Drought Breaking Fiji Day Rains
Sushil K. Sharma is an Associate Professor of Meteorology at the Fiji National University and is also a certified World Meteorological Organisation Class 1 professional Meteorologist. The views expressed are his own and not necessarily that of his employer.
Fiji Day – the 46th anniversary of independence Monday, October 10, was heralded by widespread continuous heavy rains over the entire 300 island nation. The Japanese Geostationary Meteorological Satellite named HIMAWARI, located in orbit over Papua New Guinea at a height of 13,500 kilometres, showing extensive cloud cover over and beyond Fiji in all flanks, with very high intensity rains of over 50 to 80 millimetres per hour (mm/hr).
National land-based meteorological radars around the nation at Nadi, Nausori, and Labasa, with scanning capability outwards to distances of 500 kilometres (km), showed very wide spread echoes bouncing back from very mobile and extremely active rain bands in which were embedded 100-200 km long squall lines, moving rapidly longitudinally, at intervals. Due to these rapidly moving and extremely mobile and active squall lines embedded in rain bands, some parts of the nation was put through some very strong and blustery winds of about 50 -65 km/hr with the entire nation’s land areas under a strong wind warning and a flood alert for the low lying areas. Thus, as dawn broke over the nation on Fiji Day, the heavens definitely were in a good mood to bless us all in the usual way, energetically and clearly – announcing with relentless vigour and a persistent rapturous – ecstatic – overjoyed – and a thrilled symphony of melody over our rooftops with very big heavy rain drops over our rooftops.
The dark, dreary, blistery and wet conditions with persistent gusts brought back the haunting memories of the few days and hours before the onslaught of TC Winston over Fiji this year. TC Winston had cut across the nation on February 20 and 21, 2016, as a Category 5 Severe Tropical Cyclone. The weather was almost reminiscent of the period just before the arrival of some adverse tropical revolving system that people in this part of the world are used to.
Friends cried out and asked if it was the cyclone season already, only to be corrected that the squalls were associated with a trough of low pressure with associated cloud band over Fiji, and was slowly traversing eastwards across Fiji in an easterly direction. The Fiji Day rains over were widespread and very marked and many areas received cumulative totals in 24-hour periods upwards of between 100 to 200 millimetres. The rains were widespread and heavy and provided enough rains to break the agricultural drought over Fiji’s largest islands including all maritime islands. Agricultural drought had been gripping many parts of Fiji until now especially western and northern divisions of Viti Levu and Vanua Levu and many maritime islands. The only major rain over Fiji during the dry season this year was in August, when Fiji received substantial rains which were above the monthly average totals. In some ways the synoptic systems impacting Fiji and the development and arrival of closed low pressure systems so close in the vicinity of our tropical latitude, in some ways was the defining phase for a very slow start to a transition from winter time to summer time encroachment of synoptic systems over our part of the world.
Traditionally, areas south of us, have persistent high pressure systems moving latitudinally eastwards in winter interspersed with periodic frontal systems extending area of low pressure, from migrating deep lows over the Tasman Sea and New Zealand regions. These systems sustain and maintain cool southerly winds over Fiji regions in winter, which is why our weather is supposed to be very cool, pleasant with dry air – with an absence of moist humid air. Humid airflow over us, which is common in summer, is often very unpleasant and increases the human discomfort index.
After relentless widespread rains during the whole Fiji Day with blustery and gloomy wet conditions, there came upon the nation, a temporary clearance encroaching from the Western Division, with stars and even the moon clearly visible. High level altocumulus clouds heralded the increase in the atmospheric barometric pressure, with the barograph showing a rise – as the major trough of low pressure with associated cloud and rain bands moved over Tonga. Rain had ceased completely and the winds were dead calm.
Trees and shrubs were still as if we were in the eye of a tropical cyclone, waiting for a sudden change. By morning the sun came up with bright sunny clear conditions. Satellite pictures clearly showed that the nation was in the clear but lying between the significant weather system over Tonga and a much lesser significant cloud banding far west of us over New Caledonia and Vanuatu region, anchored to a surface low pressure system. It was thus expected to provide a brief period of bad weather as it passed over the nation later Tuesday. The Fiji Day rains over the two 24-hour successive periods from 9 am 9/10/16 to 9am 10/10/16, and 9 am 10/10/16 to 11/10/16 were as follows: Nadi Airport 15, 47mm, Lautoka 29, 39mm, Rarawai 23, 74mm, Penang 16, 37mm, Nausori Airport 32, 70mm, Suva 57, 20 mm, Navua 27, 65mm, Nacocolevu 31, 45mm, Monosavu 57, 58mm, Udu Point Trace, 26 mm, Savusavu 01, 54 mm, Dreketi 09, 75mm, Seaqaqa NIL, 65 mm, Labasa Airport NIL, 100mm, Viwa 31 , 38mm, Yasawa 77, 81mm, Vunisea 04, 50mm, Matuku 03 , 49 mm, Ono-i-Lau 64, 121mm, and Lakeba 01, 71mm. Though it meant disruptions to many sporting and pleasure events during October 9 and10, 2016; a time when people flock to the beaches and cool off on a Public Holiday on Monday – after a number of days of hectic celebration and feasting with family and friends; the general population would have welcomed the drought breaking rains. By 11.30am the sunny conditions over Fiji were slowly becoming subdued with high level cirrus from the west flowing onto the group, heralding the arrival of the lesser significant feature lying to the west of Fiji. Radar pictures, clearly showing the approaching rain bands, only 200 km west of Nadi Airport and Lautoka. It was expected to give widespread rains over Fiji again Tuesday afternoon, starting at around 1 to 2 PM with some squally conditions. It was expected that late night the weather would clear with fine sunny conditions over Fiji tomorrow.