Service Assessment

Super Typhoon Pongsona

December 8, 2002 

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Weather Service

Silver Spring, Maryland
Cover: Radar image of Pongsona, showing the wall cloud surrounding the eye, as it began to

move over Guam at 3:21 p.m., Sunday, December 8, 2002.
Service Assessment

Super Typhoon Pongsona

December 8, 2002

April 2003

U.S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary

National Oceanic and Atmospheric Administration

Vice Admiral Conrad C. Lautenbacher, Jr., Administrator

National Weather Service

John J. Kelly, Jr., Assistant Administrator
ii

Preface

Super Typhoon Pongsona (Pong-sahn-WAH) was one of the most intense typhoons to

ever strike the island of Guam. It was comparable to Super Typhoon Paka (1997) and was

exceeded only by Karen (1962) and the Typhoon of 1900.

Due to the magnitude of this event and its impact on Guam, a service assessment team

was formed to examine the warning and forecast services provided to the Guam Civil Defense

and local officials, the media, and the public. Service assessments provide a valuable

contribution to ongoing efforts to improve the quality and timeliness of the National Weather

Service products and services. Findings in this assessment will help to improve techniques,

products, services, and the information provided to the American public.

John J. Kelly, Jr.

Assistant Administrator

 for Weather Services

April 2003
iii

Table of Contents

Page

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Service Assessment Team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Service Assessment Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Findings and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Appendix A Guam Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Appendix B Conditions of Readiness (COR) for Guam, CNMI, and Micronesia 

(Relationship of COR to Watches and Warnings) . . . . . . . . . . . . . . . . . . . . . . . B-1

Appendix C Pacific Daily News Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
iv

Service Assessment Team

This service assessment team was activated on December 12, 2002. The Weather

Forecast Office (WFO) Guam briefed the team on December 18. Team members visited the

Pacific Region Headquarters; WFO Honolulu, Hawaii; the Joint Typhoon Warning Center

(JTWC); and various emergency management, civil defense, government, military, and private

sector agencies and organizations, as well as broadcast media outlets. In addition, telephone

interviews were conducted with officials on the islands of Rota and Saipan, and individuals from

several external organizations. 

The team comprised the following individuals.

Paul Duval Team Leader, Meteorologist in Charge (MIC), WFO Tallahassee,

Florida

Dr. John Beven Hurricane Specialist, Tropical Prediction Center, Miami, Florida

Delores Clark National Oceanic and Atmospheric Administration (NOAA) Public

Affairs Officer, Pacific Region Headquarters

Dr. Mark Lander Professor, University of Guam

Hendricus Lulofs Warning Coordination Meteorologist, WFO Caribou, Maine

Dr. John Marra NOAA Coastal Natural Hazards Specialist, Perot Systems

Government Services

Rafael Mojica Warning Coordination Meteorologist, WFO San Juan, Puerto Rico

Ken Waters Regional Scientist, Pacific Region Headquarters

Other valuable contributors:

Col. Mark Weadon U.S. Air Force Deputy for Federal Programs and NOAA Office of

Military Affairs

William Lerner NWS Headquarters, Office of Climate, Water, and Weather Services,

Silver Spring, Maryland

Linda Kremkau NWS Headquarters, Office of Climate, Water, and Weather Services,

Silver Spring, Maryland
v

The team would like to thank the following who took time to talk with team members.

NWS Offices

Staff, WFO Tiyan, Guam

Staff, WFO Honolulu, Hawaii

Staff, NWS Pacific Region Headquarters

Federal Agency Personnel

Joint Typhoon Warning Center (JTWC)

Robert Fenton, Operations Chief, Federal Emergency Management Agency, Region IX

Joyce P. Cruz, LT(jg), Assistant Operations Officer, U.S. Coast Guard, Marianas Section

Captain Lorigan, Commander, U.S. Coast Guard, Marianas Section Operations

Brian Black, LT(jg), U.S. Navy

Bruce Best, Guam Station Administrator, PEACESAT

Guam and Commonwealth of Northern Mariana Islands (CNMI) Government Personnel

Leo Espia, Earthquake Program Manager, Guam Office of Civil Defense

Joe G. Javellana III, Administrator, Guam Office of Civil Defense

Francisco Santos, Harbor Master, Guam Port Authority

Mike Gawel, Director, Guam Bureau of Statistics and Plans, Guam Coastal Management

 Program

Anthony M. Calvo, Federal Programs Coordinator, CNMI Emergency Management Office,

 Office of the Director

John F. Blas, Executive Director of the Mayors Council on Guam

Gerald Yingling, Director, Guam Airport Authority

Media

Benny T. Flores, Operations Manager, KGTF-TV, Channel 12

Shawn Gumataotao, News 8 Anchor/Reporter, KUAM-TV, Channel 8

Edward Poppe, President, Inter-Island Communications Inc., KSTO Radio

Jon Anderson, President, Sorenson Pacific Broadcasting Inc., K57 AM Radio

Mana Silver, News Director, K57 AM Radio

Rindraty C. Limtiaco, Managing Editor, Guam Pacific Daily News

Lee Webber, Publisher, Guam Pacific Daily News

David Crisostomo, News Editor, Guam Pacific Daily News

Haidee Engenio, Reporter, Marianas Variety

Private Sector Agencies, Institutions, and Organizations

James Nelson, General Manager, Guam Visitor’s Bureau

David B. Tydingco, President, Guam Hotel and Restaurant Association

David B. Arnold, Port Engineer, General Dynamics - American Overseas Marine

Ralph Freeman, Chief Pilot, Continental Airlines

Dr. Arthur Chiu, University of Hawaii
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Acronyms

AFB Air Force Base

ASOS Automated Surface Observation System

CNMI Commonwealth of Northern Mariana Islands

COR Conditions of Readiness

EAS Emergency Alert System

FSM Federated States of Micronesia

GMS Geostationary Meteorological Satellite

HF High Frequency

JMA Japan Meteorological Agency

JTWC Joint Typhoon Warning Center

mb millibars

MIC Meteorologist in Charge

NOAA National Oceanic and Atmospheric Administration

NWR NOAA Weather Radio

NWS National Weather Service

PEACESAT Pan-Pacific Education and Communication Experiments by Satellite

RSMC Regional Specialized Meteorological Center 

SAME Specific Area Message Encoder

SDM Station Duty Manual

SOO Science and Operations Officer

TD Tropical Depression

TS Tropical Storm

UTC Coordinated Universal Time

WCM Warning Coordination Meteorologist

WFO Weather Forecast Office

WSR-88D Weather Surveillance Radar-1988 Doppler
vii

Visible satellite image of Pongsona as seen by the Japanese Geostationary Meteorological

Satellite (GMS-5) at 4:30 p.m., December 8, 2002. The island of Rota is located just north of

the eye. (Courtesy of the Wisconsin Co-operative Institute for Meteorological Satellite Studies)
viii

Damage to a commercial warehouse across from the Governor’s Complex in

Adelup, Guam. (NOAA)

Remains of the units of the Micronesia Hotel along Route 8 in MongmongToto-Maite, Guam. (NOAA)
1

Service Assessment Report

Executive Summary

Super Typhoon Pongsona was one of the worst typhoons to ever strike the island of

Guam. It was Guam’s third most intense storm with sustained winds of 144 miles per hour

(mph), gusts to 173 mph, and a pressure of 27.61 inches (935 millibars [mb]). Only two storms

exceeded Super Typhoon Pongsona—Karen in 1962, 27.52 inches (932 mb) and 155 mph winds

sustained; and the Typhoon of 1900, 27.35 inches (926 mb), wind speed unknown. Super

Typhoon Paka in 1997 equaled Pongsona in intensity while over Guam. Preliminary damage

estimates for Guam totaled more than $700 million which placed Pongsona in the top five

typhoons for damage. 

