NOAA Technical Memorandum NWSTM PR-##
2001 Tropical CyclonesCentral North Pacific
Robert W. Kelly Treena Loos Kevin R. Kodama
Central Pacific Hurricane Center Honolulu, Hawaii February 2002
Introduction
Tropical activity was light during the 2001 season. Although
the season was off to the quickest start in history with the first named
tropical cyclone ever in June, there were only four total tropical cyclones,
and two of them were short-lived.
Tropical Storm Barbara in the East Pacific moved into
Central Pacific waters June 22, but rapidly dissipated. Only two advisories
were issued by the Central Pacific Hurricane Center (CPHC) on T.S. Barbara.
Tropical Depression One-C developed September 11, but only
lasted for twelve hours before dissipating.
Tropical Depression Two-C developed September 23 over
somewhat warmer waters near 10N, and developed enough convection
to last 48 hours. Winds persisted at 30 KT through most of its cycle as it
tracked westward.
The former Hurricane Narda was the best organized of the
Central Pacific tropical cyclones. Moving into the Central Pacific as a
tropical storm October 23, it encountered a strongly sheared environment at 16
N. Despite the organized low-level center, the shearing kept the convection far
away from the center and the system gradually eroded until the last advisory
twenty-four hours later.
None of the tropical cyclones threatened the Hawaiian Islands.
The trend of neutral or La Nina conditions since 1998 continued through 2000.
The number of tropical cyclones was about the long-term average (4.5) this
season, but the systems were neither vigorous nor a threat to develop into
something more substantial.
TROPICAL STORM BARBARA
JUNE 20 � 23, 2001
HISTORY. Tropical Depression Two-E (TD-2E) formed near 12N 127W off
the southern tip of Baja California on June 20, 2001. Moving west-northwestward, TD-2E was upgraded to Tropical Storm
Barbara on June 20 at 2100 UTC by the National Hurricane Center. This is the first tropical storm to reach
the Central Pacific during the month of June. Although Barbara entered the
Central Pacific as a tropical storm, it was quickly downgraded to a tropical
depression by the CPHC on June 22 at 2100 UTC. Tropical Depression Barbara continued to weaken as it moved west
northwestward over cooler water, until 0300 UTC June 23, when CPHC issued its
last advisory.
SYNOPTIC SITUATION (JUNE 22 - JUNE 23)
LOWER LEVELS. A high
pressure center and its associated ridge remained north of the Hawaiian Islands
from June 22 through June 23. The high
center maintained its position near 39N 154W,
and weakened from 1032 hPa on June 22 to 1028 hPa on June 23. The ridge extended well to the west, and
remained well north of the Tropical Cyclone.
MIDDLE AND UPPER LEVELS. As Barbara moved westward to the south of the surface ridge, it moved
into a sheared environment as an upper level trough passed over the area. The
shear and the cool (less than 23C) sea surface temperature (SST) contributed to the
rapid dissipation of the tropical storm.
SATELLITE DATA. Convection was isolated as Barbara moved
into Central Pacific waters, and shifted away from center with westerly
shearing aloft. The shear increased, and Barbara dissipated with only a single
CB visible on satellite. (Fig. 2)
BEST TRACK.
Table 1. Best Track Barbara
Date/Time (UTC) |
Latitude (deg N) |
Longitude (deg W) |
Max winds (KT) |
June 22/ 1800 |
17.0 |
140.7 |
30 |
June 23/ 0000 |
17.3 |
141.2 |
30 |
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image002.jpg)
Figure 1. Best Track for Tropical Storm Barbara
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image004.gif)
Figure 2. Satellite picture of Tropical Depression Barbara.
Advisory 2100 UTC June 22 2001
Max Winds 30 KT
Satellite Picture at 0030 UTC June 23
TROPICAL DEPRESSION ONE-C
SEPTEMBER 11, 2001
HISTORY. Tropical Depression One-C (TD-1C) formed on September 11 more than 400 NM southeast of
the Island of Hawaii, near 14.1N 152.1W. The system moved west northwestward to 15N 153W by 0600 UTC September 11,
and then southwestward to 12.6N 154.8W by 1200 UTC September 11. The system was poorly organized, and the convection
of TD One-C dissipated by 1200 UTC September 11. Tropical Depression One-C never reached tropical storm strength.
SYNOPTIC SITUATION (SEPTEMBER 11, 2001)
LOWER LEVELS. A high pressure center 1022 hPa was located near 35N 144W,
with a ridge that extended southwest to 25N 170W. Easterly winds were maintained between the
equator and 20N. The SST was about 26C. A weak low (1012 hPa) east of the Hawaiian
chain remained relatively stationary near 22N 140W.
MIDDLE AND UPPER LEVELS. Tropical Depression One-C formed just south of a weak mid-level high
located near 25N 155W.
