Strongest storm yet could bring flooding, tornadoes, hail and high winds to L.A. area

The National Weather Service warned Southern California that the most intense in a series of storms will slam into the region before dawn Wednesday.

[Updated at 3:28 p.m.: L.A. County officials announced "residences in La Canada Flintridge and 85 residences in La Crescenta [would be evacuated] due to the possibility of debris flows resulting from forecasted rain storms in the area."

This storm could bring with it thunderstorms, hail, and even waterspouts and tornadoes along the Southern California coast early Wednesday, forecasters said.

The powerful storm could drop as much as 0.75 to 1.5 inches an hour in places, which could bring flooding not only in foothills and mountains but in neighborhoods all over L.A. County, said Stuart Seto, a specialist for the weather service in Oxnard.

“The ground will be permeated with a lot of rain, and it was a very, slow consistent rain for the past five days,” Seto said. “This is going to be more of a thunderstorm-type rain.

“This thunderstorm activity is very dynamic and intense,” Seto said. He said there’s a possibility of waterspouts along the coast, which become tornadoes if they hit land.

While the tornadoes could cause damage if they strike a house, they are generally nowhere near as powerful as the ones in the Midwest.

The coast and valleys could be pelted with 2 to 4 more inches of rain, and the foothills and mountains could see 4 to 8 additional inches, Seto said.

Wednesday’s storm will move through Southern California faster than earlier storms, but will be more intense. Forecasters said it is expected to arrive about 2 a.m. in Ventura County and sweep over to L.A. County by 4 a.m.

The storm is expected to hold over the region for six to eight hours.

Wednesday’s storm will be more energetic than the previous systems because it will result from the collision of a cool area of low pressure moving south from Seattle to Southern California and warmer, moist air from the western Pacific Ocean, beyond the International Date Line.

The collision between the two systems will produce thunderstorms, which will cause rain to fall more swiftly, Seto said. “The rapid rainfall coming on certain areas will run off a lot faster,” Seto said. “We’re going to see a lot more runoff with these storms.”

Heavy rainstorms have proved to be a problem not only in foothill communities bordering burned forest land, but also in low-lying areas of Long Beach and San Pedro, which can be overwhelmed if flood-control channels can’t handle bursts of significant rainfall.

Also a problem will be sustained winds of 15 to 25 mph along the coast and in valleys, along with gusts of up to 65 mph in the mountains. It’s possible more large trees, with their roots soaked in loose soil, could fall on Wednesday.

“We’ve already had trees go over,” Seto said. “I wouldn’t want to be parked under one.”

Downtown L.A. has already received about 6 inches of rain since Thursday -– about 40% of the precipitation the city receives on average every year.

Seto said that by the time the storm clears out late Wednesday or early Thursday, as much as 20 inches of rain may have dropped on the wettest areas.

Already, the storm systems of December have dumped tremendous precipitation around the state. The Mammoth Mountain summit has recorded 9 to 13.5 feet of snow in the last week, the weather service office in Reno said.

Partly cloudy conditions are expected to return on Thursday and Christmas Eve. A weak storm system may return to L.A. on Christmas Day, but the storm is only expected to drop less than half an inch of rain.

In San Diego County, the rain caused flooding, numerous traffic snarls and road closures. Mud slid down a hillside in La Jolla. Between midnight and noon, there had been 202 traffic accidents in the county, three times the amount of an “average” day, according to the California Highway Patrol.

Three suspected illegal immigrants were plucked from the rain-swollen Tijuana River, shivering and desperate for rescue. The San Diego Police Department is warning residents of the Tijuana River Valley to evacuate their homes and take their animals to higher ground as the water level continued to rise.

Pollution flowing into the ocean from the river caused county health officials to close the Silver Strand beach in Coronado. The main thoroughfare through Camp Pendleton -- Vandegrift Boulevard -- was closed near the base air station due to flooding.

The hardest-hit area in the North County was in the Palomar Mountain region, where numerous rock slides, mudslides and downed trees were reported. No injuries were reported.

In Orange County, four men stranded in Trabuco Canyon were rescued Tuesday morning when they were plucked from the flooded foothills by helicopter. The men were spotted soon after daybreak when the helicopter flew over the fast-moving Trabuco Creek and saw them inside their vehicle.

A woman who was swept away in her pickup while crossing a rain-swollen creek in the San Bernardino National Forest was rescued Monday night after a harrowing four-hour recovery effort, officials said.
The 29-year-old woman was crossing Lytle Creek north of San Bernardino shortly before 5 p.m. in her Ford pickup when the high water washed away the road and started carrying the vehicle downstream.