There was one indirect death attributed to the storm; a woman was cut by flying glass and

subsequently suffered a fatal heart attack. Medical help could not reach her due to the intensity

of the storm. The Guam Department of Health reported 193 injuries, mostly lacerations and

fractures caused by flying glass and other debris. Deaths and injuries were kept to a minimum

due to the public’s experience with typhoons and Guam’s strong building codes. The eyes of six

typhoons have passed over Guam in the past 10 years. Watches and warnings issued by the

Weather Forecast Office (WFO) Tiyan, Guam, gave the population significant lead time,

although the intensity of the storm on the island was under forecast. (Hereafter, WFO Tiyan,

Guam, is referred to as WFO Guam.)

The eye of Pongsona was unusually large, almost 40 miles in diameter, and passed over

the northern part of Guam. (See Appendix A for Guam Locations.) Andersen Air Force Base

(AFB) was in the eye for nearly 2 hours. Conditions in the eye are characterized by light winds

with little or no rain. The strongest winds in a typhoon are in the eyewall immediately

surrounding the eye. The storm’s track kept the eyewall over the most populated and developed

part of the island, with typhoon force winds and torrential rains for as much as 5 hours. Rainfall

amounts exceeded 20 inches over some areas in the north with a maximum of 25.61 inches at the

University of Guam. (See Figure 1 for rainfall totals.) Since such a large portion of the

population experienced the worst part of the storm, there was a perception this was the worst

typhoon to ever strike Guam.

Despite the Joint Typhoon Warning Center (JTWC) forecasts that Super Typhoon

Pongsona would miss Guam, WFO Guam issued timely watches and warnings. (See Tropical

Cyclone Forecast Responsibility in the Western North Pacific Ocean section below.) The storm

struck Guam with greater intensity than forecast, resulting in a public perception the forecast was

not good. This is discussed in more detail in the report. 
2

Figure 1: Total rainfall (in inches) midnight-to-midnight December 7-8, 2002. Maximum

rainfall occurred in a swath across central Guam that experienced the heaviest rain rates for the

longest possible time. Areas in the northeast spent as much as 2 hours in the eye, and rainfall

totals were slightly less there. Also, rainfall totals dropped off rapidly to the southwest because

of increasing distance from the eye wall and decreasing time spent within the region of high rain

rates. (NOAA)
3

WFO Guam has an excellent working relationship with the local government and the

media. John F. Blas, Executive Director of the Mayors Council on Guam, complimented the

National Weather Service (NWS) performance, saying, “The NWS did a better job with

Pongsona than with Chata0an” (in 2002), and he was “...very happy with the NWS.” The

media’s reaction to NWS performance was mixed. The consensus was the NWS does a good

job, however, this forecast could have been better.

Service assessments are undertaken by the NWS to determine the level of service

provided to its partners and customers. Service lapses, if any, are noted so corrective action can

be taken. Emergency managers, civil defense, people in the media, and local residents were

interviewed to obtain feedback on NWS performance.

WFO Guam’s area of responsibility for tropical cyclone watches and warnings includes

the island of Guam (U.S. Territory), the Northern Mariana Islands (U.S. Commonwealth), Wake

Island (U.S. unincorporated Territory), the Federated States of Micronesia (FSM), the Republic

of the Marshall Islands, and the Republic of Palau (the latter three all independent nations). The

assessment focused on service provided to partners and customers.

The assessment team learned WFO Guam did a good job in communicating information

as track and intensity forecasts changed and provided excellent coordination to partners in

government and the media. WFO Honolulu provided excellent backup when communications on

Guam failed. The team found opportunities for improvement, and developed eleven

recommendations pertaining to communications, dissemination, science, and internal and

external procedures.

Data contained in this report were compiled by the assessment team as of March 11,

2003. Final analyses may produce statistics that do not match those contained in this report.

Tropical Cyclone Forecast Responsibility in the Western North

Pacific Ocean

Tropical cyclones, with maximum sustained winds greater than 73 mph, are called

typhoons in the western North Pacific Ocean. This area is bounded by the equator to the south,

Asia to the west, the limit of tropical cyclone activity to the north, and the International Date

Line to the east. The Regional Specialized Meteorological Center (RSMC) of the Japan

Meteorological Agency (JMA) has international responsibility for monitoring and forecasting

tropical cyclones. The NWS uses the names assigned to tropical cyclones by RSMC, but does

not use its forecasts. JTWC at Pearl Harbor, Hawaii, is responsible for monitoring and

forecasting tropical cyclones for American military interests. These forecasts are also the basis

for WFO Guam’s public tropical cyclone advisories, watches, and warnings for its area of

responsibility (see Figure 2).
4

Figure 2: The WFO Guam area of responsibility, compared with the size of the continental

United States. Area bordered in blue represents aviation area of responsibility. Area bordered in

black represents tropical cyclone area of responsibility. (NOAA)
5

Chronology 

The locations of JTWC, Guam, and other places in the Pacific mentioned in this report

are separated by enormous distances as well as the International Date Line (see Figure 3). For

the reader to keep track of time, all times are referenced in Guam local time.

Super Typhoon Pongsona began as a weak disturbance about 370 miles east of Pohnpei

(FSM). At 9 p.m., December 2, the JTWC issued a Tropical Cyclone Formation Alert,

indicating the disturbance was likely to become a tropical cyclone within 12 to 24 hours. Seven

hours later, JTWC issued the first warning on Tropical Depression (TD) 31W (31st tropical

depression of the calendar year in the western North Pacific), located 70 miles north-northeast of

the island of Kosrae (1,362 miles east-southeast of Guam). (See Figure 4 for Super Typhoon

Pongonsa track.)

At 10 a.m., December 3, the JTWC upgraded the depression to Tropical Storm (TS)

31W. Twelve hours later, TS 31W was named Tropical Storm Pongsona by the RSMC. At 4

p.m., December 5, Pongsona was upgraded to a typhoon as it passed through Pohnpei State. 

Although it produced heavy rains and gusty winds, there was little damage. On December 6, the

typhoon caused tropical storm force winds on Chuuk State (about 650 miles southeast of Guam)

as it passed just north. High waves completely washed over some of the northwestern Atolls.