SATELLITE DATA. This tropical depression was never well organized, and became difficult to track accurately.
The track appears erratic, and this was related to the difficulty of identifying a system center. Satellite showed other areas
of convection in the vicinity of TD One-C. (Fig. 4)
BEST TRACK
Table 2. Best Track TD One-C
Date/Time (UTC) |
Latitude (deg N) |
Longitude (deg W) |
Max winds (kts) |
September 11/ 0300 |
13.9 |
151.5 |
25 |
September 11/ 0900 |
15.0 |
153.0 |
30 |
September 11/ 1500 |
12.6 |
154.8 |
25 |
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image006.jpg)
Figure 3. Best Track TD One-C
Table 3. Verification table for TD One-C. Table entries are
track forecast errors, measured in nautical miles. Value in parenthesis
indicates the number of forecasts.
Forecast |
12-hr |
24-hr |
36-hr |
48-hr |
72-hr |
CPHC |
130 (1) |
N/A |
N/A |
N/A |
N/A |
BAMD |
132 (1) |
N/A |
N/A |
N/A |
N/A |
BAMM |
115 (1) |
N/A |
N/A |
N/A |
N/A |
BAMS |
112 (1) |
N/A |
N/A |
N/A |
N/A |
CLIP |
131 (1) |
N/A |
N/A |
N/A |
N/A |
GFDL |
N/A |
N/A |
N/A |
N/A |
N/A |
LBAR |
131 (1) |
N/A |
N/A |
N/A |
N/A |
NGPS |
N/A |
N/A |
N/A |
N/A |
N/A |
P91E |
N/A |
N/A |
N/A |
N/A |
N/A |
Table 4. Wind Verification for TD One-C. Table entries are
errors in wind forecast, measured in knots.
Forecast |
12-hr |
24-hr |
36-hr |
48-hr |
72-hr |
CPHC |
0 (1) |
N/A |
N/A |
N/A |
N/A |
SHIP |
3 (1) |
N/A |
N/A |
N/A |
N/A |
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image008.gif)
Figure 4. Satellite picture of TD One-C
Advisory Issued 0900 UTC Sep 11, 2001
Max Winds 30 KT
Satellite picture 1000 UTC Sep 11
TROPICAL DEPRESSION TWO-C
SEPTEMBER 23 - 25, 2001
HISTORY. Tropical Depression Two-C (TD-2C) formed near 10N 147.4W on
September 22, 2001, southwest of Tropical Storm Kiko (in the East Pacific).
Throughout September 23, TD-2C remained a poorly organized system that slowly
moved west-northwestward. A slight increase in convection became apparent 0300 UTC September 24,
and was followed by a period of consistent thunderstorm activity near the circulation center. Tropical
Depression Two-C continued in the west-northwest direction, but weakened by 0300 UTC September 25.
SYNOPTIC SITUATION (SEPTEMBER 23 � SEPTEMBER 25, 2001)
LOWER LEVELS. A subtropical high center (1018 hPa) remained near 27N 130W
throughout the duration of Tropical Depression Two-C. Tropical Storm Kiko remained to the east near 18N 124W.
On September 23 at 1200 UTC a low pressure center developed near 40N 134W with a shear line that extended
north of the Hawaiian island chain to 28N 170W. By September 25, the shear line had moved
southward reaching 26N 160W. East-southeast trade winds persisted throughout the duration of Tropical
Depression Two-C.
MIDDLE AND UPPER LEVELS. There was a mid-level ridge north of TD Two-C September 24 near 15N 140-155W,
steering the system to the west. A weakness in the ridge near 15N 152-162W became noticeable by September 25.
There was an upper level low northwest of TD-2C near 22N 162W on September 23. The SST was about 26C-27C. As
the environment became more sheared the system dissipated.
SATELLITE DATA. Satellite showed the system to be generally
well organized, with persistent convection through the life cycle. Satellite
fixes were reliable (Fig. 6), and showed a consistent westward movement,
increasing in forward speed over the second half of the storm�s cycle as the
upper trough moved into the area.
Table 5. Best Track for TD Two-C
Date/Time (UTC) |
Latitude (deg N) |
Longitude (deg W) |
Max winds (KT) |
September 23/ 0900 |
10.0 |
147.4 |
30 |
September 23/ 1500 |
10.0 |
148.4 |
30 |
September 23/ 2100 |
10.0 |
149.7 |
30 |
September 24/ 0300 |
10.2 |
151.0 |
30 |
September 24/ 0900 |
10.5 |
152.6 |
30 |
September 24/ 1500 |
10.5 |
155.6 |
30 |
September 24/ 2100 |
10.4 |
155.6 |
30 |
September 25/ 0300 |
10.9 |
159.1 |
25 |
September 25/ 0900 |
11.1 |
161.2 |
25 |
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image010.jpg)
Figure 5. Best Track TD Two-C
Table 6. Track Verification for TD Two-C. Table entries are
track forecast errors, measured in nautical miles. Value in parenthesis
indicates the number of forecasts.
