‘Bomb’ Low brings Wind, Rain & Cold

January 16, 2017

Last weekend New Zealand continued in the southwest weather pattern that has lingered around since December. This means that the South Island west coast got most of the rain at the weekend while parched regions in the north and east hardly saw a drop.

Many areas in the east and north will have fine weather for the next couple of days, with 28C forecast for Tauranga and 29C for Christchurch on Tuesday. However, on Wednesday there is a rapidly deepening low approaching from the west.

“This low is set to undergo a process called ‘explosive cyclogenesis’ by meteorologists.  This means the low will deepen very rapidly in a short time.  When a low has an intensification (a change in central pressure) which exceeds a certain amount in 24 hours it can be defined as a ‘bomb’ low,” said Communications Meteorologist Lisa Murray. “This low meets the ‘bomb’ criteria and is forecast to bring damaging winds to exposed parts of the South Island and lower North Island, and extremely heavy rain to the South Island west coast later Wednesday,” she adds.

“It is important that people realise that although there has been heavy rain in these areas recently, this low brings large accumulations of rain, up to 300mm in 24 hours for some of the ranges, which could cause widespread flooding, slips and damage to roads.  Rivers and streams will rise rapidly, including those in Canterbury that feed from the Alps” advises Ms. Murray, “This event will especially impact anyone in the mountains, river users, tourists and those traveling on the roads.”


As the low moves off the country to the east on Thursday it drags up an unseasonably cold southwest flow from the south causing overnight temperatures on Thursday and Friday to plummet back to single digits, with some areas dropping to 4 degrees.

Official Severe Weather Watches and Warnings are reviewed and re-issued by MetService at least every twelve hours, and more often if necessary. To get the most up to date information on severe weather around the country, or any other forecasts, see metservice.com or on mobile devices at m.metservice.com. You can also follow our updates on MetService TV, at MetService New Zealand on Facebook@metservice  and @MetServiceWARN on Twitter and at blog.metservice.com

To learn more about rapidly deepening lows please go to our blog at http://blog.metservice.com/BombLow2012


MetService issues Warnings, Watches and Outlooks for severe weather over New Zealand.

Warnings are about taking action when severe weather is imminent or is occurring. They are issued only when required.
Recommendation: ACT 

Watches are about being alert when severe weather is possible, but not sufficiently imminent or certain for a Warning to be issued. They are issued only when required.
Recommendation: BE READY 

Outlooks are about looking ahead, providing advance information on possible future Watches and/or Warnings. They are issued routinely once or twice a day.
Recommendation: PLAN 

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