Natural variability, changes in irrigation practices, and other diversions of water for human use can influence certain drought-related measurements. A value between -2 and -3 indicates moderate drought, -3 to -4 is severe drought, and -4 or below indicates extreme drought. Submitted by rebecca.lindsey on Thu, 09/30/2021 - 10:15, Science & information for a climate-smart nation. Left:Lake Bonneville's maximal extent during the Pleistocene. See the Drought indicator for more information about these indices. Shallow seas invaded the continent, ultimately covering the whole area until the late Carboniferous. Volcanic activity intensified in the Southwest, and the Basin and Range region began to form, leading to the topography that is seen in those areas today (i.e., low valleys alternating with high mountain ranges). As of June 2022, it was more than 90% contained. At the close of the Mesozoic, global climatealthough warmer than todaywas cooler than at the start of the era. The distance between Santa Fe and Las Vegas, New Mexico, is about 65 kilometers (about 40.5 miles). The Southwest is typically dry, hot, and humid. July 1August 22, 2021 precipitation shown as a percent of the average July 1August 22, based on 19792020. Photo by James Bo Insogna. This fire, which started as two separate fires that merged, began in April 2022 and has since burned more than 138,000 hectares (340,000 acres) of land and over 300 homes. (2019)Biology Letters15: 20190114(Creative Commons Attribution 4.0 International license, images cropped, reconfigured, resized, and relabeled). We are largely unaware of this precipitation because of the Southern California Chamber of Commerce and a lack of rain gauges. The cycling layers in thesandstone represent changes in the direction of prevailing winds as large sand dunes migratedacross the desert. By 2070, one can expect up to 38 more days of freeze-free weather each year. Unless otherwise indicated, text and images on this website have Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International licenses. On the other hand, New Mexico and northern Mexico are near or a bit below average. Smog (haze caused by air pollution) over Salt Lake City, Utah, 2016. Maps showing the progressive closure of the Isthmus of Panama at 20 million years ago (A) and 15 million years ago (B). This section covers the climate of the southwestern U.S. through the Phanerozoic, from about 541 million years ago to the recent. The geography and climate of the southwestern U.S. east of the Rocky Mountains (in other words, in the Great Plains region in Colorado and New Mexico) are nearly ideal for their formation of thunderstorms and tornados, especially in the summer. Data source: NOAA, 20214Web update: April2021, Key Points | Background | About the Data | Technical Documentation. SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS. Elevation does, however, play a key role in precipitation received throughout the Southwest. In the Silurian and Devonian (430 to 359 million years ago), North America moved north across the equator, and the cycle of warming and cooling was repeated yet again. There is also an important relationship between rainfall and temperature: usually, more rain leads to cooler conditions, and less rain leads to hotter conditions. Glaciers in the Colorado Rockies are sustained largely by avalanches and wind-blown snow. Seems likely that conditions in the GM may influence annual variations in the monsoon. Temperature and drought data come from a network of thousands of weather stations overseen by the National Weather Service. However, although climate change is predicted to enhance the intensity of severe weather, there is currently no way to calculate what effect climate change will have on the frequency of specific storm eventsfor example, we might see more powerful tornados, but we do not know if we will see more of them. Photograph by Julia Manzerova (Flickr;Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic license; image resized). Rainfall, as anyone who has read the ENSO Blog before will know, is an extremely complicated thing to predict! Large glaciers were found at higher elevations, and temperatures were cool. Thanks to the region's high temperatures and low precipitation levels from summer 2020 through summer 2021, the current drought has exceeded the severity of a late-1500s megadrought that previously had been identified by the same authors as the driest in 1,200 years. Streamflow totals for the decade of 2001-2010 in the Great Basin, Rio Grande, and Colorado River were between 5% and 37% lower than their 20. Across New Mexico, Arizona, and Utah, summer rains originate from moisture brought into the area from the Gulf of Mexico. 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. The rainy season would have been critical for Native Americans for thousands of years, and, for some Native American tribes, continues to be so. Eventually, a sheet of sea ice formed over the Arctic, and ice sheets spread over northern Asia, Europe, and North America, signaling the start of the most recent ice age. The last glacial advance of the modern ice age peaked some 18,000 years ago. Taken on September 23, 2017. The Southwest is also definable, to an extent, by environmental conditions - primarily aridity. Here on Earth: Regional Guides to Earth Science, Earth Science of the Southwestern United States, Climate of the Southwestern United States. Published June 22, 2021 Updated Aug. 23, 2022. The average amount of precipitation for the United States is 85.6 centimeters (33.7 inches). This planting zone combines saline water and alkaline soil with intense