March in the West
A persistent blocking pattern developed over the US approximately ten days into March, maintaining cool and record wet conditions in the Pacific Northwest while the eastern two-thirds of the country experienced historic and unprecedented warmth.
Cool temperatures prevailed most of the month along the Pacific coast, in contrast to the record highs east of the Rockies. During the first week of March, a strong upper level ridge brought record highs to coastal states. Temperatures reached 91 F (32.7 C) in Long Beach, California and 63 F (17.2 C) in Ephrata, Washington on March 4. The brief period of warmth along the coast was followed by a “march” of storms that kept temperatures cool, with several record lows set in the Pacific Northwest in the latter half of the month. Frigid temperatures dominated Alaska this month as well, with many record lows throughout the state. Fairbanks, Alaska saw no temperatures above freezing all month; the only other sub-freezing March occurred in 1919.
Farther inland, many locations saw their warmest March on record. In eastern Montana, Billings recorded an average monthly temperature of 47 F (8.3 C), the warmest March on record since 1934. To the south, Cheyenne, Wyoming saw its warmest March since 1872 with an average temperature of 44.6 (7 C); the previous record of 44.4 F (6.9 C) occurred over a century ago in 1910. Salt Lake City, Utah, with a monthly average of 49 F (9.4 C), observed its second warmest March since 1948. Denver, Colorado experienced its second warmest March since 1872 with an average of 49.2 F (9.5 C). The warmest March on record at Denver was observed in 1910, with an average 50.4 (10.2 C) for the month. Temperatures in the Southwest were moderate, with most temperature departures within 1 F (0.6 C) of normal.
The West exhibited a strong gradient of precipitation totals this month, from inundating rains and snowfalls in the Pacific Northwest to record dryness east of the Great Basin. Some of the greatest precipitation totals were observed in Eastern Washington and the Idaho Panhandle. Kellogg, Idaho received 9.01 in (228.9 mm) of precipitation in March, surpassing the 1916 record of 6.45 in (163.8 mm). March 2012 was also the 5th wettest month (inclusive of all months) on record at this location. Spokane, Washington received 4.4 in (111.76 mm), eclipsing the previous March record of 3.81 in (96.8 mm) in 1995. Portland, Oregon, which received 7.89 in (200.4 mm) of precipitation, also experienced its wettest March since the record began in 1940. Further south, snowpack in the Northern Sierra greatly improved, bumping from 34% of normal on March 1 to 78% of normal by month’s end. The Central and Southern Sierra showed slight improvement in snowpack, but still limped along at 51% and 39% of normal, respectively as the month came to a close. Hawaii also experienced heavy rainfall and flooding this month; Lihue, Kauai recorded its second wettest March on record since 1950 at 18.17 in (461.5 mm).
On the drier side of the West, Cheyenne, Wyoming and Denver, Colorado both experienced their most arid March on record. Cheyenne received only trace precipitation, beating out the previous March low of 0.06 in (1.5 mm) in 1882. Denver recorded 0.03 in (0.8 mm), significantly less than the previous record low of 0.11 in (2.8 mm) in 1908. Further north, Havre, Montana received 11.9 in (302.3 mm) of snow, 1.91 in (48.5 mm) snow water equivalent, on March 19, accounting for more than half of its water year precipitation total of 3.25 in (82.6 mm). Most of the Southwest received all their precipitation in one event, spanning March 17-19. During this event, Flagstaff, Arizona received 26.4 in (670 mm) of snow, more than a quarter of its season-to-date snowfall of 92.5 in (234.9 cm). Phoenix received its only measurable rainfall for the month on March 18th, giving a total of 0.25 in (6.4 mm) and tying for 34th driest year on record.
Significant Events for March 2012
March 2-9: Hawaii heavy precipitation and tornado event: Heavy precipitation and flooding occurred over the islands of Kauai and Oahu during this period, as well as large hail on Kauai, Oahu, Maui, and Big Island. Hail up to 3 in (76.2 mm) in diameter was reported in Kaneohe, Oahu. Several precipitation records were set at Lihue, Kauai. An EF-0 tornado caused moderate damage in the communities of Enchanted Lakes and Lanikai near Kailua, Oahu on the morning of the 9th.
March (throughout month): Avalanche fatalities: Several fatalities occurred this month due to snow avalanches triggered by skiers and snowmobilers in the backcountry. Locations included mountains near Haines, Alaska; Jackson Hole, Wyoming; and Lake Tahoe, California. Mild temperatures, strong winds and intermittent snowfall made for dangerous avalanche conditions this month in much of the West.
March 20-21: Historic Oregon Snowstorm: Snow fell almost to sea level at locations from Portland to Eugene, Oregon. Eugene airport saw an impressive storm total of 7.5 in (190.5 mm), breaking the previous record late snowfall of 7.6 in (193 mm) on March 5-7 1951. Portland airport recorded 0.5 in (12.7 mm) snowfall for the storm total, breaking the previous late season snowfall on March 15 1946 of 0.6 in (15.23 mm). On average, Portland receives a total of 0.2 in (5.1 mm) snow in March.