As water filled her cab up to the dashboard, the woman used her cellphone to call for help, officials said.

More than 5 inches of rain have already fallen in downtown Los Angeles this month, and the record of 8.77 inches for December is within reach. Mammoth Mountain has already recorded the highest December snow levels ever.

Authorities say the mountainsides near Sierra Madre are holding up amid the rains, but a potential evacuation alert is ongoing to keep residents prepared.

Aside from some blockage on the 800 block of Skyland Drive, police are reporting unobstructed water flow. Sgt. Kenneth Berry with the Sierra Madre Police Department credited efforts in the last two months to clear out debris basins.

“As of right now, the mountainside is holding up,” Berry said. The green flag alert, Berry said, is meant solely to keep residents prepared for a quick evacuation if the expected stormy weather does cause mud flow later in the day.

“We just have to have people prepared,” Berry said.

-- Rong-Gong Lin II and Robert Faturechi in Los Angeles, and Tony Perry in San Diego

Map: A giant area of low pressure is moving from the Pacific Northwest to Southern California. When the cool system from the Gulf of Alaska collides with moist, warm air from the subtropical western Pacific Ocean, Southern California could be hit with thunderstorms, hail and even waterspouts and tornadoes, the National Weather Service said. Credit: National Weather Service.  

Photos: Series of storms hits Southern California

Comments

[John]

LA is NOT a desert. MWD attempts to make us believe otherwise (for a good reason - water conservation). This false assumption regarding LA's climate has lulled us into the erroneous view that we never seem to get regular rains like this. Thus, nobody prepares for high precip. events and they suffer as a result.
Los Angeles is technically at the dry fringe of the "humid" climates with several months of cool-season rainfall totalling about 15" a year. High amounts of rainfall from time to time in cismontane southern California like this event is by no means unusual.

[sdnative1]

"...Southern California could be hit with thunderstorms, hail and even waterspouts and tornadoes, the National Weather Service said."

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"Dogs and cats living together!"
-Dr. Peter Venkman

[Enlightenment]

ha ha, you SoCal people are funny, this is normal for lots of people in other parts of USA. let me know when you get more than 50 inch of rain in a year, then i will care.

[Paul Espinoza]

And it will be colder asit is coming from the north, not through the Hawaiian Express

[Logan]

Must be that global warming to account for the extreme cold of the summer and our cold, wet winter. Of course, when it's hot it's global warming and when it's cold it's global warming. And when pigs fly it's global warming. Why, even Europe is getting in on the act - having its coldest winter in recorded history - must be the global warming!

[Brandon]

113 degrees in the Summer. In the Winter, massive storms and TORNADOES in Los Angeles! Yeah, Global Warming needs more study.....

[Gib]

Major storm and tornadoes, what is this, The Day After Tomorrow? This weather is all just a big conspiracy by the liberals. The liberals are using their secret WMD, weather manipulation devices (housed in Area 51 no less) to make it seem like Los Angeles is being affected by global climate change. Well guess what Obama, you can't fool us. We know that the 113 degree heat back in September was also just created by the WMD. You're just trying to get us all to agree that we need to work together to stop "global climate change," (government climate change) so that we'll let the govt. install climate moderating systems in everyone's house. But these moderating systems will actually be used to control our minds. Thank goodness I have my tin-foil hat ready for me and my family!

[CreativeWaste]

Having been a NY native for 16 years before moving here, the rain here is definitely not as bad as Long Island. The problem is the amount of water is too much, too fast after not having any. The LA, San Gabriel and Santa Ana Rivers have been widened, deepened and bedded with concrete to reduce flooding but even that gets overwhelmed at times. The Santa Ana River was considered the most dangerous river west of the Mississippi 60 years ago and for good reason; half of populated Orange County has been known to be wiped away during its flooding. People think the rain is no big deal but historically the basin area is one of the most dangerous in the country. Residents are very ignorant of the area's history. I suggest taking a bike ride up any of the rivers and imagining everything within a 5 mile radius being damaged or washed away. Notice how close the rivers are and the potential for simultaneous flooding. This is the history of the LA basin.

[Ron]

Oh man just when you think its over some guy makes fun of global warming "conspiracy". You do realize the ice caps are melting right, and the Earth (on a whole) is warming up? So it's not just a hoax, although I agree with you there isn't much we can do at this point.

[JFS_PA]

When a system heats up, the contents circulate faster. Think of a pot as it start to boil. So, yes, global warming causes more extreme weather. Warmer air picks up more moisture, warmer air rises faster, gets higher, moves farther...then cools, and drops. If you're in a rising part of the pattern, you get drier winds and drought, if you're in the dump zone, you get flooding. This used to be 8th grade science.