February in the West
In contrast with January’s procession of storms, high pressure was present over the West much of this month. Persistent ridges yielded above normal temperatures and below normal precipitation for much of the region. In contrast with the anticipated strong El Niño wintertime precipitation pattern (dry in northwest, wet in southwest), southern California and Arizona were much drier than normal while western Washington, northern Idaho, and eastern Montana observed above normal precipitation this month.
February temperatures were quite warm in many areas of the West, especially in Montana and Wyoming where average daily temperatures exceeded 20 F (11 C) above normal on several days. Miles City, Montana saw its warmest February at 37.5 F (3 C), 13.1 F (7.3 C) above normal, where records began in 1937. Temperatures in Worland, Wyoming averaged 33.4 F (0.8 C), 9.2 F (5.1 C) above normal, the 4th warmest February since records began in 1960. To the southwest, Los Angeles, California, averaged 64.9 F (18.3 C), 6 F (3.3 C) above normal and 2nd warmest in a 140-year record. Nearby Camarillo reported its warmest February since records began in 1952 at 62.5 F (16.9 C), 8.8 F (4.8 C) above normal, and also observed its highest February temperature on record at 91 F (32.8 C) on the 9th and 15th. San Diego noted its warmest February on record at 63.9 F (17.7 C), 6 F (3.3 C) above normal, where records began in 1939. In Phoenix, Arizona, temperatures averaged to 65.7 F (18.7 C), the second warmest February on record. Phoenix also observed its earliest day reaching 90 F (32.2 C) on February 17; the previous record was February 24 in 1904 and 1986. Portions of the eastern Great Basin and southern Utah experienced cooler than normal temperatures, likely due to strong inversion conditions that developed under the high-pressure ridge. Temperatures in Deseret, central Utah, averaged to 27.7 F (-2.4 C), 5.2 F (2.9 C) below normal.
Precipitation throughout California was below normal this month, raising concerns for water resources and drought amelioration. Shasta Dam, on California’s largest reservoir, observed 2.99 in (76 mm), 26% of normal and its 15th driest February since records began in 1943. Southern California was very dry, where San Diego received a scant 0.05 in (1 mm), 2% of normal and the 3rd driest February since records began in 1933. Elsewhere in the Southwest, Phoenix observed no precipitation this month, as in six other years in its 84-year record. Normal precipitation there is 0.92 in (23 mm). Below normal precipitation was also observed in parts of the Intermountain West. Pocatello, Idaho, reported 0.2 in (5 mm), 21% of normal and the 4th driest since records began in 1939. Dry and warm conditions depleted snowpack in much of the West. Sierra Nevada snowpack fell from 116% to 83% of average during the month. A majority of basins in the Intermountain West reported near-normal snowpack, though percentages also fell there during the month. Basins in northern Wyoming continue to report below normal snowpack as in January. Expansion of drought conditions this month was limited to only small areas of Arizona, New Mexico, and Wyoming.
By contrast, western Washington, eastern Montana, and Colorado’s Front Range observed slightly to well above normal precipitation. Seattle recorded 5.97 in (152 mm) rainfall, 170% of normal and 10th wettest February since records began in 1945. Near normal Cascades snowpack in concert with a wet January helped to ease drought conditions in far northern California and southern Oregon. Parts of Colorado east of the Rockies were also moist; Colorado Springs had its 4th wettest February in a 69-year record at 1.0 in (25 mm), 294% of normal. Boulder observed 21.8 in (55 cm), the 12th snowiest since 1893. In southeastern Montana, Moorhead recorded 1.02 in (26 mm) precipitation, 408% of normal, the 3rd wettest February since records began in 1958.
Alaska was significantly warm for a second consecutive month. Barrow and Anchorage both observed their 4th warmest February on record at -4.1 F (-20 C) and 29.9 F (-1.2 C), respectively. The December-February period has been the warmest on record at Barrow and 2nd warmest at Anchorage. Dry conditions prevailed across Interior and Western Alaska, though some areas in the south were above normal. Kodiak’s 12.88 in (327 mm), was 210% of normal and 2nd wettest February since records began in 1931. In Hawaii, dry conditions persisted this month, typical of an El Niño winter. Honolulu observed 0.40 in (10 mm) of rainfall, 20% of normal and the 6th driest in a 77-year record. The last 3 months have been the driest December-February period on record for Honolulu.
Significant Events for February 2016
February 15-19: Warm weather triggers snowmelt, flooding in central Washington and eastern Nevada: Minor to moderate flooding occurred along the Yakima River and its tributaries in response to snow melt driven by warm conditions. In eastern Nevada, well-traveled rural roads in Elko County saw minor to moderate flooding due to snow melt. Flooding is not uncommon in these areas, but is typically a springtime phenomena. February (throughout month): Brush fires in Hawaii: A brush fire started on the 15th on the south slopes of Haleakala, Maui, and burned roughly 5,500 acres (2225 hectares), with flare-ups still occurring near the end of the month. On Big Island, brush fires consuming more than 300 acres (121 hectares) occurred in South Kohala on February 11. February 18: Avalanches in Lake Tahoe area: Following 2+ feet (61+ cm) of new snowfall dangerous avalanche conditions were present in the Sierra Nevada in the vicinity of Lake Tahoe. Two vehicles were partially buried on Alpine Meadows Road and several ski resorts were closed or delayed in opening due to avalanche hazards.