a. Synoptic History
The development of Barbara appears to be related to a weak
which crossed Dakar, Africa as a large swirl of low clouds on 24 June.
The wave moved westward over the Atlantic and then over South America with
little representation on satellite images and rawindsonde data. The wave
reached the eastern Pacific on 5 July.
There, convection developed and gradually became organized.
Satellite intensity estimates
indicated that the westward-moving system became a
at 1800 UTC 7 July about 500 n mi south of Manzanillo, Mexico. The depression intensified
and became Tropical Storm Barbara 12 hours later.
The formation of an eye indicated
strengthening and Barbara reached hurricane
status at 0600 UTC 9 July. The rapid intensification process began and both objective
and subjective Dvorak T-numbers suggested that the winds increased to
115 knots. The well
defined eye disappeared from satellite images as fast as it formed and Barbara
weakened. During that period, the hurricane was moving through a very
favorable upper-level wind environment for intensification and over warm sea-surface
temperatures. As forecast, Barbara then intensified again and re-developed
a distinct eye. It was estimated that the hurricane reached its
maximum winds of 120 knots and a minimum pressure of 940 mb at
0000 UTC 14 July (when T-numbers peaked at 7.0 on the Dvorak scale). Barbara remained a
strong hurricane for several days while moving westward south of a well
established high pressure ridge. It finally moved over cool waters and began
to weaken. Barbara crossed 140°W as a tropical storm near 1800 UTC 16 July,
and it was dissipating at 0000 UTC 18 July. A swirl of low clouds, remnants
of the hurricane, moved westward for several more days.
Barbara's track is shown in Fig. 1 [58K GIF].
Table 1 is a listing, at six-hour intervals, of the
estimated minimum central pressure and maximum 1-minute surface wind speed.
b. Meteorological Statistics.
The best track pressure and wind curves as a function of time shown in
Figures 2 and 3 [52K GIF] are based on satellite
intensity estimates from the National Hurricane Center, the
Branch (SAB) and the Air Force
Global Weather Central (AFGWC). No ship observations of tropical storm force
winds near Barbara were received at the National Hurricane Center.
c. Casualty and Damage Statistics
There were no reports of casualties or damage associated with Barbara.
d. Forecast and Warning Critique
Excluding the tropical depression stage, the NHC average official track
errors ranged from 11 n mi at 12 hours to 60 n mi at 72 hours. The 1988-94
averages for such periods are 34 and 166 n mi respectively. BAMD performed
better than the official forecast and other models at 72 hours with an error
of only 43 n mi. On the other hand, the AVN produced an error of 150 n mi
for the same period.
* Best track data west of 140°W were provided by Central Pacific
Hurricane Center at Honolulu.