February in the West
Weak upper level ridging over the West this month was interrupted by several weak to moderate storm events. By the final leap day, monthly average temperatures at most locations were within 2 degrees F (1 C) of their February normals. Among the generally seasonal temperatures this month were several warm days of note. Death Valley, California hit 91 degrees F (32.7 C) on February 23. The first normal occurrence of 90 degrees F (32.2 C) or better at this location is March 12, and temperatures greater than 90 F (32.2 C) in February have only occurred 12 times at this location since records began in 1911. The San Francisco Bay Area also recorded several record highs over this two-day period with temperatures in the mid-to-high 70’s (24-26 C). A less extreme warm outbreak occurred in the same region February 9 and 10. Most of Montana also saw large positive departures from normal the first and third weeks of the month. Cold systems passing through the second and last weeks of the month brought average daily temperatures of 6 to 8 degrees F (3-4 C) below normal into the region, moderating Montana’s otherwise strongly positive February temperature departure from normal.
Precipitation was scarce for much of the West this month. Prior to storm activity over the last four days of the month, only eastern Colorado, Wyoming, and scattered locations in the Pacific and Inland Northwest were at normal or above normal precipitation levels. Several locations in Colorado and Wyoming experienced precipitation over 300% of average for February. Julesberg, located in the far northeastern corner of Colorado, received 1.4 in (35.6 mm) of precipitation, making for the wettest February on its record dating back to 1893. Gillette, Wyoming also experienced its wettest February on record with a total of 1.56 in (39.6 mm). Records at this location began in 1902.
A series of storms February 26-29 brought further rain and snowfall to locations with already above average precipitation totals for the month in Wyoming, western Colorado, and portions of Montana. The end of February storm brought measurable precipitation to Northern California, Northern Nevada, Oregon, and Washington, but was not sufficient to bring monthly totals up to normal. The Southwest remained near dry through this event, with Phoenix tying its driest year-to-date on record with only trace precipitation recorded for February. Central California also experienced low precipitation totals; many locations saw 1% or less of average rainfall. Santa Barbara COOP station recorded only 0.07 in (1.78 mm), tying for the 14th driest February on a 116-year record at that location. The lack of rainfall this month allowed drought to persist in the Southwest and further develop in the Northwest.
One of the most notable climate features this month is the distinct lack of snowpack in the Sierra. As of March 1st, snow water equivalents for the Northern, Central, and Southern Sierra regions were at 38%, 32%, and 34% of normal for the date, respectively. Both the Northern and Central regions gained 4% of this total on the 29th; the Central Sierra did not break 30% of normal until the 29th. In terms of current snow water content percent of April 1 average, the Central Sierra just edged up to meet the driest year on record (1977) on February 29, while the Northern and Southern sections are holding only slightly above the 1977 percentages. In contrast, all of Colorado’s 8 major basins had received at least 78% of normal to-date snow water equivalent by March 1, though all were still below 90% of normal.
Significant Events for February 2012
February 13: Death Valley, California Dust Storm: Gusty winds behind a passing cold front initiated a 1000-2000 ft (300-600 m) deep dust storm in Death Valley National Park in Southern California. Park rangers remarked it was the fastest moving dust storm they have observed in the last 20 years.
February 21-22: High Winds in Rocky Mountain Front Range: Wind gusts of 60-90 mph (95-145 kph) occurred along areas of the Rockies Front Range. The winds downed power lines, leaving nearly 45,000 in central Colorado without power. Two wildfires also occurred in conjunction with the wind event. Three to five wind events of this sort are typical in this region each year.
February 25-26: Kauai, Hawaii Precipitation Event: Mt. Waialeale, Kauai received 7.52 in (191 mm) on February 26, an impressive portion of its February average of 24.63 in (626 mm). Lihue, Kauai received 6.39 in (162 mm) setting a daily record and also the record for the wettest February day at that location, previously 5.4 in (137 mm) on February 28, 1954. Hilo on the island of Hawaii also received significant rainfall. The islands have seen increasing drought for the past few months, so this heavy precipitation event provided welcome relief to dry conditions.
February 28-29: High Wind Event: A passing cold front and downslope flow brought prolonged high winds to many locations in the West. Wind gusts at Virginia Peak, Nevada reached 110 mph (177 kph). At Squaw Valley Ski Resort, winds reached 98 mph (158 kph). In California’s Owens Valley peak gusts hit 79 mph. Further north, a 78 mph (125 kph) gust was recorded near Cheyenne, Wyoming.