Monsoon season passes by with barely a trace

Sunday, Oct. 2, 2005 | 2:22 a.m.

The end of September marks the end of the traditional three-month monsoonal rain pattern for Southern Nevada, but this year the monsoons took a late summer vacation.

Only 0.78 of an inch fell during the season, well below the typical seasonal average of 1.2 inches.

From July through the end of September in most years, McCarran International Airport -- the official site for recordkeeping -- records measurable rainfall on at least seven days.

This year, however, there were only two days of measurable rain -- 0.56 of an inch of rain fell July 24 and 0.24 of an inch fell Aug. 14.

September came and went with several traces of rain, but nothing significant.

"A bunch of traces still add up to just a trace," National Weather Service meteorologist Clay Morgan said.

Ironically, the deserts in Southern California and Northwest Arizona were drenched during the monsoon season, but those weather systems generally bypassed Southern Nevada.

"Mother Nature rolled the dice and we missed out," Morgan said.

In the Colorado River basin, which is the source of nearly all of Las Vegas' drinking water, the "water year" that ends Sept. 31 finished slightly above average thanks to heavy winter precipitation.

Last winter was the wettest on record for Las Vegas, with 7.76 inches of rain, well above the average of 4.49 inches.

Southern Nevada also had an average high temperature of 100.1 degrees this summer, the coolest average high temperature in the last five summers.

Thanks to relatively cooler weather and various conservation measures, Southern Nevadans still managed to shave a little off the total amount of water used from last year, continuing a recent trend.

But Kelly Redmond, a climatologist at the Western Regional Climate Center in Reno, said there's a chance that there may be a delayed encore to the monsoon season because this year the season started later than usual.

At times, tropical storms or hurricanes in the Eastern Pacific can swing north and affect weather in the desert Southwest, deepening or extending the monsoon effect.

Hurricane Otis, swirling off Baja California, is projected to continue north and could bring moisture into Nevada around the middle of the week.

"You're never quite sure you've seen the end (of the rainy season) in September," Redmond said.

Sun reporter Launce Rake contributed to this story.