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I REPORT NUMBER. 'NAVENVPREDRSCHFAC
Technical Paper No. 19-75
2 SOVT ACCESSION NO 3- RECIPIENT'S CATALOG NUllStR
4. TITLE C«nd SubHde) 5 TYPE or REPORT « PERIOD COVERED:
AN EVALUATION OF APRA HARBOR, GUAM AS A TYPHOON HAVEN
C. PERFORMING ORS. »(EPORT NUMBCR
7. AUTHORr»J
LT Michael E. Brown, USN Samson Brand
• • CONTRACT OR GRANT NUMIERr«>
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Naval Environmental Prediction Research Faci1ity
Monterey, California 93940
"0 PROGRAM ELEMENt PROJECT. TASK AREA ft WORK UNIT NUMBERS
PE:62759N PN:52551 TA WF52-551-713 NEPRF WU: 054:2-1
II. CONTROLLING OFFICE NAME AND ADDRESS
Commander, Naval Air Systems Command Department of the Navy Washington, D.C. 20361
14. MONITORING AGENCY NAME ft ADDRESSr" dllterml from Contntllnt Ofllcm)
12 REPORT DATE
November 1975 '3. NUMBER OF PAGES
79 15. SECURITY CLASS, (al thiM rtport)
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SCHEDULE
16. DISTRIBUTION STATEMENT (of Ihit Rtporl)
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17. DISTRIBUTION STATEMENT (ot Ihm abafraet antarad In Btoek 20, II dUlmrtnt frooi Kmpott)
18. SUPPLEMENTARY NOTES
IS KEY WORDS rConrinua on ravsraa alda U nacaaaary ond Idtntlfy by Mock numbtr)
Tropical cyclone Apra Harbor Typhoon Guam Typhoon haven Marianas Tropical meteorology
20. ABSTRACT (Continut on r^varaa alda It ntctmtmrr and Idtntifr by block nambmr) T 1 '
This study is an evaluation of Apra Harbor, Guam as a typhoon "haven." Characteristics of the harbor discussed include facilities available, wind and wave action, storm surge and the topographical effects on winds prior to and during passage of tropical cyclones. Problems to be con- sidered if remaining in port and possible evasion procedures
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20, 'Abstract (continued)
for ships sailing from the port are examined. The tracks of tropical cyclones from 1947-1973 for the
western North Pacific were analyzed to determine the proba- bility of threat to Apra Harbor. Observations by the authors and information obtained in conversations with port and hart^or authorities are utilized in reaching conclusions.
In general, the results indicate that Apra Harbor is not a safe haven. Under threatening conditions, all fleet units capable of evasion at sea should sortie at the earliest possi ble moment. /
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b, IM V 1 H U N ri i~ N I A L 'r' H b. iJ i IJ i i Li N H i::. b h A K U H r f-i U i L J. i Y i N A v V ) nONTEREY CALIF- An Evaluation or Apra Harbor, btiam as a i vphoon Haven OJ.i Brown ,, r 11 c n a e .i. i:::. • Brand,Samson Nov 1975 8 2 p bN'vFKtUKbUH r "tech paper —IV /S WFS2--55i WF52-551--713 U n c 1 a s s 1 + :i. e d r e p o r t * i ypn oon s ,, *Hiixr a or s ,, "A; :I. n a „ H i r wat er i n t. er ac t :i. on s n Trop:i. ca4 cyclones. Ocean waves, Tropicai reciions, S t or mS'.r nar i n e zer m i n a i s ,, Sea st at es , Hur r i c: an e 11'" ac:;^: ;i. ng , hor t.n Fac i -f i c Cic ean „ (■•■'r oP aP i.;. 11 y , Weat r'l er f ore cast :i nq
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( U) The stuav :i s an evaluation of Apra Harbor, Guam as a j typhoon 'haven . Lnaracteristics o+ the harPor i discussed include taciiities avaiiaPle, wind and wave action, storm surge and the topographical et-fects on winds prior to arid during passage o-f tropical cyclones,. ProPiems to be considered i i- remainiiiy in port and possible evasion procedures for snips sailing -from tne port a r e e ;■•; a rti i n e d , "i fi e t r a ck s o t t r o p i c a 1 c y c 1 o n e s t v om 1947-1973 tor the western North Pacific were analysed ; to determine the proPaPilicy o+ threat to Apra Harbor. 0 b s e r v a 11 o n s b y t h e a u t i"i o r s a n d i n -f o r m a. 11 o n o b t a i n e d i n c o n V e r s a 11 o n -s w 11 h p o r t a n d n a r b o r a u. t h o r 111 e s a r e utilised in reaching conclusions. In general, the ^ results indicate that Apra Harbor is riot a sa-fe i'iaven. Under threatening conditions, ail fleet units capable of eVas 1 on at sea shou 1 d sor 11 e at the; ear 11 est ID o s s 1 b i e iTi o m e n t, (U) 0 1 407279 , ■
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tlBNfWY TSCHNJOilSJ. REPORT SECTION NAVAL POSTQW.0UATE SCHOOL MONTEREy, CALiPGRNiA 93940
NAYENVPREDRSCHFAC Technical Paper No.19-75
AN EVALUATION OF APR A HARBOR, GUAM
AS A TYPHOON HAVEN
by
MICHAEL E. BROWN and SAMSON BRAND
NOVEMBER 1975
NAVAL ENVIRONMENTAL PREDICTION RESEARCH FACIUTY /
MONTEREY, CALIFORNIA 93940
Qualified requestors may obtain additional copies from the Defense Documentation Center. All others should apply to the National Technical Information Service.
FOREWORD
COMSEVENTHFLT has requested that twenty-two western
Pacific and Indian Ocean ports be evaluated as typhoon havens.
CNO tasked COMNAVWEASERV with the preparation of th?se eva^Ma-
tions, and in response to a request from COMNAVWEASERV,
COMNAVAIRSYSCGM tasked NAVENVPREDRSCHFAC with the development
of these studies.
The present study of Guam represents one effort in the
overall task, the final goal of which is a comprehensive
typhoon havens handbook containing condensed studies for the
twenty-two ports in the western Pacific/Indian Oqean.
The assistance of the Naval Weather Service Detachment,
Asheville and the personnel of the Fleet Weather Central
Guam, and Commander, Naval Forces Marianas in providing (;lata,
reports and comments is gratefully acknowledged.
