New Zealand's worsening drought

Where I am living in Wellington, there has been 5mm of rain so far this month. The average for January is 70m.

Arthur's Pass fire takes hold

Fire crews are battling to gain the upper hand against a 300-hectare blaze in South Island high country near Arthur's Pass.

Radio NZ,

27 January, 2015

The blaze started on the Flock Hill station by the Craigieburn cutting about 2.30pm yesterday and by this morning had burned through more than 300 hectares.

Helicopters dropping water from monsoon buckets, and planes dropping fire retardant are battling the blaze from the skies for a second day.

Listen to more from reporter Patrick Phelps at the scene ( 4 min 12 esc )

An evacuation plan for people living in Castle Hill village had been put together in case north-west winds flared up but at this stage a southerly was forecast.

Listen to Craig Alexander on Morning Report ( 4 min 30 esc )

Department of Conservation (DOC) fire spokesperson Craig Alexander said the fire was still not under control.

"We've had a huge number of fires across the region so far this year, exceeding numbers for other years, so it's just been a matter of time before something like this happened."

He said water resources were limited in the area and many streams had dried up.

"Yesterday was a bit like chasing a rampaging bull, it was moving from one direction to the other," said Mr Alexander.

Mr Alexander said conditions were less extreme than yesterday, with cooler temperatures forecast.

"With the air support and other resources being brought in today hopefully we can get it under control."

Seven helicopters and four planes were being used today to douse the fire.

Six to eight crews were on their way from as far afield as Franz Joseph and Timaru, to help the 25 firefighters from DOC, the Fire Service, Selwyn District Council and crews.

The fire is not expected to be under control until tonight at the earliest, DOC says, and could take another two to three days to fully put out.

Parched scrub

The area has been hot and dry for months, leaving parched manuka, matagouri, and gorse scrub, along with massive areas of pine and beech forests.

Yesterday changing winds pushed the fire from one direction to the other, making it difficult to contain.

State Highway 73 was closed at times, causing big delays for drivers travelling between Canterbury and the West Coast. Vehicles were being escorted through by roading contractors overnight.

Sheep were moved to safety yesterday and the Fire Service was dipping monsoon buckets in nearby Lake Pearson to help extinguish the fire. The focus was on preventing the flames from reaching beech trees in Craigieburn Forest Park.

Conditions at Flock Hill were expected to be less extreme today.

NIWA’s Hotspot Watch 23/1/15

Scoop

23 January, 2015

Weekly update to help media assess likelihood of extremely dry weather preceding a drought. Regions experiencing severely to extremely drier than normal soils conditions are deemed hotspots.Friday, 23 January 2015

NIWA’s Hotspot Watch

Weekly update to help media assess likelihood of extremely dry weather preceding a drought. Regions experiencing severely to extremely drier than normal soils conditions are deemed “hotspots”.

Facts: Soil Moisture

For the North Island, except for coastal areas of the Bay of Plenty and far northern Gisborne regions, nearly all of the island is experiencing much drier to severely drier than normal soils for this time of the year. Moreover, extremely drier than normal soils for this time of the year are present over much of the southeast part of the island from southern Gisborne to Hawke’s Bay and Wellington regions. Extremely drier than normal soils for this time of year also exist over much of the Waikato as well as parts of the Manawatu-Wanganui, Auckland and Northland regions.

For the South Island, severely to extremely drier than normal soil moisture levels for this time of year continue for the northern and interior sections of Otago as well as most of Canterbury, in particular central and southern Canterbury. Much drier than normal to severely drier than normal soils for this time of year are evident for much of the far northern part of the island from the eastern Tasman to Marlborough regions. Additionally, much drier than normal soils for this time of year exist over southern Southland, near and just northwest of Invercargill. Conversely, soils are wetter to much wetter than normal for this time of the year west of the Divide from Fiordland north to near Greymouth.

Week-to-Week Comparison

When compared to this time last week widespread dryness continues to cover the majority of New Zealand. For the North Island, it’s clear that soil moisture levels have continued to decrease over most, if not all, of the entire island. Furthermore, the coverage of severely drier to extremely drier than normal soils for this time of year has increased.

For the South Island, pockets of showers and thunderstorms were able to provide for some slight to modest soil moisture gains over central and southern Otago as well as parts of the Canterbury and eastern Marlborough regions. Soil moisture levels have decreased compared to this time last week from far northwest Canterbury through to southern Marlborough, to much of the Tasman and Nelson regions.

Commentary

For the North Island, when considering the current soil moisture anomalies for this time of year, hotspots include most of the eastern part of the island from near East Cape southwest to the Kapiti Coast, as well as much of the central and western Waikato, along with sizeable portions of the Auckland and Northland regions. Southern and far north sections of the Manawatu-Wanganui region are also hotspots.

Computer models are predicting little, or no rain, through to early next week for nearly the whole of the island. As a result, it’s distinctly possible that some hotspot areas will continue to expand. Thereafter, in about 4-5 days, model guidance is suggesting the potential for some meaningful rain for parts of the east coast of the island, in particular from Gisborne to the South Wairarapa. If this were to occur, the hotspot size in this region may decrease.

For the South Island, hotspots exist throughout much of Canterbury and northern and interior sections of Otago. Continued dryness has brought about a new hotspot area from the far eastern Tasman region west and south to Marlborough. Farther south, parts of Southland have continued to dry out over the past 1-2 weeks and will need to be monitored for possible hotspot development.

While there has been a decrease in hotspot coverage over the eastern part of the island, it’s questionable if the benefits from some rain earlier this week will persist as widespread dryness is forecast to persist through early next week for much of the island. Thereafter, model guidance indicates the potential of only patchy areas of rainfall beyond 4-5 days.

For hotspot regions, sustained rainfall over an extended period of time is needed to return conditions back to normal. Additionally, if current conditions persist or worsen, then drought conditions may be imminent.

Background:

Hotspot Watch a weekly advisory service for New Zealand media. It provides soil moisture and precipitation measurements around the country to help assess whether extremely dry conditions are imminent.

Soil moisture deficit: the amount of water needed to bring the soil moisture content back to field capacity, which is the maximum amount of water the soil can old.

Soil moisture anomaly: the difference between the historical normal soil moisture deficit (or surplus) for a given time of year and actual soil moisture deficits.

Definitions: “Extremely” and “severely” dry soils are based on a combination of the current soil moisture status and the difference from normal soil moisture (see soil moisture maps at https://www.niwa.co.nz/climate/nz-drought-monitor/droughtindicatormaps)

Pictured below: Soil Moisture Anomaly Maps, relative to this time of year. On the left are values this time last week. On the right are the most recent values.

 

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