1

• The El Niño Southern Oscillation (ENSO) state in the tropical Pacific have returned to neutral level (that is neither

El Niño nor La El Niña) during March 2018;

• While the ENSO state have returned to neutral levels, Fiji’s climate may continue to have weak La Niña like influ-ence for a while due to the lag effect;

• The neutral-ENSO state is likely to continue through the end of first half of 2018, with high uncertainty for the sec-

ond half of 2018;

• Average or above average rainfall is likely through both April to June and July to September 2018 periods;

• However, rainfall activity will decrease during the forecasted period in comparison to the past couple of months;

• Above normal air temperatures are favoured over the Fiji Group during both April to June and the July to Septem-

ber 2018 periods;

• There will be occasional periods of significantly cool nights, especially during the period June to August;

• Above normal sea surface temperatures are expected in the Fiji region during April to June 2018 period;

• While the country is now into the last month of the 2017-18 tropical cyclone season, the public should remain vigi-

lant as off season tropical cyclones have occasionally occurred and environmental conditions remains conducive.

2.0 RAINFALL & TEMPERATURE OUTLOOK

1.0 HIGHLIGHTS

Fiji Climate Outlook Fiji Climate Outlook Fiji Climate Outlook Fiji Climate Outlook April to June 2018 April to June 2018 April to June 2018 April to June 2018

& July to September 2018& July to September 2018& July to September 2018& July to September 2018

Issued: April 16, 2018 *Volume 12 : Issue 04

*Prior to July 2006, the Fiji Islands Climate Outlook was incorporated in the Fiji Islands Weather Summary

FIJI METEOROLOGICAL SERVICE

Private Mail Bag (NAP 0351)

Nadi Airport, Fiji.

Ph: +679 6724888, Fax: +679 6724050

Email: climate@met.gov.fj

Also online at http://www.met.gov.fj

APRIL TO JUNE 2018 RAINFALL OUTLOOK The SCOPIC model favours average or above average rainfall over most parts of Fiji through the April to June 2018 period. The SCOPIC predictions is consistent with global climate models outlooks which favours for the above average rainfall in the Fiji region. However, as the country progresses into the dry season beginning from May, rainfall activity will decrease in comparison to the past couple of months. The SCOPIC model rainfall predictions are as follows (Table 1): Western Division : Above average or average (Confidence - generally moderate to high) Central Division : Above average (Confidence - generally moderate to good) Northern Division : Above average or above average (Confidence - moderate to good) Eastern Division : Above average (Confidence - moderate to good) Rotuma : Equal chances of below average, average and above average (Confidence - very low) Global Rainfall Models (e.g. ECMWF, NSIPP, IRI, NCEP, etc.): The global climate models favour above average rainfall in the Fiji region during the April to June 2018 period (Figures

3a & 3b: two of the several global climate models that the Fiji Meteorological Service uses). JULY TO SEPTEMBER 2018 RAINFALL OUTLOOK The SCOPIC model rainfall predictions are as follows (Table 2): Western Division : Average or above average (Confidence - generally low to moderate) Central Division : Above average (Confidence - low to moderate) Northern Division : Average or above average (Confidence - low to moderate) Eastern Division : Average or above average (Confidence - low to moderate) Rotuma : Equal chances of below average, average and above average (Confidence - very low) TEMPERATURE OUTLOOK: The air temperatures over the Fiji Group are likely to be above normal through both April to June 2018 and July to Sep-tember 2018 periods (Figures 4 & 5). However, as the country progresses into the cool/dry season, occasional periods of

The X LEPS % scores, which are used to categorize the confidence of the outlook are as follows: Very Low: X < 0. 0 Low: 0 ≤ X < 5 Moderate: 5 ≤ X < 10 Good: 10 ≤ X < 15 High: 15 ≤ X < 25 Very High: 25 ≤ X < 35 Exceptional: X ≥ 35

ISO 9001:2015

certified Climate

Services

2

Current El Niño Southern Oscillation (ENSO) Status The ENSO state in the tropical Pacific have returned to neutral levels (that is neither El Niño nor La El Niña) during

March 2018 after reaching a weak La Niña state in November 2017.

The sea surface temperatures in the equatorial Pacific Ocean are near normal, but still leaning on the cooler side of neutral

in the central to eastern equatorial region. The warm pool of sub-surface waters have expanded from western to central

equatorial Pacific Ocean over the last couple of months. The presence of the warm waters below the surface is likely to further warm the surface waters in the coming months.

The atmospheric indicators of ENSO are still leaning towards weak La Niña conditions with the presence of enhanced Trade Winds over the equatorial central and eastern Pacific Ocean and suppressed cloud cover near the Dateline during

the past month. The Southern Oscillation Index (SOI) for March was +10.5, with the 5 month running mean of +4.8

(Figure 1).