R. C. SHERAR Captain, U.S. Navy Commanding Officer Naval Environmental Prediction
Research Facility
CONTENTS
FOREWORD 1 ACKNOWLEDGMENTS 4
1. INTRODUCTION 5
2. TROPICAL CYCLONES . . . . . . .6
2.1 DEVELOPMENT 6 2.2 WIND CIRCULATION 6 2.3 MOVEMENT 8 2.4 SEA STATES AROUND TROPICAL CYCLONES 8
3. GUAM 12
4. APRA HARBOR . 15
5. TROPICAL CYCLONES AFFECTING GUAM 17
5.1 CLIMATOLOGY 17 5.2 EFFECTS OF TOPOGRAPHY 39 5.3 WAVE ACTION 42 5.4 STORM SURGE 42
6. PREPARATION FOR HEAVY WEATHER 43
6.1 TROPICAL CYCLONE WARNINGS 43 6.2 EVASION RATIONALE 46 6.3 REMAINING IN PORT 48 6.4 EVASION AT SEA 49
7. CONCLUSION 51
REFERENCES . . '. . 52
APPENDIX A - TYPHOON TRACKS 53 APPENDIX B - CASE STUDIES .".65 APPENDIX C - PORT FACILITIES .'74 APPENDIX D - SHIP'S SPEED VS WIND AND SEA STATE .... 77
ACKNOWLEDGMENTS
The authors wish to acknowledge the following people for
their contributions to this study:
LCDR Carl Hoffman who initiated the study on Guam,
Mr. Jack Blelloch for compiling and reducing climatolpgical
data, Mr. Richard Clark for the graphics work, and Ms. Winona
Carlisle for the typing.
1. INTRODUCTION
Severe tropical cyclones, also known as typhoons or *'■-^
hurricanes, are one of the most destructive weather phenomena
a ship may encounter whether it be in port or at sea. When
facfed with an approaching tropical cyclone, a timely decision
regarding the necessity and method of evasion must be reached.
Basically, the question is: should the ship remain in port,'
evade at sea, or if at sea, should it seek the shelter offered
by the harbor? This study will examine Apra Harbor, Guam to
evaluate its potential as a typhoon haven.
In general it is an oversimplification to label a harbor
as merely good or bad. Consequently, an attempt will be made
to present enough information about the harbor to aid a
commanding officer in reaching a sound decision with respect
to his ship. The decision should not be based on the expected
weather conditions alone, but also on the ship itself, as well
as characteristics of the harbor. These characteristics v ;
include: natural shelter provided, port congestion, and u .'
support facilities (normal and emergency) available to indivi-
dual type commands.
2. TROPICAL CYCLONES
2.1 DEVELOPMENT
Tropical cyclones are warm-core, nonfrontal low-pressure
centers that develop over tropical or subtropical waters.
Although the tropical cyclone formation process i? not fully
gnderstood, it is well known that they require tremendous
amounts of energy to develop and sustain the high wind veloci-
ties present. Only the warm moisture-laden air of the tropics
possesses this quantity of energy. For this reason, tropical
cyclones usually develop within 20° of the equator and begin
to dissipate as they move into the cooler mid-latitudes.
2,2 WIND CIRCULATION ,; . •
The wind circulation associated with tropical cyclones
is counterclockwise about the eye in the Northern Hemisphere
and clockwise in the Southern Hemisphere. Figure 1 depicts
the wind pattern around the eye of a large, intense 150-kt
typhoon. Note that the more intense winds are located in the
right semicircle of the circulation. For this reason the
right side of a tropical cyclone is known as the "dangerous
semi ci rcle ."
The highest winds associated with tropical cyclones have
never been accurately measured; however, based on (;iata from
past storms, tropical cyclone winds may attain speeds in exqess
of 150 kt. The following classification system concerning the
intensity of tropical cyclones has been established by
international agreement:
Tropical Depression
Tropical Storm:
Typhoon:
Max sustained winds no greater than 33 kt
Max sustained winds 1n the range 34-63 kt
Max sustained winds in excess of 63 kt
^f"\..
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76 5432101234
DECREES OF LONGITUDE
Figure 1 Distribution of surface wind speeds (in knots) around a large, intense typhoon in the northern hemisphere over open water. The arrow indicates direction of mo5e nient (after Harding and Kotsch, 1965) "'''^"'°" °^ "^^^e-
2.3 MOVEMENT
The subject of tropical cyclone movement is very compli-
cated since speed and direction of movement is primarily a
function of wind and pressure patterns from the sea surface
to the top of the atmosphere. In the initial stages of its
development, the movement of a tropical cyclone is particu-
larly difficult to forecast since the forecaster is dealing
with an ill-defined circulation. This should be allowed for
when warnings or formation alerts regarding newly developed
tropical cyclones are issued.
Appendix A shows the tracks of all typhoons for the
June-December period for the years 1946 through 1969. In
these figures it can be seen that individual cyclones may
follow erratic and widely varying tracks but, in general,
they begin in the tropics and move west-northwest. In some
cases the movement eventually becomes northward and finally
northeastward. This shifting of direction is known as
recurvature. Burroughs and Brand (1972) found that approxi-
mately 40% of WESTPAC tropical storms and typhoons recurved.
Prior to recurvature, tropical cyclones generally move
at speeds from 8 to 14 kt; however, after recurvature they
may accelerate and reach speeds 2-3 times the speed at the
point of recurvature within 48 hours. (This acceleration
varies with the time of year.) During the recurvature process
the tropical cyclone is moving farther from the tropics; in
doing so, comes into contact with cooler surface waters, and
air from extratropical regions is drawn into its circulation.
These two factors usually result in the tropical cyclone's
ultimate weakening or dissipation.
2.4 SEA STATES AROUND TROPICAL CYCLONES
It is important to realize that sea conditions affecting
ship movement will extend well beyond the wind field asso-
ciated with a tropical cyclone, and that a miscalculation
concerning sea conditions could result in a destructive
rendezvous with the storm. The extent of the sea state ' '
generated by a tropical storm is primarily a function of storm
size, duration and intensity. Figure 2 shows the combined
sea height associated with 21 WESTPAC tropical storms and
typhoons (based on 173 analyses for the year 1971) plotted as
a function of distance from the storm center and storm
intensity (Brand, ejt aj^. , 1973). There is a large variation
in the sea state with storm intensity. A tropical storm
(winds 34-63 kt) could produce 12-ft seas 217 n mi from the
storm center; while an intense typhoon (winds ^100 kt) could
produce 12-ft seas 454 n mi from the center. The distances
given are mean distances since the isopleths of combined sea
height are not symmetric about the storm center. Brand,
ej_ aj_. (1973) found that the actual wave heights are at least
partially dependent on the direction in which the storm is
moving. For example. Figure 3 shows the average combined sea
height isopleth pattern for storms moving on headings between
301° and 360° and is based on 66 sea-state analyses for
tropical storms and typhoons that occurred during 1971. The
mean speed of movement and mean wind speed for these analyses
were 9.2 kt and 69.2 kt, respectively. Note that the greatest
area of higher seas (9-15 ft range) exists to the rear and
toward the right semicircle of the storm.
The combined sea height is defined as the square root of the sum of the squares of "significant" sea and swell height. Sea is wind waves and swell consists of wind generated waves which have advanced into regions of weaker or calm winds. "Significant" will be defined here as the average height of the highest one-third of the waves observed over a specified time.
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based on The mean
were 9 1973)
2 kt and 69.2 kt, respectively (after Brand et al
n
GUAM
Figure 4 shows the western North Pacific area with Guam,
the southernmost island in the Mariana Islands group, loca-
ted approximately 1300 n mi east of the Philippines. Guam is
a relatively flat island with only a few points reaching over
1000 feet above sea level (see Figure 5).
Agana is the capital city of Guam, with Apra Harbor as
its commercial and military port. While other anchorages
are available, Apra Harbor is the only port on Guam suitable
for use by U. S. Navy or Military Sealift Command vessels.
