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Blizzard predicted to plaster Hawaii’s high peaks amid major storm

A flood watch covers the lower elevations where several inches of rain could fall from a “Kona low”

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While the Lower 48 states bask in unusual warmth, the towering peaks on Hawaii’s Big Island are bracing for a bitter blast of snow and wind. A major storm system is poised to develop west of the Hawaiian islands and stall, unleashing a foot of snow and 100 mph winds on its tallest mountain summits. Flooding rains are anticipated at lower elevations.

The National Weather Service has issued a blizzard warning for the Big Island summits starting 6 p.m. Friday local time and continuing through 6 a.m. Sunday.

“Travel could be very difficult to impossible,” the Weather Service writes. “Blowing snow will significantly reduce visibility at times, with periods of zero visibility.”

This warning only applies to the peaks of Mauna Loa and Mauna Kea, mountains that, respectively, reach 13,679 and 13,803 feet in elevation. In most other parts of Hawaii, including the beaches, only rain is expected, with temperatures in the 60s and 70s.

Snow is not at all uncommon on Mauna Loa and Mauna Kea; most years, it snows at least a few times on these summits. Memorably, they were blanketed on Christmas in 2014. In 2016, it even snowed on Mauna Kea in mid-June.

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It snows enough on Mauna Kea that skiing is sometimes an option, as long as you’re willing to use a four-wheel-drive car as your lift.

Blizzard conditions, however, aren’t as typical. Before this week, the Weather Service last issued a blizzard warning in Hawaii in 2018.

The snow is coming to the 50th state when there is hardly any to be found in the Lower 48. Just 6 percent of the contiguous United States is covered in snow as of Friday, the lowest extent in nearly two decades of records.

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Stormy weather in Hawaii often coincides with tranquil conditions over the Lower 48 states because it means the jet stream, along which storms track, is dipping over the northeastern Pacific Ocean but bulging over the western United States, bringing warm, dry conditions.

When it snowed in Hawaii on Christmas in 2014, it was mostly mild in the Lower 48, with abnormally low snow cover, just like this year.

‘Kona low’ behind the stormy weather

The culprit for the Hawaiian snow is a powerful system known as a “Kona low” or “Kona storm.” The zones of low pressure derive their name from a word meaning “leeward,” referring to the direction their winds come from. Some years may pass without a single storm, while other winters may feature up to four or five, according to the Western Regional Climate Center.

Prevailing winds over the islands are usually out of the east and northeast, but Kona lows draw in winds from the southwest, tapping abundant moisture.

This particular Kona low is predicted to be slow-moving, forming west of Kauai over the weekend and lingering into early next week.

Flood watches are in effect on all of the islands, due to the potential for “excessive rainfall,” according to the Weather Service.

“Significant flooding may occur due to the overflow of streams and drainages,” the Weather Service writes. “Roads in several areas may be closed, along with property damage in urban or low lying spots due to runoff. Landslides may also occur in areas with steep terrain.”

Computer models show the potential for at least several inches of rain over all of the islands through the middle of next week and even double-digit totals in some areas. The heaviest amounts are generally predicted on Oahu. Windward facing mountain slopes will be most prone to flooding and mudslides.

Despite the flooding potential, the days of rainfall will be potentially beneficial due to widespread drought in Hawaii. More than half of the state is dealing with drought conditions, with the most severe conditions over Maui and Molokai.