Relief from the dry and warm temperatures has only partially arrived. The past week and most of this week, daytime temperatures will remain below 60 degrees.
However, neither significant nor measurable rain is foreseen in either the short-term forecast or through winter.
Last week, the National Weather Service forecast the likelihood of a La Niña weather pattern this winter as greater than 80 percent.
Climatologists with the federal and state fire agencies are already describing the split pattern between heavy rains in the Pacific Northwest and little precipitation in Southern California as typical of La Niña weather. The NWS does not foresee the La Niña pattern dissipating until the middle or late spring of 2018.
In its forecast, the NWS stated, “The outlooks generally favor above-average temperatures and below-median precipitation across the southern tier of the United States …”
The Predictive Services unit of the Cal Fire Southern Operations reported that rain has been below normal to far-below normal this fall. “The driest conditions continued to be centered over Southern California where most locations did not experience a significant wetting rain (1˝ or greater).”
Consequently, they warned “…a warmer and drier pattern is expected during the next 4 months. Unfavorable temperature and precipitation elements combined with the possibility of a greater than normal number of offshore wind events may keep large fire potential above normal over Southern California past the first of January.”
The drier winter may cause a recurrence of the drought affects in Southern California, too. Pine Cove Water District has already begun preparations in case there is little rain in the next couple of months.
A recent article in Nature Communications from authors at Lawrence Livermore National Laboratory suggests that this divergence is attributable to the loss of Artic ice.
As the ice melts, it creates greater tropical rainfall, which affects upper atmospheric wind currents. These tend to drive the normal winter storms away from California.
The dry and windy conditions have exacerbated the Thomas Fire, which has now burned more than 270,000 acres. The Predictive Services unit has advised that these dangerous conditions may continue until the end of December.