A detailed study of the coast and bays of Guam is inclu-
ded in Hydrographic Office Publication No. 82 (formerly 165A)
For specific comments on coastal features the reader is
referred to the above mentioned publication.
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SCALE IN NM
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Figure 5. Topographical map of Guam.
14
4. APRA HARBOR
Apra Harbor, which consists of an inner and outer harbor,
is an improved natural harbor located on the southwest coast
of the island of Guam. Figure 6 shows the general harbor
layout. Orote Peninsula which projects 3.5 n mi northwestward
from the coast forms the southern boundary of the harbor.
The harbor is bounded on the north by a breakwater that is
partially man made and extends 15 ft (average) above mean sea
level.
The entrance to Apra Harbor is 500 yards wide and in
excess of 100 ft deep. Apra Harbor is extensive and contain
a substantial number of mooring buoys and piers. The outer
harbor affords a large number of deep water anchorages and the
holding capacity is considered excellent. Appendix C contains
a list of all harbor facilities including details as to type
and capacity. It should be noted that the outer harbor
contains several shoal or reef areas that are clearly marked.
While these areas pose only a limited threat to normal opera-
tions, they must be a major consideration should maneuvering
be required during periods of heavy weather.
The low hills to the east of Apra Harbor provide a wind-
break for easterly winds. However, Apra Harbor should by no
means be considered a sheltered port.
15
/ Lumlnao Rt'ef
Spanish Rock;
Fi gure 6. Apra Harbor
16
5. TROPICAL CYCLONES AFFECTING GUAM
5.1 CLIMATOLOGY ' ''-"■'■ ;-' ^'^^ ■■ ^^■^- » • '
Severe tropical cyclones can occur during any month of the year in the western North Pacific area. However, the majority of those that pose a "threat" to Guam (any tropical cyclone approaching within 180 n mi is considered a "threat") occur during the months June-December. Figure 7 gives the monthly summary of threat situations by 5-day periods, based on June-December data for the 27 years, 1947 to 1973. Note the maximum number of storms occur in the months July through November.
In Figure 8 these "threat" tropical cyclones are dis- played according to the compass octant from which they approached Guam. The circled numbers indicate the total that approached from an individual octant. The numbers in parentheses give this as a percentage of the total. It is readily seen that a majority of storms approach from the east and southeast.
Approximately 4 tropical cyclones each year will pose a threat to Guam. Since Guam is in the development area for WESTPAC tropical cyclones many of these storms are in the formative stages of their life cycle and have not, as yet, achieved typhoon intensity. Of the 107 tropical cyclones that approached or developed within 180 n mi of Guam in the period June-December, 1947 to 1973, the point where these storms attained tropical storm intensity (>^34 kt) is in many cases to the west of Guam (see Figure 9). In fact approximately 50% reach tropical storm intensity after their Closest Point of Approach (CPA) (assuming most were heading on a general east to west track).
Figure 10 shows the point at which the tropical cyclones reached typhoon intensity (^64 kt). Notice that about 75% of the typhoons attained typhoon intensity to the west of Guam.
17
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: 5 o CD
Z
JUN
(6)
JUL
(13)
AUG
(17)
SEP
(24)
OCT
(24)
NOV
(19)
DEC
(4)
Figure 7. Frequency distribution of the number of tropical cyclones that passed within 180 n mi of Guam (June- December, 1947-1973). Subtotals are based on 5-day periods and the numbers in parentheses are the monthly totals.
Figure 8. Direction of approach to Guam of the tropical cyclones (June-December, 1947-1973) which passed within 180 n mi of Guam. Circled numbers indicate the number that approached from each octant. The numbers in paren- theses are the percentage of the total sample (107) that approached from that octant.
18
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20
The fact that a large percentage of storms are not of "typhoon
intensity at CPA must not allow the reader to develop a false
sense of security. While a storm with winds of 50-60 kt is
obviously not a typhoon, the potential for damage is still
very significant.
A tropical cyclone in the vicinity of Guam will, on the
average, intensify 15-20 kt/24 hr, but the danger always
exists that the storm will rapidly intensify by 40-50 kt/
24 hr (5-10% probability for this region).
As an overview of the climatology involved. Figures 11
to 17 show a statistical summary based on tropical cyclone
tracks for the years 1947-1973.^ The data are grouped by
months, June-December. Since tracks were recorded for 5-day
periods, exact calendar months could not be used (see legend).
In these figures, the total number of storms that passed
through each 3° lat/long square for a given month, defined as
N, is printed at the top of each square. At the bottom of
each square is a number (deiined as "RAD") representing the
Pei^cent of those tropical cyclones that passed through the
square and subsequently passed within 180 n mi of Guam. To
further assess the threat to Guam, the parameters L,, L-, R,,
and R^ are defined as:
R^: Percentage of all tropical cyclones that passed
through the box and subsequently crossed the line
to the north of Guam within a distance of 60 n mi
(1° latitude).
R3: Percentage of all tropical cyclones that passed
through the box and subsequently crossed the line
to the north of Guam within a distance of 180 n mi
(3° latitude). ,
From Chin, 1972 for years 1947-70, and from FWC/JTWC Annual Typhoon Reports for 1971-1973.
21
•3-
Percentage of all tropical cyclones that passed
. through the box and subsequently crossed the line
, to the south of Guam within a distance of 60 n mi
(1° latitude).
Percentage of all tropical cyclones that passed
through the box and subsequently crossed the line
to the south of Guam within a distance of 180 n mi
(3° latitude). .
These are printed at the left and right edges of the 3°
squares. These above parameters are significant in that the
effect a tropical cyclone has on a harbor is a function of
relative positions of storm and harbor during passage. For
example, in Figure 13 the 3° square located between 147°E and
150°E, 9°N and 12°N had 5 tropical cyclones pass through it
during the years 1947-1973. Of these, 83% (5 of the 6
tropical cyclones), subsequently approached within 180 n mi
of Guam. Of the 6 tropical cyclones 33% passed within 60 n mi
to the north and 33% within 180 n mi to the north; 17% passed
within 60 n mi to the south and 33% within 180 n mi to the
south.
In Figures 18 to 24 the 1947-1973 statistics have been
reanalyzed using the RAD numbers. The solid lines present a
"percent threat" figure for any storm location. The dashed
lines represent approximate approach times to Guam based on
an approach speed of 8-12 kt. For example, in Figure 18 a
storm located at 150°E and 8°N has an 80% probability of
passing within 180 n mi of Guam and, if its speed remains in
the 8-12 kt range, it will reach Guam in slightly over IJ2-2
days (the faster the speed of an individual storm the shorter
the time required to reach Guam).
Note that R3 + L3 need not equal RAD since a storm may enter the 180 n mi circle but not cross the N-S line.
22
130 30°
LEGEND:
H • NUMBER OF TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE FOR THE MONTH
Li- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
L3- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
Rl« PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
R3- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 180 N HI (3° LAT)
RAD - PERCENT OF TROPICAL CYCLONES THAT PASSED THROUGH THE SQUARE AND SUBSEQUENTLY PASSED WITHIN 180 N MI OF GUAM
FOR THE MONTH OF;
JUN
Fi ure 11. Statistical summary of tropical cyclone tracks hat passed within 180 n mi of Guam for the month of June
(Based on data from 1947-1973.)
