30-Day Weather Outlook for December 19, 2017, to January 18, 2018
This is a short briefing in lieu of the longer discussion that is normally issued for this outlook.
Summary – Dec. 19 – Jan 18, 2018… Although support for blocking upper high pressure is less now than previously, La Niña continues in place, and will continue to oppose development of the normally occurring subtropical westerlies through the end of Dec and into January.
Greatest risk of frosts in S California appear to be on Dec 19, 21, 22 and 23, then again on the 29-30 and the first few days of January. Another period of higher frost risk is suggested for the middle portion of January, from the 10-17 with warmer dry days and cold nights with dry air masses predominating.
For Santa Ana winds, the best chance for Santa Ana's is Dec 21 and 24-25, then again on the 29-30, and Jan 1-2, and Jan 9-12.
For rains, the main chance for showers is in the Tehachapi Mountains north slope, with little more than a few areas of drizzle at the SOCAL coast and along the Santa Barbara-San Luis Obispo coastline. There is a chance for drizzle/light rain along the San Diego coast and valleys late on Dec 20-21, and possibly a better chance for more widespread rain along the coast - mountain areas on Jan 5-6. January precipitation appears to remain about normal (optimistically) but below normal (more likely) per the latest guidance from the CFSV2 and NMME short period climate prediction models.
...Alan Fox, Fox Weather LLC...