GEOGRAPHIC INTELLIGENCE REPORT DOMINICAN REPUBLIC PART V: CLIMATE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP79-01009A002700010024-6
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 16
• Document Creation Date: December 9, 2016
• Document Release Date: December 2, 1999
• Sequence Number: 24
• Publication Date: March 1, 1961
• Content Type: IR

CONFIDENTIAL
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il- 09-
EOGRAPHIC INTELLIGENCE REPORT
CENTRAL INTELLIGENCE AGENCY
OFFICE OF RESEARCH AND REPORTS
...-
DOCUMENT NO. e--.._.,..-
NO CHANGE IN CLASS. O
^ DECLASSIFIED
CLASS. CHANGED TO: TS S
NEXT REVIEW DATE: _--
AUTH ,HR 70.2
`Api+a? ~+r~.+Iase X10/08;x
"AC
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WARNING
This material contains information affecting
the National Defense of the United States
within the meaning of the espionage laws,
Title 18, USC, Secs. 793 and 794, the trans-
mission or revelation of which in any manner
to an unauthorized person is prohibited by law.
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GEOGRAPHIC 1ATELLIGEOGE REPRW1
m3.I q REF'CT lLI
RT V: C
t? /M OR L611, Part V
.wch 1961
Y
CENTRAL INTELLIGEMOM AG MW
Office of Research and. Reports
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25X1 C
tents an the Aced a ring uiiMtic )kp . . . . . . ?
Zo13.jnpc
HiAAi Re>ubiic and Haiti; C11. t1c Regime (29811) . IQ
25X1C-
. . . ? ? . . ? . . ? a *
es - L Rio .
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s'. nerai.
=_? t-o ologimi data on the 17tJa nicexi ttepubl.ic are best uescribcd as
c~3ai tncoIIpJ.ete, discontinuous, anc probably inaccurate or, at
- `-aT m .s dingo evertheles , the data are sufficient t indicate
e iSLand of i. anxoia his a ccmp.ce:x of climates in contrast to
rceignbors to the west arat east -- +:uba and Puerto Rico -- both of
ich have relatively lcanngenavw, cil tes.
a rough ;e =rail at:i , I the ecrasta i and other low-lying areas of
the Dominican Republic are not w id wet (with the exception of sc ae
pm:-1.8 o the southwest that are hot and dry)., `areas the b1gn interior
?.a wam zd oaiy f'air:iy w:t: (see Yap 2911, following pc #o)
TI. Tempe.vature
not test, areas of the country are aioug the northern coast, fry
bhitian border to the eastern tip of the island, and in the fear
r c ut. wwest, including one lower p tc oA the Bahor-uco eninsuia, In
'b sr; areaa, wean a i t eratures are ?g9?k and abate, auJ maxim=
vecurded ten r?atures have exceeded iOi?F~ The nigher parts of the
Cordillera C entra:i northerx t of. onsta nza, on the other band, have mean
annual aver ege U. L,-, be1Crw+ cor purposes of coy risOf ,
sv Li %e p ire na 'tb -ee trai k`1Qr . ., has a mean aqual temperature
at 69?' ; and Long y, in i~he suu mImmst part of the state, has a
is ea ual tenteratuce o;
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4 ae differences in temperature between the coastal area and the
Wi!:hter elevations of the interior are best exemplified by the records
of Ciudad )jiuo, 69 feet above sea level, and Constanza, some 3,900
feet is elevation. Ciudad Trujillo has mmthly average maxim= tem-
x:acures tha range crow 84OF in January to 88?F during the period
July through September and average minim= temperatures of 66?f in
.iuary and 73?F in August. Detailed climatic data on Ciudad Trujillo
are given in Table 1 (see p. 3j. Constanza is fairly representative
oP the 20 percent or the country that lies at elevations of 3,000 feet
atid above. The average maximum temperature at Constanza ranges from
76?F in January to 79OF in September and the average minimum from 49OF
in February to 55?F in My. Frosts are not unknown and probably are
f it y frequent during the winter in the 7 percent of the land area of
the .repub1.c that lies above 5,000 feet.
t.l Rainfall
_Werage rainfall varies more from one part of the island to another
than does the temperature, ranging from 60 or more inches on the north-
east coast to 15 inches or less in the southwest. Although the higher
parts of the Cordillera Central probably receive well in excess of 80
inches, no reliable records are available to validate the probability.
