity.
Table 2 lists ship encounters with 34-knot wind speeds or
higher. The ship ELSC2 reported an estimated wind of 72 knots
at 0000 UTC on the 29th. However, a reflectivity patterns from the
Acapulco radar indicated that the ship was outside of the deepest
convection and the wind speed in the official track in Table 1
is estimated to be 55 knots at the time of the above ship report.
The only significant surface wind observation available is an
east wind of 40 knots sustained and gusts to 48 knots from
Acapulco at 1145 UTC on the 29th. This was the time of closest
approach of the center
to Acapulco and the center was 60 n mi southwest of the city at this time.
The heaviest rainfall occurred in the state of Guerrero and
ranged to a maximum value of 11.16 inches at Coyuga de Benitez,
located on the coast just west of Acapulco.
c. Casualty and Damage Statistics
A report from an amateur radio operator indicates one death at
Tecpan, near the landfall location. The El Finaciero newspaper
reports at least three other persons drowned near Tecpan and
another five fishermen are missing. An Associated Press report
states that a child was killed in Acapulco when a roof collapsed.
So the total death estimate is five.
It was reported that the San Jeronimo River caused flood damage
to 40 percent of the municipality of Coyuca, affecting at least
5000 people. Countless homes were also washed away at Tecpan.
d. Forecast and Warning Critique
Boris was of tropical storm
or hurricane strength for only 48
hours and there were eight official forecasts issued during this
time. Only two 36-hour forecasts verified and none verified at
48 or 72 hours. The few forecasts that verified were generally
good, with errors ranging to an average of 101 n mi at 36 hours.
A tropical storm warning
was issued at 1500 UTC on the 28th, from Puerto Escondido to Manzanillo and a
hurricane warning was
issued at 2100 UTC from Punta Maldonado to Manzanilllo. Landfall
occurred 27 hours after the tropical storm warning was issued and
21 hours after the hurricane warning was issued.