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Weather Outlook

February 20, 2017

Summary- High pressure builds into the N Pacific and southern Gulf of Alaska while a weak southern storm track persists along 30N to the W of SOCAL. Troughs are over the Rockies and off the Calif coast. In March, the dry, cold pattern with troughing and a few mountain showers dominates during the first week. Model guidance has shown support for low latitude westerlies and cool conditions during the first half of March, with NW flow from the Gulf of Alaska. This maintains a colder than normal pattern with periods of snow showers thru the Sierras. The developing El Niño anomaly in March will induce troughing into SOCAL and central Calif and abnormally cold weather with some SOCAL showers in early March. As El Niño becomes more active during late March – early May, the southern storm track continues. The southern storm track will induce showers in N and central Calif, 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 and Kansas.

February 16, 2017

Summary- Troughing continues to focus to the west of California between 130W and 145W. Troughing also increases into the southern deserts and SOCAL as the southern storm track becomes more active.Troughing occurs during Feb 16-23 with wet conditions.Troughing migrates slightly east, putting us in a cold pattern with snow showers in the Sierras and return of cold conditions through all of California, with some offshore flow mixed in during February 24 – March 1.For March, the dry, cold pattern with troughs and showers in the southern deserts dominates during the first week of March. Although northern California turns dry for a while in March, SOCAL and the southern deserts have a tendency for recurrent cold showery conditions.There is support for the next series of storms into all of California during March 19-23, after a long, drier than normal pattern.The La Niña period ends quickly, and the current trend for an El Niño anomaly to develop will continue thru March, to induce more troughing into SOCAL and central California with a continued trend of colder and wetter than normal.As El Niño becomes more active during the next two months (March and April), and the southern storm track continues, the incidence of severe thunderstorms (TSTMS) and tornadoes may shift to above normal, along with above normal rainfall for Oklahoma, Kansas, and north Texas.

February 6, 2017

Summary- High pressure will dominate the central Pacific near the Dateline and into the Bering Sea, while troughing continues to focus to the west of Calif between 130W and 145W.In the near term, troughing continues thru February 10 with wet conditions. A dry spell with stagnant upper high pressure dominates, with offshore flow, for February 11-15. Wet conditions are most likely during February 16-18, 21, 23, 25-28, and March 3. Most of these rains appear to focus in northern and central California, but may also produce rain into SOCAL (Ventura/LA Counties).