Four tropical cyclones are swirling in the Pacific Ocean this week, at least one of which is a significant threat to land. Hector's expected to slide past Hawaii, but Typhoon Shanshan is approaching Japan and may cause flooding.

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Four tropical cyclones are swirling in the Pacific Ocean this week, at least one of which is a significant threat to land.

The most interesting of these is Hurricane Hector, which on Monday had a maximum wind speed just 1 mph short of Category 5. The storm is east of Hawaii and tracking west, but is expected to slide just south of the island chain Wednesday and Thursday. Forecasters are cautiously optimistic, but note that slight changes in Hector’s track could put Hawaii at greater risk.

Only 25 of 1,007 named storms in the eastern Pacific since 1949 have matched or surpassed Hector’s strength, according to Michael Lowry, a strategic planner at FEMA and formerly a meteorologist for the Weather Channel.

“A textbook hurricane in the upper echelon of historical storms,” Lowry wrote in a tweet Tuesday.

A hurricane hasn’t made landfall in Hawaii since 1992, when Iniki ravaged Kauai. That Category 4 hurricane generated an enormous storm surge that left water marks as high as 22 feet on the island, according to NOAA. The 145-mph wind stripped leaves and branches from trees. NOAA’s damage survey team found “few buildings” that avoided impact. Iniki is still the most destructive hurricane to hit Hawaii since the beginning of the 20th century.

Despite being in the riskiest location, the Big Island has not been struck by a hurricane since modern records have been kept. A hurricane in 1871 probably made landfall on Hawaii, north of Hilo. After that, only weaker systems – tropical depressions and storms – have hit the Big Island, although there have been several close calls.

On the other side of the Pacific, Typhoon Shanshan is approaching Japan with maximum winds around 100 mph. The Joint Typhoon Warning Center expects the center of the storm to reach northeast Japan on Wednesday afternoon, local time.

Even if the eye does not cross onto land, torrential rain will cause flash flooding and landslides in the mountainous terrain. More than a foot of rain is possible over 48 hours.

Shanshan will turn northeast away from Japan on Thursday.

Closer to the U.S. mainland, Hurricane John is strengthening in bathlike ocean water south of the Baja Peninsula. On Tuesday morning, John had maximum winds around 105 mph, making it a Category 2. Forecasters at the National Hurricane Center expect those to strengthen to 120 mph, or Category 3, Wednesday morning.

“The dangerous core of John is forecast to remain well offshore of the Baja California Peninsula,” forecasters wrote Tuesday. “However, an eastward shift of the forecast track or an unexpected increase in the size of the outer wind field of the hurricane could bring tropical-storm-force winds to portions of the west coast of the peninsula.”

The last – and weakest – cyclone in the Pacific is Tropical Storm Kristy, which is no threat to land. Kristy is spinning alone, several hundred miles west of Hurricane John, and will drift north over the next several days. National Hurricane Center forecasters predict that it will reach Category 1 status, which will make it the sixth hurricane in the eastern Pacific Ocean this year.