Western Regional Climate Center


January in the West

January 2017

A progressive storm track featuring several moderate to strong atmospheric rivers produced impressive precipitation totals across the southern two-thirds of the West. In contrast, the northern tier of the region generally saw below normal precipitation. Temperatures were below normal across the Northwest, slightly above normal in New Mexico and the Four Corners region, and near normal elsewhere. Storms impacting the West this month brought beneficial precipitation to drought stricken areas of California and Nevada, as well as damaging floods, travel disruptions, and avalanche hazards. In the coastal mountains of northern California, Venado observed 48.83 in (1240 mm) of precipitation this month, 417% of normal. This shattered the previous monthly record of 29.88 in (759 mm) set in December 2002. Records for Venado began in 1948. Sierra Nevada snowfall was well above normal; Tahoe City, California, observed 136 in (345 cm) of snowfall, the 4th snowiest January since records began in 1903. Orientation and characteristics of these storms favored moisture to penetrate inland and impact the Great Basin and Southwest. In northwestern Nevada, Reno recorded 5.57 in (141 mm), 540% of normal and set the record for wettest of any month in the station’s history beginning in 1937. Further east, Pocatello, Idaho, reported 2.85 in (72 mm), 288% of normal and the 3rd wettest January since records began in 1939. Pocatello received 32.2 in (82 cm) of snowfall, the second highest of any month in the station’s record. In the Southwest, Las Cruces, New Mexico, reported a total of 1.57 in (40 mm), 307% of normal and the 3rd wettest January since records began in 1892. In contrast, Washington, northern Idaho, northern Oregon, and much of Montana observed below normal precipitation. Seattle, Washington, reported 4.22 in (107 mm), 76% of normal. At the end of January, most major mountain areas of the West were reporting above normal snow water equivalent (SWE); some basins in the Sierra Nevada and central Rocky Mountains reported SWE in excess of 150% of normal. The exception was the northern Rockies and northern Cascades. Snowpack in these areas was generally <80% of normal. The above normal precipitation and healthy snowpack contributed to improvement of drought conditions across much of California and Nevada as depicted in the US Drought Monitor. Areas of California’s South Coast that have been entrenched in extreme to exceptional drought since 2013 observed significant rainfall this month, improving conditions such that only a small area of extreme drought conditions remain. Los Angeles, for example, recorded 8.38 in (213 mm) for the month, 269% of normal and the 10th wettest January since records began in 1877. However, moderate to severe drought still covers nearly all of southern California due to long-term impacts. Areas of improvement were also noted in at least a small portion of all other contiguous western states. Cold air masses moved over the Northwest during the first half of the month, driving temperatures well below normal. Walla Walla, Washington, reported a monthly average of 22.2 F (-5.4 C), 13.3 F (7.4 C) below normal. This was the 5th coldest January in Walla Walla since records began in 1949. In Missoula, Montana, temperatures averaged to 13.8 F (-10.1 C), 12 F (6.7 C) below normal, the 6th coldest January in a 69-year record. In contrast, New Mexico and surrounding areas observed temperatures 0-4+ F (0-2+ C) above normal. Gallup, in northwestern New Mexico reported an average temperature of 32.4 F (0.2 C), 3.7 F (2 C) above normal. Drier than normal conditions were observed across much of the state of Hawaii this month, with the exception of some Big Island windward locations. Lihue, Kauai, had its driest January on record, reporting only 0.2 in (5 mm) of rainfall, 19% of normal. Records for Lihue began in 1950. The dry conditions prompted expansion of “abnormally dry” in the US Drought Monitor from roughly 10% of the state at the beginning of the month to 54% of the state by the end of the month. In Alaska, temperatures were above normal in the northern third of the state and near to well below normal in the southern two-thirds. On the North Slope, Utqiaġvik recorded an average temperature of -0.3 F (-17.9 C), 13.1 F (7.3 C) above normal, the 3rd warmest January in its 98-year record. In the Southcentral region, Kenai reported an average temperature of 9.1 F (-12.7 C), 7.3 F (4 C) below normal. Many locations across Alaska observed near to above normal precipitation. Utqiaġvik reported 0.47 in (12 mm), 361% of normal. Further south, 1.71 in (43 mm) of precipitation fell in Anchorage, 234% of normal and the 3rd wettest January on record. This was also the 2nd snowiest January for Anchorage at 31.7 in (80.5 cm); records began in 1952. In the Southeast, precipitation was near normal, though much fell as rain rather than snow, continuing a trend of below normal snowfall seen in recent years.

Significant Events for January 2017

January 6-8: Major storm produces flooding, mudslides, and avalanches in northern California and western Nevada: A strong atmospheric river storm produced heavy rain on snow that contributed to flooding along the Truckee River and other waterways in the Sierra Nevada, northeastern California, and western Nevada. Over 1000 homes in the Reno area were evacuated and many commercial and residential areas saw minor to moderate flooding. Mudslides caused prolonged road closures on Interstate 80, Highway 17, and Highway 1 in northern California. January (all month): Snow-related hazards in the West: The storm sequence this month has been conducive to extreme avalanche danger in many areas of the West. Avalanches have closed roads in the Sierra Nevada several times this month, and three fatalities were reported across the West. Heavy snows and cold temperatures also caused building collapses in many locations in the West, impacting businesses and human safety.

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