Last week some parts of southern Kansas saw significant amounts of rainfall during what is usually a dry part of the year. A major factor was an upper air phenomenon known as the “Pineapple Express.”
This is a plume of high-level moisture from the Pacific which comes ashore along California. These systems tend to originate in the area of Hawaii, hence the name. As they move eastward, across the southern U.S., the systems tap into Gulf moisture. This combination means that parts of Kansas can enjoy a shot of moisture. 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. Areas of northwest and north central Kansas missed out on the moisture entirely. 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