LAUSR

Severe drought in California between 2013 and 2016 has been linked to the multi-year persistence of anomalously high atmospheric pressure over the Northeastern Pacific Ocean, which deflected the Pacific storm track northward and suppressed regional precipitation during California's winter “rainy season.” Multiple hypotheses have emerged regarding why this high pressure ridge near the west coast of North America was so resilient—including unusual sea surface temperature patterns in the Pacific Ocean, reductions in Arctic sea ice, random atmospheric variability, or some combination thereof. Here we explore relationships between previously documented atmospheric conditions over the North Pacific and several potential remote oceanic and cryospheric influences using both observational data and a large ensemble of climate model simulations. Our results suggest that persistent wintertime atmospheric ridging similar to that implicated in California's 2013-2016 drought can at least partially be linked to unusual Pacific sea surface temperatures, and that Pacific Ocean conditions may offer some degree of cool-season foresight in this region despite the presence of substantial internal variability.