During the next two days, Pongsona continued to intensify and move on a west-northwest

track. Late on December 7, the eye of the typhoon came into the range of the Andersen AFB

Weather Surveillance Radar-1988 Doppler (WSR-88D), when it was about 270 miles southeast

of Guam. Early on December 8, radar showed Pongsona beginning to recurve. (Most tropical

cyclones move west or northwest and begin to turn to the north or northeast as they come under

the influence of prevailing westerly winds at mid-latitudes.) The western half of the eye moved

across northern Guam between 4:15 p.m. and 7:30 p.m. on December 8. Maximum sustained

winds were estimated at 144 mph (converted from 125 knots) with higher gusts at both Hospital

Point and Two Lovers Point on the west-central side of the island. (See Figure 5 for peak wind

gusts on Guam.)

Pongsona continued to intensify as it crossed Guam, and reached peak intensity of

150 mph at 10 p.m., December 8, while in the Rota Channel between Guam and Rota. Storms

are classified as super typhoons when sustained winds reach 150 mph. On December 9, the

typhoon began to weaken as it continued to recurve to the northeast. The storm lost its tropical

characteristics on December 11.
6

 Figure 3: WFO Guam’s location in the western Pacific. (Courtesy of the American Red 

 Cross) 
7

Figure 4: Super Typhoon Pongsona’s track for December 1-11, 2002, as obtained from JTWC’s

warning graphics. Looking at the track, the open circles are the tropical depression stage, the

open center of the tropical cyclone symbol is the tropical storm stage, and the red center is the

typhoon stage. Certain benchmarks in the life of Pongsona are indicated. The inset is a closeup

of Pongsona’s passage between Guam and Rota. The three red rings are the approximate

locations of the inner edge of the eyewall at 4 p.m., 7 p.m., and 11 p.m., December 8, 2002. 

The black dots are the positions of the eye center at these times. The intensities indicated are

from the NOAA Meteorological Assessment of Super Typhoon Pongsona. (NOAA) 
8

Figure 5: Distribution of Pongsona peak wind gusts on Guam on December 8, 2002. Contour

values are in mph. (NOAA)
9

Warning and Forecast Services

WFO Guam

As mentioned in the Executive Summary, WFO Guam is tasked with issuing public

tropical cyclone advisories, watches, and warnings for its large area of responsibility in the

western North Pacific (see Figure 2). These products are based on JTWC forecasts of storm

intensity and position. The office also issues the normal suite of WFO forecast and warning

products, which become more frequent, longer, and more complex when a tropical cyclone

threatens. The suite includes local statements when portions of the WFO area of responsibility

are under tropical storm or typhoon watches or warnings. An additional tropical cyclone-related

duty is the issuing of hourly position estimates when a cyclone’s center is close enough to Guam

to be accurately tracked on the WSR-88D radar at Andersen AFB.

As Pongsona became more organized and tracked west-northwest across the North

Pacific, WFO Guam took the following actions (partial list):

• December 3, 2 p.m. — Tropical Storm Warning for portions of the Republic of the

Marshall Islands. 

• December 4, 8 p.m. — Tropical Storm Watch for Chuuk State, Federated States of

Micronesia.

• December 5, 8 p.m. — Tropical Storm Warning for Federated States of Micronesia.

• December 6, 8 a.m. — Typhoon Watch for Guam, Rota, Saipan and Tinian in the

Mariana Islands was issued for now Typhoon Pongsona. 

• December 7, 8 a.m. — Typhoon Warning for Guam, Rota, Saipan and Tinian. 

• December 7, 8 a.m. — Typhoon Watch for Agrihan, Commonwealth of Northern

Mariana Islands (CNMI).

• December 8, 6 p.m. — Typhoon Warning for Agrihan, CNMI.

As Pongsona moved toward Guam, the WFO staff coordinated with the military and civil

defense directors on Guam and in the Marianas. This coordination included participation in

three “heavy weather briefings” for Guam held at 10 a.m., December 6, and 1 p.m. and 8 p.m.,

December 7. At the 8 p.m. briefing, based on the information from JTWC, the WFO staff

continued to predict the eye would pass well to the east of the island and sustained typhoon force

winds would remain offshore. This WFO forecast was for sustained winds of 60 to 65 mph with

gusts to 75 mph (typhoon force). The forecast remained unchanged in the 11 p.m., December 7,

local statement and included the following: “HOWEVER...A SLIGHT CHANGE IN THE
10

TYPHOON’S TRACK COULD BRING TYPHOON FORCE WINDS EXCEEDING 75 MPH

ON SUNDAY [DECEMBER 8].” There would be a dramatic change just two hours later.

WFO Guam operates its typhoon warning program under a relationship with JTWC that

is unique in the NWS. The NWS presence on Guam began in 1956 as a Weather Service Office

(Taguac). In 1976, two NWS employees were assigned to the Naval Meteorology and

Oceanography Center West. This facility provided weather services to both the civilian and

military populations of Guam. In 1992, two more NWS employees were added to the staff. The

Naval facility was closed in 1995 and the NWS assumed responsibility for providing all civilian

weather services to Guam and Micronesia. In October 1997, Annex III to the Memorandum of

Agreement between the Department of the Navy and the National Oceanic and Atmospheric

Administration (NOAA) spelled out responsibilities for providing civilian weather services for

Guam and surrounding areas. Included in this Annex was the requirement that JTWC “act as

sole forecast agency for tropical cyclones within its area of responsibility and, as appropriate,

keep close liaison with the forecast office.” The WFO Guam Station Duty Manual (SDM),

section 5.1.1.5, states, “The JTWC wind field forecast, in combination with the track forecast, is

the basis for all watches and warnings.”

The Warning Coordination Meteorologist (WCM) and the Science and Operations

Officer (SOO) are both experienced forecasters who formerly worked at the JTWC. However,

both, as well as a lead forecaster, were off-island as the typhoon approached and were unable to

return until after the storm passed. The WFO Guam office policy is unclear in detailing the

number of senior staff permitted to be off-island at the same time. (Finding 1)

Staffing on the day shift (8 a.m. to 4 p.m.) Saturday, December 7, consisted of two lead

forecasters, one journeyman forecaster, a Hydrometeorological Technician (HMT), and the

Meteorologist in Charge (MIC). The Guam shift log shows a call to JTWC sometime during the

morning to coordinate the position of Pongsona, and questioned the difference between the

forecast position and the satellite observed position. The evening shift staffing (4 p.m. to

midnight) included three journeyman forecasters, an HMT, and the MIC, but no lead forecaster. 

It was unclear to the assessment team who was the designated lead forecaster. Interviews

revealed the evening shift forecasters were all concerned the forecast track was too far east. This

is supported by a shift log entry of a 10:30 p.m. call to the JTWC. However, this call was not

made until the shift was almost over. The log entry also indicates JTWC forecasters agreed to

re-evaluate the forecast track for their next advisory. (Note: JTWC issues regular tropical

cyclone position and wind forecast updates every 6 hours at 1 a.m., 7 a.m., 1 p.m., and 7 p.m.,

respectively.)

Two lead forecasters were assigned to the midnight shift (midnight to 8 a.m.), Sunday,

December 8. Interviews with the shift leader indicated when he came on duty, he was dismayed

the forecast had remained the same for 8 hours, even though the typhoon had moved farther west

than the JTWC had forecast. He stated the evening shift was a “critical shift” with respect to the

forecast, and his experience taught him if a storm reached 150 degrees east longitude and

remained at or below 10 degrees north latitude, then Guam was at “much greater risk.” He
11

immediately called the JTWC (not in the shift log), was forceful in his concern about the forecast

track, and told them he intended to make a significant increase in the wind forecast for Guam. 

