Rainfall began early Friday morning, Nov. 13, as an atmospheric river moved across the Pacific Northwest. The moisture band stretched from San Francisco to Seattle, delivering a weak‑to‑moderate effect for Lane County rather than the intense downpours seen in other parts of the region.
What an atmospheric river is
An atmospheric river is a long, narrow corridor of concentrated water vapor that can unleash heavy rain when it reaches land. Scientists note that a warming atmosphere holds more moisture, so when strong winds push that moisture inland, the result can be faster, heavier rainfall – a “sponge being wrung out.”
Local impact
National Weather Service meteorologist Daniel Hartsock called the rain “certainly beneficial,” but emphasized that the Eugene‑Springfield area remains well below normal November precipitation. The service does not anticipate major impacts from this round of rain, and strong winds or power outages that sometimes accompany atmospheric rivers are not expected.
The rain is a welcome break after a dry start to the season. Lane County experienced severe or extreme drought conditions across two‑thirds of the county in July, and October saw below‑normal precipitation across much of Oregon. September, by contrast, was above normal after a mid‑month rain event helped dampen a parched landscape.
El Niño influence
Forecasters note that a strengthening El Niño in the Pacific Ocean is contributing to the current weather pattern. While El Niño typically brings a warmer‑than‑average winter to the Pacific Northwest, its effect on rainfall is less certain. Historically, strong El Niño winters have produced wetter‑than‑average periods in December and January.
The National Weather Service estimates a 79% chance that this season will feature a historic El Niño event, potentially stronger than any recorded previously.
Looking ahead
Residents can expect the current rain to continue through Saturday before tapering off. While the precipitation helps alleviate some drought stress, the month’s total will likely remain below the climatological average for November. Continued monitoring by the National Weather Service will determine whether additional rain systems move into the area later this winter.
For now, the modest rain offers a brief respite for farmers, gardeners, and anyone hoping for a greener landscape after a dry start to the season.
Original reporting: Homepage – Lookout Eugene-Springfield — read the source article.
