1997 Warm Episode

The latest conditions are reported in the El Niño/Southern Oscillation Advisory. This document is somewhat technical.

Equatorial Pacific sea surface temperatures for near the South American coast are shown in the top panel, and for farther to the west along the equator in successive plots. These plots show how the temperatures vary about normal conditions with positive (orange shading) and negative (blue shading) values indicating temperatures above and below normal, respectively. The temperature units are degrees Celsius, with 1 degree Celsius being approximately 2 degrees Fahrenheit. As of May of this year, temperature variations near the coast are second in magnitude only to those during the record warm 1982-83 event. Ocean temperatures farther to the west (Nino 3, Nino 3.4, and Nino 4) are warmer than normal this year, but not unusually so.

ENSO typically influences the United States during the calendar months:
December through April by moving the preferred patterns of storms to produce variations in precipitation and surface temperature in the indicated regions.
June through November by changing the number of hurricanes and tropical storms in the Gulf of Mexico, Caribbean Sea, and eastern Pacific. More hurricanes and tropical storms are found in the eastern Pacific and fewer in the Gulf of Mexico and Caribbean Sea during ENSO warm episode years, as shown by the daily storm positions in the left panel. ENSO cold episodes, in contrast, are characterized by fewer Pacific and more Gulf of Mexico and Caribbean Sea storms. ENSO does not seem to affect the number of storms in the main Atlantic basin.

July 1997
Todd Mitchell (mitchell@atmos.washington.edu)