He indicated the JTWC forecaster was reluctant to make a big change, but did agree to adjust the

forecast. The shift log shows a call from JTWC at 12:30 a.m. on December 8, noting reception

of a “new warning.” The forecaster then called the Guam Civil Defense informing them the

forecast track was farther west and typhoon force winds would affect Guam. This was

30 minutes before JTWC issued the routine forecast at 1 a.m. Guam’s 1 a.m. typhoon local

statement included: “NORTHEAST WINDS WILL INCREASE THROUGHOUT THE DAY

TODAY AND REACH 90 TO 115 MPH WITH GUSTS TO 130 MPH BY THIS

AFTERNOON. WINDS THIS STRONG WILL BLOW DOWN NON-REINFORCED

CINDER BLOCK WALLS. THE CENTER OF PONGSONA IS FORECAST TO PASS VERY

CLOSE TO ROTA THIS EVENING.” At 4:45 a.m., a call was logged indicating JTWC

forecasters were now expecting the typhoon center to pass close to Guam. At 6 a.m., the lead

forecaster called the MIC about the expected eye passage. At 6:15 a.m., a shift log entry shows a

telephone call to Guam Civil Defense with information conditions would be “much worse, as we

expect eye passage with 115-130 mph winds and gusts to 160 mph.” At 7 a.m., JTWC made a

final adjustment to the storm track, bringing the center of the eye just offshore. This brought the

forecast track close to the actual track of the storm’s center. The 8 a.m. Tropical Cyclone Public

Advisory from WFO Guam headlined, “POWERFUL TYPHOON PONGSONA BEARING

DOWN ON GUAM AND ROTA.” The advisory also indicated the storm was continuing to

intensify.

Based on the above information, the assessment team concluded a clearly designated lead

forecaster on the Saturday, December 7, evening shift would have resulted in more proactive

communication with JTWC and an earlier re-analysis of the forecast track. (Finding 2)

Lead times for the typhoon watch and warning for Guam and Rota were good. The

typhoon watch was issued 47 hours before the onset of tropical storm force winds (39 mph or

more–considered damaging wind speed) at WFO Guam (located in the center of the island) and

56 hours before the closest approach of the storm’s center to the island. While a large part of the

eye crossed the island, the storm center itself remained offshore. The typhoon warning was

issued 23 hours before the onset of tropical storm force winds at the WFO Guam and 32 hours

before the closest approach of the storm’s center.

As Pongsona passed over Guam, the WFO experienced a breakdown in communications. 

The WFO could not receive phone calls from 6:10 p.m., December 8, to around 1 a.m.,

December 10. Communication with WFO Honolulu, Guam’s backup office, was limited to a

satellite telephone that could not be used inside the WFO Guam building. Office staff actually

went outside to call WFO Honolulu during the storm but didn’t wait to receive calls. 

(Finding 3) Guam staff used e-mail and its Web site until they failed. There were customer

complaints about service slow downs on the Web site. This is discussed further in the Pacific

Region Headquarters section of this report. Other communication issues are discussed in greater

detail in the Communications section.
12

WFO Honolulu began partial backup by issuing aviation products at 4 p.m., December 8. 

The WFO Honolulu assumed all WFO Guam’s duties 10 hours later. Backup responsibility was

relinquished at 8:30 a.m., December 10. Additional information on WFO Honolulu’s role is

contained in the next section.

Neither WFO Guam nor JTWC issue tropical cyclone strike probabilities or any other

product that displays the uncertainty in a tropical cyclone track forecast. The WFO does

sometimes indicate a level of uncertainty by using statements in its advisories. For example, as

stated above, the 11 p.m. local statement said, “HOWEVER...A SLIGHT CHANGE IN THE

TYPHOON’S TRACK COULD BRING TYPHOON FORCE WINDS EXCEEDING 75 MPH

ON SUNDAY [DECEMBER 8].” JTWC does issue a graphic depicting a “ship avoidance area”

which is equivalent to an uncertainty forecast. (See Figure 6.) This product is intended for

military use.

Instrument failure was another significant problem. The anemometer at Andersen AFB

did work throughout the typhoon but wind speed data were unreliable. The four HANDAR wind

sensors on Guam, which use sonic anemometers, all failed to report winds at the height of the

storm. The HANDAR instruments began working again once typhoon conditions eased. The

Service Assessment Report following Super Typhoon Paka in 1997 recommended re-siting or

replacing wind instruments on Guam. Using the best knowledge and technology available at that

time, the wind sensors on the four HANDAR units were replaced with sonic anemometers. 

Wind measurements were available from only one anemometer on the northern half of the island

during passage of the eyewall. This was the Automated Surface Observation System (ASOS)

anemometer. The Guam ASOS currently communicates data to the WFO via VHF transmitter. 

The system failed during Pongsona when the tower with the receiving antenna blew down. 

(Finding 4)

The WSR-88D radar at Andersen AFB also failed during Pongsona due to loss of power. 

The backup generator had been malfunctioning for five months before Pongsona and had not

been repaired. Another backup generator at the radar site required manual start-up but the base

commander believed it was too dangerous to send a technician to the site. The U.S. Air Force

told the assessment team the auto-start generator has now been repaired.
13

Figure 6: The JTWC forecast for Pongsona, valid at 4 a.m., December 6. The forecast positions

are labeled with date and time as 2 digits each, respectively. “Z” corresponds to Coordinated

Universal Time (UTC), Guam time minus 10 hours. Dashed line represents ship avoidance area. 

(Courtesy of JTWC)
14

WFO Honolulu, Hawaii

WFO Honolulu is the backup office for WFO Guam. When backup procedures are in

effect, WFO Honolulu is responsible for issuing all WFO Guam products, including tropical

cyclone products. WFO Honolulu began its backup responsibility with aviation products at

4 p.m., December 8, and took over all WFO Guam duties at 2 a.m., December 9. WFO Honolulu

ended its backup responsibility by 8:30 a.m., December 10. The WFO Guam lead forecaster

who was off-island worked shifts at WFO Honolulu during this backup period. The assessment

team also found the two WFOs did not hold backup drills during 2002. 

While in backup mode, WFO Honolulu issued typhoon warnings for CNMI at 2 a.m.,

December 9. WFO Honolulu discontinued typhoon warnings as Pongsona moved past

individual islands in the Marianas. The warnings for Alamagan and Agrihan were cancelled 5

hours before the closest approach of Pongsona. In interviews with WFO Guam staff, some

forecasters expressed concern warnings were cancelled too early. The Saipan emergency

manager agreed. (Finding 5)

Pacific Region Headquarters

Pacific Region Headquarters in Honolulu, Hawaii, provides administrative and technical

support to field offices in its region.

The WFO Guam Web site is hosted on a shared server located at the Telecommunications

Operations Center at NWS Headquarters in Silver Spring, Maryland. As mentioned earlier in

this report, the assessment team heard complaints from the public about the Web site’s slow

response. In addition, limited disk space resulted in an inability to update WFO Guam’s Web

page. This problem of limited disk space lasted 3 hours until Pacific Region staff deleted files. 

