Weak La Niña is a winter wild card for Utah's snow outlook
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Utah has an elevated chance of a warm winter and, in the southern half of the state, a dry winter as well.
The big picture: That's the projection of the annual NOAA winter outlook, which calls for weak La Niña conditions in the tropical Pacific Ocean to be a key factor in influencing the path storms take.
Zoom out: A warmer and drier than average winter is the favored projection along the country's southern tier, with the likely emergence of drought conditions in the Southwest states in particular.
Other factors, like the stratospheric polar vortex and patterns of air pressure in the North Atlantic are likely to assert themselves this winter, leading to large week-to-week variability, NOAA experts said Thursday.
How it works: NOAA's climate outlooks are probabilistic, which means they communicate the likelihood of a particular outcome, rather than definitively predicting conditions.
- Therefore, the projections show above-average likelihood for a colder, snowier winter than normal in the Pacific Northwest; a greater chance of drought expansion into the Southwest; and a strong probability of a milder-than-average winter from the southern part of the U.S. to parts of the East Coast.
Yes, but: The world's oceans are near record warm, which could shift some of the predicted effects.
Between the lines: Human-caused climate change could overcome the typical effects of a weak La Niña to be a top factor influencing winter weather for regions.
- "Winter for many regions across the U.S. is the fastest warming season of all the seasons," said NOAA climate expert Tom Di Liberto.
Context: The past two winters have brought enormous amounts of snow to Utah, providing short-term drought relief but potentially leading lawmakers to delay conservation measures.
The bottom line: El Niño, La Niña or the absence of these conditions tend to be the biggest predictors of winter weather patterns across the U.S.
- However, the expected weakness of La Niña could allow less-predictable factors to play a significant role in winter weather.