Significant rain and snow event expected for Northern California and Pacific Northwest
A strong Atmospheric River is set to bring significant low-elevation rain and high-elevation snow to the Pacific Northwest and Northern California beginning Tuesday evening, November 12, 2024. The system will continue moving eastward, impacting a wide swath of the western and central United States with varied precipitation, including rain, snow, and thunderstorms.
Image credit: NOAA/GOES-18, RAMMB/CIRA, The Watchers. Acquired at 12:40 UTC on November 12, 2024
- The peak of the atmospheric river event will bring some higher rainfall rates on Tuesday and Wednesday, November 12 and 13.
A new Pacific frontal system combined with an Atmospheric River will bring heavy rain to lower elevations and mountain snow at higher elevations across the Pacific Northwest and northern California starting Tuesday evening, November 12.
This system follows a frontal system already moving through the northern Rockies and Great Basin, bringing light to moderate precipitation that will reach the central Rockies by Tuesday evening.
The approaching Atmospheric River will intensify precipitation across the West, bringing heavier coastal rains and high-mountain snow as it moves inland through Wednesday.
Favorable upslope conditions along the Cascades and coastal ranges are expected to bring locally intense rainfall, with the potential for isolated flooding, especially in northern California’s coastal regions.
Snow accumulation in the mountains is anticipated to be significant, affecting higher elevations throughout the northern Rockies and Great Basin.
The multiple frontal systems are expected to maintain cooler temperatures across the western United States.
On Tuesday, high temperatures are forecast to range between 4 – 10 °C (40 – 50 °F) in the Pacific Northwest and interior areas, around 15 – 20 °C (60 – 70 °F) along the California coast, and approximately 15 – 25 °C (60-70 °F) in the Desert Southwest. Temperatures are expected to moderate by Wednesday, increasing by approximately 3 – 5 °C (5 – 10 °F).
Additionally, a departing low-pressure system may bring light rain and snow showers across the Interior Northeast and Maine through Tuesday morning, while heavy showers and thunderstorms are forecasted along the central Gulf Coast due to moist inflow from the Gulf of Mexico.
This moisture is expected to spread further on Tuesday night, as the initial Western front moves toward the Plains, increasing rain and thunderstorm coverage.
By Wednesday, the Lower Ohio and Tennessee Valleys, Mid-South, and Lower Mississippi Valley are expected to experience widespread rain and thunderstorms, with locally heavy rainfall possibly leading to isolated flash floods in areas with already saturated ground.
Light to moderate rain is forecasted for the Great Lakes, though with less intensity due to limited instability and moisture. The weather system is projected to reach the Appalachians by Thursday morning, continuing its eastward path across the U.S.
Read more:
References:
1 Short Range Forecast Discussion – NWS/WPC – Issued at 07:25 UTC on November 12, 2024
2 Pacific Northwest and Northern California brace for incoming atmospheric rivers – The Watchers – November 9, 2024
I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.
Commenting rules and guidelines
We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules.