The oceans between Gondwana and North America began to close. In the middle Cretaceous, oceans covered most of the Southwest, with the exception of parts of Arizona and New Mexico. Large lakes formed in low areas, and the Southwests most striking ice age feature was Lake Bonneville, a massive pluvial lake that covered much of Utah. Agua Caliente solar farm, Maricopa County, Arizona. Northwestern Mexico receives upwards of 75% of its average annual precipitation from it, and Arizona and New Mexico more than 50%, during JulySeptember. Pangaea was completed when North America finally collided with Gondwana. Yet this landscape actually supports a vast array of plants and animals, along with millions of people who call the Southwest home. contiguous U.S. (CONUS) into the Northern Plains. ; Precipitation was above-average across portions of the Great Basin and Southwest, from the southern Plains to the Great Lakes and across much of the eastern U.S. Mississippi had its wettest summer on record with Alabama, Michigan, New York and Massachusetts . SW Precipitation Precipitation in the Southwest has two distinct seasons. Shallow seaways spread over many of the continents, including South America, Africa, Eurasia, and North America. The satellite loop in this post shows Gulf of Mexico moisture moving west into the monsoon region. As the continents moved closer to their modern positions, the Southwest experienced a hot and humid tropical climate. The strengthened Gulf Stream carried more warm, moist air with it into the northern Atlantic, which caused increased snowfall in high latitudes, leading to accelerating cooling. In the early Carboniferous (Mississippian), ice capped the South Pole and began to expand northward. Photo by James St. John (flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized). That timeworn classic is only partially true--May and September can also be great summer months. Data source: NOAA, 20212Web update: April2021. Agriculture accounts for more than half of the Southwests water use, so any major reduction in the availability of water resources will create a serious strain on ecosystems and populations. Cities like Phoenix, Las Vegas, Yuma, and Palm Springs have average highs over 100 F (38 C) during the summer months and lows in the 70s or even 80s. Extreme high temperatures. By the end of the Cretaceous, uplift to the west was great enough that the resulting hills shed large amounts of sand and gravel in an easterly direction, pushing the shoreline eastward until sediment (combined with a worldwide drop in sea level) filled the area formerly occupied by the Western Interior Seaway. Left:Jaw with teeth. Right:Sabalites, a palm leaf. Zack and Mike mention that last year was an extremely dry monsoon, and this year is extremely wet. Source:Figure 1 from Erdei et al. For example San Diego county has a population of azalea otherwise not seen for hundreds of miles to the north. It is the largest wildfire that New Mexico has ever witnessed. As the Triassic period began, the Southwest moved north from the equator. On the other hand, New Mexico and northern Mexico are near or a bit below average. Some areas were more than2F warmer than average (see Figure 1). Cold continental conditions dominate the higher altitudes, especially within the Rocky Mountains. For example, the difference in annual mean temperature between Pikes Peak (4302 meters or 14,114 feet) and Las Animas (1188 meters or 3898 feet), only 145 kilometers (90 miles) to the southeast, is equivalent to that between Iceland and southern Florida! In the podcast episode 2021a generational monsoon? Zack listed some of the factors that influence how much moisture is available to the monsoon, including the position of the high-pressure area, wind patterns, and transient weather features. As Pangaea reached its greatest size during the early Triassic, the monsoons intensity increased, and the vast dune deserts of the late Permian were replaced by rivers and floodplains. Digital Encyclopedia of Earth Science: Why talk about climate change? The event devastated the Southwest, shifting a densely forested landscape to one primarily covered with fast-growing herbs and ferns. Fossil plants, Late Cretaceous Fruitland Formation, San Juan Basin, New Mexico. Precipitation, while sparse, peaks in the summer during the monsoonal storms, and again in the winter from storms originating in the Pacific Ocean. Spring- The spring in the Southwest region is cool. The formation of precipitation also causes electrical charging of particles in the atmosphere, which in turn produces lightning. By comparison, the average high and low temperatures for the entire United States are 17C (63F) and 5C (41F), respectively. Utahs distance from both the Pacific Ocean and the Gulf of Mexico prevents heavy precipitation, and much of the state is typically sunny year-round, with light to moderate winds. Copyright 2021 Paleontological Research Institution. Across New Mexico, Arizona, and Utah, summer rains originate from moisture brought into the area from the Gulf of Mexico. As of June 2022, it was more than 90% contained. And yet another element of the monsoon system that needs more study to resolve. While this will help with the ongoing drought in the southwest, in many regions the