Tropical Cyclone Report
Tropical Storm Boris
8 - 11 June 2002
James L. Franklin
National Hurricane Center
24 June 2002
Boris was a short-lived tropical storm that brought heavy rains
to portions of the southwest coast of Mexico.
a. Synoptic History
Boris appears to have developed from an interaction of an
Atlantic tropical wave with a broad and persistent eastern North
Pacific disturbance southwest of Acapulco, Mexico. On 1 June, a
broad trough of low pressure, accompanied by a large area of
showers and thunderstorms, extended from the Gulf of Tehuantepec
southwestward for several hundred miles. The disturbance remained
nearly stationary with little change in structure until 6 June,
when convection became more concentrated about 200 n mi southwest
of Acapulco. A tropical wave, which was located in the extreme
southwestern Caribbean Sea on 1 June, moved slowly westward and was
near the Gulf of Tehuantepec by late on 6 June. As the wave reached
the disturbance on 7 June, the organization of the disturbed
weather increased and Dvorak classifications began. By 1200 UTC 8
June, the system had developed a distinct circulation center with
enough organized convection to be considered a tropical depression.
At this time the center of circulation was located about 150 n mi
west-southwest of Acapulco.
The "best track" chart of the tropical cyclone's path is given
in Figure 1, with the wind and pressure histories shown in
and Figure 3, respectively.
The best track positions and intensities are
listed in Table 1. The depression moved to the west-northwest at
7-8 kt and strengthened during the day, reaching tropical storm
status by 0000 UTC 9 June, when it was about 150 n mi
south-southeast of Manzanillo, Mexico. Boris reached its peak
intensity of 50 kt at 0600 UTC 9 June. At this point, Boris'
forward speed slowed dramatically when the cyclone became caught
between weak mid-level ridges to its north and south. However,
upper-level easterly flow did not abate and the resultant easterly
shear put an end to the intensification stage. Boris moved little
on 9 June and began to weaken late in the day. On 10 June, Boris
drifted to the northeast and then east while generating very little
deep convection, and weakened back to a depression by 1800 UTC, when
it was located about 100 n mi south-southeast of Manzanillo. The
last deep convection occurred early on 11 June, and Boris
degenerated to a non-convective remnant low by 1800 UTC 11 June.
The remnant low then moved southeastward and had dissipated by 0600
UTC 12 June.
b. Meteorological Statistics
Observations in Boris (Figure 2 and Figure 3)
used to construct the best
track are largely limited to satellite-based Dvorak technique
intensity estimates from the Tropical Analysis and Forecast Branch
(TAFB), the Satellite Analysis Branch (SAB) and the U. S. Air Force
Weather Agency (AFWA). The peak objective Dvorak intensity estimate
is included for completeness, but was likely contaminated by an
erroneous assumed center position; it was disregarded in the
construction of the best track. The ship ELYL8 (P&O
NEDLLOYD AMAZON) reported 39 kt winds and a pressure of
1003.8 mb at 2100 UTC 9 June, when it was located about 75 n mi
north of Boris' center. No tropical storm force winds were reported
over land. An isolated 60 kt rain-flagged QuikSCAT vector appeared
in the 1232 UTC 9 June overpass; this has been discounted as
neighboring values were in the 35- 40 kt range.
The National Meteorological Service of Mexico reported maximum
storm total rainfalls for the period 8-11 June from the following
states: Michoacan 163.4 mm (6.43 in), Jalisco 130.2 mm (5.13 in),
Guerrero 118 mm (4.65 in), and Colima 98.1 mm (3.86 in). Specific
observation sites were not provided.
c. Casualty and Damage Statistics
The Associated Press reported that several homes along the
Mexican coast were damaged due to heavy rains from Boris. The
precise location of this damage was not reported. There was also a
report of damage to homes in the town of Tequila in western Jalisco
due to heavy rainfall, but these rains were not likely associated
with the tropical cyclone. There are no known reports of casualties
associated with Boris.
d. Forecast and Warning Critique
Boris was a tropical storm for less than 48 h. Average official
track errors (with the number of cases in parentheses) for Boris
were 46 (5), 105 (3), and 191 (1) n mi for the 12, 24, and 36 h
forecasts, respectively. These errors are greater than the average
official track errors for the 10-yr period 1992-2001 (36, 67, and
97 n mi, respectively). Initial forecasts of Boris' track relied
mostly on the BAM and statistical guidance models and did not
anticipate the abrupt decrease in forward speed. However, both the
GFDI and AVNI did forecast the slowdown and their errors were lower
than the official forecast.
Average official intensity errors were 8, 12, and 10 kt for the
12, 24, and 36 h forecasts, respectively. For comparison, the
average official intensity errors over the 10-yr period 1992-2001
are 7, 12, and 16 kt, respectively.
A tropical storm watch was issued at 2100 UTC 8 June for the
coast of Mexico from Punta San Telmo to Cabo Corrientes. The watch
was discontinued at 1500 UTC 10 June.
Table 1: Best track for Tropical Storm Boris, 8-11 June
|08 / 1200||16.1||102.4||1004||25||tropical depression
|08 / 1800||16.5||103.1||1004||30||"
|09 / 0000||16.6||103.8||1002||40||tropical storm
|09 / 0600||16.8||104.1||997||50||"
|09 / 1200||16.9||104.2||997||50||"
|09 / 1800||17.1||104.3||1000||50||"
|10 / 0000||17.2||104.2||1000||45||"
|10 / 0600||17.3||104.1||1002||40||"
|10 / 1200||17.3||103.9||1004||35||"
|10 / 1800||17.1||103.7||1004||30||tropical depression
|11 / 0000||17.1||103.6||1004||30||"
|11 / 0600||17.1||103.5||1004||25||"
|11 / 1200||17.1||103.3||1004||25||"
|11 / 1800||17.0||103.2||1006||20||remnant low
|12 / 0000||16.8||102.7||1006||20||"
|12 / 0600||dissipated
|09 / 0600||16.8||104.1||997||50||minimum pressure
Best track positions for Tropical Storm Boris, 8-11 June 2002.
Selected wind observations and best track
maximum sustained surface wind speed curve for Tropical Storm
Boris, 8-11 June 2002. Objective Dvorak estimate is a 3-h
Selected pressure observations and best
track minimum central pressure curve for Tropical Storm Boris, 8-11
June 2002. Objective Dvorak estimate is a 3-h average.