Hurricane Lane is barreling toward the Hawaiian Islands as a Category 4 storm as of Tuesday (Aug. 21, 2018).

Updated on Wednesday, Aug. 22, at 2:30 p.m. ET

Hawaii is bracing for a Category 4 hurricane, with high winds forecast to hit the Big Island as early as this afternoon.

Yesterday (Aug. 21), Hurricane Lane was bumped up to a Category 5 storm — the highest ranking assigned to a storm based on wind speeds and expected damage. [Hurricane Season 2018: How Long It Lasts and What to Expect] Today, it was downgraded back to a Category 4.

A hurricane warning is in place for Hawaii County on the Big Island and Maui County, while a hurricane watch is in effect over Kauai County and all of Oahu, according to the National Weather Service. All of Hawaii is under a flash flood watch.

The storm is currently southeast of the Hawaiian Islands and is expected to turn northwest and pass the south-southeastern part of the Big Island tonight (Aug. 22). Damaging winds from the storm could hit the Big Island as early as this afternoon. But the center of the storm, carrying maximum winds of around 155 mph (250 km/h), is expected to move "dangerously close" to the main Hawaiian Islands Thursday through Saturday (Aug. 23 to Aug. 25), according to the National Oceanic and Atmospheric Administration (NOAA).

Over 20 inches (50 centimeters) of rainfall — as well as flooding, tornadoes and high surf — are possible, according to NOAA.

"Hurricane Lane is not a well-behaved hurricane," Hawaii Gov. David Ige said in a statement. "I've not seen such dramatic changes in the forecast track as I've seen with this storm. I urge our residents and visitors to take this threat seriously and prepare for a significant impact."

In anticipation of the storm, Ige signed an emergency proclamation that declares certain counties of Hawaii disaster areas and allows for the spending of state money for quick and efficient relief for damages, loss and suffering.

Residents can find information about how to prepare here.

Editor's Note: This story was updated. As of 2 pm ET, Hurricane Lane has weakened to a Category 4 storm and a hurricane warning was also added for Maui county and a watch was added for Kauai County.

Originally published on Live Science.