Summary:
- Persistent hemispheric blocking events have upended the second half of winter for many. Blocking over the North Pacific has allowed storm systems to extend further southward along the west coast and supported colder air masses migrating south out of the Arctic. The result has been rare snowfall for many and historic amounts for numerous western US regions.
- Much colder than average1 February for nearly the entire western US.
- Even with a very wet last week of February, a dry first half of the month dominated the monthly statistics, with most locations drier than average overall, especially the PNW. A wetter than average month was observed in central California, scattered areas of the southwest, and the northern Rockies.
- The short-term forecast is calling for continued cooler and wetter than average conditions in the west, with further hints at early to mid-March being overall cool and wet for much of the west. Warming to seasonal is forecast for the end of the month.
- The winter has brought continued improvement in drought conditions across the west. Snowpacks range from 90-120% of normal in the PNW and 100-250% above average in California, the Basin, and much of the Rockies. The unexpected is oh-so welcome, and continued improvement in drought conditions is forecast into spring.
- The spring forecast has the odds pointing to a cool period at least through April for the western US with California likely closer to seasonal while the PNW is likely to be cooler. Precipitation amounts are expected to be closer to average, continuing to lower drought concerns. The CPC is forecasting La Niña to slowly fade away with some hints at El Niño in late summer or fall. Cold near-shore SSTs along the western coast of North America
