Olivia was a tropical storm that formed off the southwest coast of mainland
Mexico, and generally tracked west-northwestward and remained over open
water. After dissipating as a tropical cyclone, the remnant low-level
circulation tracked across central Baja California, northwest Mexico and the
desert southwest United States.
a. Synoptic history
Tropical Storm Olivia originated from a tropical wave that emerged from the
coast of Africa on 16 September. The wave tracked westward across the
tropical North Atlantic with disorganized convection, until 25 September
when the wave reached the central Caribbean Sea. While the structure of the
wave improved while tracking across the western Caribbean Sea and Central
America, the convection remained weak and disorganized. Even after emerging
over the eastern North Pacific on 28 September, little thunderstorm activity
was associated with the wave until a burst of deep convection developed late
on 30 September near the region of maximum vorticity.
The lack of deep convection over the eastern Pacific may have been the
result of (1) much of the low-level inflow being drawn into major Hurricane
Keith located in the western Caribbean Sea east of Belize and (2) the
upper-level outflow from Keith creating northeasterly shear on the
pre-Olivia wave. However, by 2345 UTC 30 September, the separation between
the wave and Hurricane Keith increased enough to allow sufficient convective
banding to develop, and the Tropical Analysis and Forecast Branch (TAFB)
began satellite classifications on the system. At 0000 UTC 2 October, the
TAFB designated the system as a tropical disturbance with low-level cyclonic
winds of 20 to 25 kt, and shortly thereafter the NHC upgraded the
disturbance to Tropical Depression Seventeen-E at 1200 UTC. By 0600 UTC 3
October, satellite classifications from both TAFB and the NOAA/NESDIS
Satellite Analysis Branch (SAB) indicated the depression had strengthened
into Tropical Storm Olivia about 220 n mi south of Manzanillo, Mexico.
Olivia tracked west-northwestward and eventually northwestward away from the
west coast of Mexico and reached a peak intensity of 55 kt late on 3
October. Tropical Storm Olivia maintained that intensity for another 36
hours before gradual weakening ensued, apparently due to an increase in the
northeasterly shear again created by Hurricane Keith as the latter system
moved westward across the Yucatan Peninsula of Mexico and into the Bay of
Campeche and extreme southwest Gulf of Mexico. Once Keith moved inland over
northeast Mexico and weakened, the northeasterly shear previously caused by
Keith's outflow decreased enough to allow Olivia to strengthen back to 55 kt
early on 8 October. However, by that time, Olivia had tracked far enough
westward over cooler sea-surface temperatures to begin the final weakening
phase and eventual demise of the tropical cyclone. Olivia decreased back to
tropical depression strength at 0600 UTC 9 October and dissipated over water
at 0600 UTC 10 October about 520 n mi west-southwest of the southern tip of
the Baja California Peninsula of Mexico.
The remnant low-level circulation of Olivia tracked steadily north and then
northeastward, and persisted as a swirl of low clouds until early 11 October
when a brief burst of moderate convection developed northeast of the
low-level center. However, the new convection was unable to persist near the
low-level center due to increasing southwesterly shear ahead of an
approaching mid-to upper-level trough from the west. The remnant circulation
did eventually make landfall along the west coast of Baja California about
midway between Punta Eugenia and Cabo San Lazaro, and tracked across the
Gulf of California and into northwest mainland Mexico and the southwest
United States. While not classified as a tropical cyclone at landfall, the
remnant of Olivia did bring much needed rainfall to the normally arid
regions of Baja California, northwest Mexico, and the Desert Southwest U.S.
Although not spectacular by most standards, rainfall totals exceeded 3
inches across those areas and produced localized flash flooding.
b. Meteorological statistics
The "best track" of Olivia is given in
Table 1 and Figure 1.
Figure 2 and Figure 3
show the best track maximum sustained (1 min average) surface (10 m
elevation) wind speed and minimum central pressure, as well as the
associated observations. These include Dvorak satellite technique position
and intensity estimates from the TAFB, the SAB, and the Air Force Weather
Agency (AFWA).
c. Casualty and Damage Statistics
Olivia developed well offshore the west coast of mainland Mexico and
remained well to the south of Baja California. There were no reports of
tropical storm force winds. Olivia had no direct effect on any land areas
and no reports of damage or casualties were received by the National
Hurricane Center.
d. Forecast and Warning Critique
NHC official average track forecast errors for Olivia were 33, 51, 70, 93,
and 133 n mi at 12 (23 cases), 24 (21 cases), 36 (19 cases), 48 (17 cases)
and 72 h (13 cases), respectively. These errors are considerably smaller
than the 1990-1999 average of 37, 69, 101, 132, and 189 n mi. A few of the
objective aids had slightly lower forecast errors than the official forecast
at 12, 24, and 36 h, whereas the official forecast errors were considerably
better than most of the objective aids at 48 and 72 h, especially at 72 h
where the GFDL, NOGAPS, and UKMET models had errors of 180, 170, and 175 n
mi, respectively.
