Fig. 1: Latest NOAA/NWS weather watch, warning, and advisories.
Discussion: The atmospheric river pattern into California is more appropriately described as an atmospheric tsunami. A 960 MB low-pressure area is forecast off the Oregon Coast tonight. Coupled with the high terrain of California, the interaction will create a widespread dangerous windstorm (Fig. 1) capable of knocking out power for much of the state, particularly central and north sections. Excessive rain will cause additional flooding in urban areas, rivers, streams, and creeks. Dangerous mountain travel with multiple feet of snow beginning around 6,000 feet. Another long duration storm for the weekend into early next week. The NOAA 7-day quantitative precipitation forecast indicates potential for >20 in. of rain for a large part of California (Fig. 2). This amount is unprecedented and is likely to cause widespread damage including life threatening conditions. Flooding, mudslides, and widespread power outages are the primary issues. There is some winter weather across the Upper Midwest and northern New England in the forecast with snow and ice likely for those areas while tornado risk rambles on in Georgia and Florida today. Flash flooding is ongoing in southeast Mississippi/southwest Alabama. The U.S. population weight HDD forecast trends warmer (Fig. 3).
Fig. 2: NOAA/WPC 7-day quantitative precipitation forecast goes off the charts in California.
Fig. 3: The gas population weight HDD forecast using all models, their consensus and compared to 24 hours ago plus the 10-day/30-day normal.