Western Regional Climate Center


June in the West

June of 2011 brought unprecedented extremes of wet, dry, snow pack, and atmospheric humidity to the western United States.

Temperatures were cooler than normal throughout the West except for the southeast portion of the region where temperatures were slightly to well above normal. At Clayton New Mexico 2011 brought the warmest June on record 75.9 F (24.4 C), which was 6.0 F (3.3 C) above average. The previous warmest June was one year ago.

Precipitation was far above its usually low normal in central and northern California, and continued to be above normal especially in eastern Montana. Other wet pockets were found in the northern Great Basin and the Wasatch. Even with a rainless month in the desert, preliminary figures show that California experienced its statewide wettest June on record (1895+). At San Francisco downtown, the month was the 2nd wettest June (behind 1884) in a record that begins in July 1849. The southern part of the region was significantly drier than its meager normal, where preliminary figures show that New Mexico experienced its driest June since 1895. The station at Carlsbad New Mexico reported no precipitation for the 223 days preceding June 2, received a scant 0.01” on that day (0.2 mm), and then no rain for the rest of June.

The cool temperatures of the month greatly reduced the melt rate of the deep snowpack that affected most mountain locations outside of Arizona and New Mexico. This has significantly extended the snowmelt season, and the associated streamflow runoff season, far into the summer, with record late runoff, and floods exceeding the flood of record in many small basins in Utah and Colorado. Heavy precipitation combined with deep snow and cool temperatures led to melted snow and rain producing record releases from Fort Peck Reservoir in Montana, by far the greatest flows on the Missouri River since the dam was closed off in 1937.

Significant Events for June 2011

June 4-6, 28-29: Heavy Rain in California. Two unusually wet late season storms produced heavy rainfall in parts of California from the 4th to the 6th and again on the 28-29th. Santa Barbara recorded their wettest June on record dating back 108 years and Sacramento Airport broke their June record dating back 70 years with 1.50 inches (38.1 mm). Precipitation was spotty, but some locations in the northern and central parts of the state (coastal and inland) recorded over 4 inches (102 mm) of rain for the month breaking numerous long-term records for June. On average, most of the state receives little or no rain at all for June.

June (all month): Arizona Wildfires. Extremely dry and windy conditions fanned numerous wildfires in Arizona. The Wallow fire began on May 9th near Alpine, AZ, and eventually erupted into the largest fire in Arizona history with nearly 3,500 personnel involved in the fight at one time. By the end of June the fire had burned over 538,000 acres (218,000 ha) and was 82% contained. Thirty-two residences had been destroyed and numerous road closures on state and federal Highways 180, 191, 261 and 373 had occurred. The fire eventually spilled over into New Mexico. The Horseshoe 2 fire in Southeast Arizona started on May 8th near Chiracahua National Monument had burned 223,000 acres (90,000 ha) until its containment on June 25th. Nine residences and 14 outbuildings were damaged or destroyed.

June 26: Los Alamos, NM, wildfire. The Las Conchas fire near Los Alamos began June 26th and quickly spread to over 103,000 acres (42,000 ha) by the end of the month. The fire has threatened the town of Los Alamos and the National Labs and was only 3% contained as of July 1. The city of Los Alamos remained evacuated as of month end.

June 27: Extremely Dry Air, Las Vegas NV. Las Vegas recorded a temperature of 107 F (41.7 C) and a dew point temperature of -22 F (-30 C) late in the afternoon, for a dew point depression record of 129 degrees F (53.9 C) and relative humidity of 0.6% . This is the driest air ever recorded in this desert city, and may be the driest recorded at any climate station in United States history. Death Valley may have exceeded this low humidity, but only sporadic atmospheric moisture measurements exist for that location.

June(all month): Western Flooding. Heavier than normal precipitation and spring snowmelt caused June flooding in Idaho, Montana, Utah, and Washington. Montana flooding resulted in Presidential Disaster Declaration for 31 counties and 4 tribal reservations with damages estimated at $8.6 million through month end.

June 2011 Departure from Normal Temperature and Percent of Normal Precipitation for Western United States

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