23
LEGEND-
N - NUMBER OF TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE FOR THE MONTH
Li= PERCENT OP ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
L3> PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSEO A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
RT PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
R3- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
RAD ' PERCENT OF TROPICAL CYCLONES THAT PASSED THROUGH THE SQUARE AND SUBSEQUENTLY PASSED WITHIN 180 N MI OF GUAM
FOR THE MONTH OF:
JUL
Figure "12. Statistical summary of tropical cyclone tracks that passed within 180 n mi of Guam for the month of (Based on data from 1947-1973.)
July
24
LEGEND:
N - NUMBER OF TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE FOR THE MONTH
L]" PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
L3- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 180 N HI (3° LAT)
Rl- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
R3« PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
RAO • PERCENT OF TROPICAL CYCLONES THAT PASSED THROUGH THE SQUARE AND SUBSEQUENTLY PASSED WITHIN 180 N MI OF GUAM
FOR THE MONTH OF:
AUG
Figure 13. Statistical summary of tropical cvclone trark<; that passed within 180 n mi of Guam ' ^^cione tracks (Based on data from 1947-1973.)
for the month of August
25
LEGEND:
H
«-3 "3 _IAE_
/••l*
3° lOHS
N • NUMBER OF TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE FOR THE MONTH
L]- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
L3- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
RT PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
R3- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 180 N HI (3° LAT)
RAD " PERCENT OF TROPICAL CYCLONES THAT PASSED THROUGH THE SQUARE AND SUBSEQUENTLY PASSED WITHIN 180 N MI OF GUAM
FOR THE MONTH OF:
OtZi
Figure 14. Statistical summary of tropical cyclone tracks that passed within 180 n mi of Guam for the month of September. (Based on data from 1947-1973 )
26
30° 130°
20°
0° 130°
140° 150° 160°
,GUAM : 15 s: <* :
0.0 . ojo o:o o|o 0 ojo o/o:o 0 o|o
nin n'.n 7 n'n ni n
Ojo 0;0 0^ 0 ofo 0 ".'o 0 ": {I " ■
' olo * olo ' o:
13:0 ^ 0:0 oj
■ •■■■i^aaBaa^aBaaaa |
** 38:o 20:0 0:
uo**
■■■■•■■■■■%■
38!i»0 2*67, OL. 75 : 60 : 67 r 2 • 0 ■ 1 ;
50:0 0:0 0;
, 50 . 0 • 100 I ■ n • n ' n :
" olo "ojo " 0:
0 °f° 0 "i" 0 oi
150° 160°
170° 30°
20°
10°
17B°
LEGiND:
N - NUMBER OF TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE FOR THE MONTH
'■'" ?u?^^^n„?o/!;Ll?S'"'- "CLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 60 N HI (1° LAT)
"■3" !""!)I O"" *'■'- TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 180 N HI (3» LAT)
''^" ?S?^^cn„2»/l;bJ?°E'"'- "CLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 60 N HI (1° LAT)
''^' ?S??^?jM2 = r*l;L^cfiSJ"'- "CLONES THAT PASSED THROUGH Innru^l^Al^ *"'' SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROH GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
"*" " cnnJEr^?'' ''''°'''t:AL CYCLONES THAT PASSED THROUGH THE SQUARE AND SUBSEQUENTLY PASSED WITHIN 180 N MI OF GUAM
FOR THE MONTH OF;
OCT
15 Fi gure that October
Statistical summary of tropical cyclone tracks passed within 180 n mi of Guam for the month of
(Based on data from 1947-1973 )
27
130" so-r-
20°
10°
140" 150°
; ft : 7 •0 0:0 Old
160°
^..„ ._. 5 : i^: old ,o;o
GUAM 0;o
0
1
|o '%:o ''nio oio ^ ojo I olo ^ ojo
I" 0 "1° 0 »:o 0 o:o
jo 0.0 o;o ojo
■0 0;0 o;o 0 "j" 0 . ^ ■ > - ■ ^ • aS •■«>■■> ^B ■■■■•■BUI
■n 17 „• 12 ; 9 • l'' OJO nio o:o
o;o o;c 0
0 ojo Q oio ,, 0
oio oio ■' 0
0 0 " :""8""T
3 3:13
OJO ^ OJO
;o ojo *• o;o '^ ojo
,'.2. J2'_ : 8 ■ ^
3a;o oio 0 ,58:13^^53.0 53io , 0
'bWi^Ui^'i i7;30^°'toii'»''1*3:0 '*5o:
,,iii50 i7|ita.„'»oi28 57I23 75 "' ■ ''i 90 Jioo! 100
' 0;20 ^20|i40 ^20:100^ oiso ^50'
170° -130°
20°
10°
170"
LEGEND:
H
L3 R3
- «AP
L
N • NUMBER OF TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE FOR THE MONTH
'■'" ?u?^^cI„?L*i;!r TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
^3' Tu?i^oI„?L*l;'- TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
''^' ?M?c^cn„?L*!;i;J?'"'"^*'- "CLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
''^' ^u^c^cL.JL**!;.^ TROPICAL CYCLONES THAT PASSED THROUGH IncTu^l^n*."^ ^'*° SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
RAO . PERCENT OF TROPICAL CYCLONES THAT PASSED THROUGH THE SQUARE AND SUBSEQUENTLY PASSED WITHIN 180 N MI OF GUAM
FOR THE MONTH OF:
NOV
Figure 16. Statistical summary of tropical cyclone tracks that passed within 180 n mi of Guam for the month of November. (Based on data from 1947-1973.)
28
130" 30" r"
140° 150°
20'
10'
Hi"
GUAM YV""-"^" W.o o;o
0° 130°
•0 " olo
1 : 0 ■ OjO 0;0
1 ■ 0 ■ o:o o:o
■ ■
0 °\° 0 "jo ^ ■ 1 ■ ' o;o ^ OJO ,"|o 0 oio
• ■ ■ ■ ^i ■ ■ ■ ■ ■ 4> ■ ■ 2 ■ 3 ■
o:o ^ o;o 50 "l^eT^^zs
^ 0-0 o:o
. ■■a«fc aakaSBSaa
1 ! 1 I OiO QjO
0 "1° 0 ol"
0 o:
o| la^
"I o:
■ ■ a ■ ■
Oj 2 5J-
oi 0 Oj
"oi » 0;
170° 30°
20°
10°
140° 150° 160° 170°
LEGEND:
N " NUMBER OF TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE FOR THE MONTH
Li- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 60 N MI {1° LAT)
L3« PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING SOUTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
Rl- PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 60 N MI (1° LAT)
R3« PERCENT OF ALL TROPICAL CYCLONES THAT PASSED THROUGH THIS SQUARE AND SUBSEQUENTLY CROSSED A LINE EXTENDING NORTH FROM GUAM WITHIN A DISTANCE OF 180 N MI (3° LAT)
RAD - PERCENT OF TROPICAL CYCLONES THAT PASSED THROUGH THE SQUARE AND SUBSEQUENTLY PASSED HITHIN 180 N MI OF GUAM
FOR THE MONTH OF:
DEC
Figure 17. Statistical summary of tropical cyclone tracks that passed within 180 n mi of Guam for the month of December. iBased on data from 1947-1973 )
29
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36
For the remainder of this section, only those tropical
cyclones that passed within 180 n mi (3° of latitude) of
Guam will be considered. It is realized that storms which
did not approach within this limit may have affected the
harbor. However, a criterion had to be chosen that would
limit the data sample; 180 n mi was the limit selected.
