36 FOUR SEASONS BREEZE | OCTOBER 2023
"Understanding the Weather" – A Series by Mel Zeldin, Retired Meteorologist
As we move into the fall months, the impacts from a developing
El Niño could produce substantial winter rains. But, at least through
the fall months, precipitation is only indicated (see Figure 1) as equal
chances for above- or below-average precipitation. According to
the National Oceanic and Atmospheric Administration, the experts
are projecting about a 66 percent chance of a strong El Niño from
December through February. How this impacts us here is still too
early to determine, but, in all likelihood, we will have above-average
precipitation during the winter.
And, as shown in Figure 2, the projections are leaning toward
above-average temperatures for the fall months, with a 40 to 50
percent probability of that occurring.
And now a few words here about tropical storm Hilary that moved
over Southern California in August. The reason this has not happened
in 84 years is that you need a perfect set of conditions which rarely
occurs with an eastern Pacific tropical storm. The ingredients were:
(1) the storm formed off of the central Mexican coast and reached a
very strong Category 4 hurricane, so what normally dissipates during
northward movement over colder waters, in this case, still had a lot
of circulation momentum; (2) there was an upper-level low pressure
off the California coast which helped to direct the storm toward us;
and (3) normally these systems curve northeastward into Mexico,
but we had a very strong high pressure system over the central
states and northern Mexico which blocked the system from moving
northeastward. Fortunately for us here in Four Seasons, the amount
of rainfall was not much different than a strong winter storm, with
Hilary's greatest impacts in the mountains and deserts.
Fall 2023 Weather Outlook … And Some Comments About Hilary
Fig. 1. Precipitation outlook for fall Fig. 2. Temperature outlook for fall