precipitation deficit has been building for a long time. Large portions of the Southwest have experienced drought conditions since weekly Drought Monitor records began in 2000. The Southwest's overall average high temperature of 19.2C (66.6F) and average low of 2.8C (37.0F) are indicative of a varied climate, one much less uniform than that found in many other parts of the United States. Has hurricanes and tornadoes. Extensive Permian deposits throughout the Southwest are home to a host of fossils, including terrestrial amphibians, reptiles, and synapsids. Winds and waves shape the landscape, and rain showers support lush vegetation. Left:Trilobites identified asDolichometoppus productusandAlokistocare althea. Answer: Winter, June, July, and August. Calf Canyon-Hermit Creek Fire near Holman, New Mexico, on May 8, 2022. Modified from illustrations by Wade Greenberg-Brand originally published inThe Teacher-Friendly Guide to the Earth Science of the SouthwesternUS. So is climate change increasing monsoon variability? Since 1980, tree mortality in forests and woodlands across the Southwest has been higher and more extensive than at any time during the previous 90 years. . Dark gray is land, white and light gray are submerged areas. The state's mountainous areas, however, have climate characteristics that more closely follow those found in the Colorado Rockies. Cattle ranches throughout the southwestern states rely on rain-fed grazing forage, making them extremely susceptible to climate change and drought. Scale bar = 1 centimeter (about 0.4 inches). Published June 22, 2021 Updated Aug. 23, 2022. During winter months, daytime temperatures may average 70 degrees F, with night temperatures often falling to freezing of slightly below in the lower desert valleys." Introduction The overall climate of the Southwestits weather patterns over a long period of timetends to be warm and dry. In winter, rising temperatures have increased the number of frost-free days. Brown indicates where precipitation has been less than average; green is greater than average. A large, low-latitude desert formed along Pangaea's western margin, generating extensive dune deposits. The warmer the air near the surface is relative to the air above it, the more potential energy it has to move up. Warmer temperatures also make it easier for insect pests to overwinter and produce more generations. Summer- The summer in the Southwest region is hot and desert-like. The world warmed, and would stay warm through the Mesozoic. In southern New Mexico, Pleistocene fossil mammals are found that now live at higher elevations in the mountains of northern New Mexico, indicating cooler temperatures and more available moisture in the area during the late Pleistocene. In the late Eocene, the Earth began to cool, and global temperatures fell sharply at the boundary between the Eocene and Oligocene epochs (approximately 35 million years ago), due in part to the separation of South Americas southern tip from Antarctica. When you add in the sparse rain-gauge observations available in the U.S. Southwest and Mexico, it becomes even more difficult to make confident statements about the effects of the monsoon and how it can be predicted. Every part of the Southwest experienced higher average temperatures between 2000 and 2020 than the long-term average (1895-2020). Warm, moist air from the south occasionally but infrequently moves into Colorado during the summer. The Southwest is also definable, to an extent, by environmental conditions - primarily aridity. How would that result in less total JulyAugust rain? Good question! Image adapted from an image by Scenarios for Climate Assessment and Adaptation, first published in The Teacher-Friendly Guide to the Earth Science of the Southwestern US. The daily range between maximum and minimum temperatures sometimes runs as much as 50 to 60 degrees F during the drier periods of the year. It's made up of the states of Arizona, New Mexico, Oklahoma, and Texas. 830 AM EST Thu Feb 16 2023. Droughts also contribute to increased pest outbreaks and wildfires, both of which damage local economies, and they reduce the amount of water available for generating electricityfor example, at the Hoover Dam.1. Where the land was exposed, deposits of dust (loess) accumulated and were blown across much of the Southwest. Because warm air can hold more moisture than cool air can, convective mixing with cool air forces moisture to condense out of warm air as vapor (clouds) and precipitation. Record high temperatures for the Southwest range from 53C (128F) in Arizona to 47C (117F) in Utah, while record low temperatures range from 56C (69F) in Utah to 40C (40F) in Arizona. Of the southwestern states, Arizona emits the most greenhouse gases, releasing 92.5 million metric tons of energy-related carbon dioxide (CO2) in 2019. Dry conditions are common throughout the Great Plains, Colorado Plateau, and Basin and Range. Photo by James St. John (flickr, Creative Commons Attribution 2.0 Generic license, image resized). Official websites use .gov In the latest Cretaceous, sea level dropped again and the western Southwest became a broad coastal plain that hosted lush forests, abundant dinosaurs, and large swamps. Reconstruction created using basemap from the. For example, high