CLIMATE SUMMARY MARCH 2017
Samoa Meteorology Division
Ministry of Natural Resources and Environment
W: www.samet.gov.ws
Ph: (685) 20855/20856
F: www.facebook.com/Samoa Meteorological Services
HIGHLIGHTS
ISSUED: APRIL
 Rainfall in March 2017 was
Figure 1: SPCZ Position in March 2017
Figure 2: Normal Position of SPCZ in March
generally ‘average to below
average’. Pg 1 & 2
ITCZ
 March 28th recorded the warm-
SAMOA
est day time temperature of
34.8oC at Apia. The coolest
night
time
temperature
of
17.20C at Afiamalu on the 6th.
GLOBAL SCALE OBSERVATIONS
Pg 3
In March 2017, the Inter-tropical Convergence Zone (ITCZ) was evidently suppressed near and
 Generally, easterlies wind was
east of the International Dateline (~180oW longitude) in relation to its normal position as
registered throughout the is-
shown in Figure 1 and Figure 2. It was enhanced to the east of the Philippines. Additionally,
land in March 2017. Pg 4
the South Pacific Convergence Zone (SPCZ) was displaced southwest of its long term average
location east of the Solomon Islands and extended further southeast of its normal position in
 Neutral phase of El Nino
Southern
Oscillation
(ENSO)
March.
LOCAL SCALE OBSERVATIONS
persists in the Pacific with increased chance of El Nino in
second half of 2017. Pg 5
 Continuous warming of the far
eastern, south of the Pacific
Precipitation in March 2017 was relatively drier than average as rainfall stations observed
‘average to below average’ precipitation. Statistically, 12 stations recorded ‘below average’
rainfall, 9 stations observed ‘average’ and 6 stations registered ‘well below average’
precipitation. The wettest station with the highest total of 403.8mm recorded at Matautu
Falelatai in the western part of Upolu. The second highest total was Falelima in the western
region of Savaii island with 330.0mm of rainfall. Conversely, Lefagaoalii station observed the
and western Pacific sea sur-
lowest total of 42.8mm followed by Aopo station with 56.4mm. Generally, most of March
face waters were observed in
monthly totals across rainfall stations were within the range of 100mm - 295.0mm. The top
March. The equatorial region
maximum rainfall in 24 hours of 131.2mm was observed at Falelima on the 29 th followed by
on the other hand was near
average.
Cooler
sub-surface
84.6mm at Tuasivi on the 13th. Other stations registered their 1-day fall on various days fall
within the range of 10mm –80mm which is classified as ‘light rain to heavy rain’. March
2017 is recorded to be drier than March 2016 as indicated by Figure 7 in Appendix. In fact, it
waters were recorded in the
was the third (3rd) driest March in history of Apia and Nafanua stations since establishment in
eastern
the year 1905 observing 91.9mm and 135.1mm respectively.
region
with
warm
anomalies in the western area.
Climate Summary March 2017
Page 2
Table 1: Rainfall Statistics in March 2017
This table displays the rainfall status of all stations in the country in March 2017
Stations
March
Rainfall
(mm)
March
30 Year
Long Term
Average
% of
Average
1 day fall
(mm)
Date
# of
Rainy
Days
Rainfall Status
UPOLU
Afiamalu
219.5
528
42
40.5
7th
28
Below Average
Alafua
143.2
348
41
52.6
22nd
22
Below Average
Apia
91.9
354
26
19.0
22nd
18
Well Below Average
Faleolo
141.3
250
57
28.8
8th
18
Below Average
Laulii
224.1
427
52
43.2
22nd
22
Below Average
Leauvaa
145.4
463
31
66.4
22nd
20
Well Below Average
Lepa
249.2
247
101
27.4
13th
26
Average
Lotofaga
239.1
231
104
64.4
13th
25
Average
Matautu Falelatai
403.8
513
80
72.8
8th
27
Average
Nafanua
135.1
392
35
32.2
22nd
25
Well Below Average
Nuu
126.6
252
50
45.0
22nd
17
Below Average
Nuusuatia
271.6
243
112
77.8
13th
19
Average
Salani
221.6
231
96
27.2
18th
28
Average
Saleilua
263.1
331
80
49.4
17th
17
Average
Saoluafata
200.2
295
68
52.0
22nd
23
Below Average
Savalalo
148.3
354
42
36.0
31st
13
Below Average
Tiavea
171.8
289
59
27.0
17th
25
Below Average
Togitogiga
295.0
305
97
56.0
1st
31
Average
Vailoa Aleipata
152.2
277
55
28.2
13th
22
Below Average
Aopo
56.4
375
15
12.4
4th
16
Well Below Average
Falelima
330.0
484
68
131.2
29th
24
Below Average
Lefagaoalii
42.6
249
10
15.6
16th
20
Well Below Average
Letui
111.0
375
30
33.6
4th
21
Below Average
Salailua
212.8
231
92
42.8
15th
20
Average
Maota
113.0
292
39
50.0
10th
6
Well Below Average
Tuasivi
189.2
373
51
84.6
13th
18
Below Average
Vaiaata
304.0
331
92
50.4
17th
23
Average
Page 3
Climate Summary March 2017
Figure 3: Rainfall Status Map in March 2017
