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Published July 25, 2012
Monsoon Summary(data through 7/14/12)
Data Source(s): Western Regional Climate Center
The monsoon is off to a strong start, delivering substantial precipitation in many locations in southern Arizona. While the early and frequent rainfall in parts of the Southwest bodes well for above-average total monsoon rainfall, the season is only a month old. With two months remaining, a promising start can fade. In other words, it is too early to tell if this monsoon will be a boom or a bust.
Between June 15 and July 14, most of southern Arizona and northwest New Mexico received above-average rainfall (Figures 9a–c). The highest rainfall totals for this period reported from official weather stations occurred on the border between central Pima and Pinal counties in Arizona.
In Tucson, several storms have produced very high, localized precipitation, with amounts exceeding 3 inches—values that have been reported on www.rainlog.org, a citizen science effort to record daily precipitation across the Southwest. Other weather stations across southeast Arizona reported above-average rainfall between June 15 and July 18. These include 3.85 inches at Tucson International Airport (1.22 inches is average); 4.19 inches at Nogales International Airport (2.71 inches is average); 3.81 in Wilcox (1.54 inches is average); and 1.33 at Picacho Peak (0.43 inches is average). For more rainfall statistics in Arizona, see: http://www.wrh.noaa.gov/twc/monsoon/rainfall.php.
The southwestern part of Arizona has benefited from Gulf of California surges that have ferried moist near-surface air into the region. However, the corner of southeast Arizona has not fared as well, in part because it imports moisture from southwest New Mexico, which has been dry so far.
The better-than-average start to the monsoon conforms to the NOAA-Climate Prediction Center (CPC) forecast issued in mid-June, which called for elevated chances for above-average rainfall in July. Looking ahead, the CPC forecast for August again calls for elevated chances for above-average rain. However, other forecasts noted that August rain might not be as vigorous as it was in July (see http://www.climas.arizona.edu/feature-articles/jun-2012).
The continuous color maps (figures above) are derived by taking measurements at individual meteorological stations and mathematically interpolating (estimating) values between known data points. Interpolation procedures can cause aberrant values in data-sparse regions.
Average refers to the arithmetic mean of annual data from 1971–2000. Percent of average precipitation is calculated by taking the ratio of current to average precipitation and multiplying by 100. Departure from average precipitation is calculated by subtracting the average from the current precipitation.
These data are obtained from the National Climatic Data Center: :
Southwest Climate Outlook Staff
- Michael Crimmins, UA Extension Specialist
- Stephanie Doster, Institute of the Environment Editor
- Dan Ferguson, CLIMAS Program Director
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, CLIMAS Associate Staff Scientist
- Gigi Owen, CLIMAS Assistant Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Swetish, CLIMAS Publications Assistant
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
The CLIMAS Web site contains official and non-official forecasts, as well as other information. While we make every effort to verify this information, please understand that we do not warrant the accuracy of any of these materials.... Read full disclaimer