Opinion

OPINION: We’re Facing Extended Drought, Says Expert

Dr Sushil K Sharma BA MA MEng PhD is an Associate Professor of Meteorology at the FNU and a WMO Class 1 professional meteorologist. He was the adviser to the
22 Jul 2015 15:04
OPINION: We’re Facing Extended Drought, Says Expert

Dr Sushil K Sharma BA MA MEng PhD is an Associate Professor of Meteorology at the FNU and a WMO Class 1 professional meteorologist. He was the adviser to the late Permanent Secretary of the National Disaster Management Office Manasa Vaniqi during the 2009-2010 two seasons of back to back severe drought in Fiji. He was the Manager of the Climate Special Services and Research Division of the Fiji Meteorological Service at that time. The views expressed are his own opinion and neither of his employers nor this newspaper.

 

A very rapidly expanding El Nino phenomenon is now driving the weather pattern leading to drought over Fiji and a very startling start to the Northern Hemisphere tropical cyclone season. Since the onset of the very rapidly expanding El Nino, in the last two months we are now experiencing triplet cyclones in the northwest China seas.

 

Large visible eyes

These are in simultaneous action, like three little sisters linked together, feeding, sustaining and controlling the movement of each other, as they move in a north westerly direction initially, towards Japan.

Each one is a very severe revolving system, with great punch and fury, due to its small diameter. All three have very large eye walls clearly visible from geostationary satellites in orbit some 13,500 km above over Papua New Guinea. The “eyes” are clearly very large, of some 100-150 km wide. Compared to the entire revolving system size of no more than 300-400 km wide, the size of the eye is almost 30% of the entire system.

This morning one of the tropical cyclones made landfall and dissipated, whilst the other two remaining active and powerful systems were approaching Japan for a final possible re-curvature to the northeast into the higher latitudes.

 

Pronounced Drought

Over Fiji it is my assessment that the prevailing dry spell is now a drought. Drought will become very pronounced, due to the El Nino now seen to even become more intense. Thus the El Nino phenomenon is now driving the entire regional weather anomaly system, dictating areas of drought and even floods.

The drought will be very marked over Fiji, all the way into the month of November 2015. November is a month which traditionally has much lower rainfall than the other wet season months of December to April. However adverse weather such as tropical cyclones in the month of November, lend to statistics an artificially elevated average value.

Often the atmosphere is low to respond that quickly to seasonality change, also. Though the tropical cyclone season is November to April, as an expert also in Fiji’s weather and climate, I had already classed with my own research many decades ago for the wet season in Fiji to be only for five months—December to April and the dry season of seven months —May to November.

With the present El Nino indices and trends I expect the drought over Fiji to become severe similar in rank to 2009-2010 drought, come September to October 2015 when the soil moisture deficits would become even more marked. By October to November 2015, the country will be just hoping for the rains to arrive in December, as the livestock, agriculture and the people of Fiji would be in a hopeless situation.

 

Active Cyclone Season

With the behaviour of the very rapidly strengthening and expanding El Nino, we expect by November 2015 for a start to a very active phase in tropical cyclone activity and severe weather. Tropical cyclones in the Southwest Pacific will be expected to be far above the average of the 9 we normally have in the entire Southwest Pacific in the tropical cyclone season of November to April on an annual basis.

The majority of the tropical cyclones in 2015-2016 will form between Fiji and Samoa region with much increased threats to Cook Islands, Samoa, Tonga, Tokelau and eastern parts of Fiji. Tropical cyclones approaching Fiji would come more from the north eastern sector with greater threats to northern, eastern and central divisions.

There will be decreased risks to the western parts of Fiji and less tropical cyclone activity in the Coral Sea, between Fiji –Australia—Solomon Islands region. The rain and weather bearing South Pacific Convergence Zone (SPCZ), being one of the major immediate climate drivers in our part of the world, will be more displaced to the far northeast of Fiji.

 

Acute Water Shortage

Acute water shortage will be expected over all maritime regions and most areas on the northern and western parts of Viti Levu and Vanua Levu. Major crops like sugar cane in hilly areas of Rakiraki, Tavua, Ba, Lautoka and Nadi will be severely impacted, as the months pass by with September-October-November becoming critical.

Fire danger index will be elevated, due to very dry conditions and persistent fresh to strong winds from the southerly quarter fanning fires, due to the intensity and frequency of the trade bearing high pressure systems, passing close by in a latitudinal manner in a west to east direction—very close south of Fiji.

Due to forced orographic lifting of the trade winds over the southern and eastern parts of the larger islands like Vanua Levu and Viti Levu, we have continued to have light drizzle and passing showers often with some cloudy conditions. These physical conditions have continued to provide relief to the shallow root based plants in the earlier part of the dry season, though the overall rain has been far below normal in these areas also.

The trough that is now passing across Fiji has given some rain but these systems are few and far between and will not be able to replenish water losses. Thus efforts and planning will need to be continued in regards to large scale water distribution by the relevant agencies for Fiji, with a good understanding that their resources may even get far more stretched in the coming months.

It is possible that the 2014-2015-2016 dry seasons can be a back breaker with back-to-back three dry season of below average rains. Authorities will need to be aware of this; however the elevated numbers of cyclones in the region for the 2015-2016  seasons are expected to bring about rain bearing systems during the coming wet season—to provide some relief from the large water deficits in our water tables.

 

Rapidly Expanding El Nino

Now we will look at the specifics of the case of the very rapidly expanding EL NINO over the last few months. We note that in comparison with all other similar developments in this same period for all past El Nino since 1950, as shown by the NOAA updates (Klaus Wolter) for April-May show that the Multivariate El Nino Southern Oscillation (ENSO) Index called the MEI has risen by 0.61 standard deviations in one month to +1.57, for a high ranking above the ‘strong’ El Niño threshold (upper 10 percentile).

According to the NOAA analysis this is the highest MEI value in 17 years, surpassing the peak of the 2009-10 El Niño.  The current El Niño has ranked above the weak El Niño threshold for four months in a row, and above the strong threshold for two months running.

It would be safe to state that El Niño conditions are virtually guaranteed through 2015. Nevertheless, the odds for a substantial El Niño during the next six months appear better than since at least 2009. Positive SST anomalies have consolidated over the equatorial Pacific, all the way from the dateline to the South American coast. While most of these anomalies reach +1 to +2C, one can find anomalies in excess of +3C near Galapagos.

El Niño disappeared and then returned for two months last year, and then went back to an El Niño-flavoured neutral status in January 2015. However since then it has steadily grown to its highest value in 17 years as of April-May 2015. If it stays above +1.2 for just one more month, it will have exceeded the upper decile threshold for three months running, thus joining the somewhat exclusive ‘club’ of strong events.

A severe drought with this strong El Nino onset, with an active 2015-2016 Southwest Pacific cyclone season can be forecast well in advance, due to the intimate link between the El Nino phenomenon and the reversal of weather patterns in our region.

Feedback: jyotip@fijisun.com.fj


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