SAN FRANCISCO -- Hurricane Hilary is heading towards Baja California, and it could bring heavy rain to the southwestern U.S. by the weekend. There will be a threat of flooding rains across Southern California from Sunday through Tuesday. The U.S. National Hurricane Center said a tropical storm watch has been issued for Southern California, the first time that has ever been done.
The video in the player above is from a previous report.
Hurricane Hilary has been downgraded to a Category 1 hurricane from a Category 2 Saturday evening as evacuations in at-risk areas continue to be issued, according to ABC News.
Tropical storm warnings are in effect for more than 42 million Americans in Southern California, as Hilary is expected to be the first storm of its kind to hit the region since Nora in 1997.
Hilary is currently a category 1 hurricane with sustained winds up to 90 mph.
Sources tell ABC News that the center of Hilary is located roughly 175 miles southeast of Punta Eugenia, Mexico, and 535 miles south-southeast of San Diego.
Rain will start to reach the southern regions of California and Arizona later Saturday and continue into Monday.
Flood watches are in effect from Southern California and Arizona to Oregon and Idaho.
California Governor Gavin Newsom declared a state of emergency for much of Southern California on Saturday ahead of Hurricane Hilary making landfall, ABC News reported.
"California has thousands of people on the ground working hand-in-hand with federal and local personnel to support communities in Hurricane Hilary's path with resources, equipment and expertise," the governor said in a statement.
There are currently "more than 7,500 boots on the ground deployed" to help local communities the governor's statement continued.
The impacts of the storm are expected to begin Saturday evening lasting through Monday, according to the statement.
VIDEO: Officials give update on CA's Hurricane Hilary response, preparedness efforts
Officials as far north as Los Angeles scrambled to get the homeless off the streets, set up shelters and prepare for evacuations.
Hilary is expected to plow into Mexico's Baja peninsula on Saturday night.
Hurricane Hilary "has sped up a bit, along with a slight shift eastward in its track," as it gained speed, moving toward Baja California, according to the National Weather Service Saturday morning. "This results in Sunday morning through Sunday evening being the time frame of most impact, along with slightly weaker winds."
Early on Saturday, the storm was centered about 235 miles (375 kilometers) west of the southern tip of the Baja peninsula. It was moving north-northwest at 16 mph (26 kph) and was expected to turn more toward the north and pick up speed.
The latest forecast track pointed to Hilary making landfall along a sparsely populated area of the Baja peninsula at a point about 200 miles (330 kilometers) south of the Pacific port city of Ensenada.
It is then expected to continue northward up the peninsula, raising fears that its heavy rains could cause dangerous flooding in the border city of Tijuana, where many homes in the city of 1.9 million cling precariously to steep hillsides.
Hilary will rapidly weaken as it enters cooler ocean waters and interacts with the mountain terrain of Baja California Sunday.
The current track has Hilary moving into Southern California late Sunday into Monday as a tropical storm. Life-threatening and potentially catastrophic flooding is possible. For the first time ever, Tropical Storm Warnings have gone up for Southern California.
No tropical storm has made landfall in Southern California since Sept. 25, 1939, according to the National Weather Service.
Hurricanes require ocean temperatures above 80 degrees to survive. Hilary is currently sitting in 85-degree water and will remain in those warm waters through Saturday. As Hilary moves closer to Baja California, ocean temperatures will quickly cool into the 70s and eventually the 60s along the California coast.
That temperature drop may not seem like a lot but ocean temperatures in the 70s will essentially kill Hilary and water in the 60s will never support a tropical system. Thus, we see a very rapid weakening as the system approaches the California-Mexico border.
HEAVY RAIN THREAT IN SOCAL
The moisture from Hilary will bring the possibility of excessive flooding in Southern California.
The National Weather Service issued a flood watch that will be in effect starting at 11am tomorrow through Monday evening across San Diego and Los Angeles counties. Rainfall amounts of 3 to 6 inches, with isolated amounts of 10 inches, are expected across portions of southern California and southern Nevada, which would lead to significant and rare impacts. Elsewhere across portions of the Western United States, rainfall totals of 1 to 3 inches are expected.
Rough surf and strong winds will also impact Southern California.
CENTRAL VALLEY IMPACTS
The Central Valley is forecasted to have remnants of rain and thunder from Hurricane Hilary by Monday and Tuesday.
Portions of the South Valley could first experience rainfall by Monday morning. The rest of the Central Valley will see a chance of thunderstorms by Monday afternoon.
Projected rain totals continue to change as the Valley is still a few days out from the storm, with the possibility of Hilary also downgrading.
BAY AREA IMPACTS
The current track of Hilary keeps the bulk of the moisture in Southern California and the Sierra but, we still have a possibility of seeing isolated showers here Sunday and a chance of showers Monday. Remnants of Hilary will bring higher humidity and tropical cloud cover between Sunday and early next week.
We will monitor the track of this storm and any small shifts would mean an increased chance of rain here. That is something we will fine-tune in the coming days.
The Associated Press contributed to this report.
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