In the 27 years 1947-1973 (considering the months June
through December), an average of four tropical cyclones per
year passed within 180 n mi of Guam (107 total). The largest
number that occurred in any single year was seven (1958, 1965,
and 1971). In Table 1, the 107 storms which passed within
180 n mi, are grouped according to their effect at Guam."*
It can be seen that of the total 107, only 34 storms (approxi-
mately 32%) resulted in winds of 22 kt or greater at Guam.
Only 8 tropical cyclones (7%) resulted in gale force winds '
or greater (>34 kt).
Table 1. Extent to which tropical cyclones affected Guam (NAS Agana) during the period June-December, 1947-1973.
Number of storms that passed within 180 n mi of Guam
Number of storms that resulted in winds >22 kt at Guam
Number of storms that resulted in winds >34 kt at Guam
107
34
Figure 25 shows the tracks of the 8 gale associated
storms. When the tracks in Figure 25 are compared with the
mean tracks in Appendix A, it becomes anoarent that the
4 ■ '■ • '■ Wind information is based on hourly wind observations
from Naval Air Station, Agana, which is felt to be representa- tive of the winds experienced in Apra Harbor.
37
38
majority that caused gale force winds have approached along
a major threat axis that is oriented east-southeast from Guam.
This axis is also shown in Figures 18-24 by the "percent
threat" lines and in Figure 5 by octant approach arrows.
Another significant feature indicated in Figure 25 is
that of the eight storms that resulted in gale force winds
during June-December 1947-1973, 4 occurred during the month
of November. This is not to say that gale force winds may not
occur during the other months (the fact is, WESTPAC typhoons
can effect Guam during any month of the year) but climatology
does indicate that the peak "threat" is apparent during
November. ,
5.2 EFFECTS OF TOPOGRAPHY "'
Of the 107 tropical cylones that passed within 180 n mi
of Guam in the June-December, 1947-1973 period, approximately
60% passed to the north and 40% passed to the south.
Figure 26 shows the positions of the tropical cyclone ,,
centers (June-December,1947-1973) when strong winds (^22 kt)
were first and last recorded at NAS Agana (based on hourly
wind information). It is apparent that these strong winds do
not occur until the storms reach approximately the longitude,
or just to the east of Guam. Notice that a number of storms
will continue to give strong winds to Guam at distances of
200 n mi or more to the west. In general, strong winds can
arise from storms passing 200 n mi to the south, and from
storms passing 100 n mi to the north. There are more strong
wind situations for storms passing to the south than to the
north even though more storms had their CPA to the north.
This is logical since storms passing south would place Guam
in the high wind or dangerous semicircle. This bias is also
evident in Figure 27, which shows the tropical cyclone center
positions when gale force (^34 kt) winds were first and last
39
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40
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•H ■§ 0)
tn Q 'd OJ c Q
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•^ e m o
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41
recorded at NAS Agana. Notice that there was one gale occur-
rence at NAS Agana when the storm was centered over 200 n mi
from Guam.
5.3 WAVE ACTION
Because of its extensive area and limited sheltering
topographical features, Apra Harbor experiences considerable
wave action during periods of tropical storm/typhoon passage.
Wave heights are primarily a function of wind speed,
duration and fetch. Since Apra Harbor is open to the west,
those storms that result in a westerly wind field over Guam
expose the harbor entrance to severe wave action. In the
outer harbor waves of 6-10 ft are "common" during storm
passage and it is possible the maximum could exceed 20 ft 5
under a westerly wind field of typhoon intensity. It is
important to keep in mind that wave action may commence before
local wind conditions reach particularly dangerous levels and
may continue after the winds abate.
5.4 STORM SURGE
Storm surge can be defined as the difference in observed
water level at a given location during storm and non-storm
conditions. Storm surge is a major problem in Apra Harbor.
Typhoon conditions have created surges 10-12 ft above mean
lower low water level, while at the northern tip of Guam,
surges in excess of 18 feet have been recorded. Obviously,
these extreme changes in water level must be taken into
account when planning for heavy weather situations.
Details of wave action damage under typhoon conditions are contained in case studies of Appendix B.
42
• 6. PREPARATION FOR HEAVY WEATHER AT APRA HARBOR
6.1 TROPICAL CYCLONE WARNINGS i-
Western Pacific Ocean tropical cyclone warnings are
issued by FWC/JTWC Guam. The warnings are numbered serially
commencing with the first warning issued on each cyclone and
continued throughout the life cycle of the cyclone irrespec-
tive of a change in classification. The initial warning
will be issued when the existence of a tropical depression
has been established and the decision to designate it has
been made. In order to maximize the use of all available
reconnaissance platforms and spread warning workload in
multiple storm situations, a variable warning time may be
employed. Warnings will be issued within 2 hours of OOOOZ,
0600Z, 1200Z and 1800Z with the constraint that two conse-
cutive warnings may not be more than 7 hours apart.
In addition to warnings, FWC/JTWC Guam issues a tropical
cyclone formation alert when interpretation of synoptic
and other meteorological data suggest that formation of a
significant'tropical cyclone is likely. Alerts are not
numbered, but will specify a valid period not to exceed
24 hours and will either be cancelled or reissued by the
end of the valid period.
Through aircraft reconnaissance and satellite observa-
tions, modern techniques for locating tropical cyclones and
monitoring their progress have become quite sophisticated.
Nevertheless, the present state of meteorological knowledge '
does not permit a perfect prediction of storm movements.
As stated previously, many variables exist which can alter
the path of a typhoon; hence, every typhoon should be treated
with the utmost respect.
COMSEVENTHFLT OPORD 201-(YR), Annex H, describes the
techniques to be used when plotting the FWC/JTWC typhoon
43
warning track positions. The average 24-hr forecast error
of 135 n mi should always be incorporated when plotting the
24-hr forecast position in order to expand the radius of
30-kt winds, given in the warning, by the average forecast
error. Figure 28 demonstrates this procedure and utilizes
the 135 n mi average 24-hr forecast position error in ob-
taining the "danger area." Note the radius of 30-kt winds
is greater on the right side of the storm track -- the
dangerous semicircle. In this example the radius to the
30-kt isotach is 200 n mi to the north and 150 n mi to the
south of the storm at the current position. The radius to
the 30-kt isotach is forecast to expand to 225 n mi to the
north and 175 n mi to the south of the storm at the 24-hr
forecast position. At the 24-hr forecast time the danger
area is then 360 n mi (225 plus 135) to the north and 310 n mi
(175 plus 135) to the south of the storm. The 48- and 72-hr
forecasted positions given in the FWC/JTWC warning provide
a planning forecast, but must also be adjusted to consider a
275 n mi and 400 n mi average forecast error, respectively.
