Summary- Westerlies occur across most of Calif. The troughing pattern is bi-modal, with some troughs developing just off the coast of central and N Calif, and some focusing into the Great Basin. Forcing for troughs occurring from the Calif coast southwestward is from the sea surface temperature anomaly (SSTA) pattern W of Calif. Forcing for troughs over the Great Basin are related to the current new El Niño that has begun. Periods of WNW flow with troughing occur, bringing more occurrence of cold conditions with lower snow levels into N and central Calif, due to troughing over the Great Basin. Individual troughs contain moisture but lack strength as they reach the coast, but intensify while moving inland. This new pattern of development, related to El Niño favors development of troughs in S and SE Calif, NW Mexico, and Arizona, and a colder and occasionally showery pattern in central and N Calif. This maintains a colder than normal pattern with periods of snow showers thru the Sierras. As El Niño becomes more active during late March thru early May, the southern storm track continues. The southern storm track will induce showers and continued snowy conditions in the Sierras in late March thru April. The southern storm track will tend to support the development of severe weather events (thunderstorms and tornadoes), with above normal rainfall in Oklahoma, north Texas in April and Kansas-Nebraska in May.