Shotover Jet operations manager Simon Thew deals with ice
which clogged the river in 2007. This year has not been as
bad, but consistent frosts caused the river to partially
freeze to a slurry last week. Photo by Chris Morris.
Having had to cancel a day of operations last week
because of a "Margarita... slurry" of ice in the Shotover
River, Shotover Jet general manager Clark Scott said the
problem was not as bad as two years ago.
"The last time it froze was two years ago and we lost 11 days
over the winter," he said.
This winter is proving slightly colder than average -
temperatures were 0.8degC down for June, Queenstown weather
forecaster David Crow said.
However, frosts had not been severe enough to freeze the
Shotover River completely or form chunks of ice, which
pleased Mr Scott.
He said he was surprised there had not been more ice as the
river flows were lower than during the winter of 2007 when
"almost tabletop-sized" chunks of ice disrupted the company's
operations.
Leading into the winter, the company had been concerned about
the possibility of it happening again, but realised "you
can't beat Mother Nature".
Having cancelled trips last Wednesday, Mr Scott said an
inversion layer that night had warmed the water slightly and
the boats returned to the river the next day.
Throughout June, Queenstown experienced the second-lowest
average minimum air temperature since records began in 1871,
at minus 2.1degC, but Mr Crow said there had not been severe
frosts in Queenstown - just consistent ones.
The coldest ground frost on record was -13.4degC in 1953.
"We have had nothing in double figures this year [in
Queenstown]," Mr Crow said.
However, Arrowtown, which is often colder than Queenstown,
experienced a -14degC frost last week.
Mr Crow said a factor to consider with the freezing in the
Shotover River was the low river levels caused by a very dry
June and start to July.
Only 11.5mm of rain fell during June - well below the 67mm
average.
Until this week's rain, July had been even drier with only
1.9mm falling in the first 20 days of the month, Mr Crow
said.
Mr Scott was confident the onset of rain would raise the
Shotover River's flow levels and temperature, allaying
further concerns about the river freezing.
A name, residential address, and (preferably residential) telephone number is required from readers who comment on ODT Online. These details will not be visible to site visitors.