The criteria for setting local weather readiness condi-
tions are set forth in COMMANDER IN CHIEF PACIFIC REPRESENTATIVE
GUAM AND THE TRUST TERRITORY OF THE PACIFIC ISLANDS and NAVAL
FORCES MARIANAS JOINT INSTRUCTION 3141.1. In addition, this
instruction requires specific action to be taken by various
naval activities when weather conditions pose a threat to
life or property. One such required action is that all
Commanding Officers/Masters of Naval/Merchant ships present,
attend a Heavy Weather Planning Meeting to discuss necessary
action and the time required to complete this action. Since
this meeting will cover evasion plans and heavy weather
security it is imperative all personnel concerned attend.
44
^3
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ra ^ CJ
C3 E LkJ oe Lb
C3 lO "-^^ O- PO h-
Lkl
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UJ CD CO
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45
6.2 EVASION RATIONALE
A most important aspect of any decision concerning
heavy weather is an early appraisal of the threat posed by
an individual tropical cyclone. Since the U.S. Navy's
typhoon forecasting assets are readily available to units at
Guam, a timely threat appraisal will be readily available
and individual unit commanders will be able to take part in
the evasion planning meetings called by COMNAVMARIANAS.
Historically, tropical cyclones have approached Guam
from all directions and since most are in the developing
stages, their movement as well as intensity and wind distri-
bution, are difficult to forecast. This makes long range
evasion planning very difficult. However, some rough guide-
lines that might be of use are presented in conjunction with
Figure 29.
I. An existing tropical cyclone moves into or signifi-
cant development takes place in area A with forecast
movement toward Guam:
a. Review material condition of ship. A sortie
may be desirable 2-4 days hence.
b. Reconsider any maintenance that would render
the ship incapable of getting underway within
48 hours.
II. Tropical cyclone moves into or significant develop-
ment takes place in area B with forecast movement
toward Guam: ■
a. All units consider possible course of action
if sortie should be ordered.
b. Reconsider any maintenance that would render
the ship incapable of getting underway within
24 hours .
46
Xi X) ca o u a* • Oi+J nJ C
0) 'd e § > o to a <u C) m fl 0 (0
-P ^0 w (j
■H (j Q a
n • +)
h A;
3 CNJ a rH
u 00 0 m c
(d tn
■H c X o (0
t3 -p Q) (C CO aj (0 nxt
X! +J g
(d (1) r3 C o o H g O o >i M O m
■H ^3 OJ (U O M
•H 13 UJ CO 0 (0 ^1 (I) EH g
0) • u (Tl (0 CN
CO fl) (I) H s 3 •H iji+l
■H Cn
47
III. Tropical cyclone enters area C moving toward Guam:
a. Execute sortie.
6.3 REMAINING IN PORT
Because of its lack of natural protection, Apra Harbor
provides little or no haven qualities. As a result, remaining
in port is not the recommended course of action when typhoon
conditions threaten. In the past U.S. Navy ships have
remained in port during typhoon conditions for various
reasons. Case studies of two situations are presented in
this study as Appendix B.
Should a unit be required to remain in port, berths and/
or nesting assignments will be made by Naval Station Guam/
SOPA (ADMIN) Guam as specified in COMNAVMARIANAS Disaster
Preparedness Plan 101, Individual unit commanders should
be ready to rapidly respond to movement orders, because
maneuvering after the onset of heavy weather (winds ^ 20 kt)
will be extremely hazardous. Remaining in port poses the
problem of deciding on and then requesting the "best" possible
mooring location. Such a location would be a function of
ship type, expected sea state, wind speed/direction and time
available for the move. In Appendix B it is concluded that
a general rule for winds up to 50 kt would be: "Obtain an
inner harbor berth as close to the upwind shore as possible."
It is recognized any ship subjected to high winds while
moored will take some amount of beating but this rule should
minimize the damage sustained.
Weather warnings concerning Guam and the trust territories
of the Pacific islands are based on information gathered at
Fleet Weather Central/Joint Typhoon Warning Center, Guam
(FWC/JTWC). All information and warnings are then broadcast
to fleet units on appropriate Fleet Broadcast Channels. In
addition, warnings are broadcast on Apra Harbor Control
48
Frequency 2716 KHZ and Tug Control Frequency 3216 KHZ during
typhoon/tropical storm conditions. v. ■ • . .. ■
6,4 EVASION AT SEA .'.-:•>■,•; .^.'^ ,.-•, ^ .^: • : , .. ■,,
Evasion at sea is the preferred course of action when
confronted with potential typhoon conditions on Guam. The
commanding officer, with his experience and knowledge of his
unit, will always make the final evasion decisions; however,
the following evasion techniques are suggested for the more
common "threat" situations. ■ ' • r. ■- ... ■. ■ i'; . ; • i .
I. ^ Tropical cyclone approaching from the east or south'
- .. ; east and forecast to pass north or within 60 n mi
south of Guam.
a. Evasion should be southwest. The units will
be in the safe or navigable semicircle with
following wind and sea. i
II. Tropical cyclone approaching from the east or
southeast and forecast to pass more than 60 n mi
south of Guam:
a. Evasion should be northeast.
III. Tropical cyclone approaching from the south and
forecast to pass east of Guam:
a. Evasion should be west-southwest. '
■ . ■ i
IV. Tropical cyclone approaching from the south and
forecast to pass west of Guam:
a. Evasion should be east-southeast.
In evading, whichever case presents itself, the following
general comments should be noted:
4S
1. Crossing ahead of an approaching typhoon as recom-
mended in I above, is not without hazard, and must be
accomplished well ahead of the typhoon. If, in attempting
this track crossing, the ship is caught in the wave/swell
pattern ahead of the storm, the speed of advance may be
reduced to the point that the ship will be unable to maneuver
clear of the storm (see Appendix D).
2. It is very possible during the peak typhoon season
for rapid storm development to occur, resulting in multiple
tropical cyclones co-existing in the western Pacific area.
(This occurs approximately 50 days of each year.) This
possibility would greatly complicate the evasion problem,
and should be kept in mind as evasion plans are formulated
and executed .
50
7. CONCLUSION
There are no aspects of Apra Harbor that recommend it as ,
a typhoon haven. The surrounding topography is low and does
not provide an extensive wind break. The harbor entrance is
open to the west and is in close proximity to the berths and
moorings in the outer harbor. Consequently, westerly winds
and seas associated with the typhoon passage have a devasta-
ting effect within the harbor.
In the past all U.S. Navy ships capable have sortied
from the harbor upon the approach of a typhoon. Additionally,
the Port Operations Officer desires that ships not use Apra
Harbor as a typhoon haven since the harbor's and NAVSHIPREPFAC
Guam's yard and service craft occupy virtually all desirable
berths in the harbor during typhoon conditions. •': |'''. 'V.
■-■, "!