Such wide variations in the average annual rainfall of the Dominican
Republic result in part from the relationship between two strong climatic
controls -- the trend of the mountain ranges and the direction of the
prevailing winds. The mountains of the Dominican Republic trend from
slightly west of north to slightly east of south and from west-northwest
to east-southeast whereas the prevailing winds blow from the northeast
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-Taws
Feb u=7
March
April
MV
3+e
July
August
September
October
.November
December
Niont
mean I-Ai -
3is uax y
!~:bruary
ch
April
I.kw
June
July
August
September
October
November
December
Relative
min E idity Average Number
(Paroent) S3nSUE) sue
2.4
1.4
1.9
3.9
6.8
6.2
6.4
6.3
7.3
6.1
4.9
2.4
7.1
5.6
4.3
6.3
5.5
2.3
3.2
2.9
3.9
4.7
14.6
9.3
_3_
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to east. -i a result all four motmtaiu chains car,;t some rain shadows
because tbb r Yin -beari ; vir ds deposit most of their moisture ,an the
NrI dward sin s and blow down the leeward side of the mountains as
drying or relatively dry wind-s. The rain shadows are not deserts,
however, because they receive moisture in the fora of tropical downpours
in My to cxly, the period of high sun dad copious rainfall associated
with the 1c +r pressure cress, including hurricanes, that pass over the
island in ,eptember arad October. Although these areas are not forested,
-Vh ey receive precipititiot; zui:zieient to support a gt.ass and scrub
general;, the rai ''))XL decreases from the very rainy northeast
recast --- the stretch between iu rto Plata and the eastez e tip of the
Island to the semiarid sera. :;west corner of the country. Detailed
of tic data on Puerto , Lata are ,given in Table 1. Exceptions to the
above gerxe;r?ai1zatic>xi occur in areas of heavy rainfall such as n
Crtst6bal (72 inches), Da anon. (60 incased), and El. s Fiat (55 inches)
a ad in the subbuxi id western end of the Clbao Valley bet ;ern N. ntecristi
((30 inches) and Valverde x,28 inks) Uhare rainfall is aromolousl,?y
1i:4xt emd quite, a e i.iable .
The reliability' and the predictability of rainfall. decreases from
nee ?thc a t to southw-rest i from east to west. In the drier parts of
west, ire the natural vegetation Is thorn forest and scrub., it
t - not. ;musua. L for area t o receive 0.1 inch of rain i n, a given month
In o n e year and receive.:: i3 inches during t h e s month in the follow-
ing years Even in. -c;ha huai.d east rainfall c. be vnrellable. According
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to records, Seibo in hoe eastern part of the republic had 14 inches of
rainfall in March one year-, but In the next two years March was com-
pletely rai `Less.
The number of dry seasons per year and their duration varies con-
siderably from one part of the country to another. Along the rainy
northeast coast there is no truly dry season but merely a less rainy
season that usually lasts from January through April. The southeast
and parts of the southwest along the Haitian border have a singe dry
season, which occti,rs from December through March or April in the more
humid southeast and from November through April in the southwest. The
rest of the country, about 50 percent of the total area, has two dry
seasons -- a fairly W3i-defined one from December through April s a
shorter and less pronounced dr3r season during June and July.
1)urin most of the year, rain occurs chiefly In the form of heavy
downpours accompanied by lightning and thunder. Bast of a line drawn
arbitrarily through San Cristobal, La Vega, Santiago, and Puerto Plata
some UO to 120 days with rain can be expected annually. Four inches
of rainfall in 24 hours is not exceptional.. The heaviest recorded
21-hour raizifall was 12.36 inches in Puerto Plata.