Forecast |
12-hr |
24-hr |
36-hr |
48-hr |
72-hr |
CPHC |
54 (7) |
84 (5) |
147 (3) |
185 (1) |
N/A |
BAMD |
64 (7) |
149 (5) |
219 (3) |
309 (1) |
N/A |
BAMM |
43 (7) |
94 (5) |
153 (3) |
237 (1) |
N/A |
BAMS |
43 (7) |
128 (5) |
175 (3) |
221 (1) |
N/A |
CLIP |
53 (7) |
153 (5) |
227 (3) |
324 (1) |
N/A |
GFDL |
84 (4) |
141 (4) |
233 (2) |
261 (1) |
N/A |
LBAR |
60 (7) |
141 (5) |
193 (3) |
272 (1) |
N/A |
NGPS |
N/A |
N/A |
N/A |
N/A |
N/A |
P91E |
N/A |
N/A |
N/A |
N/A |
N/A |
Table 7. Wind Verification for TD Two-C. Table entries are
errors in wind forecast, measured in knots. Value in parenthesis indicates the
number of forecasts.
Forecast |
12-hr |
24-hr |
36-hr |
48-hr |
72-hr |
CPHC |
1.4 (7) |
7 (5) |
13.3 (3) |
20 (1) |
N/A |
SHIP |
5 (7) |
12 (5) |
19 (3) |
29 (1) |
N/A |
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image012.gif)
Figure 6. Satellite picture of TD Two-C
Advisory issued 2100 UTC Sep 23, 2001
Max Winds 30 KT
Satellite picture at 2300 UTC Sep 23
TROPICAL STORM NARDA
OCTOBER 20 � 25
HISTORY. In the East Pacific near 11.3N 125.8W,
sea surface temperatures of 27C to 28C on October 20, 2001 1500 UTC, supported the
development of Tropical Depression Sixteen-E (TD-16E) from a band of convective
clouds. Six hours later TD-16E was upgraded to Tropical Storm Narda near 11.9N 127W.
Maintaining a west-northwestward path, Tropical Storm Narda steadily intensified until it
reached hurricane status October 21, 2100 UTC near 14.2N 131.2W. Narda reached
a maximum wind speed of 75 knots October 22, and then began to weaken from an
increase of vertical shear aloft. Narda was downgraded to a Tropical Storm near 16.3N 135.7W
0300 UTC October 23. Tropical Storm Narda continued to weaken as it crossed into the
Central North Pacific, where CPHC downgraded the storm to a Tropical Depression at 0300 UTC
October 24 near 16.5N142W. CPHC issued the last advisory on Tropical
Depression Narda at 0300 UTC on October 25, 2001.
SYNOPTIC SITUATION (OCTOBER 23 � OCTOBER 25
LOWER LEVELS. A high
pressure center of 1032 hPa was positioned at 42N 137W on
October 23, with a ridge extending to 17N 168W. The high center gradually weakened and moved
northeastward with a pressure of 1024 hPa at 37N 134W by
October 25. A tropical wave ahead of
Narda was apparent from 15N 154W to 30N 150W on October 23. The wave moved across the island chain from Hawaii to Kauai with a final
position west of the islands from 5N 172W to 25N 162W.
MIDDLE TO UPPER LEVELS. Tropical Storm Narda entered the Central Pacific south of an upper-level
ridge near 17N 160W to 20N 140W. The immediate environment was dominated by a
ridge at mid and upper levels. Narda dissipated before an upper level trough,
to the northwest, moved into the storm�s vicinity.
SATELLITE DATA. Narda entered Central Pacific with very
little deep convection, but with a well-defined low level circulation. (Fig 8)
Convection developed about 60 NM northeast of the center as Narda moved into a
more strongly sheared environment. Convection continued in bursts north and
east of the center, with upper level outflow indicating strong shear. The low
level circulation gradually weakened and dissipated.
BEST TRACK.
Table 8. Best track Narda
Date/Time (UTC) |
Latitude (deg N) |
Longitude (deg W) |
Max winds (KT) |
October 23/ 2100 |
16.3 |
139.6 |
35 |
October 24/ 0300 |
16.4 |
141.2 |
30 |
October 24/ 0900 |
16.5 |
142.4 |
30 |
October 24/ 1500 |
16.7 |
143.5 |
30 |
October 24/ 2100 |
16.9 |
144.0 |
30 |
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image014.gif)
Figure 7.Best track Narda
Table 9. Track Verification for Narda. Table entries are
track forecast errors, measured in nautical miles. Value in parenthesis
indicates the number of forecasts.