;,«..:^
> ■ ' t' \ ''■
i- f
51
REFERENCES
Brand, S., J.W. Blelloch and D.C. Schertz, 1973: State of the sea around tropical cyclones in the western North Pacific Ocean. ENVPREDRSCHFAC Technical Paper No. 5-73.
Burroughs, L.D., and S. Brand, 1972: Speed of tropical storms and typhoons after recurvature in the western North Pacific Ocean. ENVPREDRSCHFAC Technical Paper No. 7-72.
Chin, P.C., 1972: Tropical cyclone climatology for the China Seas and western North Pacific from 1884 to 1970. Royal Observatory Hong Kong, 207 pp.
Crenshaw, R.S., Jr., Capt., USN, 1965: Naval Shipbuilding Maryland, U.S. Naval Institute, 533 pp.
Gray, W.M., 1970: A climatology of tropical cyclone and and disturbances of the western North Pacific with a suggested theory for their genesis and maintenance. NAVWEARSCHFAC Tech. Paper No. 19-70.
Harding, E.T., and W.J. Kotsch, 1965: Heavy weather guide Maryland U.S. Naval Institute, 209 pp.
Nagle, F.W., 1972: A numerical study in optimum track ship routing climatology. ENVPREDRSCHFAC Tech. Paper No. 10-72
U.S. Fleet Weather Central/Joint Typhoon Warning Center, 1971-73, Annual typhoon reports.
52
■■^'v'-- '.■'■. ''/-w.-*i "x.:^T"'' ■? ^Tto-^'w v.'-^ f-ai-.-jf^-.i*
APPENDIX A
.'■■; Figures A-1 through A-ll show monthly and half-monthly
(June-Dec) tracks of western North Pacific (1946-1969)
tropical cyclones which were at one time of typhoon intensity
(Gray, 1970).
"vi'^T- \''T-i ■-
54
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63
64
APPENDIX B
Case studies of Typhoon Karen (11 Nov 1962) and Typhoon
Olive (29 April 1963).
■ I
65
ABSTRACT
The cases of Typhoons Karen and Olive, described briefly
in this section are evidence of Apra Harbor's inability to
provide appreciable protection against typhoon damage.
TYPHOON KAREN (NOV 1952)
(Based on FWC Guam Special Typhoon Report of 23 Nov 1962)
The Island of Guam had approximately four days warning
to prepare for Typhoon Karen which struck on 11 November 1962
(see Best Track chart Figure B-1). The center of Karen's eye
passed across the southern part of Guam, four n mi north of
the southern tip of the island and nine n mi south of FWC/JTWC ,
located on Nimitz Hill, moving 265 degrees with a speed of
17 kt. The diameter of the eye in relation to the wall clouds
was eight n mi, while the diameter of the wind eye was
approximately six n mi.
During the passage of this storm, Apra Harbor was hit by
sustained winds of 150 kt 'and gusts up to 180 kt. The winds
raised tumultuous seas in the inner and outer harbors, notwith-
standing the short fetch, and caused all ships and craft to
beat heavily against their piers and moorings. Precautionary
measures for the typhoon were in accordance with current
instructions. All ships capable of steaming sortied from the
harbor prior to the typhoon's arrival. Other precautions were:
(a) All small craft including LCM's were lifted from the
water and placed on Wharf "L".
(b) All non self-propelled active craft, too large to
be removed from the water, were moored to buoys in the Inner
Harbor.
(c) YD-120, a 125 long ton capacity floating crane, was
secured at the pier on Wharf "U" using a well-tested typhoon
mooring plan.
66
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67
(d) Two YOG'S and four YTM's were secured to their
berths on Wharf "V" at the tug base. One YTM was moored at
a buoy in the Inner Harbor.
(e) Out of Service - In Reserve Craft always moored at
Drydock Point with typhoon secure moorings received no special
precautions.
(f) Two PC's, being modernized at SRF, had access
openings replaced in a temporary fashion and their moorings
at Wharfs "N" and "0" were greatly strengthened.
The harbor was hit with 150 kt sustained winds and 180 kt
gusts during the passage of Karen. The following damage was
inflicted(seeFigureB-2):
(1) ROKS Han Ra San (PC-705), an Ex-USN 173 foot PC,
capsized and sank at its berth at Wharf "0".
(2) RPS Negros Oriental (C-26), the same type ship as
PC-705, capsized and sank at its berth at the west end of
Wharf "N".
(3) The Trust Territory 10 inch hydraulir dredge JOHN S.
CAMPBELL sunk adjacent to the east end of Wharf "N".
(4) The YFN - 693 broke loose from its typhoon mooring
at a buoy in the Inner Harbor and floated free. It was seen
the morning of the 12th of November passing Drydock Point on
a northerly course and was notedto have a large hole in the
corner of the hull. The YFN - 693 went aground and sank 300
yards west of Berth "F".
(5) YC - 1419 also broke loose from its mooring at a
buoy in the Inner Harbor and went aground on the north side
ofPadFive.
(6) YSR - 11 broke its mooring at Drydock Point and was
found floating in a cove immediately west of Berth "H".
(7) YSR - 19 broke its mooring at Drydock Point and
grounded on the Glass Breakwater about 1,500 yards from the
harbor entrance.
68
Figure B-2. Apra Harbor, Guam showing the locations of damaged ships and craft following Typhoons Karen and Olive.
69
(8) YD - 120 broke its mooring at the northern end of
Wharf "U" and grounded on the LSI beaching ramp at the southern
end of the Inner Harbor.
(9) YTM - 417 broke away from its mooring at the northern
end of Wharf "V" and broached port side to the beach adjacent
to the southern end of Wharf "V".
(10) YTM - 521 broke away from its mooring at the northern
end of Wharf "V" and grounded bow first on the beach imme-
diately east of YTM - 417.
(11) The MV Hope, an ex YMS 200-ton wooden vessel, sank
after heavy damage at its berth at the southern end of Wharf
"V".
TYPHOON OLIVE (April 1963)
(Based on FWC Guam Special Typhoon Report of 7 May 1963)
Typhoon Olive gave little warning to the Island of Guam.
The first warning was given at 1015 Sunday, 28 April 1963.
The eye of the storm passed 20 n mi west on a northerly course
the afternoon of 29 April (see Best Track chart, Figure B-3)
Typhoon Olive generated waves of 30 to 40 feet in the
open sea. The mean waves inside the barrier reef of Guam
were 6 to 10 feet, while Apra Harbor had waves of 6 feet with
a mean high water mark of 3 to 4 feet above the mean low water
mark. The following measures were taken in preparation for
Typhoon Olive:
(1) Two PCs at SRF under the Military Assistance Program
were taken to buoys in the Inner Harbor.
(2) All other craft which were not secure were taken to
■buoys if possible. Because of the late start, the rapid build
up of the winds, and since the Naval Station had only three
operable tugs, this could not be completely carried out. It
became too rough in the Outer Harbor by early evening and too
windy to move the larger craft such as the YD - 120 and an APL.
