Rare Pacific hurricane expected to bring rain to California and Oregon

PORTLAND, Ore. (KOIN) -- Tropical Storm Hilary is growing in strength and size over the warm waters of the Pacific Ocean. Not yet a hurricane, models show it could reach category three strength hurricane by Friday.

Warm ocean waters are what fuel the growth and development of any hurricane, but Pacific waters are usually colder than the Atlantic. That's why the Atlantic hurricane season is typically sees stronger and more frequent hurricane activity than the Pacific.

This year, Pacific waters are much warmer thanks to the development of El Niño. Those warmer sea surface temperatures will help strengthen Tropical Storm Hilary into a hurricane in the coming days.

Thankfully, cooler sea surface temperatures off the shore of the Baja California Peninsula will help rapidly weaken the storm. Forecast models are predicting a weakening trend from a category three storm with winds of 111-129 mph to a category one hurricane with winds of 74-95 mph within a matter of a day. From there, cooler water will continue to weaken the storm to a post-tropical cyclone. This is more typical of a regular storm that moves into the west coast states with very little tropical characteristics left. However, strong winds and heavy rain is still likely at this stage.

Cooler temperatures, increased cloud coverage, and wet weather east of the Cascades will be the impacts felt from Hilary. These soaking rains and cooler temperatures should help the wildfire potential greatly in California and eastern Oregon and Washington. Very little rain is expected to impact the western half of Oregon and Washington next week. A few light sprinkles with cooler temperatures will be the biggest impacts felt.