After a prolonged period of dry and unusually warm weather in January, the western United States is in for a change. A cooler and wetter pattern is expected, bringing some much-needed relief to the region, particularly in terms of mountain snowpack. The record-breaking warmth has led to abysmal snowpack levels, with every western watershed below average as of February 7th. However, there are some pockets of resilience, such as the southern Sierra Nevada and northern Rockies, where heavy precipitation earlier in the season resulted in "cement-like" snow that has persisted despite the heat. The unusual warmth has caused plants, animals, and skiers to behave strangely, and tourism in mountain towns has suffered. Concerns about wildfire risk and water supply are growing, especially in the interior West and Pacific Northwest. The "Warm West/Cool East" pattern, characterized by a strong Western U.S. ridge and Eastern U.S. trough, has contributed to this unusual weather. But the good news is, cooler temperatures, rain, and mountain snow are on the way, offering a glimmer of hope for the ongoing "Great Western Snow Drought."
A series of Pacific weather systems will bring much-needed relief, starting with a system arriving in central California on Tuesday. This system will bring widespread rain and gusty winds, particularly near and south of San Francisco, impacting the SF Bay Area and I-80 corridor. While it may not significantly improve the snowpack situation, it will lower snow levels to more reasonable levels. Following this, a stronger storm or two is possible in California during the upcoming cycle, with a high likelihood of additional storms along the West Coast and across the interior West. This pattern is favorable for recurring precipitation events, with a strong Pacific jet likely to be draped across California, bringing 1-2 strong low-pressure systems and the potential for widespread moderate to heavy rain, strong winds, and heavy mountain snowfall.
The ongoing marine heatwave in California's near-shore waters is another factor to consider. This heatwave has intensified during January's calm weather, causing water temperatures to be 3-5°F above average. This warm anomaly will influence weather conditions, potentially causing warmer near-shore temperatures and adding moisture to the atmosphere, which could lead to thunderstorms and downpours. However, the uncertainty regarding the rest of February is high, with the possibility of another major polar vortex disruption and a re-emergence of the "Warm West/Cool East" pattern. The outcome will depend on the broader hemispheric pattern, and the potential for a strong and persistent blocking ridge over the North-Central Pacific is a concern. Despite this, the upcoming pattern change and storms offer a chance to address the snowpack situation and mitigate the impacts of the "Great Western Snow Drought".
