Colorado: Will El Niño be a drought buster?

Drought likely to persist for several more months

The National Climatic Data Center temperature map for June 2012 clearly shows the extraordinary heat centered over Colorado.

By Summit Voice

SUMMIT COUNTY — A tilt toward El Niño conditions in the Pacific Ocean could start putting a dent in the western drought, according to the latest update from the Western Water Assessment climate summary.

El Niño, when sea surface temperatures in the equatorial Pacific climb above average, can help deliver average to above-average summer and fall moisture to Colorado and the Intermountain West, including drought-busting September rains in 2003 that helped end Colorado’s last serious drought.

El Niño doesn’t guarantee a wet winter. During many previous episodes, mid-winter conditions have been relatively dry, as the main storm track dives far to the south. But springtime during an El Niño phase can deliver copious precipitation to the Front Range and to the mountains along, and just east of, the Continental Divide.

The climate summary for June 2012 draws a number of comparisons to conditions in 2002, when conditions were even more dry across parts of western Colorado.

2002 extreme drought conditions were more widespread across Colorado than they are this year.

The early surge of monsoonal moisture in Colorado helped take the edge of dry conditions and reduced the fire danger, but won’t completely alleviate drought conditions.

Percent of average precipitation for the current water year to date, current year on the left, 2002 water year on the right.

Parts of eastern Colorado saw up to 5 inches of rain in early July, but much of the state has moisture deficit built up over several months. Near-record and record-high temperatures in preceding months resulted in a significant moisture deficit that can’t be erased by a few summer thunderstorms.

Altogether, the March-May period was the 2nd warmest spring in Colorado in the past 118 years, the 3rd warmest in Wyoming and the 8th warmest in Utah. This extended warmth hastened the meltout of the already-low snowpack.

June 2012 continued the streak of warm months, with temperatures 2–8 degrees above average across the region. The hottest area was eastern Colorado, with many record daily highs in late June, including a tie for the all-time highest statewide temperature for Colorado with 114°F in Las Animas on June 23.

Above-average temperatures were much more widespread in the West this year as compared to 2002.

Around the Intermountain West (and clearly visible in Summit County), ranchers reported that there was no real green-up, with pasture losses reported at 70 to 90 percent in some areas, especially in northwest and northeast Colorado.

On July 3, the US Department of Agriculture made a a disaster declaration for 62 of 64 Colorado counties due to crop and livestock production losses, following similar declarations in late June for four counties in Wyoming.

The bottom line is that, despite the early July rains, drought conditions  persist in Colorado and across the region. Given the magnitude of the precipitation departure and water supply deficit, drought impacts will likely persist for months to come, according to the assessment.

“While NOAA has not yet officially declared an El Niño event, it has hoisted an ‘El Niño Watch,’ indicating that sea surface temperatures in key areas in the tropical Pacific averaged over a 3-month period are nearing the thresholds for declaring an event “

 

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