March 1986: A sunny month, especially over the North Island. Southerlies prevailed over the north of the North Island, with fewer strong winds than usual. The frequency of southeasterlies was the 2nd highest since records began in 1956. West to northwesterlies prevailed over the south of the South Island, where strong winds were less frequent than usual. Mean sea level pressures were 1hPa above average in the north of the North Island, and up to 3hPa above in the South Island. On the 12th and 13th, an almost stationary depression had developed in the Tasman Sea, and a convergent easterly airstream affected the Canterbury region. Rainfall was heaviest in parts of South Canterbury, where serious flooding resulted. 114mm was recorded at Timaru Airport in the 24 hours to 9am on the 13th. Many roads were scoured and the main trunk line was undermined in many places. About 50 bridges were partly washed away or seriously damaged. The worst affected township was Pleasant Point, where 1200 people were evacuated as the Tengawai River burst its banks and water up to 1.5m deep flooded the town. There were major stock losses, and the total damage has been estimated to have cost $39 million. Fogs caused morning closures at 7 airports on the 15th.
Rainfall: Rainfall was below average in the North Island, apart from in Wairarapa and Wellington. Only 16mm (12% of average) was recorded at Whangarei, and 12mm (18%) at Taupo Airport. 188mm (247% of normal) was recorded at Waingawa, Masterton. In the South Island it was drier than average in Nelson and on the West Coast north of Hokitika, with totals of 50-70% of average. On then east coast from Cape Campbell to Dunedin, monthly totals were much higher than average, with a record high of 187mm (328% of normal) at Timaru Airport, records from 1956. The whole of Canterbury received over 200% of average, due mainly to the heavy rainfall on the 12th and 13th. A thunderstorm on the evening of the 12th affected the whole of the Dannevirke Power Board region from Norsewood to Woodville. During the afternoon and evening of the 13th, thunderstorms and heavy rain produced surface flooding in Masterton. 122mm was recorded in the 24 hours to 9am on the 14th, a record there for March.
Some totals (mm): Peel Forest 263, Christchurch 218, Waimate 192; Cape Reinga 16, Palmerston North 18, Taihape 26.
Temperatures: Over most of the North Island temperatures were between 0.5C below normal and near normal for March. In the South Island temperatures were about 1C below average in Marlborough and 1C above in Central Otago. Elsewhere they were near normal.
29.0C maximum at Te Teko on the 14th,
-2.0C minimum at Waiouru on the 30th.
Sunshine: March was a particularly sunny month over much of the country. Record high monthly hours were recorded in many western North Island locations from Taranaki to Auckland, where totals were 120-140% of average. Sunshine hours were slightly below average in Otago and Southland. Some of the greatest departures from normal were (start of record, total, departure, rank): Auckland City 1962, 246 hours, +66, highest; Auckland Airport 1969, 259 hours, +77, highest; New Plymouth Airport 1972, 262 hours, +68, highest; Stratford 1963, 231 hours, +58, 2nd highest; Levin 1956, 218 hours, +52, 3rd highest.
[Some totals: Kaitaia 233, Waitangi 244, Whangarei 233, Leigh 225, Tauranga 222, Whakatane 228, Rotorua 225, Taupo 222, Auckland Aero 259, Hamilton 244, New Plymouth 262, Masterton 197, Dannevirke 182, Gisborne 214, Napier 212, Wairoa 209, Paraparaumu 244, Ohakea 227, Palmerston North 196, Levin 218, Wellington 221, Stratford 231, Wanganui 226, Takaka 223, Westport 168, Arapito 183, Hokitika 180, Greymouth 175, Nelson 248, Blenheim 234, Grassmere 203, Kaikoura 183, Mt Cook 116, Methven 167, Christchurch 192, Timaru 156, Palmerston 124, Dunedin Aero 136, Dunedin 131, Te Anau 139, Queenstown 185, Cromwell 197, Alexandra 175, Gore 151, Invercargill 121]
Sources: NZ Met. Misc. pub. 107 (Climatological table, NZ Gazette) and NZ Met. Misc. pub. 109 (Meteorological Observations).
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April 21, 2012, 12:58:35 PM