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 Manuel
10 - 18 October 2001
James L. Franklin
National Hurricane Center
31 October 2001
Tropical Storm Manuel was a weak and generally disorganized
eastern North Pacific tropical cyclone that formed from the
remnants of Atlantic Hurricane Iris.
a. Synoptic History
Manuel formed from the remnants of
Atlantic Hurricane Iris,
which struck southern Belize as a Category Four hurricane (on the
Saffir-Simpson Hurricane Scale) early on 9 October. By 1800 UTC,
the core circulation of Iris had dissipated over the mountains of
eastern Mexico, while new convection was developing a short
distance away over the waters of the Pacific. This area became
better organized over the next 18 hours and became Tropical
Depression Fifteen-E at 1200 UTC 10 October, about 175 n mi
south-southeast of Acapulco, Mexico. (Note: current operational
policy is that tropical cyclones crossing into another
basin retain their original name; since Iris had dissipated as a
tropical cyclone prior to entering the eastern North Pacific basin,
the new depression was properly named Fifteen-E, rather than
The "best track" chart of the tropical cyclone's path is given
in Figure 1, with the wind and pressure histories shown in
Figure 2 and Figure 3, respectively.
The best track positions and intensities are
listed in Table 1. The depression moved at 13-14 kt, first westward
and then west-northwestward. An upper-level anticyclone centered
over southern Mexico was producing some easterly shear in the
environment of the depression, but when this shear lessened the
system became Tropical Storm Manuel at 0600 UTC 11 October, about
200 n mi south-southwest of Zihuatanejo, Mexico. An estimated
initial peak intensity of 45 kt was reached at 1800 UTC that day
when the first clear banding features developed. However, the
banding was short-lived, deep convection diminished, and satellite
microwave imagery early on 12 October suggested that the
circulation was becoming elongated. Wind shear returned, this time
from the northwest, and Manuel turned to a west-southwesterly track
and slowed. By 1200 UTC 12 October, Manuel had weakened to a
Manuel remained a disorganized depression for the next two and a
half days. It continued moving to the west-southwest, but slowed to
a drift as a mid-level ridge to the north of the cyclone gradually
weakened. An upper-level trough dug southward to the west of Manuel
early on 15 October, and Manuel began to move to the
north-northwest. Convection redeveloped near the center and Manuel
regained tropical storm strength at 0600 UTC 15 October about 520 n
mi south-southwest of Cabo San Lucas, Mexico. Wind shear decreased
and Manuel strengthened, reaching its peak intensity of 50 kt near
1200 UTC 16 October about 540 n mi southwest of Cabo San Lucas. By
this point, water temperatures under the cyclone were decreasing
and shear, this time from the southwest, was increasing. Manuel
began to weaken while moving to the west-northwest and northwest.
It became a depression at 1800 UTC 17 October about 660 n mi
west-southwest of Cabo San Lucas, and dissipated to a
non-convective low shortly after 0000 UTC 18 October. The remnant
low moved slowly westward for a couple of days over cool waters
before its circulation dissipated completely.
b. Meteorological Statistics
Observations in Manuel (Figure 2 and Figure 3)
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). A number of QuikSCAT
scatterometer passes were influential in the construction of the
best track intensities; some of these were at odds with the Dvorak
estimates. A pass near 1300 UTC 12 October did not support the
tropical storm status then indicated by the Dvorak classifications.
Neither did the pass near 0100 UTC 14 October, and the best track
at this time is consistent with the scatterometer, rather than with
the Dvorak estimates or the operational best track. Manuel is
judged to have regained tropical storm status near 0600 UTC 15
October, based on an increase in deep convection that resulted in
the Dvorak T number to increase from 2.5 to 3.0. Microwave imagery
near 1200 UTC 16 October showed a ring of core convection that
suggests that Manuel was best organized near this time.
There were no ship reports of winds of tropical storm force
associated with Manuel.
c. Casualty and Damage Statistics
There were no reports of damage or casualties associated with
d. Forecast and Warning Critique
The genesis of Tropical Depression Fifteen-E was correctly
anticipated in Tropical Weather Outlooks. Manuel was a tropical
storm for two short intervals, the first one lasting 30 h and the
second lasting 60 h. There are too few verifying forecasts to
conduct a meaningful evaluation. Most of the intensity forecasts
Table 1: Best track for Tropical Storm Manuel, 10 - 18 October 2001.
|Lat. (°N)||Lon. (°W)
|10 / 1200||14.1||99.2||1007||30||tropical depression
|10 / 1800||14.0||100.6||1006||30||"
|11 / 0000||14.4||102.0||1006||30||"
|11 / 0600||14.7||103.3||1005||35||tropical storm
|11 / 1200||15.2||104.7||1003||40||"
|11 / 1800||15.7||105.9||1000||45||"
|12 / 0000||15.9||107.3||1000||45||"
|12 / 0600||15.7||108.4||1003||40||"
|12 / 1200||15.4||109.5||1005||30||tropical depression
|12 / 1800||14.9||110.5||1005||30||"
|13 / 0000||14.8||111.2||1005||30||"
|13 / 0600||14.6||111.9||1005||30||"
|13 / 1200||14.3||112.6||1005||30||"
|13 / 1800||14.1||113.0||1005||30||"
|14 / 0000||13.9||113.3||1005||30||"
|14 / 0600||13.9||113.6||1005||30||"
|14 / 1200||14.0||113.8||1005||30||"
|14 / 1800||14.3||113.9||1005||30||"
|15 / 0000||14.7||114.1||1005||30||"
|15 / 0600||15.3||114.4||1004||35||tropical storm
|15 / 1200||15.9||114.8||1004||35||"
|15 / 1800||16.5||115.3||1004||35||"
|16 / 0000||17.1||115.9||1002||40||"
|16 / 0600||17.5||116.9||1000||45||"
|16 / 1200||18.0||118.1||997||50||"
|16 / 1800||18.6||119.3||1000||45||"
|17 / 0000||19.2||120.2||1000||45||"
|17 / 0600||19.8||120.8||1003||40||"
|17 / 1200||20.5||121.3||1005||35||"
|17 / 1800||21.1||121.6||1007||30||tropical depression
|18 / 0000||21.8||121.8||1009||25||"
|18 / 0600||dissipated to low
|16 / 1200||18.0||118.1||997||50||minimum pressure
Best track positions for Tropical Storm Manuel, 10-18 October 2001.
Best track maximum sustained surface wind
speed curve for Tropical Storm Manuel, 10-18 October 2001, and the
observations (excluding QuikSCAT) on which the best track curve is
Best track minimum central pressure curve
for Tropical Storm Manuel, 10-18 October 2001, and the observations
on which the best track curve is based.