Utah's present drought is not an isolated event. It is part of a greater climate system that extends both in geography and through time.
"It's not unusual to have drought somewhere in (the United States)," said Douglas LeComte, senior meteorologist with the federal government's Climate Prediction Center at Camp Springs, Md. "It's a big country."
At any given time, some spot is likely to be affected by drought, he noted. But this year, the extent of drought across America is unusual.
"Roughly, about a third of the country is in drought, and about half of the country is experiencing at least abnormal dryness." By one measure, 20 percent of America is classified as experiencing severe drought.
In the winter of 2000-01, unusual weather patterns "blocked the storm systems from making it to the northwestern quadrant of the country," he said.
Storms that normally would have landed there from the Pacific Ocean instead veered north or south. Parts of Utah "missed some of that precipitation and the Southwest got it.
"This past winter, they got a lot of Pacific storms in Washington, Idaho, Oregon, northern California, northern Nevada," and that provided some relief, LeComte said.
"But the Northwest's gain is the Southwest's loss, and some of the Southwest's lack of precipitation has affected parts of Utah."
According to the center, some parts of the country, like the Midwest corn belt, have had excessive precipitation. But more areas are in drought.
Several sections are experiencing abnormal lack of precipitation:
The Eastern seacoast. "We still have severe drought from Georgia up to Maine." The Southeast has been in and out of drought since 1988, particularly Georgia and South Carolina.
Northern and central Rockies, "in particular, a large chunk of Montana and Wyoming," where the drought is classified as extreme. Snowfall there during the winter of 2001-02 was below normal, on top of far-below precipitation the preceding winter.
Most of the rest of the West, except from central California northward. The area clear of drought extends in the north through the Idaho Panhandle.
Southern Utah is classified as in severe drought, a swath through the state's center is in moderate drought, while the center lists northwestern Utah as merely "abnormally dry."
Utah is entering its fourth straight year of abnormally low precipitation. Drought conditions are rarely as widespread in the state as they are now. But a discovery about the fate of ancient civilizations shows that dangerous cycles can repeat.
For more than a thousand years, American Indian cultures had farmed and built villages in Utah, Colorado, New Mexico and Arizona. They built beautiful cliff dwellings out of sandstone. They constructed dams and irrigated their crops, raised turkeys and grew corn, beans and squash.
But they abandoned their cities around the year 1300. What happened to them was long a mystery to archaeologists.
Now the popular held theory is that they were driven from the land by a severe sustained drought lasting at least several decades.
It wasn't the last time a section of Utah was abandoned because of dry conditions.
Severe drought struck the inhabited section of western Utah from 1895 through 1907.
"There were 25,000 people who lived on what I call the west desert," said Donald T. Jensen, the state climatologist, based at Utah State University, Logan.
He wasn't talking about places in the salt flats where nobody lived. These are farming towns like Vernon in Tooele County and Grouse Creek in Box Elder County.
When the drought dragged on, "those 25,000 people were driven off that land."
The picture is muddied somewhat, Jensen says, because around the same time the U.S. Forest Service changed the homesteading rules, which also likely played a role in depopulating that section of Utah.
"But it really did happen, and those people left."
Will it happen again? Probably not this time around.
Conditions are changing in the Pacific Ocean, where most of the U.S. weather systems originate. The latest drought outlook called for drought to continue in parts Utah and Arizona into July, but then conditions may change.
"From then on, though, if we get normal thunderstorms . . . we should see at least some improvement," said LeComte of the Climate Prediction Center.
"For the longer term, it looks pretty good for next winter in the Southwest."
E-mail: bau@desnews.com