TROPICAL CYCLONE REPORTS
Tropical Storm Barbara
Tropical Storm Cosme
Tropical Storm Erick
Tropical Depression Six-E
Tropical Storm Henriette
Tropical Storm Ivo
Tropical Storm Lorena
Tropical Depression Fourteen-E
Tropical Storm Manuel
Tropical Cyclone Report
Tropical Storm Ivo
10 - 14 September 2001
Lixion A. Avila
National Hurricane Center
23 October 2001
a. Synoptic History
Ivo formed from a large tropical wave that moved off the African
coast on 26 August. The wave was accompanied by a large cyclonic
rotation at the low to middle levels and numerous thunderstorms
when it entered the eastern Atlantic. On the 28th, the
wave spawned a northward-moving vortex in the eastern Atlantic, but
the wave's southern portion continued westward with very limited
convective activity. Once the wave reached the western Caribbean
Sea on 5 September, the shower activity increased and the whole
system continued slowly westward over Central America. The cloud
pattern gradually became better organized and by 9 September,
satellite images showed a low to middle level circulation centered
near Acapulco, Mexico. The next day, a portion of the system moved
over water and it became a tropical depression about 100 n mi
south-southwest of Acapulco at 1200 UTC 10 September.
The center of the depression moved slowly west and
west-northwestward with its circulation hugging the southwest coast
of Mexico. There was moderate easterly shear over the depression as
indicated by the location of the convection to the west of the
center. Satellite images and a report from a ship indicated that
the depression reached tropical storm status by 0600 UTC 11
September. Thereafter, there was only slight strengthening and Ivo
reached its maximum intensity of 45 knots and an estimated minimum
pressure of 997 mb at 1800 UTC 12 September. The tropical storm
moved toward the northwest and then west over increasingly cooler
waters, and gradually weakened. It became a low pressure system
devoid of convection by 0000 UTC 15 September.
b. Meteorological Statistics
gives the best track positions and intensities of Ivo at
six-hourly intervals. Figure 1
shows a plot of Ivo's track.
Figure 2 and Figure 3
depict the curves of maximum one-minute average (10 m above
sea-level) wind speed and minimum sea-level pressure, respectively,
as functions of time. Also plotted are the observations on which
the curves are based. These consist primarily of satellite-based
Dvorak-technique estimates using satellite imagery by the Tropical
Analysis and Forecast Branch (TAFB), Satellite Analysis Branch
(SAB), and the U.S. Air Force Weather Agency (AFWA). A 37-knot wind
reported at 0600 UTC 11 September by the ship ZDEB2 located about
135 n mi from the center of the tropical cyclone was used to
upgrade the system to Tropical Storm Ivo.
c. Casualty and Damage Statistics
No reports of casualties or damage associated with Tropical
Storm Ivo have been received.
d. Forecast and Warning Critique
Ivo formed and moved very close to the southwest coast of Mexico
and then headed for Baja California. This proximity to land
prompted watches and warnings which are summarized in Table 2.
However, Ivo was close enough to the coast to produce tropical
storm force winds on shore.
The preliminary track errors for the 12, 24, 36 and 48 hour
forecasts averaged 40, 60, 85 and 124 n mi respectively. These
numbers are similar to the past 10-yr average official track errors
for these periods of 37 68, 99, and 128 n mi respectively.
Initially, Ivo was forecast to become a hurricane, but it peaked at
45 knots only.
Table 1: Best track for Tropical Storm Ivo, 10 - 14 September 2001.
|Lat. (°N)||Lon. (°W)
|10 / 1200||14.8||98.9||1004||25||tropical depression
|10 / 1800||14.9||100.1||1004||25||"
|11 / 0000||15.2||101.4||1002||30||"
|11 / 0600||15.7||102.7||1000||35||tropical storm
|11 / 1200||16.7||104.3||1000||35||"
|11 / 1800||17.3||105.5||1000||35||"
|12 / 0000||17.9||106.7||999||35||"
|12 / 0600||18.5||108.0||999||35||"
|12 / 1200||19.4||108.8||999||40||"
|12 / 1800||20.3||109.6||997||45||"
|13 / 0000||21.0||110.3||998||45||"
|13 / 0600||21.8||111.2||998||45||"
|13 / 1200||23.0||112.5||998||45||"
|13 / 1800||23.9||113.8||1002||40||"
|14 / 0000||24.6||114.6||1004||35||"
|14 / 0600||25.0||115.2||1004||30||tropical depression
|14 / 1200||25.2||116.2||1005||25||"
|14 / 1800||25.1||117.0||1006||25||"
|15 / 0000||25.1||117.5||1007||20||"
|12 / 1800||20.3||109.6||997||45||minimum pressure
Table 2: Watch and warning summary, Tropical Storm Ivo, 10 - 14 September 2001.
|11/0900||Tropical Storm Warning issued||Acapulco to Cabo Corrientes
|11/1500||Tropical Storm Warning
discontinued||East of Lazaro Cardenas
|11/2100||Tropical Storm Warning
discontinued||East of Manzanillo
|12/0300||Tropical Storm Warning issued||Cabo San Lucas to Cabo San
|12/0900||Tropical Storm Warning
discontinued||Manzanillo to Cabo Corrientes
|13/2100||Tropical Storm Warning
discontinued||Cabo San Lucas to Cabo San
Best track positions for Tropical Storm Ivo, 10-15 September
Best track maximum sustained 1-min 10
meter wind speed curve for Tropical Storm Ivo, 10 -15 September
Best track minimum central
pressure curve for Tropical Storm Ivo, 10-15 September,