The onltr place in the entry wbere rainfall would be likely to
have a direct and adverse effect oxi overland movement would be long
the northeast coast, including the Sv a Peninsula. There the tor-
rential downpours could produce water-logged soils and streams in spate
and could temporarily, at least, slow or halt uav nt.
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IV . Winds
over most of the isiaxed the Northeast Trades are the predominant
winds. These winds may veer to the east and occasionally to the south-
east, but they are so dominantly from the eastern quarter that the
words barlovento (windward) and So to (lee exd) are often used in
giving directions. The Trade Winds are fairly constant and are respon-
sible for the equitable and relatively comfortable temperatures of the
island. Their velocities commonly range from 5 to 3a miles an hour.
Another set of winds that help create a pleasant climate are the
land-sea, breezes that moderate the temperatures along the coast, blow-
ing onshore during the day and offshore at night.
The Dominican Republic lies in the midst of the hurricane belt and
occasionally has suffered dire damage from these tropical cyclones.
In 1930, most of the city then called Santo Domingo was laid flat. In
rising Phoenixlike from its rubble the stricken city became the prese at
Ciudad TTujillo. In the 8g year period between 1851 and 1935, some 20
tropical storms -- not all of them of hurricane strength -- passed over
t .:ee republic, an average of about 1 every fourth year. Portun teIy g
the damaging part of the storm path usually bas been relatively narrow,'
and on the average the areas actua.l.ly affected have been free from
storm damage for periods considerably longer than YF years. 'The north
coast of the republic and the Cibao Valley experienced no hurricane
age from 1900 to :938.
Tropical storms that do not pass nor enough to the south coast to
) ke their presence env Ldent in the w?eatber sometimes cause heavy seas.
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=ihhi$ phenomr~ non is known locally as mar desbordado (inundating sea) and
is especially dangerous to shipping because it appears with little or
no warning.
25X1 C V. Weather Factors
25X1 C
hurricanes during the period from May through
November, p ticularLy during the late sumaaer and early fall. Except
for conditions encountered in the vicinity of hurricanes the weather is
25X1 C generally favorable throughout the year. The percentage
knots) in the Dominican Republic for at least 1 or 2 days at a time is
as follows:
risk of encountering unfavorable weather (winds in excess of 27
Duration of
Percentage of aRisk
Unfavorable Weather
Feb
may
A
Nov
y
7
3
12
6
d Ay s
3
0
5
3
25X1 C A.
The high- percentage of low rea swells and low wind speeds is favor-
25X1 C
pole at sea. Delays or damage may
occur when hurricanes de clop, especially along the south coast, which
is iib jest to the mar des bordado . Fog is too rare to be considered
either as aiding or ha Bring n vigation
25X1 C
25X1 C B. Air
Light ground fog occurs in the low areas along the north coast during
December and January; otherwise, only rain might restrict visibility.
ere is considerable cloudiness throughout the year, with a maxim=
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ring the rainy seasons. Icing below 12,000 feet is negligible
'?okxhout the year, but conditions conducive to icing do occur in
cumulonimbus clouds from 13,000 to 18,000 feet-.,
25X1 C .; ? Movement
Along all coasts, land and sea breezes are the predominant surface
wilds, with the weakest winds occurring during the early morning and
the strongest during midafternoon. Surf conditions will be most pro-
nounced along the exposed beaches at times when the pressure pattern
and swell direction coincide with the sea breeze. Sigh surf also can
be expected during squalls, hurricanes, and the mar desb9 do?
25X1 C 25X1 C
The visibility-cloudiness factor is generally favorable
25X1 C the year round. Thunderstorms are numerous, however,
and the storms and cloud are likely frequently 25X1 C
during the rainy seasons.
