Occasional snow flurries on the hills, frosts and cool
windy days all added to Dunedin reportedly experiencing its
coldest October in 63 years, hydrologist Dave Stewart says.
Normally, in October, Dunedin experiences regular rainfall,
but this year, a series of fronts were predominantly from the
southwesterly quarter and the following southerly winds
brought snow to the hills.
Those conditions resulted in generally below, to well-below,
average rainfall in most of Otago, with the rain's
effectiveness often cancelled out by the wind's drying
effects.
Rainfall was unusually low in the southern lakes area, with
the result that lake levels were very low for October, and
this was compounded by the main snow packs on the mountains
not beginning their melt period, as they usually do in
October, he said.
Farmers reported the month to be cold with little rain, which
did not help grass growth.
In North Otago, rainfall totals were below average and this,
combined with the colder than usual temperatures, resulted in
slower than usual grass growth for this time of the year.
Total falls at the indicator sites (average monthly totals in
brackets) were:
Waikoura 35mm (49mm) 30% below average; Oamaru Airport 32mm
(47mm) 32% below average; Oamaru Town 34mm (44mm) 21% below
average; Kauru, the Dasher 39mm (63mm) 39% below average;
Palmerston 32mm (49mm) 36% below average.
Significant falls were:
8th-9th, Waikoura 13mm, Oamaru Airport 14mm, The Dasher 13mm.
Average river flows were generally close to, or below, their
long-term averages.
The rain during the month was sufficient to hold flows close
to average for much of the month, he said.
In Central Otago, rainfall was generally close to average.
Total falls were:
Lindis Crossing 39mm (45mm) 15% below average; Cromwell 33mm
(39mm) 15% below average; Alexandra 32mm (25mm) 29% above
average; Ranfurly 34mm (40mm) 15% below average; Tima 46mm
(51mm) 11% below average.
Significant falls were:
8th, Lindis Crossing 11mm, Hills Creek 15mm; 16th, Cromwell
13mm, Tima 14mm.
Average monthly river flows were well below their long-term
averages.
River flows tended to decline from the beginning of October
to about the 17th but flows improved after that.
It was likely that snowmelt kept flows higher after that
until the end of October, Mr Stewart said.
In lakes Wanaka, Wakatipu and Hawea and surrounding areas
rainfall totals were generally quite low.
Total falls were:
Makarora Station 84mm (252mm) 67% below average; Glenfinnan
92mm (208mm) 55% below average; Hawea Flat 32mm (66mm) 52%
below average; Routeburn Station 119mm (246mm) 52% below
average; Queenstown 60mm (83mm) 27% below average.
Significant falls were: 1st-2nd, Makarora 26mm, Glenfinnan
28mm; 14th Makarora 22mm, Routeburn 16mm; 16th, Queenstown
26mm; and 21st , Routeburn 22mm.
Average monthly river flows were well below their long-term
averages.
Lakes Wanaka and Wakatipu began the month at 277.09m and
309.82m, 0.4m and 0.3m below average respectively.
Both declined slowly throughout the month to end October at
276.79m and 309.68m, 0.70m and 0.45m below average
respectively.
Lake Hawea began the month at 342.59m, 3.4m below full.
It slowly declined during the month as Contact Energy
released a limited amount of water for power generation
throughout the month.
The lake level was 342.30m at the end of October, 3.7m below
full.
In Strath Taieri, Lower Taieri and Dunedin below average
rainfalls were recorded.
Total falls were:
Garthmyl Middlemarch 33mm (49mm) 32% below average;
Musselburgh Dunedin 49mm (62mm) 21% below average; Lee Flat
59mm (65mm) 9% below average; Maungatua 53mm (71mm) 25% below
average; Dunedin Airport 40mm (57mm) 30% below average.
Other raingauge totals for October included Ross Creek 61mm
and Sullivans Dam 83mm.
The only notable falls included Pine Hill 11mm and
Musselburgh 10mm on October 28.
Average monthly river flows were well below their long-term
averages.
In South and West Otago rainfall totals were all below
average.
Total falls were:
Balclutha 45mm (60mm) 25% below average; Waikoikoi 64mm
(76mm) 15% below average; Slopedown 114mm (127.5mm) 10% below
average; Moa Flat 57mm (82mm) 31% below average; Clarks Flat
46mm (65mm) 29% below average.
Significant falls during the month were:
2nd-3rd, Balclutha 13mm, Slopedown 34mm; 25th-26th Slopedown
15mm, Moa Flat 15mm; and 28th, Slopedown 16mm.
Average monthly river flows were all well below average.
The Clutha was below average because of the below average
outflows from lakes Wanaka and Wakatipu and all other rivers
were below average, Mr Stewart said.
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