Summary:
- A westward shift in the North Pacific high-pressure area in early December allowed the storm path to dip southward and mix with modified Arctic air. The result was some very welcomed rain and snow, even into many of the most drought-impacted areas in the west.
- ​December was warmer than average* over most of the west. Near-average to slightly cooler than average along the coast and into the Olympics and northern Cascades.
- Drought concerns have lowered but are not gone. Over 95% of the west is still in some level of drought, but the areas in severe to exceptional drought have dropped to below 35%. Continued improvement in drought conditions is likely through the second half of the winter.
- The storm path continues to bring systems south along the west coast with more precipitation through the first ten days of the month. The second week of January is likely to start a drying out period with temperatures remaining seasonal to cooler than average over the west.
- The second half of winter continues to be strongly influenced by cool SSTs in both the northern and tropical Pacific with cool and wet conditions north transitioning to cool and near average to dry south and east.
