It's about time to plug that hole in your roof, Los Angeles!
The atmospheric river that's been causing debris flows and shutting down roads, is coming for us next. It's expected to park itself over the area Tuesday night, bringing especially heavy rain — as much as one inch per hour — which could overwhelm small rivers and streams, and lead to urban flooding.
And once again, authorities are pleading with drivers to slow down on these wet roads and to not drive into standing water — seriously, very little water can push your car into danger. We've already had a number of deaths this year due to drivers making this mistake. Please do not do this.
Here is the updated afternoon rainfall forecast map through Wednesday evening. Periods of heavy rain tonight will transition to scattered showers Wednesday. The showers will end from NW to SE through the afternoon and evening, lingering longest in the mountains. #cawx pic.twitter.com/S8lrFhL107
— NWS San Diego (@NWSSanDiego) March 14, 2023
Latest radar loop, valid at 936 PM:
— NWS Los Angeles (@NWSLosAngeles) March 15, 2023
Light to moderate rain continues to move across #SoCal. Ventura and LA counties most likely to experience an increase in rainfall intensity this evening. #CAwx pic.twitter.com/eAHlGKsbNV
Santa Barbara County got hit by the brunt of the storm on Tuesday, seeing 3 inches of rain in some spots. Schools remained closed and roads near Lompoc and Santa Maria were at least partially shut down due to debris.
Meanwhile, residents living in and around Montecito and Carpinteria were told to evacuate. The good news is that the area, known for suffering deadly damage during storms, hasn't reported any substantial flooding or debris flows yet, and evacuation orders for areas around the Alisal, Cave, and Thomas fire burn scars were cancelled as of 5:30 p.m.
Evacuation Orders for the identified properties and areas associated with the Alisal, Cave and Thomas Fire burn scars in south Santa Barbara County are CANCELLED as of 5:30 PM. Take caution when returning home. Expect slick roads and debris in the area. pic.twitter.com/na9iiXjTV6
— Santa Barbara County (@countyofsb) March 15, 2023
As of Tuesday afternoon, Ventura and L.A. counties had evacuation warnings in place.
@CountyofVentura Road closures due to local flooding. Visit https://t.co/w90W5iWyBt for more information.
— Ventura County Sheriff (@VENTURASHERIFF) March 14, 2023
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Cierres de carreteras debido a inundaciones locales. Visite https://t.co/w90W5iWyBt para obtener más información.#VCSheriff #CountyofVentura #VCOES pic.twitter.com/Ow2qs4bvRZ
As the storm migrates South, flood watches will likely remain in effect for much of SoCal into Wednesday.
A list of maps that should display evacuation warnings and orders when they're issued.
By the time this rainstorm wraps up on Wednesday, coastal and valley areas should've gotten between 2 to 4 inches inches of rain, while our foothills could see up to 8.
On Tuesday, rainfall rates exceed a quarter inch per hour, a general threshold of concern for debris flows.
That raises serious concerns about mudslides, particularly in areas that've seen them before and on hillsides that've recently burned.
Think Montecito or any number of spots along Pacific Coast Highway that are regularly inundated with debris during rains.
There's also elevated concern of mudflows up in the mountain areas that've received substantial snow.
“The real threat looks like the foothills at or below 6,000 feet where you have pure saturated ground, continued snowmelt running down the creeks, and then you have this period of heavy rain,” said Alex Tardy, meteorologist with the National Weather Service.
Those above 8,000 to 9,000 feet will likely see a couple of inches of heavy and wet snow by the end of Wednesday.
Concentrated areas of heavy rainfall combined with snowmelt over the higher terrain, and especially the foothills of the central and southern Sierra Nevada will foster locally significant runoff and flash flooding concerns going through the afternoon and evening hours. https://t.co/e4AGq1MWM0
— National Weather Service (@NWS) March 14, 2023
Expect high wind gusts starting Tuesday afternoon peaking late at night into Wednesday morning. Wind gusts are expected to reach 30 miles per hour in the coastal/valley areas and 65 miles per hour in the mountains/deserts, according to the weather service.
Here's an excerpt from our guide to understanding flood warnings:
Read more: Flash Flood Warnings? Watches? Here’s What You Need To Know
Warning in effect Monday (March 13) at 6 p.m. through Tuesday (March 14) at 10 p.m.
Warning in effect Monday (March 13) at 6 p.m. through Thursday (March 16) at 10 a.m.
Warning in effect Monday (March 13) at 6 p.m. through Wednesday (March 15) at 10 a.m.
Expected to wrap up Wednesday, this atmospheric river is shorter lived than others we've seen recently.
Curious why we focus so heavily on these , storm systems when they pop up?
We make a big deal about them for a few reasons.
One is that, on average, they're responsible for roughly half of our precipitation each year. And just a handful of atmospheric rivers can be the difference between a wet year and another bleak, drought-ridden one.
The second reason is that because they can drop so much water, they're also some of our most destructive storms, causing billions of dollars of flood damage to states across the Western U.S.
This atmospheric river is ranked as a 2-3 on a 5-point intensity scale.
• AR 1 (Weak): Primarily beneficial. For example, a Feb. 2, 2017 AR hit California, lasted 24 hours at the coast, and produced modest rainfall.
• AR 2 (Moderate): Mostly beneficial, but also somewhat hazardous. An atmospheric river on Nov. 19-20, 2016 hit Northern California, lasted 42 hours at the coast, and produced several inches of rain that helped replenish low reservoirs after a drought.
• AR 3 (Strong): Balance of beneficial and hazardous. An atmospheric river on Oct. 14-15, 2016 lasted 36 hours at the coast, produced 5-10 inches of rain that helped refill reservoirs after a drought, but also caused some rivers to rise to just below flood stage.
• AR 4 (Extreme): Mostly hazardous, but also beneficial. For example, an atmospheric river on Jan. 8-9, 2017 that persisted for 36 hours produced up to 14 inches of rain in the Sierra Nevada and caused at least a dozen rivers to reach flood stage.
• AR 5 (Exceptional): Primarily hazardous. For example, a Dec. 29 1996 to Jan. 2, 1997 atmospheric river lasted over 100 hours at the Central California coast. The associated heavy precipitation and runoff caused more than $1 billion in damages.
Roadway safety experts advised motorists to:
Here's what you need to know when storms hit Southern California:
