El Nino and La Nina events in the eastern Pacific affect weather around the world, and the 2023-early 2024 super El Nino really Super-Soaked the U.S. West and East coasts. In today's blog you'll read about it from the National Oceanic and Atmospheric Administration (NOAA). Last Summer, all the New England states experienced the rainiest June on record. I've also added some effects in southern Maine, where it's been cloudy about 4 out of every 7 days.
(Fig1_Mar24_ENSOBlog (left to right) The precipitation difference from average for this past winter (Dec-Feb 2023-24) and the geographic pattern of precipitation we'd expect for this past winter based on past El Niño winters from 1952-2022. The precipitation pattern for this past winter is a reasonably good match to the El Niño pattern. NOAA Climate.gov image, based on analysis by Nat Johnson.)
How much did El Niño influence precipitation over the United States this past winter?Last November, I wrote about how a strong El Niño might shape precipitation over the U.S. this winter (December – February). So, what happened? With crocuses now starting to bloom and the chirps of spring peepers in full chorus, we’re ready to investigate!
An El Niño-ish big picture
First, let’s acknowledge that a strong El Niño occurred this winter, as NOAA had been forecasting since issuing an El Niño Watch in April 2023. (If we couldn’t check that box, this would be a very short post!) We unofficially consider El Niño to be “strong” when the Oceanic Niño Index (ONI) exceeds 1.5 °C (2.7 °F), and the ONI value for this past December – February was well above that threshold at 1.8 °C.
What happened with precipitation around the contiguous U.S.?
Winter was wetter than normal overall, and as the map above and to the left indicates, wetter conditions were most pronounced across coastal areas, especially the West and Gulf Coasts and from the Mid-Atlantic to the Northeast. Wetter conditions also prevailed over most of the Central and Northern Plains. Drier-than-average conditions were much less expansive, but below-normal precipitation occurred around the Northern Rockies and portions of the south-central U.S. and extending southward into northern Mexico.
Of course, we shouldn’t just sweep the mismatches under the rug. There were many backyards this winter that did not experience the typical precipitation impacts for an El Niño of this strength. In particular, the Pacific Northwest and Northeast were considerably wetter than the expected El Niño pattern, while portions of the southern tier from southern Texas to the Southeast were notably drier.
In December 2023: A Nor'Easter Flooded most of Maine
(Source: ENR New England, By Johanna Knapschaefer: https://www.enr.com/articles/57914-maine-hardest-hit-by-powerful-east-coast-storm)
A coastal storm Dec. 18 that brought flooding, downed power lines and damaged infrastructure in many Northeastern states, delivered its most powerful punch to Maine, causing significant infrastructure damage. The fierce storm that stretched from Florida to Maine blew into Atlantic Canada Dec. 19, leaving more than 400,000 in Maine without power.
In a Dec. 20 press conference, Maine Gov. Janet Mills (D) said, “As of this morning, MaineDOT has reopened more roads and bridges as flood waters have receded.” There were 68 state road closures on Dec. 20, down from nearly 100 the prior day “as a result of downed trees and power lines, flooding, and significant infrastructure damage,” Mills said. While all Maine counties have been affected by the storm, more than half of the road closures are in Oxford, Franklin and Kennebec counties.
Source for NOAA article: https://www.climate.gov/news-features/blogs/enso/how-much-did-el-nino-influence-precipitation-over-united-states-past
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