The assessment team learned Pacific Region is in the process of upgrading server capabilities

which should resolve the problems of slower response and limited disk space.

Joint Typhoon Warning Center

Note to the casual reader: this section contains detailed technical information about

forecast errors.

Tropical cyclone forecasts in the western North Pacific issued by the JTWC are the basis

for Guam’s tropical cyclone watches and warnings. The JTWC issues 6 hourly advisories,

including forecast track, wind speed, and wind radii (distance from the storm center of tropical

storm force and typhoon force winds). A discussion of the meteorological aspects of the tropical

cyclone is issued every 12 hours.

Military forecasters serve a 3-year tour of duty at JTWC. Hurricane/typhoon forecasters

in civilian national meteorological services typically have more experience. JTWC forecasters
15

follow a specific process in preparing typhoon track and intensity forecasts which place a heavy

reliance on guidance from computer models. Computer models, and the forecasts based on it,

were consistent in placing the storm track too far east of Guam in the 2 days prior to landfall. 

(See Figure 7.)

The JTWC track forecasts for the three days leading up to Pongsona’s passage across

Guam were much better than JTWC’s forecasts for all tropical cyclones for the period 1997-

2001. The average position error for 24-hour forecasts for Pongsona was 59 miles versus the 

5-year average of 109 miles. The average position error for 48 hours was 97 miles versus the 

5-year average of 171 miles. For 72 hours, the position error for Pongsona was 124 miles versus

285 miles for the period 1997-2001. Note the 72-hour forecast position error for Pongsona was

smaller than the 48-hour error for the 5-year period mentioned above, and the 48-hour forecast

position error for Pongsona was smaller than the 5-year average for 24 hours.

Despite JTWC’s above average track forecasts, the fact that a direct hit from a major

typhoon was not forecast resulted in below average service to the population of Guam. As

mentioned above, the average forecast position error for all 72-hour forecasts was 124 miles. 

The position error for the 72-hour forecast verifying at the time the storm was over the island

was 64 miles. The average 48-hour forecast position error was 97 miles, but the 48-hour forecast

position error for the time the storm was over the island increased to 121 miles. The 24-hour

forecast position error for the time the storm was over the island was 95 miles versus the average

error for all 24-hour forecasts of 59 miles.

While JTWC did forecast intensification of the storm, the trend was underestimated. In

the three days prior to landfall, JTWC consistently under forecast storm intensity by almost

30 mph. For example, the Thursday evening, December 5, forecast indicated a maximum

sustained wind of 115 mph for Sunday afternoon, December 8 (the time the storm was over

Guam). The actual maximum sustained wind was estimated at 144 mph.

Analysis of satellite images by the assessment team indicated 24 hours prior to landfall,

the storm was undergoing significant intensification as it continued to track farther west than

forecast. However, as late as 12 hours before landfall, JTWC forecasters continued to

underestimate the threat to Guam. The WFO Guam lead forecaster on the midnight shift,

December 8, called JTWC shortly after midnight to urge a modification in the forecast track. 

This forecaster told the assessment team he was convinced Super Typhoon Pongsona was going

to pass close by or make a direct hit on Guam. This forecaster stated he sensed a reluctance on

the part of JTWC to make a major change in the forecast track. (Finding 6)
16

Figure 7: A composite of JTWC track forecasts for Super Typhoon Pongsona from the first

advisory until it recurved northeast and lost tropical characteristics. Six hourly track forecasts

are in grey, with markers at 12, 24, 36, 48, and 72 hours. The actual “best” track of Pongsona is

shown in yellow, with markers every 6 hours. (Courtesy of JTWC)
17

Partners and Customers Coordination

The effectiveness of the weather warning system is dependent on close coordination,

cooperation, and a clear consistent message among the various agencies responsible for public

safety. This includes the NWS, the media, Guam Civil Defense, and other government entities.

Feedback from partners and customers varied. Some in government and media

interviewed by the assessment team said they were satisfied or very satisfied with the forecast.

These people are aware of the uncertainties in typhoon forecasting, and knew any change in the

track and intensity of a tropical cyclone that close to Guam could have a major impact. Others

said they were not properly informed about the track and intensity of the super typhoon and were

not prepared for a direct hit.

Civil Defense/Emergency Management

WFO Guam has a close working relationship with Guam Civil Defense. Leo Espia, 

Guam Civil Defense, said, “Civil Defense maintains good communications with NWS. NWS

calls Civil Defense on a routine basis.” During the Pongsona threat, the WFO Guam MIC was

in frequent phone contact with Guam Civil Defense.

Civil defense officials told the assessment team they often use the NWS and JTWC Web

sites. They also used HURREVAC software as Pongsona was approaching the island. 

HURREVAC is a restricted-use U.S. Government program used by emergency managers and

civil defense officials since 1988 to track hurricanes and assist in decision making for their

communities.

 

During tropical cyclone events, WFO Guam participates in heavy weather briefings at

Civil Defense Headquarters, attended by government representatives and the media. There were

three heavy weather briefings for Super Typhoon Pongsona, prior to civil defense activation of

COR 1. Guam Civil Defense uses Conditions of Readiness (COR). COR is used by the military

to indicate the period between current time and onset of damaging winds (greater than 39 mph). 

COR levels 4, 3, 2, and 1 correspond to the onset of damaging winds in 72, 48, 24, and 12 hours,

respectively. (See Appendix B.) COR was adopted by the Guam Civil Defense and is

understood by Guam’s general population, because until 1995 the military forecast the weather

for Guam. The emergency response system on Guam is keyed to changes in COR levels and not

to NWS tropical cyclone watches and warnings. (Finding 7)

There were differing opinions concerning the relationship of COR to watches/warnings.

Random interviews with the public indicated several people were confused about the different

terms used by Guam Civil Defense and the NWS. Because of the long military presence, some

are familiar with COR and do not understand NWS watches and warnings. Mr. David Tydingco,

Hotel and Restaurant Association, stated, “The NWS watch and warning terminology—people

don’t know how to take it.” In contrast, Mr. James Nelson of the Guam Visitor’s Bureau said

there was no confusion about COR levels.
18

Guam Civil Defense is an active participant at WFO Guam workshops and coordination

meetings. Civil defense officials participated in the annual typhoon exercise (fictitious Pakyo

2002), annual typhoon workshops, and joint NOAA/Federal Emergency Management Agency

courses on typhoons.

CNMI emergency management praised NWS performance. Mr. Anthony Calvo, CMNI

Emergency Manager, indicated although the actual intensity of the storm was greater than

expected and the damage was “incredible,” he was satisfied with the information received from

the NWS. He stated, “...very good information from NWS; we were not caught off-guard.”

Government of Guam

Several local government agencies were interviewed by the assessment team. A key

partner in the warning process is the Guam Council of Mayors. The mayors assist in notifying

people in their communities, sometimes driving through villages using portable public address

systems to announce typhoon warnings. Members of the Council are active participants in WFO

Guam workshops and briefings and receive NWS products by facsimile several times a day. 

