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Drought in Hawaii is fueling rare November wildfire concerns

Nearly a third of the island chain is facing at least moderate drought

The U.S. Drought Monitor's current outlook for Hawaii. (U.S. Drought Monitor) (U.S. Drought Monitor)

You don’t often expect to hear “Hawaii” and “fire danger” in the same sentence, but wildfire concerns have been very real in the Aloha State in recent days. An ongoing drought is dehydrating the landscape, with noticeable effects on agriculture and ecosystems.

More than half of Hawaii is currently experiencing abnormally dry conditions, with 30 percent facing a moderate or worse drought. That’s according to the federal government’s Drought Monitor, which provides detailed synopses of drought intensity and impacts across the United States each week.

More than 80 percent of the U.S. is facing troubling dry conditions

The Drought Monitor even warns that, in the few isolated locales entrenched in extreme drought, “feral donkeys move into populated areas” and “trees are dry and dropping leaves.” That further exacerbates the wildfire risk, something the local National Weather Service office in Honolulu is growing increasingly concerned about.

“A combination of strong winds, low relative humidity, and warm temperatures can contribute to extreme fire behavior,” it cautioned Monday, having issued a red-flag warning. Such warnings don’t predict the ignition of wildfires, but rather convey that any sparks can quickly grow into raging infernos.

The red-flag warning in effect Monday was the first in Hawaii in November since 2012.

Red-flag warnings are more commonly issued in the late summer months of August and September, when the landscape tends to become moisture-starved after the summer dry season.

According to the Hawaii Wildfire Management Organization, “0.5 percent of Hawaii’s total land area burns each year, equal to or greater than the proportion burned of any other U.S. state.”

Autumn rains ordinarily bring an end to the summer dry season, but they have been unreliable this year. Only 0.09 inches of rain has come down so far in November in Honolulu, roughly an inch and a half behind average, and October only got half its normal rainfall.

Since the start of the year, Honolulu has picked up 9.8 inches, compared with an average of 13.6; while representing a 28 percent deficit, it’s nowhere near as bad as 1998, when only 3.34 inches had fallen through mid- to late November.

Temperatures are also at their peak during the late summer, which means the greatest amount of evaporation. That desiccates the landscape, with rapid drying ensuing between late July and the start of October. The drought peaked in early September this year, when 94 percent of the state was affected.

The rainfall deficit “kind of goes back to last wet season,” explained John Bravender, warning coordination meteorologist at the National Weather Service in Honolulu. “We had a really wet December that wiped out all out drought, then January, it all just went dry.”

A string of quiet Pacific hurricane seasons, balanced out by a busy Atlantic, limited the amount of moisture streaming north toward Hawaii through the summer.

Much of Hawaii remained in drought until late October when beneficial rains arrived. But dry weather has since returned.

“In the wake of drought-easing rainfall, Hawaii turned somewhat drier amid a predominantly trade-wind regime,” wrote the Drought Monitor. “As a result, no further improvement was noted in Hawaii, following 9 consecutive weeks with a reduction in drought coverage.”

The dearth of rainfall this year has led to low relative humidity, at times dropping below 45 percent. While 45 percent is humid by California standards, it’s quite dry on a tropical island chain like Hawaii situated at about 20 degrees north latitude. In recent days, a strong clockwise-spinning high pressure system north of the archipelago has been swirling dry air southward, while also leading to gusty winds.

Beyond the obvious issues of wildfire risk, the ongoing drought is having agricultural and ecosystem impacts too. In August, about 8 percent of Maui was listed as being in “exceptional” drought — the highest tier.

SFGate.com, an online news publisher in San Francisco, reported that the lack of rain and past pineapple farming practices in the mountains of western Maui have made it harder to retain and conserve water affecting reservoir levels and ranchers.

On Molokai and Maui, wild deer have been encroaching into farmland and competing with livestock for resources in part because of the dry conditions. Donkeys are also wandering into populated areas.

“Despite ongoing efforts, the axis deer population has grown to approximately 60,000 or more, which cannot be sustained by the environment in Maui County,” read a proclamation from Hawaii governor David Ige (D) released on Nov. 18. This is the governor’s fifth consecutive proclamation pertaining to the deer crisis, with special measures remaining in effect until Jan. 17.

“This includes corralling of axis deer, culling of the deer to sustainable levels, clearing vegetation along fence lines, and erecting and/or reinforcing fence lines to keep axis deer away from roadways, airports, and runways,” the document said.

The National Weather Service’s Climate Prediction Center winter outlook does call for gradual improvement in the state’s drought conditions.

“We’re hoping for some improvements,” said Bravender. “The wild card is where that above-normal rainfall will occur. Especially with La Niña patterns, there’s more uncertainty. If it’s a stronger event, then that tends to have more trade winds, which would focus that rainfall more across the windward parts of the islands. If it’s weaker, we might see the trade winds break down, as is typical during the wintertime, and get more rainfall on the leeward sides. Right now it’s the leeward sides that really need it.”

Hawaii joins large parts of the Lower 48 that are also currently experiencing considerable drought. The Drought Monitor’s Nov. 15 update showed 82 percent of the contiguous United States dealing with abnormally dry or drought conditions — near the highest percentage on record (85 percent on Nov. 1 of this year).

A July study in the Journal of Climate noted that drought conditions in Hawaii, which have prevailed for much of the past decade, are among the most severe on record. It was unable to link the drought to long-term climate change, however, as computer models evaluating its drivers were unable to detect a human influence.

“[N]ot every event has an apparent and simple ‘first cause’ — natural weather mechanisms are demonstrated to be powerful in yielding extreme events and trends over considerable periods,” wrote the Climate Program Office of the National Oceanic and Atmospheric Administration in a news release.

The U.S. government’s fourth National Climate Assessment, published in 2018, cautioned that in the future rising temperatures will increase the risk of extreme drought and flooding in Pacific island communities.

Jason Samenow contributed to this report.

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