El Niño Southern Oscillation Prediction The neutral-ENSO state is likely to continue through the end of first half of 2018, with further warming of the ocean ex-

pected over the coming months. For the second half of 2018, majority of climate models predict neutral ENSO condi-

tions, while others predict a warming to weak El Niño levels beginning in the third or fourth quarter of 2018. However,

uncertainty about the ENSO condition beyond the second quarter is high, as forecasts whose lead-time passes through the

March-June period are known to have lower confidence than those made at other times of the year.

Despite the decay of the La Niña conditions, Fiji’s climate may continue to have weak La Niña like influence due to the

lag effect. Fiji typically experiences enhanced rainfall during a La Niña event, especially during the wet season from No-

vember to April.

Issued: April 16, 2018 Fiji Climate Outlook Volume 12 : Issue 04

SOI (in bars) and 5 month running mean (continuous pink line) The SOI for March was 10.5, with the 5

month running mean

of +4.8. Sustained values of SOI above +7 indi-

cates presence of La

Niña conditions.

ECMWF Seasonal SST Forecast favours

slightly normal SSTs

in the Fiji region. (https://

www.ecmwf.int/en/

forecasts/charts/

seasonal/

season-

al_charts_public_euro

sip_sst)

3.0 EL NIÑO SOUTHERN OSCILLATION (ENSO) CONDITIONS

Figure 1: Southern Oscillation Index (SOI) Graph

Figure 2a: ECMWF Sea Surface Temperature (SST) for April to June 2018

3

Figure 3a: ECMWF Rainfall Outlook for April to June 2018

Issued: April 16, 2018 Fiji Climate Outlook Volume 12 : Issue 04

ECMWF Seasonal Forecast favours above

average rainfall in the Fiji region. (https://www.ecmwf.int/

en/forecasts/charts/

seasonal/

season-

al_charts_public_eurosi

p_precipitation?

time=2017090100,2904

,2017123100&forecast_

type_and_skill_measure

s=tercile%20summary)

Figure 2b: NCEP Coupled Model - SST April to June 2018

NCEP Coupled Model favours normal to below

SSTs in the Fiji region. (http://

www.cpc.ncep.noaa.gov/

products/CFSv2/

imagesInd3/

glbSSTSeaMaskInd1.gif )

Figure 3b: NCEP Coupled Model - Rainfall Outlook for April to June 2018

NCEP Coupled Model forecast favours aver-

age rainfall in the Fiji region. (http://

www.cpc.ncep.noaa.go

v/products/CFSv2/

imagesInd3/

glbPrecSeaInd1.gif)

4

Station (Locations in Figure 4) Dry 33 % Normal 67 % Wet

(%) (mm) (%) (mm) (%)

Western Division

Dobuilevu 19 411 41 599 40 Penang Mill 24 344 35 532 41 Yasawa-i-rara 16 280 40 425 44 Vatukoula Mine 18 314 36 477 46 Rarawai Mill 20 287 31 440 49 Lautoka Mill 19 263 33 390 48

Nadi Airport 23 255 32 375 45 Nabou Pine 8 232 31 364 61 Lomawai 14 252 38 350 48 Olosara 15 257 41 420 44 Nacocolevu 12 276 43 388 45 Monasavu Dam 23 858 40 1171 37

Central Division Navua 23 755 31 985 46 Lami 16 920 41 1092 43 Laucala Bay, Suva 24 678 32 809 44 Tamavua 19 758 38 1094 43 Nausori Airport 18 646 34 770 48 Koronivia 17 646 39 807 44 Naduruloulou 32 673 30 920 38

Eastern Division St. John’s College, Levuka 14 354 35 686 51 Lakeba 20 351 37 501 43 Ono-i-lau 13 312 42 463 45 Matuku 23 346 36 481 41 Vunisea 21 462 35 598 44

Northern Division Nabouwalu 13 485 41 659 46

Seaqaqa 20 323 37 491 43 Labasa Airfield 23 320 38 448 39 Savusavu Airfield 18 396 27 629 55 Wainigata 17 431 37 616 46 Udu Point 22 432 41 620 37 Matei Airfield 23 528 33 704 44 Rotuma 35 746 34 916 31

Vaturu 17 310 32 468 51

Dreketi 21 297 29 496 50

Table 1: Three Months: April to June 2018 Rainfall Outlook

Issued: April 16, 2018 Fiji Climate Outlook Volume 12 : Issue 04

The FMS uses the Seasonal Climate Outlook for Pacific Island Countries (SCOPIC) Model as its main guidance for predicting climate on a three to six month timescale. SCOPIC bases its calculations on there being a correlation between sea surface temperatures and rainfall/air temperatures. For some parts of Fiji e.g. the middle of the Dry Zone, this link is very strong. For others e.g. Suva, the link is not as strong, but it is still a useful indicator.

When calculating rainfall for example for the upcoming three month period (e.g. February to April 2015), SCOPIC uses measurements from the current three month period (in this case November to December 2014) to look for similar ocean patterns in the historical record. The rainfall for the following three month period are then used to calculate the probabilities for the outlook period.

