30-Day Weather Outlook for January 22, 2018, to February 22, 2018
Summary- The MJO Cycle will continue in the inactive phase until Jan 29th. During the inactive phase, there will be support for more upper high pressure near the coast and into central California and S California, along with above normal temperatures. As the MJO becomes more active, there should be a more normal increase in the number of frontal passages through California (Jan 30-31st), and some seasonable rainfall again during Feb 14-18.
Support continues in the mid-latitude sea surface temperature anomaly (SSTA) field W of California for troughing at 140-145W, extending NE into Oregon-Washington coast and at times into N and northcentral California.
The El Niño Southern Oscillation (ENSO) continues in the cool (La Niña) phase. This leads to decreased energy in the subtropical westerlies, resulting in erratic cutoff lows near SOCAL and W Mexico.
In the Near Term – Jan. 27 – Feb. 14… In the southern California avocado growing areas, from San Luis Obispo County to San Diego County, we still have risk of warm, dry offshore flow with locally cold nights after mild or warm days. Rain days appear to focus on Jan 30-31st, Feb 6, and Feb 14-18th. Watch for Santa Anas on Jan 28, and again on Feb 2-5. Frosts are more likely Feb 8-12th.
Summary – Feb. 15-28… In the southern California avocado growing areas, from San Luis Obispo south, it will be drier and warmer than normal, overall. Showers on Feb 15 -18th are followed by frosts about the 19-20th, then rains on the 27th -28th.
Seasonal Outlook / La Niña Update...March 1 – April 25… Latest solutions suggest near or a little above normal rainfall for March as a whole. Rains resume in March with some heavy amounts possible in NW and central California coastal mountains, and N and central SierraNV. Heavy snow in the central SierraNV and near Tahoe during March. Rainy and cold conditions possibly reach into Ventura and Santa Barbara Co’s.
For N and Central California, the rainy and showery conditions in March may be followed by freeze events in the first week or several days of April. However, April appears to turn warmer and drier than normal for most of the month after about the 12th.
In central California, the SierraNV has a better than even chance for above normal rain and snow across the entire Sierra in March. There is a chance for some frosts in the first week or so of April in coastal valleys (Salinas/Pajaro/San Benito Valleys, Edna Valley), followed by a shift to warmer and drier than normal during April 8-25th.
For S California, the ensemble (NMME) model suggests more showers in the first half of March 2018 for southern California. In late Mar – early April, watch for frosts. After the first few days of April, SOCAL appears to turn warmer and drier than normal.
...Alan Fox, Fox Weather LLC...