30-Day Weather Outlook for January 30, 2017, to March 2, 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 California between 130W and 155W. In the near term, troughing returns on February 1-3 with wet conditions. The latest indications are that periods of warm and dry upper high pressure with sunny conditions in the mountains and patchy fog in central valley area of Calif will focus in central and southern California during February 4-6th, followed by rains mostly in the northern half of California on the 7-8th and again on the 12-14th. General wet periods are Possible about February 19-22nd and 25-26th. Most of these rains also appear to focus in the northern portions of California.
In the Near Term – February 1-22… In the southern California avocado growing areas, from Santa Barbara County to San Diego County, after showers on February 2-3rd, we transition into a dry and warmer period, starting with freezes on the mornings of the 4th and 5th. Warmer than normal days and crisp cold nights in the valleys occur, going forward during the 5-11th. Santa Ana winds are still possible during this period, and recur during the 15-18th. Fronts affect central and northern California on the 12-14th, and the 19-22nd, but may only produce minimal rain for SOCAL.
Summary – February 23 – March 9… In the southern California avocado growing areas from San Luis Obispo, south, our guidance from CFSDaily suggests that the next rains in northern and central Calif focus on 22-23rd, 26-28th, and Mar 9-10th. In SOCAL these rains may tend to be sparse, or not extend into the SOCAL avocado/citrus areas. For those areas, we still see a risk of frosts in early to mid-March with CFS suggesting colder than normal conditions overall for the San Joaquin Valley and most of Calif, including SOCAL.
Seasonal Outlook/La Niña Update...March 11 – April 30, 2017… La Niña becomes weak or nonexistent. Guidance from the NMME (Ensemble) model show La Niña ending this spring, followed by an onset of El Niño conditions by June in the equatorial Pacific. While this would not be expected to affect California rains in the near term, it could produce a cool start to summer, and then gain importance for production of rainfall in SOCAL and central California for the fall tropical cyclone season, and next winter rainy season beginning in Nov 2017.
For SOCAL, March has a little rain, focusing in San Diego and west Riverside Counties. Arizona also turns wetter than normal in the north with snow on the northern Plateau. April continues the cooler than normal and showery trend for SOCAL and Arizona.
...Alan Fox, Fox Weather LLC...