During Super Typhoon Pongsona, the Council used HURREVAC to evaluate the typhoon’s

threat to Guam. The Executive Director of the Mayors Council, John F. Blas, said, “The NWS

did a better job with Pongsona than with Chata0an.” He went on to say he was “very happy with

the NWS.”

According to James Nelson, General Manager, Guam Visitors Bureau, there were

10,000 visitors on Guam before Pongsona struck. Mr. Nelson said WFO Guam in general “is

doing the job very well.” However, he noted the forecast projections for Pongsona were off this

time. He commented people were relaxed on Saturday morning, December 7, with some

choosing to ignore the warnings.

Frank Santos, Guam’s Port Authority Harbor Master, said “people were expecting a

banana typhoon” with winds of 50 to 60 mph. (In the tropics, a “banana typhoon” refers to

winds strong enough to blow down banana trees but not do major damage.)

Private Sector

Most of the major hotels in Guam are members of the Hotel and Restaurant Association,

a non-profit trade group which has actively participated in WFO Guam typhoon workshops and

other briefings. Mr. David Tydingco, President, explained the association has an emergency

action plan, ensuring all the hotel properties receive weather bulletins. One of the member

hotels (Pacific Island Club) receives the weather bulletins from NWS via facsimile and then

releases the information to other hotel members. Mr. Tydingco said the forecast for Super

Typhoon Pongsona was off and led people to be too relaxed and complacent. 
19

Media

Guam is served by one major daily newspaper, four television stations, and eleven radio

stations. Two smaller daily newspapers published in CNMI are also available on Guam.

WFO Guam began media outreach in 1995 when it assumed responsibility for issuing

weather forecasts from the military. A concerted effort was made to educate the media about

NWS products, including watch and warning definitions, and safety preparedness via regular

briefings and publications. In 1996, WFO Guam instituted an annual typhoon workshop for

media and civil defense. Comments by the media to the assessment team showed WFO Guam

has developed a strong working relationship. NWS products are faxed to all broadcast and major

print media on Guam. 

Guam media is proactive about covering weather and relaying NWS information to the

public. Most of the media interviewed use the NWS and JTWC Web sites.

Guam’s main newspaper, Pacific Daily News, regularly advertises the WFO Web site and

phone numbers for recorded weather information, including a phone number for the NOAA

Weather Radio (NWR) broadcast. During typhoons, the paper provides extensive coverage,

including preparedness information, and an explanation of watches and warnings. Lee Webber,

Publisher of Pacific Daily News, advocated the development of graphics to give the public a

better idea how the typhoon track might vary. Mr. Webber said, “Explaining things graphically

is better than telling. It would be good to have a graphic showing the strike probabilities and

margin of error. People would take more heed.”

One television station, KUAM-TV, produces live daily news programming and weather

segments, but is off the air from midnight to 6 a.m. KUAM-TV did not come back on the air

Sunday morning, December 8, because the antenna blew down during the night. The other three

stations broadcast taped-delayed programming and cable channels, but KTGM-TV breaks in as

necessary to report weather updates. Several radio stations operate around the clock but

broadcast taped programming after midnight. Newspapers have print deadlines that cannot be

changed. The Pacific Daily News goes to print at 11 p.m. Since the significant change to the

typhoon forecast came at 1 a.m., Sunday, December 8, these media outlets could not disseminate

the information. For example, the Sunday morning edition of the Pacific Daily News showed the

forecast as of 11 p.m., Saturday night, December 7, which indicated the typhoon tracking east of

Guam when the forecast already been changed to bring the storm over the island (see Figure 8). 

However, newspaper staff did post updates on the Pacific Daily News Web site and responded to

calls from the public seeking information. 
20

Figure 8: This is a copy of the JTWC track forecast published by the

Pacific Daily News, Sunday morning, December 8, 2002. Yellow circle

represents the storm position at 7 p.m., Saturday, December 7. Black

circles represent forecast positions at 4 a.m. and 4 p.m., Sunday,

December 8, respectively. (Courtesy of JTWC)
21

The Guam media recognized the efforts of WFO Guam and understood the limitations of

typhoon forecasting. K57 AM Radio Jon Anderson, President, Sorenson Pacific Broadcasting,

Inc., said, “I don’t have any problems with the forecasts issued by NWS. I think it was handled

well.” KSTO Radio, Edward Poppe, President, Inter-Island Communications, Inc., said, “You

guys did a wonderful job.”

Public

One theme stood out in assessment interviews with the public: people did not receive

advanced warning of a storm of Pongsona’s intensity. 

• Several people referred to the expectation of a banana typhoon and not the intensity of a

super typhoon.

• Tracking graphics published in the newspaper each day consistently placed the typhoon

east of the island. As mentioned in the Media section, the Sunday morning graphic of the

forecast storm track, the day the storm struck, showed the typhoon passing east of Guam. 

One person said, “It was not that people did not prepare adequately. The actual track

was the problem and the way it was communicated.”

• Interviews indicated people accept track and intensity forecasts as accurate. There are no

products which indicate the inherent uncertainty in these forecasts.

• Several people interviewed reported radio stations downplayed the strength of the

typhoon (based on the forecast) by encouraging the public to go shopping and take in a

movie.

• The storm was also downplayed on KUAM-TV when a government official announced in

a live interview on the 6 p.m. news, Saturday night, December 7, that COR 1 would be

declared at midnight but “we don’t expect it to be a bad storm.” (Finding 8)

The December 21, 2002, issue of the Pacific Daily News published the results of a survey

about satisfaction with NWS information during Pongsona. Out of 350 responses, 42.2 percent

said they were not satisfied with NWS information during Pongsona, while 20 percent expressed

satisfaction. (See Appendix C for newspaper survey.)

WFO Guam has been proactive in community outreach activities. During the past four

years, there have been more than 20 public safety presentations, more than a dozen island-wide

awareness programs, numerous media contacts, school talks, and efforts at establishing

partnerships with the private sector for printing and distributing NWS brochures.
22

Communications

WFO Guam uses conventional facsimile as the principal product dissemination method. 

Products are faxed to media, civil defense, the hotel association, Council of Mayors, the military,

the airport, government agencies such as the Federal Aviation Administration, the Port

Authority, and other users. If the island phone lines fail during severe weather events, WFO

Guam may not immediately be aware faxes are not being received. During Pongsona, the WFO

also provided updated information by cell phone and Internet.

Emergency Alert System

During Pongsona, the Governor of Guam maintained control of the Emergency Alert

System (EAS). There was no signed EAS Plan in place, and the system did not function as it

does on the Mainland. Records did show the EAS was activated at 8:34 p.m., December 7,

announcing COR 1 would go into effect at midnight. Interviews with at least two television

stations and one radio station indicated they did not receive the alert. Media representatives

stated to the team, “There are no procedures in place,” and “We are waiting for special

equipment from Civil Defense in order to use EAS.” Recent discussions with WFO Guam have

confirmed funding for Homeland Security will allow the EAS system to be upgraded and an

EAS Plan has now been signed. WFO Guam’s WCM is serving on a committee to help

implement the new plan and EAS equipment. Edward Poppe, KSTO Radio (the EAS station on

Guam), stated, he is “excited. This is the first time in 8 years things have gone the right way. 

