08 Nov 2022 | 04:25 AM UTC
US: Adverse weather forecast across southern California through at least early Nov. 9.
Heavy rainfall and snow forecast across southern California, US, through at least early Nov. 9. Disruptions likely.
Event
Heavy rainfall and snow are forecast across southern California through at least early Nov. 9. A significant storm is forecast to bring 2.5-12.5 cm (1-5 inches) of rain across the affected area, with mountain snow and winter driving conditions over the passes, including the Grapevine. Excessive rainfall may result in floods and flash floods, especially over recent burn scars in Los Angeles County.
Duarte City issued a mandatory evacuation order for 25 homes in the Fish Fire burn scar from late Nov. 7 due to the danger of debris flows. Reports indicate that several streets are closed, while officials have suspended the Duarte Transit Service through at least Nov. 8. Authorities in Orange County issued a voluntary evacuation warning for Silverado Canyon, Williams Canyon, and Modjeska in the Bond Fire burn area effective from early Nov. 8.
Government Advisories
As of early Nov. 8, the National Weather Service (NWS) has issued flood and flash flood watches across parts of the affected area.
The NWS's Weather Prediction Center (WPC) has warned of a "Moderate Risk" (Level 3 on a four-tier scale) of excessive rainfall across the Transverse Ranges of southern California. A "Slight Risk" of excessive rainfall is in place across the rest of southwestern California. Officials could update and possibly extend the coverage of weather alerts over the coming days.
Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.
Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days and tornado warnings advising the public to shelter in place. Disruptions to electricity and telecommunications services are possible where severe weather impacts utility networks.
Transport
The severe weather will likely contribute to transport disruptions throughout the region. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.
Severe weather will also likely trigger flight delays and cancellations at airports across the affected region, including but not limited to Phoenix International (PHX) and Albuquerque International Sunport (ABQ) airports. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.
Localized business disruptions may occur in flood- or tornado-hit areas; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and some employees' inability to reach work sites.
Advice
Monitor local media for updated emergency and weather information. Seek updated information on weather and road conditions before driving or routing shipments through areas where severe weather is forecast. Plan accordingly for potential delivery delays if routing shipments by truck through the affected area. Do not attempt to drive through flooded areas. Confirm flights. Charge battery-powered devices in the case of prolonged electricity outages.
