City braces for heavy rain, winds
A small shift in the path of Tropical Cyclone Lusi may mean less rain for Christchurch than feared but more wind, says a forecaster.
However, authorities are preparing for the worst in case Lusi brings more gale-force winds and heavy rain for Christchurch residents still mopping up after last week's storm.
Christchurch City staff were checking storm drains, stop banks and preparing sandbags ahead of the expected heavy rain this weekend.
Forecasters say the remains of Tropical Cyclone Lusi could dump 60mm to 100mm of rain on Christchurch this Sunday.
The city is already saturated from last week's storm in which more than 80mm of rain fell on the city, forcing dozens of people from their homes. Up to 150mm fell in some parts of Banks Peninsula.
Christchurch mayor Lianne Dalziel said authorities were preparing for the "worst-case scenario" this weekend.
"We'd rather be over-prepared than under-prepared," she said.
"The city is treating this very very seriously. We regard ourselves as on very high alert."
Stormwater drains had already been checked and all response and welfare agencies would be meeting again tomorrow to make sure the city was ready.
Dalziel said she was personally encouraging people to check on their families, friends and neighbours before the storm hit to "make sure people aren't quietly sitting at home not knowing what to do".
Welfare centres in Mairehau, Fendalton, Woolston and New Brighton were "on standby" just in case, and sandbags would be available in "key locations", although those were yet to be determined.
Sandbags were effective for protecting "isolated" areas, such as garages and commercial shops, and for diverting water that was running down hills.
"[However] sandbags will not hold out the water that comes up through your floorboards. It will not hold water out that finds other ways to come into your house," Dalziel said.
WEAK LINKS IN STORMWATER
Council environment group acting general manager Terry Howes said there were a number of "weak links" in the city's stormwater system, but the council had "done all we can" to mitigate potential issues this weekend.
High tide was due to arrive at 5am on Sunday - before the storm was due to hit the city, meaning it should not have such a big impact this time, he said.
The forecast heavy rain was also not expected to cause further land subsidence at the site of a slip that damaged a Mobil-owned aviation fuel tank in Lyttelton last week, spilling 1500 litres of fuel into the harbour.
"The cliff-face is stable and should not cause us a great deal of concern," Howes said.
CHANGE IN STORM COULD MEAN HIGHER WINDS
MetService meteorologist Daniel Corbett said yesterday Lusi was lying east of Vanuatu with average winds from 119kmh to 157kmh. The system had potential to intensify further because of the warm tropical waters surrounding it, he said.
As of midday today, the storm has been upgraded to a category 3 cyclone and had begun tracking southwards towards New Zealand.
Blue Skies weather forecaster Tony Trewinnard said it was certain Lusi would hit New Zealand, bringing heavy rain and likely flooding to parts of the North Island.
"These systems are very small, very compact, very powerful, and like any small but powerful thing it only needs a small change in its movement or direction to have a very different outcome."
The widespread flooding that caused havoc in Christchurch last week was caused by a different kind of weather event, but people should also make preparations for Lusi, he said. "This storm has the potential to have similar outcomes to last time."
Since yesterday, the projected track of the storm had changed and Trewinnard said it seemed it would now further westward than earlier predicted.
"This is looking somewhat better than we had yesterday."
Yesterday Trewinnard said 40 to 60mm of rain could hit Canterbury, but today he said that looked more likely to be 30 to 40mm.
But because of the change in track, he said the storm could bring higher winds to the region.
"People do still need to be taking it seriously. It's a weather system that needs to be treated with respect."
He expected rain to arrive in Canterbury late on Saturday night, with the heaviest rains on Sunday afternoon. Strong winds around midday Sunday could get towards gale-force strength.
Trewinnard said the changes to the storm would bring more rain than previously predicted to Nelson, Tasman and Golden Bay.
Christchurch City Council civil defence emergency manager Murray Sinclair said authorities were more prepared after last week's storm, but were worried about the potential for more damage.
He said he wanted an emergency operations centre ready on Saturday in case the storm did reach Canterbury.
"We're worried if it does come. We don't want to get caught."
Sinclair said more heavy rain could cause further land movement in vulnerable hillside areas and geotechnical engineers were "elevating" their monitoring of such areas.
Councillors and community board members were briefed by Civil Defence this morning, and more information from engineers would be discussed later today.
The CCC is also liaising with the Army and volunteer groups to secure extra resources, should an emergency response be required.
Diane Shannon's Carrick St house flooded last Wednesday.
Shannon said there was not much she could do if Lusi brought more heavy rain to Christchurch this weekend. "Everything is so wet at the moment. If we have another lot of heavy rain now, it's going to flood very quickly."
The fire service received almost 450 weather-related calls for help during last week's flooding.Fire Service Canterbury area manager David Berry said firefighters were always organised for major events and were keeping in touch with Civil Defence.
- Council engineers are prioritising areas where sandbags might be used to address localised flooding, including areas in Lyttelton where there were landslips last week.
Sandbags would not be effective for houses where flood waters came through the floorboards. Residents could call the council if they thought sandbags would help address a specific flood issue.
- Council staff have been clearing drains and waterways this week. Known flood areas will be checked again today and over the weekend to ensure the waterways are kept clear when the rain starts.
- Roads known to be affected by surface flooding will be closed early, and council crews will staff some closures. Bow waves caused by vehicles can make residential flooding worse.
- Engineers are assessing stopbanks to ensure they are ready for heavy rainfall.
- Locals are advised to protect their health should flooding occur. Wastewater is likely to mix with flood waters, so people should avoid contact with flood water or should wash their hands and clothes after coming into contact with the water.