winter temperatures between 2000 and 2003 correlated to bark beetle outbreaks that devastated pinyon pine throughout the Southwest, leading to nearly 90% mortality at some sites in Colorado and Arizona. Facebook Tweet During much of the year, the prevailing wind over northwestern Mexico, Arizona, and New Mexico is westerly (blowing from the west) and dry. There is some variability in the onset and demise of the monsoon. Average temperatures found in the Southwest tend to decrease northward, which is largely the influence of latitude and elevation. Photograph by Bill Morrow (Flickr;Creative Commons Attribution 2.0 Generic license). Photo source:National Park Service (public domain). In southern New Mexico and Arizona, shallow marine deposits, laid down when the ice in Gondwana retreated and sea level rose, alternate with layers of dust blown in when the ice in Gondwana advanced and sea level fell. The warm, arid Southwest region presents extreme challenges to turf grasses in low- and high-desert climates. However, the Southwest is located between the mid-latitude and subtropical atmospheric circulation regimes, and this positioning relative to shifts in these . By early to mid-September, wind patterns have generally reverted back to the westerly pattern, bringing an end to the monsoon. In general, places in the east and south of the UK tend to be drier, warmer, sunnier and less windy than those further west and north. MacDonald, G.M. An increased frost-free season length also leads to increased water demands for agriculture and heat stress on plants. We are largely unaware of this precipitation because of the Southern California Chamber of Commerce and a lack of rain gauges. This planting zone combines saline water and alkaline soil with intense sunlight, high temperatures and varying elevations. There is also an important relationship between rainfall and temperature: usually, more rain leads to cooler conditions, and less rain leads to hotter conditions. Soil moisture, ground water, and streamflow are part of Drought Monitor calculations (Figure 2), and they are all sensitive to human activities. The North American Monsoon is a seasonal change in the atmospheric circulation that occurs as the summer sun heats the continental land mass. A= Tropical (equatorial),B= Arid,C= Temperate (warm temperate),D= Continental (cold),E= polar. Summer heat waves will become hotter and longer, while winter cold snaps will occur less often. In the Southwest, average precipitation ranges from only 34 centimeters (13.4 inches) in Utah to 39.9 centimeters (15.7 inches) in Colorado, which reflects the area's general aridity. Photo of USNM 166396 from the Cretaceous Atlas of Ancient Life(Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license, image cropped). Snowfall will be below normal in most areas that normally receive snow, with the snowiest periods in early to mid-January and early February. This may be due to the growth of solar energy, and voluntary commitments to reduce emissions made by large utility companies in the state. All rights reserved. This chart shows the percentage of land area in six southwestern states (Arizona, California, Colorado, Nevada, New Mexico, and Utah) classified under drought conditions from 2000 through 2020. However, while the effect of warming on the storms is uncertain, temperatures have been increasing. Average annual preciptiation for the southwestern U.S. Is the tropical storm season done for this part of the country? Burning those fossil fuels releases carbon into the atmosphere, which warms the Earth. The Southwest has a hot desert climate, at lower elevations. Although much of the Southwest falls within the category of an arid zone, using a single label to describe the Southwest's climate would belie its diversity. Monsoon region averaged over all land gridpoints, 20N37N, 102W115W. NASA Earth Observatory image by Lauren Dauphin (NASA Earth Observatory,used following NASA's image use policy). Accessed March 2021. www.ncdc.noaa.gov/cag. During the winter, moisture travels from the west, as storms from the Pacific Ocean move east. USA 107(50):2125621262. Summer temperatures on the South Rim, at 7000 feet (2134 meters), are especially pleasant from 50 to about 85 F (10s to 20s C). The large ice sheets in the Northern Hemisphere did not extend into the Southwest, even at their maximum area. Climate changepast, present & future: a very short guide. (Prescribed burns are an important forest management tool; they are used to consume fuels like dry wood that can ignite and feed wildfires as well as maintain forest health.) The full time series for precipitation and temperature values is shown in Figure 2. Credits for individual images are given in figure captions. The Palmer Index is calculated from precipitation and temperature measurements at weather stations, and has been used widely for many years. SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS. The cycling layers in thesandstone represent changes in the direction of prevailing winds as large sand dunes migratedacross the desert. Photo by Richard Stephen Haynes (Wikimedia Commons, Creative Commons Attribution-ShareAlike 4.0 International license, image resized). Ideas and explanations found in these posts should be attributed to the ENSO blog