Weather news has mentioned something called “the Pineapple Express” as heavy rains hit the West Coast. Also known as an “atmospheric river”, this is a plume of high level moisture from the Pacific which comes ashore along California. The systems tend to originate in the area of Hawaii, hence the name. As they move eastward, across the southern US, the systems tap into Gulf moisture. This combination means that parts of Kansas can enjoy a period of heavier than normal precipitation. Without the Arctic component, temperatures tend to be milder, increasing the chance that the precipitation will be rain rather than snow. Unfortunately, there usually is a sharp gradient to the moisture, and the form can be an ice component as well as snow. There are several additional systems in line to arrive on the West Coast over the next 8 to 10 days, increasing our chances for above normal precipitation over the period.
Mary Knapp, Weather Data Library