Western Regional Climate Center

PROVIDING CLIMATE SERVICES SINCE 1986

May in the West

May 2014

Unsettled spring weather continued this month with periods of high pressure and above normal temperatures interrupted by the passage of several weak low-pressure systems. Temperatures were generally near normal throughout the West, with a gradient from slightly above normal along the coast to slightly below normal in the Rocky Mountain states. Scattered areas of above normal precipitation dotted the West this month, though a majority of the region saw drier than normal conditions.

Following several months of above normal precipitation, most of the Inland Northwest saw less than 75% of normal in May. Idaho Falls received only 0.17 in (4 mm) of precipitation, 11% of normal, and the fourth driest May in a 67-year record. Dry conditions continued for much of California, especially the coastal regions. Much of the San Francisco Bay Area received less than 0.1 in (3 mm) for the month. San Jose recorded no measurable rainfall in May, tie for driest with 21 other years in its 122-year record. Further south, Paso Robles and Los Angeles also received no measurable precipitation. May is typically the tail end of the precipitation season here and brings little relief from drought. In 121 years at Paso Robles and 138years at Los Angeles, 32 and 39 other years, respectively, saw no measurable May precipitation. Also in the Southwest, Arizona experienced typically dry conditions. Tucson averages 0.23 in (6 mm) of rainfall in May but received none this month; however, the same is true for 41% of Mays in the station’s 120-year record. Snowpack continued to dwindle in the Sierra Nevada and Great Basin, while holding near to above normal in the northern Cascades and northern and central Rockies. Below average streamflow is expected throughout the Great Basin, while copious runoff is anticipated on both sides of the Continental Divide in early summer.

A slow-moving low-pressure system towards the end of the month brought beneficial precipitation to the drought-stricken western Great Basin as well as portions of the Four Corners states. Reno, Nevada saw above normal monthly precipitation for the first time since August 2013 with a total of 0.54 in (14 mm), 110% of normal. Bishop, California received 0.24 in (6 mm) of precipitation, 126% of normal. This low helped to drive moisture from the Gulf of Mexico northward into New Mexico, resulting in heavy precipitation in the eastern portion of that state on the 23rd and 24th. Roswell received 4.44 in (112+ mm) on the 24th, making for the wettest single day in the past 69 years. Roswell received 4.45 in (113 mm) for the month, 281% of normal and the 2nd wettest May on record. Moab, in eastern Utah had its wettest May in a 121-year record at 2.65 in (67 mm). In the Pacific Northwest, areas within and west of the Cascades saw abundant precipitation this month as well. Seattle recorded 3.15 in (80 mm) for the May, the 8th wettest since records began in 1948.

Warmer than normal temperatures dominated coastal areas of the West this month. In Southern California, Santa Maria experienced its warmest May in a 67-year record at an average 64.0 F (17.8 C), 6 F (3.3 C) above normal. This included a recording of 105 F (40.5 C) on the 15th, the highest May temperature and the second highest all-time temperature observed in Santa Maria. Further up the coast, temperatures at North Bend, Oregon, averaged to 56.8 F (13.8 C) for May, 3.9 F (2.2 C) above normal and the fourth warmest since records began in 1902. Elsewhere in the West, average May temperatures were 1-4 F (1-2 C) cooler than normal in the Four Corners region and northern Montana.

Precipitation was variable across Alaska this month. Above average precipitation was observed along the North Slope, where Barrow recorded 0.9 in (23 mm), the wettest May in a 113-year record. Temperatures were warmer than normal for much of the state, especially in the northern and southern coastal areas. The average temperature at Anchorage this month was 52.1 F (11.2 C), 4.3 F (2.4 C) above normal and the warmest May since records began in 1952. Further south, precipitation was near to above normal throughout Hawaii. On Oahu, Honolulu received 3.35 in (85 mm) of rainfall, the 6th wettest May in a 65-year record. Molokai Airport had its 3rd wettest May since records began in 1949 with 4.51 in (115 mm), 406% of normal.

Significant Events for May 2014

May 26: Large landslide near Collbran, Colorado: Following two days of heavy rain, a landslide one-half mile (0.8 km) wide and three miles (4.8 km) long occurred in a remote area of western Colorado. Three people were killed in the slide.

May 20 and on: Slide Fire, north of Sedona, Arizona: This fire burned over 21,000 acres (8498 hectares) and was 90% contained at the end of the month. The cause of the Slide Fire is still under investigation. The fire reduced air quality in surrounding areas as well as prompted the evacuation of hundreds of people and many road closures.

May 19 and on: Funny River Fire, Kenai Peninsula, Alaska: This human-caused fire burned over 193,000 acres (78,104 hectares). At month’s end, fire containment was at 58% with over 700 firefighters were working on the fire. No homes were lost and no casualties occurred, but many people had to evacuate, some recreational areas were closed, and burn bans were in effect for two weeks.

May 13-17: San Diego County Wildfires: At least 10 wildfires broke out between May 13 and 15, burning more than 20,000 acres (8093 hectares). The fires destroyed over 20 homes and businesses and tens of thousands were evacuated from their homes. The blazes were fanned by strong Santa Ana winds.

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