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: [email protected]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
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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
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
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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
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
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.