Climate: Intermountain West warm & dry in September

Warmer than average temperatures prevailed across much of the intermountain West during September.

Mild autumn expected to continue

By Summit Voice

SUMMIT COUNTY — September temperatures were above average across most of the intermountain West, with dry conditions prevailing, especially in Wyoming, northern Utah and southeastern Colorado, according to the monthly climate summary from the Western Water Assessment.

In parts of Wyoming and Utah, temperatures were as much as 4 degrees above normal, while pockets of cooler-than-average readings occurred in eastern Colorado.

September precipitation was below average across the region, especially in much of Wyoming, northern Utah, and southeastern Colorado, which recorded less than 40 percent of its average September precipitation. The only wet anomalies of note were in parts of southern Utah and east-central Colorado, where a single storm dropped a record-breaking 6 inches of rain on Colorado Springs.

Temperatures across northwestern Colorado, including Summit County, were 2 to 4 degrees above average.

For the 2011 water year ending Sept. 30, the region mostly experiences wetter-than-average conditions, with more than 150 percent of average precipitation occurring in much of northern and western Utah, southwestern Wyoming, and northwestern Colorado.

Most of this widespread wet anomaly occurred during the December–May period as the storm tracks consistently favored those regions, leading to record snowpacks in many mountain locations. Both Utah and Colorado experienced a strong gradient from wet conditions in the northwest to dry in the southeast, with southeastern Colorado seeing less than 70 percent of average precipitation for the water year.

September precipitation was below average across much of the Intermountain West, with a single rainstorm accounting for the blue blob of above average readings south of Denver.

After a large and moist storm system moved through the region during the first week of October, manyt high-elevation SNOTEL sites throughout the region showed well-above-average snow-water-equivalent readings for the date, with some sites in southwestern Colorado, northeastern Utah, and central Wyoming reporting up to 4 inches of snow-water equivalent.

An early October snowstorm resulted in some above-average readings at automate SNOTEL sites.

The full Western Water Assessment October report is online here.


2 thoughts on “Climate: Intermountain West warm & dry in September

  1. This article appears to be grasping at straws to make the case for the alleged global warming. I spent months in all parts of Wyoming this year and it was the greenest, wettest year I have seen in over 40 years of travel in that state. One month does not constitute a pattern. I encourage reporting of these statistics, but please acquire them in a manner that shows a clear trend, not “the world is ending because one month was dry!”.

    1. Not to quibble, but I report these and other stats on a regular basis, month by month. I just recently reported that Breckenridge reported its 4th-wettest year on record, going back more than 100 years.

      I’ve been reporting these stats for about 15 years, so that gives me a pretty good feel for trends, and the fact is, it’s getting warmer and drier. I think you’re the one who is cherry picking by saying that, since Wyoming happens to be wet and green for a few months, maybe there is no global warming.

      If you look just at Summit County temps as recorded by Denver Water at their Dillon station, there have only been two or three months in the past 10 years when temps have been below the 20th century average, and that holds true for most other official weather observation sites across the West.

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