February in the West
Persistent ridging over the West Coast this winter weakened at times in February, allowing much-needed precipitation to reach the coastal states. Nevertheless, ridging prevailed over the West Coast this month, keeping temperatures warmer than normal over the Southwest and driving moisture into the Rocky Mountain region.
The coastal states and northern Great Basin finally saw significant precipitation this month after dry conditions dominated for much of the winter season. A tap into subtropical moisture called an atmospheric river provided abundant rain and snow to northern California and southern Oregon between the 7th and 9th. Totals in northern California’s coast range exceeded 20 in (508 mm), and over 10 in (254 mm) of rain fell along the western slope of the Sierra Nevada. A second atmospheric river pushed moisture into Washington and Oregon from the 12th -16th. Seattle, Washington and Medford, Oregon both saw their 7th wettest Februarys at 6.11 in (155 mm) and 4.55 in (116 mm), respectively. Seattle’s records began in 1948 and Medford’s in 1911. Further east, Boise, Idaho logged 2.2 in (56 mm) precipitation for the month for its 3rd wettest February in the past 75 years. To the south, Elko, Nevada received 1.92 in precipitation (49 mm) for the month, 229% of normal and the 9th wettest February in a 127-year record. A third atmospheric river favored central and southern California over the last few days of the month with storm totals of 3-4 in (75-100 mm) observed at low elevations and totals in excess of 10 in (254 mm) in the coastal ranges. These storms allowed snow water equivalent in the Sierra Nevada to increase from 15-20% of normal at the end of January to 30-50% of normal by the end of the February. Snowpack in the northern Cascades reached over 100% of normal at month’s end, a significant improvement on the 45-75% of normal observed at the end of January. Drought conditions improved in the Pacific Northwest and northern Great Basin, though expanded in California.
This winter’s wetter than normal conditions continued for the Rocky Mountain region. Billings, Montana saw 37 in (94 cm) of snow this month, 30.8 in (78 cm) above the February normal and the highest February total since records began in 1934. It was also Billings’ wettest February on record with a total 2.06 in (52 mm) precipitation, 429% of normal. Missoula, Montana recorded an impressive 40.2 in (102 cm) of snow this month for the second highest February snowfall total in 120 years of records. This February was also Missoula’s second wettest with 2.43 in (62 mm). Cold temperatures accompanied the precipitation; Missoula had its 7th coldest February with an average 20.6 F (-6.3 C) and Billings tied for 6th coldest with 18.7 F (-7.4 C). With the exception of their extreme southern extent, snow water equivalent is above average throughout the Rocky Mountains. In contrast, the dry conditions seen in January continued this month in the Southwest. Phoenix, Arizona recorded no measurable precipitation this month, tied for driest February with four other years since 1933. Areas of drought expanded and increased in severity in southern Arizona and eastern New Mexico.
Ridging over the Southwest this month resulted in warmer than normal temperatures. In southeastern California, several locations logged their highest February temperatures on record. Bishop hit 81 F (27.2 C) on 13th to tie February 27, 1986 for the highest February temperature in a 120-year record. Temperatures soared to 84 F (28.9 C) in Palmdale on both the 13th and 14th, the highest February temperature recorded since records began there in 1934. Fresno recorded its warmest February in a 67-year record with an average 56.8 F (13.8 C). Further east, Tucson, Arizona saw its second warmest February on record with an average 60.7 F (15.9 C). This winter (December-February) was the warmest in Tucson’s 85-year record at an average 57.0 F (13.9 C), 3.8 F (2.1 C) above normal.
Much of Alaska received less than 70% of normal precipitation this month. McGrath tied for 8th driest February in a 74-year record with 0.09 in (2 mm). The eastern Interior and North Slope saw totals slightly above normal. In Hawaii, the greatest positive departures from normal precipitation were observed in the northwestern part of the state. Lihue, Kauai recorded 8.69 in (221 mm) of rainfall this month, 5.53 in (140 mm) above normal and the 5th wettest February since records began in 1950.
Significant Events for February 2014
February 7-10: Freezing rain in Portland, Oregon area: Several days of snow followed by freezing rain impacted travel over several days in the Portland area. The storm also caused power outages, falling trees, and prompted school closures.
February 26-28: Flooding in southern California: Flooding and mudslides prompted evacuations in the Colby Fire burn area near Glendora and closures along the coastal Highway 1 near Malibu and Carmel. Three rescues occurred on the Los Angeles River, and 15,000 Los Angeles area residents were without power for a period during the storm.
February (all month): Drought conditions persist in California: By February 25, 26% of the state was categorized as D4, ‘exceptional drought’ according the US Drought Monitor. At the beginning of 2014, no portion of the state qualified for this category. Most of this D4 region lies in the central part of the state, which received significant precipitation over the last few days of the month, so it is anticipated improvements will be seen in next week’s iteration of the Drought Monitor. Rangelands are in very poor condition and hundreds of thousands of acres of agricultural land will likely be fallowed this growing season.