NHC intensity forecast errors were near the 1990-1999 average at 12 and 24 h
and worse than the average at 36, 48, and 72 h. There was a negative bias
(underforecast) during the first 36 hours as Olivia was strengthening and a
positive bias (winds overforecast) in all of the forecasts afterwards, but
especially in the 36, 48, and 72 h forecasts. The overforecasts of intensity
were apparently due to the underestimation of the effects of vertical shear
caused by Hurricane Keith's outflow, even though Keith remained located well
to the northeast of Olivia over the western Caribbean Sea and southwest Gulf
of Mexico.
There were no tropical cyclone watches or warnings associated with Olivia.
Table 1.
Best track, Tropical Storm Olivia, 2-10 October 2000.
Date/Time (UTC) | Position |
Pressure (mb) |
Wind Speed (kt) | Stage |
Lat. (°N) | Lon. (°W) |
02 / 1200 | 15.3 | 103.1 | 1006 | 25 | tropical depression |
02 / 1800 | 15.3 | 103.6 | 1005 | 30 | " |
03 / 0000 | 15.3 | 103.7 | 1005 | 35 | tropical storm |
03 / 0600 | 15.3 | 103.8 | 1003 | 35 | " |
03 / 1200 | 15.3 | 103.9 | 1002 | 40 | " |
03 / 1800 | 15.4 | 104.5 | 994 | 55 | " |
04 / 0000 | 15.5 | 104.8 | 994 | 55 | " |
04 / 0600 | 15.7 | 105.2 | 994 | 55 | " |
04 / 1200 | 15.8 | 105.5 | 994 | 55 | " |
04 / 1800 | 15.9 | 105.9 | 994 | 55 | " |
05 / 0000 | 16.0 | 106.5 | 994 | 55 | " |
05 / 0600 | 16.0 | 107.0 | 994 | 55 | " |
05 / 1200 | 15.9 | 107.6 | 994 | 50 | " |
05 / 1800 | 15.8 | 108.0 | 1000 | 50 | " |
06 / 0000 | 15.7 | 108.4 | 1000 | 45 | " |
06 / 0600 | 15.6 | 108.7 | 1002 | 35 | " |
06 / 1200 | 15.5 | 109.1 | 1001 | 45 | " |
06 / 1800 | 15.6 | 109.5 | 1003 | 45 | " |
07 / 0000 | 15.9 | 110.0 | 1002 | 45 | " |
07 / 0600 | 16.1 | 110.6 | 1000 | 45 | " |
07 / 1200 | 16.5 | 111.3 | 997 | 45 | " |
07 / 1800 | 16.9 | 111.9 | 994 | 45 | " |
08 / 0000 | 17.4 | 112.5 | 997 | 50 | " |
08 / 0600 | 17.8 | 113.3 | 1000 | 55 | " |
08 / 1200 | 18.1 | 114.0 | 1000 | 50 | " |
08 / 1800 | 18.5 | 114.9 | 1000 | 40 | " |
09 / 0000 | 18.9 | 115.7 | 1004 | 35 | " |
09 / 0600 | 19.4 | 116.6 | 1006 | 30 | tropical depression |
09 / 1200 | 19.9 | 117.4 | 1006 | 30 | " |
09 / 1800 | 20.3 | 117.8 | 1006 | 30 | " |
10 / 0000 | 20.7 | 118.3 | 1007 | 25 | " |
10 / 0600 | 21.0 | 118.7 | 1008 | 20 | " |
|
03 / 1800 | 15.4 | 104.5 | 994 | 55 | minimum pressure |
Figure 1.
Best track for Tropical Storm Olivia, 2-10 October 2000.
Figure 2.
Best track maximum sustained 1-minute 10 meter wind speed curve for Tropical
Storm Olivia, 2-10 October 2000.
Figure 3.
Best track minimum central pressure curve for Tropical Storm Olivia, 2-10
October 2000.