a. Synoptic History
Hurricane Dolores formed from a disturbance
of uncertain origin. The development could have been related to a
tropical wave that
traversed the Atlantic Ocean from 17-26 June and moved slowly
westward over the eastern North Pacific Ocean
during the following week. On the 3rd and 4th of July, clouds increased in the
vicinity of the wave. The cloudiness was initially elongated from north to
south, but some circular symmetry was noted by the end of the day
on the 4th. Ship data indicated that surface pressures in the area
were a little lower than usual, near 1005 mb, at that time.
Dvorak T-numbers were first assigned to the
tropical disturbance early on the 5th.
Banding of deep convection then quickly increased in an environment
characterized by upper-level diffluence. It is estimated that the
disturbance became a tropical depression at 1200 UTC 5 July,
about 600 nautical miles to the south of the southern tip of Baja
California (Table 1 and
Fig. 1 [35K GIF]).
With a strong and deep ridge to the north, Dolores moved toward 280
to 290 degrees at 10 to 15 knots for most of the cyclone's
lifetime. Despite some northeasterly wind shear, the initial pace
of development continued for about a day (Figs. 2
[27K GIF] and 3 [21K GIF]), during
which time the cyclone became
Tropical Storm Dolores and winds
increased to 45 knots. The cyclone was then
generating convection with cloud top temperatures lower than -80C. After a pause
in development, strengthening resumed on the 7th while the outflow became
more symmetrical. Dolores became a hurricane that day and
developed a mostly cloud-filled, ragged-appearing eye,
analyzed to be 10-20 nautical miles in diameter by the
Air Force Global Weather
Center (AFGWC). The hurricane attained its peak strength of
80 knots around 0600 UTC on the 9th,
shortly after becoming the first hurricane in two years to cross 125°W.
The eye then disappeared and the cyclone gradually weakened while
becoming sheared from the southwest and moving over progressively
cooler waters from the 9th-11th. Only a few clusters of deep
convection were generated on the 10th and 11th. Dolores crossed
140°W and entered the central Pacific hurricane basin as a
tropical depression on the 11th. Analyses from the
Central Pacific
Hurricane Center in Honolulu indicate that Dolores dissipated the
following day.
b. Meteorological Statistics
Table 1 lists the post-storm, i.e.,
"best track" analysis of
Dolores' location and intensity. Figures 2 and
3 show the
hurricane's estimated central pressure and maximum one-minute wind
speed, respectively, versus time and the associated satellite data.
Position and intensity estimates from satellite pictures were provided by the AFGWC,
NOAA
Tropical Analysis and Forecast Branch (TAFB) and NOAA
Synoptic Analysis Branch (SAB).
There were no observations of tropical storm force winds from
surface sites. Surface wind estimates derived from a pass of the
ERS-2 were helpful operationally in defining the structure of the
surface wind field.
c. Casualty and Damage Statistics
Dolores did not directly affect land and the NHC received no
reports of casualties or damages.
d. Forecast and Warning Critique
The NHC average track forecast errors were smaller than the long-term averages
(Table 2). On average, the NHC track forecasts also
were generally better than the numerical guidance.
It is noted that the
UKMET
had rather small track forecast errors in their few forecasts that could be evaluated.
Unfortunately, that model frequently dissipated the cyclone prematurely.
The NHC intensity forecast errors were remarkably low, with about
75% of the 12-72 hour forecasts in error by 0 or 5 knots.
Coastal watches and warnings were neither issued nor necessary.
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