What are Kelvin waves? El Niño’s hidden threat that could impact several states on the West Coast

Sea level rise could enhance substantial California floodingOff the west coast of Mexico, a mass of unusually warm water is creeping north. This wave will reach California and could bring the threat of coastal flooding, beach erosion, impacts to surfing and even potential damage to roadways by the water. More of these waves could follow, enhancing a potentially wetter winter for California due to the ongoing El Niño. An aerial view of the incoming tide and swell at Aliso Beach in Laguna Beach in September, where recent storm surges caused damage to the parking lot area and erosion. (Los Angeles Times via Getty Image)How it worksNow, this wave isn’t anything like a tsunami. It is a slow-moving wave, only moving north at about 6 mph, that you probably won’t even see. It is called a coastal trapped Kelvin wave, if you want the technical term. El Niño is the culprit. It changes how the winds blow in the Pacific, allowing warm water to collect near South America. As water gathers, it can lead to a wave that moves along the shore and sets its sights on California, which we are seeing now.

A meteor streaks across the sky over a desert in China during the Orionid meteor shower on Oct. 22, 2023.(VCG/VCG via Getty Images)The Orionid meteor shower is peaking this week, and it promises to be one of the most dazzling displays of the year. And while some of you will have clear skies, rain and clouds could impact the view for others. Here's what you need to know about the Orionids and your forecast:Fast factsPeak day: The meteor shower peaks Wednesday night, Oct. 21, into the early hours of Thursday morning, Oct. 22. Peak time: From midnight to dawn are the best hours to catch the meteors streaking through the sky, so plan on a late night or really early morning. What the Orionids are known for: The Orionid meteors are known for their brightness and their speed. As they streak across the sky at around 41 miles per second, the meteors leave behind a glowing "train" that can last several seconds to minutes. While you can make the perfect plan to catch the Orionids, the key to stellar viewing is still in Mother Nature's hands. The good news is that many of you should have good meteor shower-watching conditions. Much of the central and eastern U. S.

(urbanbuzz/shutterstock)Could a cheap roll of duct tape help protect your home from flooding? New research suggests it could make a surprisingly big difference. In controlled tests, correctly applied duct tape on the outside of a household door reduced water leakage by 97-98%. The findings suggest that a simple low-cost measure could substantially reduce the amount of water entering a home during a flood. This is important as one of the key lessons from flood resilience research is that the best time to protect a property is before floodwater arrives. The UK government’s 2025 FloodReady Review called for practical, affordable measures that help households understand their risks and to prepare for flooding. And one potential contribution to this agenda might sound unlikely, at first glance. Duct tape is more commonly associated with household repairs than flood protection. However, tests colleagues and I conducted at the University of Hull demonstrated how much water can enter a property through an unprotected doorway during a flood. Three doors, ready for flood-testing.

Hurricane Trudy will bring flood threat to the Southwest USTrudy is off the Mexican coast, however, its moisture will pour into the Southwestern U. S., helping fuel a multiday flood risk across seven states this week from California to Colorado. A dip in the jet stream will also funnel in moisture from the Pacific as a strong low pressure system moves into the region. Timing out this week’s rainfallWednesday: The highest risk of flooding on Wednesday covers much of Arizona and parts of New Mexico, as well as southern portions of Colorado and Utah. There will be an abundance of moisture available to support heavy downpours and training storms. This means storms will produce heavy rain over the same areas for long periods of time. The Weather Prediction Center is forecasting rainfall rates as high as 2 inches per hour. Some of the biggest concern will be the possibility of mudslides over recent burn scar areas as well as slow canyons and arroyos. If you have plans to visit any of the national parks in the West this week, make sure you check the forecast daily and pay attention to any warnings or advisories issued.

An October nor'easter is developing in the Atlantic, where it will bring high surf, rip currents, coastal flooding and winds to parts of the East Coast for several days this week. The National Hurricane Center has highlighted it as an area to watch this week for the potential development of Josephine. However, regardless of whether we call this system a nor'easter or Josephine, the impacts will be the same. The bottom line: This system will bring dangerous conditions to the East Coast for multiple days this week.(MORE: What is a nor'easter?)Fortunately, this nor'easter doesn't look to be as strong as the one in September. But the bad news? It could linger for much of the week, so impacts could have a longer duration. Coastal flood alerts are in effect for parts of coastal North Carolina and Virginia, where anywhere from 1 to 4 feet of inundation is possible. Get More of Our News on GoogleSet The Weather Company as a 'Preferred Source' to get quicker access to the news you value. Key takeawaysWe do not expect this storm to be as strong as the late September nor'easter.

We have the maps you need to track all the systems ongoing in the Pacific and Atlantic below. Tracking the AtlanticTropical development areasSea surface temperatures Wind shear These are areas of strong wind shear, the difference in wind speed and direction with height, which are shown in purple. High wind shear is hostile to mature tropical cyclones and those trying to develop.(MORE: What is wind shear?)Get More of Our News on GoogleSet The Weather Company as a 'Preferred Source' to get quicker access to the news you value. Dry, dusty airAnother nemesis of tropical systems is dry air. In hurricane season, plumes of dust-laden air stream across the basin from Africa's Sahara Desert, as you can see in the map below. This sinking, dry air squelches thunderstorm development, the building blocks of tropical storms and hurricanes. So areas in the brown shading below are generally unfavorable for development. Atlantic tracks so far this seasonThese are the tracks of systems that were at least tropical or subtropical storms so far in the Atlantic Basin.