NOAA: Drought Worsened in Southwest, Southern Plains During Winter Season; Northwest Had Heavy Rains
The 2005-2006 winter season was the fifth warmest December-February period on record for the contiguous United States, according to scientists at the National Oceanic and Atmospheric Administration's (NOAA) National Climatic Data Center in Asheville, N.C. During the same time, drought conditions worsened in the Southwest and southern Plains, while the Northwest endured heavier-than-average precipitation.
Based on preliminary data, the average temperature for the contiguous United States for December-February was 36.3 degrees Fahrenheit (2.4 degrees Celsius). This was 1.2 degrees Fahrenheit (0.7 degrees Celsius) above the 1895-2005 mean, making it the fifth warmest winter on record. A record warm January dominated the winter average, with December and February near average nationally. The mean 2005-2006 winter temperature in 41 states was above -- or much above -- average, with only seven states near average and none cooler than the long-term mean.
Overall, winter precipitation was near average for the nation, however, extremely dry conditions prevailed throughout much of the Southwest and central and southern Plains. Much of the Far West and Northwest was much wetter than average for December-February. For Arizona, this was the driest winter on record and second driest on record for New Mexico and Oklahoma. Five other states (Texas, Missouri, Arkansas, Kansas and Nebraska) were much drier than average. At the end of winter, moderate-to-extreme drought (as defined by a widely-used measure of drought -- the Palmer Drought Index) affected about 25 percent of the contiguous United States. This is the largest combined area of drought in the nation since July 2004.
Exceptional drought was focused in an area from southern Texas through eastern Oklahoma, western Arkansas to southwest Missouri. As of March 6, Phoenix had reached 140 days without measurable rainfall, a string that eclipsed the previous record of 101 days, which occurred Sept. 23, 1999 through Jan. 1, 2000. Additionally, Tulsa, Okla., had its driest winter since records began in 1888, with just 1.59 inches of precipitation during the three-month period.
The dryness exacerbated wildfire activity that burned more than 500,000 acres across the country since January and approximately one million acres since the first of November, according to preliminary data from the National Interagency Fire Center in Boise, Idaho. The vast majority of wildfire activity has been in the southern Plains, particularly Oklahoma and northeast Texas, where lack of precipitation and much warmer-than-average temperatures have prevailed this winter. By contrast, a series of powerful Pacific storms hit the Northwest and parts of the West during December and January and four western states (Washington, Oregon, Idaho, and Nevada) were much wetter than average for the season.
Snowpack across the West reflected the general distribution of precipitation with parts of the Northwest at more than 150 percent of normal, while much of the Southwest had far less than 50 percent of normal winter snowpack at the end of February. Both Arizona and New Mexico have seen a nearly unprecedented lack of snowfall this season. In Flagstaff, Ariz., as of Feb. 28, only 1.6 inches of snow had fallen since autumn began. This contrasts with a normal snow total of 72.5 inches for the period.
Several significant snow storms impacted the nation during the winter, including a powerful storm that hit the East Coast on Feb. 11-12. Areas of New Jersey, New York and Connecticut received more than 20 inches of snow during the event, which was classified as a Category 3 ("major") snow storm by the new Northeast Snowfall Impact Scale.
Also during the winter, Tropical Storm Zeta developed near the end of December becoming the 27th named storm during the record-setting 2005 Atlantic hurricane season. It weakened below tropical storm strength during the first week of January without making landfall.
National Climatic Data Center: http://www.ncdc.noaa.gov/oa/ncdc.html
This article originally appeared in the 03/01/2006 issue of Environmental Protection.