70
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71
(3) The Trust Territory dredge John S. Campbell had
just been rebuilt following Karen damage and a secure haven
for the dredge was sought. It was finally decided to beach
the dredge broadside to the LST beaching ramp at the south
end of Inner Apra Harbor. This position was selected because
it appeared to be unlikely that the winds would be northerly
during the storm. In the proposed location, the dredge would
be protected from three directions other than north. If the
storm did generate northern winds, the waves may have
destroyed or damaged the wooden deckhouse, causing the dredge
to swamp. But even in that event, the dredge would not be a
inajor salvage problem. The dredge was beached at about 2300
on 28 April, and wires were passed to bollards and stretched
taught by two bulldozers. (The dredge was undamaged by the
storm and was removed from the beach on 3 May by one YTM.)
Maximum winds in Olive were 125 kt while winds reached
88 kt at Guam. Damage to ships and craft which required
salvage efforts was as follows (see Figure B-2):
(a) YRDM - 2, which had been moved to an outer harbor
buoy, broke its 2" wire mooring pendant and grounded on a
spit of land to the east of Wharf "F" and south of Cabras
Island.
(b) YRDH - 2, which had also been moved to an outer
harbor buoy, parted its mooring bridle (two legs of 1 5/8"
wire) and was driven aground on a coral ledge west of Pier "B"
(c) YC - 1419, which had been moored to an Outer Harbor
buoy, broke loose and damaged itself against the Glass
Breakwater. It sank adjacent to the breakwater about 800 -
yards from the Outer Harbor entrance.
(d ) YFN - 693 was washed out of the AFDM-8 during the
typhoon and rested on the bottom immediately to the east of
the dock.
72
(e) The privately-owned hulk ADAK ISLAND, an ex-LST,
parted its mooring wire and was driven aground against the
inner end of the Glass Breakwater. 1 .■• ■ :
CONCLUSIONS: ., . ^|: .:
It is readily apparent that in a severe typhoon situation
such as Karen, none of the berths/buoys in Apra Harbor are
safe. However, for less intense wind situations (say approxi-
mately 50 kt maximum) the inner Apra Harbor appears to provide
some protection. Although there is limited information on
which to base this judgement, it appears the preferred berths
would be in the inner harbor, and in the upwind section of the
harbor. i
73
APPENDIX C
PORT FACILITIES FOR APRA HARBOR, GUAM
1. PIERS
Berth
A B D
■ E •■ H n M N 0 P
Rl R2 SI S2 S3 S4 n T2 T3 Ul U2 VI V2 V3 V4 V5 V6 XI X2 X3
Length
600' 600' 663' 744' 530' 570' 570' 275' 550' 560' 520' 257' 516' 516' 500' 500' 393' 494' 498' 498' 450' 450' 450' 482' 482' 200' 280' 660' 660' 493' 493' 493'
Depth at MLW
44' 35' 42' 40' 32' 26' 34' 34' 34' 34' 34' 30' 32' 33' 35' 35' 33' 30' 29' 32' 32' 32' 32' 30' 29' 30' 31 ' 30' 30' 32' 31 ' 29'
Wharves F and G are not included in the above list since they are controlled by the Government of Guam, Commercial Port
74
2. MOORING BUOYS
NUMBER SIZE & TYPE - LOCATION DEPTH HOLDING POWER
951 17'X10'6" AA 0/H SOUTH 125' 300,000 LBS 701 9'6"X12' A O/H SOUTH 167' 150,000 LBS 702 9 ' 6 " X1 2 ■ A 0/H NORTH 150' 150,000 LBS 703 9'6"X12' A O/H NORTH 140' 150,000 LBS 704 9'6"X12' A 0/H SOUTH 120' 150,000 LBS
501 10'6"X6'6" B 0/H NORTH 160' 125,000 LBS 502 10'6"X6'6" B O/H NORTH 157' 125,000 LBS
302 10'6"X6'6" C 0/H NORTH 115' 100,000 LBS 303 10'6"X6'6" C 0/H NORTH 108' 100,000 LBS
201 9'6"X5'6" D 0/H SOUTH 105' 75,000 LBS 202 9'6"X5'6" D 0/H SOUTH 108' 75,000 LBS 12/13 9'6"X5'6" D 0/H SOUTH 105' 75,000 LBS 12- 9'6"X5'6" D 0/H SOUTH 105' 75,000 LBS 13 9'6"X5'6" D 0/H SOUTH 97' 75,000 LBS 14 9'6"X5'6" D 0/H SOUTH 97' 75,000 LBS 14/15 15/16
9'6"X5'6" 10'6"X6'6"
D D
0/H 0/H
SOUTH SOUTH
97' 97'
75,000 75,000
LBS LBS 16 10'6"X6'6" D 0/H SOUTH 87' 75,000 LBS 17 9'6"X5' D 0/H SOUTH 69' 75,000 LBS
25-N 9'6"X5' B , I/H 46' 125,000 LBS 25-S 9'6"X5' B I/H 48' 125,000 LBS 26-E 9'6"X5' B I/H EAST 48' 125,000 LBS 26-W 9'6"X5' B I/H WEST 48' 125,000 LBS 27-E 9'6"X5' B I/H EAST 37' 125,000 LBS 27-W 9'6"X5' _ B I/H WEST 32' 125,000 LBS 28-E 9'6"X5' ■t I/H EAST 36' 125,000 LBS 28-W 9'6"X5' BJ I/H WEST 36' 125,000 LBS 23 23/22
9'X12' 9'X12'
B B
0/H 0/H
EAST EAST ,
58' 58'
125,000 125,000
LBS LBS 22 9'X12' B 0/H EAST 58' 125,000 LBS
75
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76
APPENDIX D
SHIP SPEED VS SEA STATE AND WIND CHARTS _ ; .„„,,„. ,,
! Figures D-l(a) and D-l(b) represent the estimated result- ^
ant speed of advance of a ship in a given sea condition. The" f
original relationships were based on data of speed versus seal '. % state obtained from studies of many ships by James, 1957. 'i' • \ They should not be regarded at truly representative of any
particular ship (Nagle, 1972). •■ . ;
• For example, from Figure D-l(a), for a ship making 15 kt ' -
encountering waves of 16 ft approaching from 030° (relative ; ?
to the ship's heading) one can expect the speed of advance :, \ \ \ to be slowed to about 9 kt. Twenty feet seas, under the same' ., ;
conditions, would result in a speed of advance of slightly • t,^; |
less than 6 kt. However, it is emphasized that these figures; ! \ are averages and the true values will vary slightly from ship ^ \ 'to shi p. / I • . i I
{ .Figure D-2 shows the engine speed required to offset , { selected wind velocities for various ship types (computed for , I normal loading conditions). , . — ,. .. , |
77
28 24 20 16 12
6 12
SHIP SPEED {knotsi
40'^WAVEHEIGHTS|feetl - 0 =
10°
20°
30°
40°
50°
60°
70°
80°
90°
-•28 24 20 16 12 840
100°
110°
120°
130°
140°
150°
160°
170°
180 0
(b)
18 20
DIRECTION OF WAVES RELATIVE TO SHIP HEADING
SHIP SPEED iknots)
Figure D-1. Expected ship speed as a function of wave height and wave direction relative to ship's heading for a ship making 15 kt (a) and 20 kt (b) (from Nagle, 1972).
78
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