This rainfall map is generated using observation data from Table 1
TEMPERATURE
Table 2: Air Temperature Statistics
This table displays the temperature statistics recorded across stations in March 2017
Temperature (Degree Celsius)
Stations
Mean Daily
Temperature
Extreme Temp
Max
Date
Extreme Temp
Min
Date
Afiamalu
23.5
30.5
26th
17.2
6th
Alafua
27.7
34.0
26th
20.6
8th
Apia
29.7
34.8
28th
24.2
17th
Faleolo
28.7
33.9
8th
23.3
13th
Maota
N/A
N/A
N/A
24.0
3rd
Nafanua
N/A
N/A
N/A
22.0
27th
Saoluafata
27.5
32.8
6th
22.3
4th
Salailua
27.7
33.3
26th
21.6
27th
Togitogiga
26.4
34.6
9th
20.0
20th
Vaiaata
27.1
33.0
14th
21.2
4th
N/A = Data Not Available
Apia recorded the warmest day time temperature of 34.80C on March 28th followed by 34.60C registered at
Togitogiga on the 9th. Conversely, Afiamalu station observed the coolest night time temperature of 17.2 0C on the
6th with the second coolest temperature of 20.00C registered at Togitogiga on the 20th. Mean daily temperatures
range from 23.50C to 29.70C with Apia recording the highest. The mean daily temperature of Apia is 2.5 0C warmer
in comparison to its 30 year long term average.
Climate Summary March 2017
Page 4
ATMOSPHERIC PRESSURE
Table 3: Atmospheric Pressure at Mean Sea Level (MSL)
This table displays the atmospheric statistics recorded across two stations in March 2017
Station
Highest MSL
Pressure (hPa)
Date
Lowest MSL
Pressure (hPa)
Date
Average MSL
Pressure (hPa)
Apia
1014.6
21st
1001.1
1st
1010.5
Faleolo
1014.9
21st
1005.6
2nd
1010.8
Faleolo recorded the highest MSL pressure of 1014.9hPa on March 21st . On March 1st the lowest MSL pressure of
1001.1hPa was recorded at Apia. The average MSL Pressure for Apia is 0.7hPa higher than the 30 year long term
average of 1009.0hPa.
(Note: High pressure systems associate with good weather conditions whereas low pressure systems associate
with bad weather conditions)
WIND
Figure 4: Wind Speed and Directions
The following diagrams show the different wind speed and direction that recorded daily at 9am across the country in
March 2017.
Figure 4a : Apia Station
Figure 4b: Faleolo Station
Figure 4c: Afiamalu Station
Figure 4d: Togitogiga Station
Figure 4e: Vaiaata Station
Figure 4f: Nafanua Station
Generally, easterlies to south east winds prevailed over Samoa in March 2017 dominating the wind recorded
across the stations exceeding 40% of the time. All stations experienced light winds (0-10km/hr) with some gentle
winds (10-20km/hr) at times. Significant calm conditions were also observed at Nafanua station.
Page 5
Climate Summary March 2017
EL NINO SOUTHERN OSCILLATION (ENSO)
CURRENT ENSO STATUS
Atmospheric Indicator of ENSO
The current status of ENSO is still in “Neutral” phase
with signs of an increase possibility of
Southern Oscillation Index (SOI)
El Nino to
develop in 2017. Climate models being surveyed are
The 30 day SOI value to 9th April was +3.8 with 90 day
forecasting
value of +1.0. The SOI has been within neutral range
steady warming of the tropical pacific
ocean is likely to continue and 7 out of 8 models pre-
since mid-October 2016.
dicting SST will exceed El Nino thresholds during the
second half of 2017.
(Sustained positive values of the SOI above +7 indicate La
Nina. Whereas sustained negative values below –7 indicate
Oceanic Indicator of ENSO
El Nino. Values within –7 and +7 shows neutral conditions.)
Figure 5: Sea Surface Temperature in March 2017
Figure 5 shows the sea surface temperature anomalies
in which warmer conditions were experienced in the far
eastern Pacific, across most of the Pacific south of the
equator and the western Pacific just east of the
Australian region. The equatorial region was mainly close
to average in March. The March values for the NINO3,
NINO3.4 and NINO4 regions were +0.5 °C, +0.2 °C and
0.0 °C, respectively. The Nino 3 remained the same
from February and the other two regions have increased
by +0.20C and +0.10C respectively.
Figure 6: Sub-surface Temperature
The sub-surface temperature water anomalies for March
2017 shows the sub-surface of the central to the
eastern equatorial Pacific Ocean was cooler than average. These cool anomalies were similar in strength to
those observed for February. Areas of weak warm
anomalies were present in the top 150 m of the tropical Pacific west of 160°E.
Page 6
Climate Summary March 2017
APPENDIX
Figure 7: Graphically representation of total monthly rainfall in March 2016 vs March 2017 in all rainfall stations.