Tropical Storm Calvin bears down on Hawaii: Here's what to expect on Big Island and more

Tropical Storm Calvin, now downgraded from a hurricane, continued to churn across the Pacific Ocean toward Hawaii on Monday. The storm was forecast to hit or graze the Big Island of Hawaii by midweek, bringing the risk of strong winds, high surf and heavy rainfall, which could lead to flash flooding and mudslides, the Central Pacific Hurricane Center said.

A tropical storm watch has been issued for Hawaii County, which is the Big Island. A tropical storm watch means that tropical storm conditions are possible within the watch area within the next 36 to 48 hours.

As of Monday afternoon ET, Calvin had sustained wind speeds estimated at 50 mph, the hurricane center said. It was moving west at 20 mph and was 850 miles east of Hilo, Hawaii.

Flooding rain, rough surf likely

A flood watch has been issued from Tuesday evening through Wednesday afternoon for Maui and Hawaii counties, Hawaii News Now said.

According to the hurricane center, "from Tuesday night into Thursday, storm total rainfall amounts of 4-7 inches are possible along windward areas of the Big Island of Hawaii, with lower amounts (1-4 inches) expected elsewhere in the state."

The center added that ocean swells from Calvin "are likely to cause life-threatening surf along exposed east-facing shores."

Calvin had been a major hurricane

Calvin had been a major hurricane late last week, but lost much of its power as it moved across the cooler waters of the central Pacific Ocean over the past few days.

"Calvin will continue to struggle as it faces drier air and wind shear," Hawaii News Now said. "There will be slightly warmer ocean temperatures near the islands that may help Calvin stay as a tropical storm near Hawaii Island."

Calvin was the third hurricane of the Pacific hurricane season, following Adrian and Beatriz.

Up to 20 storms possible this year in the eastern Pacific

According to the preseason hurricane forecast from the National Oceanic and Atmospheric Administration, 14 to 20 named storms are expected in the eastern Pacific basin in 2023. Of those, seven to 11 are predicted to become hurricanes.

An average eastern Pacific hurricane season produces 15 named storms, of which eight are hurricanes, NOAA said.

With the strengthening El Niño, an active eastern Pacific hurricane season is likely, forecasters say. While El Niño tends to boost hurricane activity in the eastern Pacific, it usually has the opposite affect in the Atlantic.

Track Tropical Storm Calvin

Tropical Depression Don spins in the Atlantic

While Calvin zooms across the Pacific, Tropical Depression Don continued to spin in the Atlantic on Monday, the hurricane center said. The depression is forecast to meander around the central Atlantic Ocean and strengthen into a tropical storm over the next few days. It poses no threat to land at the present time.

Don is the fifth named storm to form this year in the Atlantic. So far, none of the storms have reached hurricane strength of 74 mph.

Storm warning: Hurricane season could turn 'hyperactive' amid unprecedented conditions, new outlook warns

This article originally appeared on USA TODAY: Tropical Storm Calvin eyes Hawaii, could bring problems to Big Island