Portal Weather

Meteorological data at the Portal LTREB has been recorded since 1980. Annual precipitation is distinctly bimodal, with peaks in winter (November to March) and summer (July and August).

Occasionally, in late summer or early autumn, dissipating tropical storms affect the southwestern portion of North America, producing widespread and intense precipitation. While such storms can affect the region several times per decade, they are sufficiently severe to cause heavy flooding approximately once every twenty years. In late September 1983, tropical storm Octave generated record flooding throughout southeastern Arizona and southwestern New Mexico. During a period of less than a week, the study site received 129 mm of precipitation which was equal to about 50% of the yearly average. This caused declines in several rodent populations, especially bannertail kangaroo rats.

El Niņo events are thought to be associated with exceptionally heavy winter precipitation in the Southwest desert region. there has been no consistent relationship between El Niņo and winter precipitation at Portal, however. Simiarly, rodent population increases or peaks are not related to El Niņo events.

UNM undergraduate biology student, John Haskell, stands in knee-deep water, holding a snake stick, at the Portal research site, just after one of the biggest catastrophic rain events recorded for the area.

After the storm. A summer rainstorm passes through the Portal site.

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