Forecast |
12-hr |
24-hr |
36-hr |
48-hr |
72-hr |
CPHC |
36 (4) |
107 (2) |
N/A |
N/A |
N/A |
BAMD |
197 (3) |
372 (1) |
N/A |
N/A |
N/A |
BAMM |
71 (3) |
134 (1) |
N/A |
N/A |
N/A |
BAMS |
28 (3) |
67 (1) |
N/A |
N/A |
N/A |
CLIP |
36 (30) |
66 (1) |
N/A |
N/A |
N/A |
GFDL |
N/A |
N/A |
N/A |
N/A |
N/A |
LBAR |
57 (3) |
108 (1) |
N/A |
N/A |
N/A |
NGPS |
47 (1) |
N/A |
N/A |
N/A |
N/A |
P91E |
22 (3) |
27 (1) |
N/A |
N/A |
N/A |
Table 10. Wind Verification for Narda. Table entries are
errors in wind forecast, measured in knots. Value in parenthesis indicates the
number of forecasts.
Forecast |
12-hr |
24-hr |
36-hr |
48-hr |
72-hr |
CPHC |
0 (4) |
5 (2) |
N/A |
N/A |
N/A |
SHIP |
5.3 (3) |
14 (1) |
N/A |
N/A |
N/A |
![](https://webarchive.library.unt.edu/web/20130217145033im_/http://www.prh.noaa.gov/cphc/summaries/2001/image016.gif)
Figure 8. Satellite picture of Tropical Storm Narda
Advisory 2100 UTC Oct 23 2001
Max winds 35 KT
Satellite picture at 0030 UTC Oct. 24
Summary
Although there were not sufficient data to give a strong
statistical base, CPHC did demonstrate better skill than most of the models
during 2000. The Shallow layer Beta and Advection Model (BAMS) showed the
greatest skill. Compared to the eight models used, CPHC produced the second
best forecasts.
Figure 9. Composite forecast track errors, all storms,
nautical miles. Number in parenthesis indicates number of forecasts.
(There were no 72 hour forecast verifications because all
tropical cyclones dissipated by 48 hours.)
Forecast |
12-hr (12) |
24-hr (9) |
36-hr (5) |
48-hr (3) |
CPHC |
54 |
100 |
147 |
185 |
BAMD |
104 |
172 |
205 |
349 |
BAMM |
57 |
108 |
189 |
240 |
BAMS |
40 |
94 |
117 |
150 |
CLIP |
125 |
117 |
187 |
261 |
GFDL |
84 |
141 |
233 |
261 |
LBAR |
63 |
128 |
185 |
261 |
NGPS |
47 |
|
|
|
P91E |
23 |
78 |
209 |
357 |
Figure 10. Total forecast errors for intensity (KT). Number in
parentheses indicates number of forecasts.
Forecast |
12-hr (12) |
24-hr (9) |
36-hr (5) |
48-hr (3) |
CPHC |
1 |
6 |
13 |
20 |
SHIP |
5 |
12 |
19 |
29 |
CPHC showed better skill than the SHIP model in forecasting
maximum wind. The sample was too small to be considered too significant, but
the trends were in the right direction.
ACRONYMS that may have been used in this report.
Acronym |
Full Spelling/Definition |
AOR | Area of Responsibility |
AVNO | Operation global forecast system model |
BAMD | Deep Layer Beta Advection Model (mean layer averaged between 850 hPa and 250 hPa) |
BAMM | Medium Layer Beta Advection Model (mean layer averaged between 850 hPa and 400 hPa) |
BAMS | Shallow Layer Beta Advection Model (mean layer averaged between 850 hPa and 700 hPa) |
CLIP | Climatology and Persistence |
CPHC | Central Pacific Hurricane Center |
GFDL | Geophysical Fluid Dynamics Laboratory model |
hPa | Hectopascal (formerly millibar) |
ITCZ | Inter-tropical Convergence Zone |
JTWC | Joint Typhoon Warning Center |
kts | knots |
LBAR | Barotropic limited area sine transform |
mb | millibars |
NA | Not Available |
NGPS | NOGAPS (Navy Operational Global Atmospheric Prediction System) Vortex Tracking Routine |
NHC | National Hurricane Center |
nm | nautical miles |
P91E | Pacific Statistical Dynamic Model (adapted from NHC90 for the Eastern Pacific) |
SHIFR | Statistical Hurricane Intensity Forecast |
SHIP | Statistical Hurricane Intensity Prediction |
SST | Sea Surface Temperature |
TD | Tropical Depression |
TPC | Tropical Prediction Center, Miami, FL |
TUTT | Tropical Upper Tropospheric Trough |
UTC | Universal Time Coordinated |
WFO | Weather Forecast Office |
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