Alvord
Desert
The Alvord Desert
is a desert located in Harney County, in southeastern Oregon in the western United States. It is roughly southeast of Steens Mountain. The Alvord Desert is a 12-by-7-mile (19 by 11 km)
dry lake bed and averages 7 inches (180 mm) of rain a year. Two mountain ranges separate it from the Pacific Ocean—the Coast Range, and the Cascade Mountains. Along with Steens Mountain, these topographical features create a rain shadow. The Alvord Desert lies at an elevation of approximately 4,000
feet (1,200 m).
During the dry season,
the surface is flat enough to drive across, or land small aircraft on. An
unofficial women's world land speed record was set in 1976 on the Alvord Desert
by Kitty O'Neil at 512 miles/hour (843 km/hour).[1]
Name
The desert is named
after General Benjamin Alvord,
who served as commander of the U.S. Army's Department of Oregon during the American Civil War.[2]
Climate
The Alvord Desert is
classified as a cold semi-arid desert
(BSk) under the Köppen
climate classification.
The Desert receives very little rainfall throughout the year. Some eastern
areas of the desert may receive as little as 5 inches (13 cm) of rain
annually. The desert lies within a rain shadow created by the Coast and Cascade
mountain ranges as well the adjacent Steens Mountain.
Winter
Winter temperatures in
the Alvord Basin are moderated through airflow from the south that stops the
temperature from dropping too heavily. While many areas in the Oregon High
Desert frequently dip below 0 °F (−18 °C) through the winter months, the
Alvord Desert rarely sees these frigid temperatures. On average, highs will
commonly reach between 40 and 50 °F (4 and 10 °C),
with a few rare instances where the temperature fails to break 32 °F (0 °C).
At night, the temperature falls to between 20 and 30 °F
(−7 and −1 °C), but will not normally fall much further unless Arctic
air masses arrive. The basin sees a moderate amount of its rainfall in the
winter months from storms coming off the Pacific Ocean while the strong winter
jet stream is aimed at the Pacific Northwest. Storms that are strong enough to
bring moisture to the Southeastern area of Oregon are usually related to
tropical storms feeding from the Hawaiian Islands. Snow does sometimes occur in
the rare instances when cold air from the arctic to the north meets a strong
flow of moisture from the Pacific to the West.
Spring
Spring is when the bulk
of precipitation falls from thunderstorms. These storms attribute to the
rainfall in April, May, and June that form in the south and move their way
north across the desert and surrounding sagebrush plains. Clear nights continue
to bring cold overnight temperatures which commonly drop to between
30 and 45 °F (−1 and 7 °C), but afternoon warming
raises temperatures to between 50 and 60 °F (10 and
16 °C) in early spring and 70 and 80 °F (21 and
27 °C) in late spring. This warming can help trigger thunderstorms in
combination with the unstable spring atmosphere. Extremes in temperature can
still be seen at this time of year where temperatures have fallen to
0 to 10 °F (−18 to −12 °C) in March, and climbed to
over 100 °F (38 °C) in early June. Rainfall turns the playa into a small lake, and for a short time, makes travel across it
difficult.
Summer
Summer in the Alvord
Desert has some of the hottest temperatures in the state of Oregon. High
pressure sets in over the Pacific Northwest and the jet stream pushes north into
Canada. This high pressure means very little precipitation, averaging less than
1 inch (2.5 cm) throughout the summer months. Late day heat begins to set
in by late June where highs reach between 85 and 90 °F
(29 and 32 °C). In July the temperature commonly climbs to between
90 and 100 °F (32 and 40 °C). Night-time lows vary,
with overnight temperatures dropping down between 60 and 65 °F
(16 and 18 °C) throughout much of the basin. In some locations temperatures
will only drop to between 65 and 70 °F (18 and 21 °C).
August remains hot with highs ranging between 90 and 100 °F
(32 and 40 °C) and lows between 50 and 60 °F
(10 and 16 °C), though dropping towards the end of the month.
Fall
Fall is moderate with
high temperatures ranging between 60 and 80 °F (16 and
27 °C) and lows between 40 and 50 °F (4 and
10 °C). Fall is also one of the driest times of the year.
Geology
Three primary geothermal
areas are along the western edge[4] as well as cold springs following NE to SW trending normal
faults. On the western edge of the desert is Alvord Hot Springs (
42°40′41″N 118°20′48″W42.6781°N 118.3467°W): an assortment of bubbling mud, geysers and a
small pool. At the south is Borax Lake (
42°19′37″N 118°36′10″W42.3269°N 118.6028°W) which is a thermal spring complex. To the east
is an unnamed natural hot spring, one of 40 or more along 25 miles (40 km)
of the Alvord fault. To the southwest is seasonal alkali Alvord Lake which once extended 100 miles (160 km)
north and south—covering the desert. Several of the geothermal features in
Alvord Desert Basin have been examined by a team of scientists and geologists[5] from the University of Idaho, Boise State University, and Idaho
State University.[6]
Fauna
Despite the barren
nature of the playa, some opportunities for wildlife observation exist. Wild horses sometimes drink from the springs on the eastern edge of the
desert. In areas where natural hot springs flow into the playa, especially around the Alvord Hot Springs,
one can usually find nesting long-billed curlew. Further out into the playa proper are numerous
killdeer and snowy plover, along with the occasional American avocet. The outlet waters from the springs typically flow roughly one
mile into the desert, and their reach roughly delineates the bird habitat. The
nearby Steens
Mountain Wilderness contains populations of
bighorn sheep, mule deer, elk, and pronghorn. Further west is the Malheur National Wildlife Refuge, which is popular for birding.
The entire wiki link with images can be found
at:
http://en.wikipedia.org/wiki/Alvord_Desert
No comments:
Post a Comment