It's the new administration.”

NOAA Weather Radio

NOAA Weather Radio (NWR), the voice of the National Weather Service, reaches all

parts of Guam, as well as Rota and Saipan, through two transmitters. Normally, when watches

and warnings are issued, the NWS transmits a signal alarming or turning on radio receivers with

the proper technology. Specific Area Message Encoder (SAME) allows radio receivers to be

programmed to turn on automatically or sound an alarm for designated geographic areas. At the

request of Guam Civil Defense, the NWS does not use either capability except for tsunami

warnings. (Finding 9)

The Guam transmitter has a backup generator serviced by U.S. Navy Public Works, an

arrangement which has been unreliable. The Saipan transmitter has two diesel generators which

are very old and serviced by a private company contracted by the Saipan Emergency

Management Office. All NWR equipment is slated for replacement by the end of September

2003.
23

StormReady Program

The NWS StormReady Program is successful in enhancing severe weather, tropical

storm, flood, and tsunami preparedness. StormReady improves a community’s ability to receive

critical NWS products, fosters communication between the NWS and communities, and

improves public response by supporting education efforts. 

This was exemplified by what happened in Van Wert, Ohio, which became a

StormReady community in January 2002. In Van Wert County, a communications system was

established which allowed the rapid transmission of emergency weather information. On

November 10, 2002, the manager of the Van Wert Cinema Complex used information from this

communications system to direct 60 people to safety. The building was destroyed but no

fatalities occurred. Had communities on Guam achieved StormReady certification, the 1 a.m.

typhoon forecast change would have received more widespread dissemination.

The WFO Guam MIC established a StormReady Local Advisory Board toward the end

of 2001. A detailed plan was created allowing for application by “any village or community”

for StormReady recognition. Changes in the emergency management and civil defense

administrations in the CNMI and on Guam, and the lack of a WCM at WFO Guam for seven

months in 2002, resulted in the program remaining inactive. No applications were submitted. 

(Finding 10)

PEACESAT and High Frequency Radio

The University of Guam relays weather information from the WFO using a public service

satellite telecommunications network, Pan-Pacific Education and Communication Experiments

by Satellite (PEACESAT). The university also transmits information via high frequency (HF)

radio to small outer islands in the FSM. This is the only means of communication with some of

these islands. 

There is no operational HF radio transceiver and antenna installed at WFO Guam. An

HF radio would provide a backup system, allowing WFO Guam to contact Weather Service

Offices (WSOs) and smaller islands in the FSM, CNMI, the Republic of the Marshall Islands,

and the Republic of Palau. The NWS is allocated four frequencies for use with this type of radio

in the western North Pacific. (Finding 11)
24

Wreckage of a gas station along Route 4 in Agana, Guam. The Bank of

Guam is in the background. (NOAA)

Downed utility pole along a back road east of the Bank of Guam (upper

right) in Agana, Guam. (NOAA)
25

Facts

Executive Summary

FACT: Super Typhoon Pongsona was one of the worst typhoons to ever strike Guam. 

It resulted in one indirect death, 193 injuries, and over $700 million in

damage.

Warning and Forecast Services

WFO Guam

FACT: A lead forecaster, WCM, and SOO were off-island when Super Typhoon

Pongsona struck Guam. The lead forecaster worked at the WFO Honolulu,

Hawaii, during the event.

FACT: There was no designated lead forecaster assigned to forecast duties on the

evening shift (4 p.m.-midnight) on December 7, 2002.

FACT: WFO Guam issued a typhoon watch for the island of Guam at 8 a.m.,

December 6. This was 47 hours before the onset of tropical storm force winds

(39 mph).

FACT: WFO Guam issued a typhoon warning for the island of Guam at 8 a.m.,

December 7. This was 23 hours before the onset of tropical storm force winds

(39 mph).

FACT: Wind measurements were available from only one anemometer on the

northern half of the island during passage of the eyewall. This was the ASOS

anemometer.

WFO Honolulu, Hawaii

FACT: WFO Honolulu began partial backup by issuing aviation products at 4 p.m.,

December 8, took over all WFO Guam duties at 2 a.m., Monday, December 9,

and ended its backup responsibility by 8:30 a.m., December 10.

FACT: WFO Guam and WFO Honolulu did not hold backup drills during 2002.
26

Joint Typhoon Warning Center

FACT: The JTWC track forecasts for the three days leading up to Pongsona’s passage

across Guam were much better than JTWC’s forecasts for all tropical cyclones

for the period 1997-2001.

FACT: Pongsona made a direct hit on Guam which was not forecast.

FACT: While JTWC did forecast intensification of the storm, the trend was

underestimated.

Partners and Customers Coordination 

Civil Defense/Emergency Management

FACT: Guam Civil Defense is an active participant at WFO Guam workshops and

coordination meetings.

Media

FACT: WFO Guam has developed a strong working relationship with local media.

FACT: The primary local newspaper, the Pacific Daily News, from Friday,

December 6, through Sunday, December 8, showed a map of the forecast

track with Super Typhoon Pongsona passing to the east of Guam.

Public

FACT: One theme stood out in assessment interviews with the public: people did not

receive advanced warning of a storm of Pongsona’s intensity.

Communications

FACT: WFO Guam uses conventional facsimile as the principal product

dissemination method.

FACT: During Pongsona, the WFO also provided updated information by cell phone

and Internet.
27

Emergency Alert System

FACT: During Pongsona, the Governor of Guam maintained control of the EAS. 

There was no signed EAS Plan in place, and the system did not function as it

does on the Mainland.

FACT: Recent discussions with WFO Guam have confirmed funding for Homeland

Security will allow the EAS system to be upgraded and an EAS Plan has now

been signed.

NOAA Weather Radio

FACT: WFO Guam does not use NWR SAME encoding or tone-alert on any products

except tsunami warnings.
28
29

Findings and Recommendations

Warning and Forecast Services

WFO Guam

Finding 1: A lead forecaster, WCM, and SOO were off-island as Super Typhoon

Pongsona approached Guam, and were unable to return until after the

storm passed. The WFO Guam office policy is unclear in detailing the

number of senior staff permitted to be off-island at the same time.

Recommendation 1: WFO Guam should establish clear office policy detailing the number

of senior staff permitted to be off-island at the same time.

Finding 2: The evening shift staffing on December 7 included three journeyman

forecasters, an HMT, and the MIC. It was unclear to the assessment

team who was the designated lead forecaster. Interviews revealed 

evening shift forecasters were concerned the forecast track was too far

east. However, a call to JTWC was not made until the shift was

almost over. The assessment team concluded a clearly designated lead

forecaster on the Saturday, December 7, evening shift would have

resulted in more proactive communication with JTWC and an earlier

re-analysis of the forecast track. 

Recommendation 2: WFO Guam should ensure every shift has a clearly designated lead

forecaster.

Finding 3: Communication with WFO Honolulu, Guam’s backup office, was

limited to a satellite telephone that could not be used inside the WFO

Guam building. Office staff actually went outside to call WFO

Honolulu during the storm but didn’t wait to receive calls. 

