Evacuation warnings were set to go into effect across Los Angeles County on Thursday evening as an atmospheric river approached Southern California, bringing with it the potential to put an early end to fire season while also bringing fresh risks of flooding and mudslides. <\/p>\n
Under the storm scenario deemed most likely by forecasters, downtown L.A. would see 2.62 inches of rain Friday morning through Sunday, according to the National Weather Service. That could be enough to flood roads, swell rivers and creeks and cause minor shallow debris flows. <\/p>\n
Rain of that extent would also make this L.A.\u2019s wettest November in 40 years. And there\u2019s a 30% chance of even higher precipitation \u2014 4.81 inches over the same time period for downtown L.A. <\/p>\n
That would raise the possibility of significant mud and debris flows, as well as localized flooding of homes and businesses. <\/p>\n
There\u2019s also a 10% chance that just about 1.4 inches of rain could fall downtown, which would result in only minor problems. <\/p>\n
The day of highest risk is Saturday. For that day, \u201cthe main message is that there\u2019s still a pretty substantial potential for heavy rain over parts of our area, with a reasonable risk for flash flooding and debris flows,\u201d said Ryan Kittell, a meteorologist with the National Weather Service office in Oxnard. Debris flow are a type of landslide in which rainfall combines with mud and debris to move with destructive potential off hillsides. <\/p>\n
However, as far as fire season is concerned, \u201cthis will certainly help,\u201d Kittell said. <\/p>\n
\u201cIf we do end up getting the rainfall that we expect, this will certainly get us close to the end of the fire season,\u201d he said, and give Southern California a real buffer against a potential Santa Ana wind event. <\/p>\n
That would be a far cry from last year, when Southern California grappled with a record dry streak<\/a> over the fall and winter that left vegetation withered and primed to burn. Those \u201coff the charts\u201d conditions,<\/a> combined with exceptionally erratic<\/a> Santa Ana winds, fueled the rapid spread of the Eaton and Palisades fires, which rank among the deadliest and most destructive in California history. <\/p>\n Meteorologists say that Southern California needs 3 to 4 inches of widespread rain in the lower elevations for the high fire season to end. Downtown L.A. has already received 1.41 inches, almost all of it from just one stormy day in October. <\/p>\n Last year, downtown L.A. saw just 0.07 inches of rain from the start of October through mid-November. By Jan. 7 \u2014 the day the Eaton and Palisades fires roared to life<\/a> \u2014 downtown had received only a cumulative 0.16 inches. It wouldn\u2019t be until February, well after the blazes had devastated Altadena, Pacific Palisades and Malibu, that the region saw enough rain to bring the fire season to a close. <\/p>\n But the silver lining of the upcoming storm also carries a touch of gray. Rain of this magnitude could trigger damaging flows of mud and debris.<\/p>\n Evacuation warnings are in effect from 6 p.m. Thursday through 11 a.m. Sunday in areas near recent burn scars, due to the risk of mud and debris flows. This includes areas near the Palisades, Eaton, Kenneth, Sunset and Hurst fires that burned in January<\/a>.<\/p>\n There are many reasons California has faced extraordinary fire risk in recent years. Climate change<\/a> has fueled increasingly extreme heat, withering shrubs and grasses. Residential development has increased in fire-prone wildlands. Power infrastructure<\/a> and the failure to extinguish an arson-caused fire<\/a> have been the suspected culprits behind recent devastating blazes. <\/p>\n All this heightens the stakes of California\u2019s already delicate year-end dance between the Santa Ana winds<\/a> \u2014 the strength and heat of which have turbocharged many a fire \u2014 and the arrival of the rainy season. <\/p>\n The expectation for this autumn was considered grim with the return of La Ni\u00f1a in the central and eastern Pacific Ocean. Californians commonly think of La Ni\u00f1a, a natural climate pattern involving cooler sea surface temperatures, as a herald of drought, and the sibling El Ni\u00f1o pattern as synonymous with wet winters. <\/p>\n There\u2019s a reason for that. California saw epic rains during a significant<\/a> El Ni\u00f1o in 1982-83. Another in 1997-98 coincided with massive flooding all over the West Coast, as well as L.A.\u2019s wettest February on record. That was followed by a strong<\/a> La Ni\u00f1a in 1998-99, which was very dry. <\/p>\n More recently, 2020-21 and 2021-22 were La Ni\u00f1a seasons, and were drier than normal for downtown Los Angeles. <\/p>\n But using La Ni\u00f1a as your only crystal ball can prove spectacularly disappointing<\/a>. As noted<\/a> by meteorologist Jan Null, two of California\u2019s costliest flood seasons \u2014 2016-17 and 2022-23 \u2014 were during La Ni\u00f1as.<\/p>\n This week\u2019s rains are not a definitive sign that the rest of autumn and the winter will be especially soggy. A number of La Ni\u00f1as have gotten off to wet starts only for the storm door to suddenly shut, according to Kittell. <\/p>\n There continues to be uncertainty regarding how intense this storm will be for Southern California, though expected rainfall totals have been rising as the system approaches. A review of more than 100 different computer projections show most suggest a moderate-to-heavier rain scenario. But because the Saturday storm will come from a \u201ccut-off low,\u201d which is cut off from the jet stream, the storm is expected to spin like a top \u2014 making its path inherently unpredictable.<\/p>\n We \u201ccan\u2019t completely discount this thing pulling off the coast a little bit and resulting in less rain,\u201d Kittell said. <\/p>\n What is more certain is that forecasters expect two peaks of the storm. In L.A. County, the first peak is expected Friday during the day, but will probably bring mostly beneficial rain. Downtown L.A., for instance, is expected to receive 0.72 inches on Friday.