. Radar and Line-of-Sight Radio
Atmospheric conditions conducive to extended ranges of ducting of
line-of-sight radio and surface radio are frequently present in the
area to the north of the Dominican Republic. When the trade-wind
inversion becomes well established in the winter and spring, anomalous
patterns (radio holes) of air-search radar will occur in the vicinity
of the Dominican Republic.
Sonar
The best sonar conditions, on the basis of variations of wind-velocity
and sea-temperature profiles, occur during the winter and the poorest
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conditions during the summer. Ideal echo-ranging conditions in deep
water vary from about 60-65 percent in February to 35.40 percent in
August. Sonar conditions are poor in the areas of shallow water. In
all sonar operating areas, extensive areas of moderate background
noises (20 to 40 decibels; 0.2 to 20 kilocycles) are created by major
concentrations of snapping shrimp and sonic fish.
0. Survival in Water
Sea-water temperature ranges from 77?F in February to 83?F in
August. An individual with ordinary clothing and a life jacket can
be expected to survive more than 12 hours in 77-degree water and up
to his fatigue factor in water above 80 degrees.
VI. Comments on the Accoing Climatic Map
Although the map that accompanies this report, Dominican Republic
.ndHaiti: Climatic Regions (Map 29811), has much to recommend it, it
also has a few deficiencies that should be noted. According to more
recent rainfall statistics, the area of Climate 1 (rainfall heavy all
year) is too large, extending too far south and east. In the eastern
reaches, an area shown on the map as having Climate 1 actually has
Climate 4 (dry season nearly half year); and in the south the boundary
of Climate 1 should be moved northward and an area of Climate 3 (rain-
fall heavy most of year) should be inserted. The northwest part of the
country (northwest of Moneion) and the southwest (on the southwest shores
of the Bahoruco Peninsula) should be shown as having Climate 5 (mean
ar ua]. rainfall less than 80 centimeters) rather than Climate 4.
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!ac v v : o : the. unreliability of Dominican statistics tbee ?:at a it o
rainfall shown in the bar graphs for various stations, although possibly
correct, is c iscrepatot in relation to similar data appearing in other
sources. (incidentally, appreciable discrepancies occur among the
ether sources.) Regardless of differences in monthly and a tusl Trans,
for rainfall., the pattern of annual rainfall distribution is to close
a, eemerec, among all. tour oes
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Climatic Regions
to
as 1
N
The numbers above the climatic graphs are mean
annual temperature in degrees centigrade and
mean annual rainfall in centimeters.
[A
II
J F MA MJ J ASON0
EL CERCADO
C. F.
30-1- 80?
0 50 100 150 200 Miles
I I 1
1 -T I I I
0 50 100 150 200 Kilometers
TROPICAL CLIMATES (Mean of coldest month more than 18?C.)
RAINY ALL OR MOST OF YEAR LONG DRY SEASON OR DRY MOST OF YEAR
(Mean annual rainfall usually more than 120 cm.) Mean annual rainfall less than 180 cm.)
Rainfall heavy all year (not more than one month with mean rainfall less
than 6 cm.) 4
~ 0
3
0 30 0 0
CONVERSION SCALES
r 70
60
cm.
40
30 1
105
COOL HIGHLAND CLIMATES
(Mean of coldest month less than
Dry season nearly half year (4.6 months with less than 6 cm. mean monthly
rainfall); usually November - April. (Mean annual rainfall 80180 cm.).
Rainfall heaviest in winter months ( usually between September and Mean annual rainfall less than 80 cm. where mean annual temperature
February); short semi-humid period usually March - August, with 5 exceeds 25?C. Rainfall maximum usually May - October
secondary maximum usually in May
R~n
Rainfall heavy all year (not more than of
mean rainfall less than 6 cm.)
8
Long dryseason (4-6 months with less
mean monthly rainfall)
than 6 cm. mean monthly rainfall) usual) December, April with """?"'?""?" "" 1101 11 ?11. wnern mean 1 nnual em,erature
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