Weather and Climate Extremes in a Changing Climate. Regions of ...

sity from the mid-1970s
to early 1980s are also
suggested by substantial
pressure decreases at an
elevation above sea level
of about 3000 m over the
eastern North Pacific and
North America (Graham,
1994), indicating that the
pattern of variability of
extreme storm conditions
observed at San Francisco
(as shown in Figure 2.21)
likely extends over much
of the North Pacific basin
and the United States.
The oscillatory pattern of
variability is thought to be
influenced by teleconnections from the tropics,
predominately during ENSO events (Trenberth
and Hurrell, 1994), resulting in a deepened
Aleutian low shifted to the south and east that
causes both ETC intensification and a shift in
storm track. It is interesting to note that peaks in
the 5-year moving average in Figure 2.21 generally
correspond to peaks in extreme rainfall in
Figure 2.10, suggesting that the influence of El
Niño and broad-scale atmospheric circulation
patterns across the Pacific that affect sea level
variability along the West Coast are associated
with storm systems that affect rainfall variability
across the United States.
The amplitude and distribution of ocean wave
energy measured by ocean buoys is determined
by ETC intensity and track location. Changes in
long period (>12 sec), intermediate period, and
short period (