The <a href="https://247newslive.com/tag/national-weather-service/”>National Weather Service (NWS) has issued warnings for an atmospheric river event poised to bring a trifecta of hazardous weather conditions—heavy rain, scattered flooding, and strong winds—to a wide swath of the western United States, stretching from the Pacific Northwest through the northern Great Basin and into the Rockies.
It’s Important: What are the impacts of Atmospheric Rivers?
It is important to be aware of the potential dangers associated with this atmospheric river, especially in Interior Northwest. NWS warned specifically that the combined effects of heavy snowmelt and rain, which is expected to reach its peak Sunday, would increase both the risks of river flooding as well as flash flooding. Property damage, road closings and possible disruptions to the daily lives of residents could result from this situation. Preparation requires an understanding of the impacts that atmospheric rivers have on different regions.
Flood Risk Areas & Rainfall Forecasts
On Saturday, the NWS published a map that showed areas with heightened risk of flash flooding and excessive rainfall. On Sunday, the map showed a “marginal risk” (5-15 percent) in parts of eastern Washington, western Oregon, western Idaho and western Montana. There was a “light” (between 15 and 40 percent chance of occurrence) risk for certain isolated locations in Washington and Oregon, especially along the Oregon Coast. The potential impact on a section of northwest California has also been examined. Forecasts suggest that the area of flood danger will be reduced on Monday, and the main focus is now the Westernmost Regions in Oregon and Washington.
NWS estimates that rainfall will be substantial in many parts of the country between the weekend and Monday. Estimates range from 3 to 10 inches. The topography, including mountainous terrain, may lead to much higher rain totals. This could reach 6-10 inches at favorable locations. It is important to monitor river level forecasts.
Flood warnings are in place across several states including Oregon, Washington Idaho Montana Wyoming and North Dakota. The warnings included a variety of flood types including river flood warnings and area flood watches, which reflected the potential impacts that the atmospheric river could have. Residents should monitor the local forecasts as well as any safety or evacuation recommendations from local authorities. Flooding is a threat in the following areas:
- Montana: Flathead County includes Lake County as well as Sanders County Mineral County Missoula County Ravalli County.
- Idaho: Clearwater County, Idaho County
- Washington: Grays Harbor County is comprised of Skagit County and King County. Also included are Lewis County. Pierce County. Snohomish County.
NOAA (National Oceanic and Atmospheric Administration) defines atmospheric river as long corridors with concentrated air vapor. They act as a conduit, transporting huge quantities of water from tropical areas to higher latitudes. The average atmospheric river, despite its size and intensity being variable, carries water vapor equal to that of the Mississippi River’s flow at the mouth. Most powerful atmospheric rivers are capable of transporting up to fifteen times the volume. At landfall atmospheric rivers can release moisture as heavy rain or snow, which often leads to flooding, particularly in mountainous coastal regions. The intensity of atmospheric rivers can be classified by using scales.
Weather Service Experts’ Perspectives
NWS Portland, Oregon: On Saturday the agency sent a message via X (formerly Twitter) stating that the next round of rain is moving into the region. There are three separate rainy periods: this afternoon and tonight, then Sunday morning until evening, followed by another period on Monday.
NWS Seattle On Saturday, Via X said: “Reliable rain will continue in western Washington until tonight.” Due to the heavy rain and warmer temperatures, rivers are likely to continue rising. The Skokomish is under a flood alert in Mason County.”
Look Ahead to the Duration of Flood Advisory
The latest flood warning for affected areas remains in place until Tuesday evening. The flood warning indicates conditions that are likely to cause flooding. Residents and business owners are encouraged to be informed about local weather conditions and take precautions in order to safeguard life and property.