Recommendation 3: WFO Guam should procure a satellite phone system, or modify the

existing one, which can be used from inside the WFO building.
30

Finding 4: The four HANDAR instrument stations on Guam, which used sonic

anemometers, all failed to report winds at the height of the storm.

Wind measurements were available from only one anemometer on the

northern half of the island during passage of the eyewall. This was the

ASOS anemometer. However, data from this anemometer were not

available due to the collapse of the tower that received radio

transmissions from ASOS. 

Recommendation 4a: Pacific Region should replace the four existing HANDAR sonic wind

sensors with the sensors capable of providing accurate data in super

typhoon wind and rain.

Recommendation 4b: Pacific Region should install a communication link between the Guam

ASOS and the WFO capable of withstanding super typhoon force wind

and rain.

WFO Honolulu, Hawaii

Finding 5: Typhoon warnings for Alamagan and Agrihan Islands in the Marianas

were cancelled 5 hours before the closest approach of Pongsona. In

interviews with WFO Guam staff, some forecasters expressed concern

warnings were cancelled too early. The Saipan emergency manager

agreed. The two WFOs did not hold backup drills during 2002. 

Recommendation 5: WFO Honolulu should review the portion of its SDM dealing with

backup of WFO Guam. Particular attention should be paid to backup 

drills, staff profiles, and coordination of warnings.

JTWC

Finding 6: JTWC track forecasts for Pongsona were better than average. 

However, a direct hit on Guam was not forecast and storm

intensification was underestimated, resulting in below average service

to the population. JTWC was reluctant to make a major change in the

forecast track despite satellite imagery indicating the storm was

moving farther west than forecast. Military forecasters at JTWC

typically have less experience than civilian forecasters.

Recommendation 6a: The NWS should review JTWC service to WFO Guam, including

staffing, techniques, and underlying science used by JTWC for

typhoon forecasting in general, and for Super Typhoon Pongsona in

particular. The review should determine why (a) the track was

consistently too far east, (b) the magnitude of the change in intensity
31

was under forecast, and (c) there was a delay in updating forecasts to

reflect the storm’s actual movement.

Recommendation 6b: NWS should review existing agreements with JTWC concerning

forecast responsibility in the western North Pacific and determine if

modifications are needed.

Partners and Customers Coordination

Civil Defense/Emergency Management

Finding 7: The emergency response system on Guam is keyed to changes in COR

levels and not to NWS tropical cyclone watches and warnings.

Recommendation 7: WFO Guam should work with appropriate Guam officials to resolve

terminology differences between COR levels and watch/warning.

Public

Finding 8: One theme stood out in assessment interviews with the public: people

did not receive advanced warning of a storm of Pongsona’s intensity. 

Several people referred to the expectation of a banana typhoon and not

the intensity of a super typhoon. Tracking graphics published in the

newspaper each day consistently placed the typhoon east of the island. 

Several people interviewed reported radio stations downplayed the

strength of the typhoon (based on the forecast). There are no products

which indicate the inherent uncertainty in track and intensity forecasts.

Recommendation 8a: The Pacific Region should request a graphical product from JTWC

showing uncertainty in track and intensity forecasts.

Recommendation 8b: WFO Guam should stress forecast track uncertainty and its potential

consequences in all public tropical cyclone products and should

emphasize forecast uncertainty in outreach activities.
32

Communications

NOAA Weather Radio

Finding 9: WFO Guam does not use NWR SAME encoding and tone-alert for

severe weather watches and warnings, including typhoon watches and

warnings. The communications infrastructure on Guam is vulnerable

to typhoon strikes. The primary communication methods used by the

WFO to disseminate tropical cyclone products to users are easily

disrupted.

Recommendation 9: WFO Guam should use NWR SAME encoding and tone-alert for

typhoon watches and warnings. 

StormReady Program

Finding 10: The WFO Guam MIC established a StormReady Local Advisory

Board toward the end of 2001. A detailed plan was created allowing

for application by “any village or community” for StormReady

recognition. Changes in the emergency management and civil defense

administrations in the CNMI and on Guam, and the lack of a WCM at

WFO Guam for seven months in 2002, resulted in the program

remaining inactive, with no applications submitted. 

Recommendation 10: WFO Guam should promote participation in StormReady throughout

its area of responsibility.

PEACESAT and High Frequency Radio

Finding 11: There is no operational HF radio transceiver and antenna installed at

WFO Guam. An HF radio would provide a backup system, allowing

WFO Guam to contact WSOs and smaller islands in the FSM, CNMI,

the Republic of the Marshall Islands, and the Republic of Palau.

Recommendation 11: The Pacific Region should install an HF radio transceiver and antenna

system at WFO Guam capable of communicating with WSOs and

smaller islands in WFO Guam’s area of responsibility. The system

should be designed to operate during super typhoon conditions.
A-1

Appendix A

Guam Locations
B-1

Appendix B

Conditions of Readiness (COR) for Guam, 

CNMI and Micronesia

(Relationship of COR to Watches and Warnings)

1. Guam - The Navy, Air Force and GovGuam have agreed to standardize COR categories

associated with tropical storms and typhoons. CORs are based on the timing of the

forecast onset of 60 mph (50 kt) winds. They use either TS or TY CORs based on the

forecast of the maximum intensity of the storm as it passes near Guam.

TS/TY COR 4 - normal conditions, winds of 60 mph (50 kt) or greater are possible 

within 72 hours.

TS/TY COR 3 - winds of 60 mph (50 kt) or greater are possible within 48 hours.

TS/TY COR 2 - winds of 60 mph (50 kt) or greater are anticipated within 24 hours.

TS/TY COR 1 - winds of 60 mph (50 kt) or greater are anticipated within 12 hours.

2. CNMI - The CNMI Government declares CORs for tropical storms and typhoons based

on timing of the onset of damaging winds of 39 mph (34 kt) or more.

COR 4 - normal conditions, no threat identified, preparedness phase of operations.

TS/TY COR 3 - winds of 39 mph (34 kt) or greater are anticipated within 48 hours.

TS/TY COR 2 - winds of 39 mph (34 kt) or greater are anticipated within 24 hours.

TS/TY COR 1 - winds of 39 mph (34 kt) or greater are anticipated within 12 hours.

3. Micronesia - COR are based on the timing of the forecast onset of 39 mph (34 kt) winds. 

They use either TS CORs or TY CORs based on the forecast of expected winds. 

Micronesian islands are much more subject to damage from winds than Guam or Saipan.

COR 4 - normal conditions, no threat identified, preparedness phase of operations.

TS/TY COR 3 - Tropical storm/typhoon conditions are possible within 48 hours.

TS/TY COR 2 - Tropical storm/typhoon conditions are expected within 24 hours.

TS/TY COR 1 - Tropical storm/typhoon conditions are expected within 12 hours.
C-1

The results of a survey conducted

December 20 and published December 21,

2002, by the Pacific Daily News, regarding

reader satisfaction with the NWS forecasts

before and during Pongsona. (© Pacific

Daily News. Further reproduction is

prohibited without the express permission of

the Pacific Daily News)

Appendix C

Pacific Daily News Survey