team, and not to NOAA (the agency) itself. Figures 2 and 3 show two ways of measuring drought in the Southwest: the Drought Monitor and the Palmer Drought Severity Index. Four of western North America's major watersheds lie within its boundaries: the Colorado River basin, the Rio Grande basin, the Sacramento-San Joaquin watershed, and most of the Great Basin. Another factor besides latitude and elevation that influences temperature in the Southwest is its arid climate. I did a quick comparison of the average JulyAugust rainfall in the monsoon region with the Nio-3.4 index, using 70 years of records. Since 800,000 years ago, an equilibrium has been reached between warming and cooling, with the ice caps growing and retreating primarily due to the influence of astronomical forces (i.e., the combined gravitational effects of the Earth, Sun, moon, and planets). Figure by climate.gov; data from CPC Unified data. These increased temperatures lead to a whole host of other effects, including a decrease in snowpack, declines in river flow, drier soils from more evaporation, and the increased likelihood of drought and fires. Unfortunately, unpredictable winds spread the flames, which, combined with dry conditions, caused the Calf Canyon and Hermit Peak fires to grow beyond control. Thick salt deposits accumulated in the northwestern Four Corners area as the seas evaporated. Nighttime winter temperatures in the desert can drop slightly below freezing. A value between -2 and -3 indicates moderate drought, -3 to -4 is severe drought, and -4 or below indicates extreme drought. Acad. Summer temperatures on the South Rim, at 7000 feet (2134 meters), are especially pleasant from 50 to about 85 F (10s to 20s C). Shelly sandstones in Utah represent vast tidal flats. Famous sheriffs like Wyatt Earp and outlaws like Billy the . More on that later Now, lets take a sojourn through some North American Monsoon basics (1). Inset image from the NASA Jet Propulsion Laboratory (PIA03397). Photo by James St. John (flickr,Creative Commons Attribution 2.0 Generic license, image cropped and resized). Although there has been a fair amount of research into the monsoon, there are still far more questions than answers about how it works, and if the seasonal amount of rain, potential start date, or other characteristics can be predicted. Ornithopod-type tracks, Powell Fossil Track Block Tracksite, Jurassic Navajo Sandstone, Glen Canyon National Recreation Area, Arizona and Utah. Notice that North America has separated from Africa and there is a spreading center in the Central Atlantic Ocean. For southern and western Colorado, the intrusions of moist air are most common from mid July into September associated with wind patterns sometimes called the Southwest Monsoon. Resilient Bermudagrass is widely used in the region, but sufficient watering is essential in the desert climate . Like the summer monsoons, the milder storms . Photo by Daniel Mayer (Wikimedia Commons, Creative Commons Attribution-ShareAlike 3.0 Unported license, image resized). A major contributing factor to this event was a geological change that occurred far to the south. Accessed March2021. www.ncdc.noaa.gov/cag. Figure by Climate.gov. The intensification recorded since about the 1970s has been partly driven by greenhouse gas emissions (medium confidence). In 8.4, What are the projected water cycle changes?, the summary statement is there is low agreement on a projected decrease of NAmerM precipitation, however there is high confidence in delayed onsets and demises of the summer monsoon.. But El Nio leads to more tropical storms than average, youre saying, because youre not new here. Glaciers covered most of the world's southern landmasses, which were located over the South Pole. February 2023 ENSO update: the ENSO Blog investigates, part 3, How the pattern of trends across the tropical Pacific Ocean is critical for understanding the future climate, January 2023 La Nia update, and the ENSO Blog investigates, part 2, Albuquerque, NM National Weather Service office, ENSO does influence Pacific tropical storms, Tucson recorded its wettest month ever this July, Monsoon causes deadly flash flood in Arizona, Images of CO2 emissions and transport from the Vulcan project, TreeFlow: Streamflow Reconstructions from Tree Rings. :https://earthathome.org/de/talk-about-climate/, Digital Encyclopedia of Earth Science: What is climate? The average precipitation for the United States is 85.6 centimeters (33.7 inches). Low annual precipitation, clear skies, and year-round warm climate over much of the Southwest are due in large part to a quasi-permanent subtropical high-pressure ridge over the region. Higher elevations (such as those found in the Rockies and on the Colorado Plateau) are also cooler, with approximately a 1.5C (3F) decrease in mean annual temperature for each 300-meter (1000-foot) increase in elevation. Every part of the Southwest experienced higher average temperatures between 2000 and 2020than the long-term average (18952020). As average temperatures rise and the Southwest becomes drier with a longer annual fire season (season conducive to the ignition and spread of wildfires), the number and intensity of wildfires is expected to increase.
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