<\/p>\n The more concerning peak is Friday night through Saturday. Saturday is the \u201cperiod of particular concern,\u201d Kittell said. \u201cThere\u2019s a lot of indicators that have spinning thunderstorms, which can produce either damaging rain or tornadoes.\u201d <\/p>\n As a result, Kittell said Southern California would be under a severe weather threat Saturday, with the period of most concern between midnight and 9 p.m. <\/p>\n \u201cWhile 99% of the area will not see such conditions, any portion of our area, especially in the coastal and valley areas, could see it,\u201d Kittell said. \u201cConsider changing any plans that you might have for Saturday. Stay home and indoors, and it\u2019ll protect you from all these hazards.\u201d<\/p>\n \u201cIf you hear thunder or see lightning or rapidly changing winds, no need to panic. Just go inside. Stay away from the windows, and you should be fine,\u201d Kittell said. \u201cAnd then, likewise, with the flood situation, if you are out on the roads and experience a flooded route \u2014 find a different route.\u201d<\/p>\n For Orange County, the Inland Empire and San Diego County, the heaviest rainfall is also expected late Friday through Saturday. <\/p>\n A flood watch will be in effect across a huge swath of Southern California on Saturday between 4 a.m. and 10 p.m.<\/p>\n Through Sunday, the most likely scenario is for Long Beach to receive 2.38 inches of rain; Redondo Beach, 2.48; Oxnard, 2.49; Thousand Oaks, 2.63; Santa Clarita, 2.77; Covina, 2.89; and Santa Barbara, 4.21. <\/p>\n San Diego could get 2 to 2.5 inches of rain; Riverside, San Bernardino, Escondido, and San Clemente, 2.5 to 3 inches; and Anaheim and Irvine, 3 to 4 inches, according to the weather service. <\/p>\n Even the deserts could tally impressive rainfall. Palm Springs may get 1 to 1.5 inches of rain, and Joshua Tree National Park could receive 1.5 to 2 inches. <\/p>\n Peak rainfall rates on Saturday for Southern California could be between 0.75 and 1.25 inches per hour. <\/p>\n \u201cIt\u2019s just not certain where that swath, that line, that band is going to center itself. If you look at all of our projections, it\u2019s really all over the map between L.A. County, Ventura County, Santa Barbara County,\u201d Kittell said. <\/p>\n \u201cWherever that line focuses in, we\u2019re looking for around an inch-per-hour rates over pretty wide, larger-than-normal area,\u201d while areas farther away from that line will get more like half an inch of rain per hour, Kittell said. <\/p>\n Mudflows and debris flows can be triggered in rains of half an inch per hour, Kittell said. <\/p>\n Topanga Canyon Boulevard between Pacific Coast Highway and Grand View Drive will close at 10 p.m. Thursday due to the high potential for heavy debris flows, according to the California Department of Transportation. The roadway is expected to remain closed through the Friday morning commute and potentially through the weekend.<\/p>\n Major snow accumulation is not expected in Southern California\u2019s mountains with this storm. In the San Bernardino Mountains, most snowfall will be just on the highest peaks, around 10,000 feet above sea level or higher. <\/p>\n In Sierra Nevada, snow levels are expected to fall to around 8,000 feet above sea level around Tahoe and in Mono County from Thursday night into Friday morning. Mammoth Mountain is moving up its opening date to Saturday because of the storm, but Tahoe-area ski resorts Heavenly and Northstar are set to open Nov. 21; and Palisades Tahoe, Nov. 26. <\/p>\n For those traveling through Sierra passes in Mono County, forecasters warned that about 6 inches of snow is expected to fall, and travelers should be prepared for delays or road closures. At Yosemite National Park, up to 6 inches of snow could accumulate at elevations 8,000 feet above sea level on Thursday.<\/p>\n The storm began hitting the San Francisco Bay Area and the Sacramento Valley Thursday. The most significant impact was expected to be strong winds, with possible gusts in the range of 50 to 60 mph. Some tree damage is possible, and strong winds may make driving difficult for high-profile vehicles. Minor urban and small stream flooding is possible. <\/p>\n San Francisco and San Jos\u00e9 could get 1 to 1.5 inches of rain Wednesday through Friday, and Sacramento, Santa Cruz and wine country could see 1.5 to 2 inches. <\/p>\n Looking to next week, there is the possibility of rain Monday as well as Thursday in Southern California. But at this point, meteorologists expect those storms will have relatively minor effects.<\/p>\n","protected":false},"excerpt":{"rendered":"Evacuation warnings were set to go into effect across Los Angeles County on Thursday evening as an atmospheric…\n","protected":false},"author":2,"featured_media":290174,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18],"tags":[23,14854,125595,43830,152270,152271,125000,58630,24030,3,24338,152268,6318,31641,152272,152269,50306,21,19,22,20,25,24],"class_list":{"0":"post-290173","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-united-states","8":"tag-america","9":"tag-area","10":"tag-debris-flow","11":"tag-downtown-l-a","12":"tag-early-friday","13":"tag-fire-season","14":"tag-inch","15":"tag-la-nina","16":"tag-national-weather-service","17":"tag-news","18":"tag-rain","19":"tag-ryan-kittell","20":"tag-saturday","21":"tag-southern-california","22":"tag-storm-door","23":"tag-stormy-day","24":"tag-thursday-night","25":"tag-united-states","26":"tag-united-states-of-america","27":"tag-unitedstates","28":"tag-unitedstatesofamerica","29":"tag-us","30":"tag-usa"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/290173","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=290173"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/290173\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/290174"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=290173"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=290173"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=290173"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}