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Station (Locations in Figure 4) Dry 33 % Normal 67 % Wet

(%) (mm) (%) (mm) (%)

Western Division

Dobuilevu 24 208 37 287 39

Penang Mill 25 147 35 232 40

Yasawa-i-rara 26 129 29 209 45

Vatukoula Mine 16 125 38 213 46

Rarawai Mill 19 130 39 230 42

Lautoka Mill 17 123 41 219 42

Nadi Airport 18 129 42 212 40

Nabou Pine 16 158 38 258 46

Lomawai 22 151 43 256 35

Olosara 22 198 39 311 39

Nacocolevu 23 196 36 289 41

Monasavu Dam 39 589 28 721 33

Central Division

Tokotoko, Navua 26 532 32 683 42

Lami 26 613 34 847 40 Laucala Bay, Suva 28 384 33 561 39

Tamavua 29 578 30 809 41

Nausori Airport 30 368 33 531 37

Koronivia 31 377 30 550 39

Naduruloulou 34 411 29 603 37

Eastern Division

St. John’s College, Levuka 16 232 45 328 39

Lakeba 26 200 31 316 43

Ono-i-lau 25 252 35 335 40

Matuku 26 224 37 354 37

Vunisea 29 273 26 382 45

Northern Division

Nabouwalu 23 210 35 369 42

Seaqaqa 22 123 37 241 41

Labasa Airfield 23 109 38 192 39

Savusavu Airfield 24 241 40 345 36

Wainigata 24 283 27 445 49

Udu Point 27 229 33 346 40

Matei Airfield 21 287 39 399 40

Rotuma 37 578 35 788 28

Vaturu 28 191 26 358 46

Dreketi 21 143 38 221 41

Table 2: Three-months: July to September 2018 Rainfall Outlook

Issued: April 16, 2018 Fiji Climate Outlook Volume 12 : Issue 04

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Figure 4: Air Temperature Outlook - April to June 2018

Issued: April 16, 2018 Fiji Climate Outlook Volume 12 : Issue 04

Figure 5: Air Temperature Outlook - July to September 2018

Figure 4. Location of climate monitor ing stations in Fiji.

Multi-model ensemble for air temperature predictions. Source APEC Climate Centre.

Multi-model ensemble for air temperature predictions. Source APEC Climate Centre.

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4.0 TROPICAL CYCLONE SEASON 2017/2018 OUTLOOK

Issued: April 16, 2018 Fiji Climate Outlook Volume 12 : Issue 04

The Tropical Cyclone (TC) activity in the 2017-18 TC season within the Regional Specialized Meteorological Center Nadi – Tropical Cyclone Centre (RSMC Nadi-TCC) Area of Responsibility (AoR) (Equator to 25˚ South between 160˚

East and 120˚ West) is anticipated to be below average with moderate confidence. The official 2017-18 TC Season began on 1st November 2017 and ends on 30th April 2018. Four to six (4 to 6) tropical cyclones are expected to occur in the RSMC Nadi-TCC AoR during the 2017-18 season. The average for all the 47 seasons from 1969-70 to 2016-17 is 7.1 cyclones. The average for El Niño, La Niña and neutral sea-

sons are 8.6, 6.1 and 6.3 tropical cyclones, respectively. Analogues of nine (9) seasons with similar atmospheric and oce-

anic conditions, were used for this outlook. Tropical cyclone activity in the South Pacific region is likely to be shifted westward (Coral Sea) during the 2017-18 sea-son. This outlook is based upon the status of the El Niño - Southern Oscillation (ENSO) over the preceding July to Sep-

tember period. During this period in 2017, neutral to borderline La Niña conditions were present. Furthermore, the ana-

logue seasons were narrowed based on international guidance forecast for neutral to weak La Niña conditions during most of the coming TC season. Historically, these conditions have favoured a westward shift in tropical cyclone activity in the

South Pacific. TC activity in southern Vanuatu, New Caledonia, Fiji and Wallis & Futuna Waters is likely to be normal this season,

while there is reduced risk for Solomon Islands, Tokelau, Samoa, Tonga, Niue, Cook Islands and French Polynesia. TC activity in the Kiribati and Marquesas area is unlikely. There is normal risk of severe TCs for Vanuatu, New Caledonia, Fiji and Samoa, while there is reduced risk for Solomon Islands, Tokelau, Samoa, Tonga, Niue, Cook Islands, Society Islands, Austral Islands and Tuamotu Archipelago/Gambier

Islands. Severe TC is unlikely in the Marquesas, Pitcairn Islands and Kiribati regions. For Fiji, one to two (1-2) TCs could be expected this season of which one (1) may reach or exceed category 3 status. For

those tropical cyclones passing close to the country, associated active cloud and rain bands may occasionally affect Fiji with marked rainfall and possible flooding, including sea flooding of low lying coastal areas. With the expectation of trop-

ical cyclone genesis to lie to the west of the Dateline in the Coral Sea region, there is high chance of TCs to approach Fiji from the Northern, Western and Southern sectors. Historical records show that TCs have occasionally formed outside the official TC Season. Therefore, it is critical that members of the public are to remain alert and prepared throughout the 2017-18 TC season and beyond.