Western Regional Climate Center


July in the West

July of 2011 saw a continuation of much below normal temperatures in the Pacific Northwest, and much above average temperatures in New Mexico. Precipitation was above average in the coastal Northwest, and in parts of the Southwest, and below average in a broad swath from California through Montana and Wyoming. The Southwest monsoon began about on schedule and brought a mixed precipitation response.

Temperatures were slightly below normal throughout the coastal West, with record lows set or tied throughout Oregon, Washington, and Utah. Seattle saw four record-breaking daily lows during the month. The most significant were lows of 50 F (10 C) on July 9th and 23rd, below former records of 53 F (12 C). They did see one record high of 79 F (26 C) on the 6th, above the former record of 77 F (25 C). During this cool month Meacham, Oregon fell to a daily record 31 F (-0.6 C) the 23rd, over a period that begins in 1929. Many daily records for coolest high temperature were also set throughout the Pacific Northwest in July. Temperatures were slightly to well above normal in New Mexico, Colorado, Wyoming and southeast Montana.

The Pacific Northwest also experienced several rainfall records during what is normally the driest month of the year. On the 18th downtown Portland, Oregon received 0.82 inches (20.8 mm), exceeding the previous record of 0.53 inches (13.5 mm) set in 1974. The next day Medford, Oregon topped its previous daily record of 0.36 inch (9.1 mm) with 0.48inches (12.2 mm). The Southwest remained generally drier than normal, though monsoon activity began this month, bringing scattered relief from drought conditions.

Significant Events for July 2011

July 2-4, Late skiing. Four Lake Tahoe area ski resorts were open for the 4th of July weekend for the first time since the mid 1990’s. Other resorts were also open for holiday skiing in Oregon, Colorado, and Utah.

July 5, Arizona Dust Storm: Monsoon activity began in Arizona this week following a period of drought. Strong thunderstorm downdrafts kicked up dry, loose sand forming a dust storm 5,000 feet (1500 m) deep moving at up 50 mph (80 kph) and 100 mi (161 km) long on its leading edge. The dust storm traveled 150 to 200 miles (241 to 322 km) from Tucson to Phoenix. Visibility was reduced to between 0 and 5 feet (1.5 m) causing flight delays and interrupting ground travel. Trees and power lines were knocked down but no injuries were reported. Numerous videos captured this visually arresting event.

July 14, Utah Flooding: Heavy rains associated with thunderstorms and arrival of a moist air mass combined with rapid snowmelt to produce flooding in the Western two-thirds of Utah. Many streams and rivers along the south aspect of the Uinta Mountains, notably the Duchesne River, remained at or above flood level for several days. Near Tabiona, Utah, a portion of State Highway 35 a washout during the night caused two vehicles to drive into a gulch, and led to a fatality.

July (all month), Las Conchas Fire in New Mexico: The Las Conchas Fire near Los Alamos began on June 26, and continued to burn throughout the month of July. The fire consumed 156,593 acres and destroyed 63 residences. Smoke from the fire has caused poor air quality in surrounding areas throughout the month. As of July 31, the fire was 99% contained. Flash flooding occurred in burned areas July 21 and 22 as a result of monsoon activity in the area. Two weather stations in Valles Caldera recorded the passage of the flame front, but escaped major damage because of low vegetation.

July (all month), Severe drought: The Southwest experienced moderate to exceptional drought during the month of July. In New Mexico sixteen counties declared a natural disaster due to exceptional drought. Wildfires and severe water shortages were experienced across the state. Twelve counties in Colorado received similar declarations, and disaster status is sought after for six additional counties. Low crop yields are expected for Colorado farmers, and livestock production is becoming expensive due to lack of grasses and supplemental feeding.

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

© Western Regional Climate Center