sunlight, high temperatures and varying elevations. Paleontological Research Institution Special Publication 38, Ithaca, NY, 200 pp. Every part of the Southwest experienced higher average temperatures between 2000 and 2020than the long-term average (18952020). Water vapor animation for the afternoon of August 22, 2018 showing the monsoon circulation and thunderstorm formation (dark blue, green, dark red). Global temperatures during the Cretaceous were very warm, as much as 10C (18F) above those at present. While changes in the growing season can have a positive effect on some crops (such as melons and sweet potatoes), altered flowering patterns due to more frost-free days can lead to early bud bursts, damaging perennial crops such as nuts and stone fruits. Resilient Bermudagrass is widely used in the region, but sufficient watering is essential in the desert climate . 1. Sand dunes started to become widespread. Earth 300 million years ago, during the end of the Carboniferous Period (Pennsylvanian). By early to mid-September, wind patterns have generally reverted back to the westerly pattern, bringing an end to the monsoon. Also extreme dryness which means days & weeks on end without rain. Go to the full list of resources about the climate of the southwestern U.S. Go to the full list of general resources about climate. Thick salt deposits accumulated in the northwestern Four Corners area as the seas evaporated. On the other hand, there is not much agreement among projections for future change in the monsoon, except for regarding the timingmost projections suggest that, under continued climate change, the monsoon will start later in the summer and end later in the fall than it currently does (3). While most of the evidence for cooling at the Eocene-Oligocene boundary comes from the deep sea, fossil mammals in the Rocky Mountains show clear evidence of a change from forests to grasslands, which is associated with global cooling. In winter, rising temperatures have increased the number of frost-free days. Precipitation has become more variable from year to year, and heavy downpours across the U.S. have increased in the last 20 years. 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. For example San Diego county has a population of azalea otherwise not seen for hundreds of miles to the north. Right (2):Crown of leaves from a mature plant. Photograph by "Cathy" (Flickr;Creative Commons Attribution-NonCommerical 2.0 Generic license). There were spots that received large amounts of rain, but overall Nora was a bust. 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. Dark gray is land, white and light gray are submerged areas. The impact vaporized both water and rock, blocking out sunlight for weeks to years, which led to a collapse of photosynthesis and food webs on land and in the oceans. How would that result in less total JulyAugust rain? Good question! More on that later Now, lets take a sojourn through some North American Monsoon basics (1). :https://earthathome.org/de/talk-about-climate/, Digital Encyclopedia of Earth Science: What is climate? While the state is generally arid, its high western mountains experience more precipitation each year than the desert southwest and the high northeastern plateau do. Much of the Southwest became an archipelago of warm shallow seaways and uplifted islands, with terrestrial swampy forests and shallow sea floors populated by bivalves, brachiopods, arthropods, corals, and fish. Also, the occasional eastern Pacific tropical storm can increase monsoon moisture and rainfall. Later in the Jurassic, the climate became more moderate; dune fields were replaced by rivers and floodplains populated by a rich dinosaur fauna (exemplified by the Morrison Formation) and large trees along rivers, streams, and grasslands. The Southwest has a very unique culture, climate, and geography. The size and location of various lakes in which the Green River Formation sediments were deposited during the Eocene epoch. Photo by Archaeopoda (Wikimedia Commons,Creative Commons Attribution-ShareAlike 3.0 Unported license, image cropped, resized, and labeled). The inset image is a shaded relief image that shows the edge of the crater on the Yucatn Peninsula with sinkholes in the rock surrounding it. 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. The Southwest contributes significantly to climate change. There is some variability in the onset and demise of the monsoon. Photo by Center for Land Use Interpretation(Creative Commons Attribution-Noncommercial-ShareAlike 3.0 license, image resized). Map modified from amap by Chiche Ojeda (Wikimedia Commons,Creative Commons Attribution-ShareAlike 4.0 International license, image cropped and modified). Cambrian trilobites from the Bright Angel Shale (Tonto Group), Grand Canyon National Park, Arizona. With the start of the Paleozoic era, climates across the world were warm, and North America was located in the low and warmer latitudes of the Southern Hemisphere. The location of the Southwest and the topographical extremes across this area strongly influence its weather. A strong temperature difference at different heights creates instability. The desert experiences large temperature extremes, especially between day and night; daily temperature may change as much as 15C (60F) during the driest parts of the year. Digital Encyclopedia of Earth Science: Why talk about climate change? Declining water supplies, reduced agricultural yields, health impacts in cities due to heat, and flooding and erosion in coastal areas are additional concerns. Some earlier studies suggested that El Nio may be related to lower JulyAugust rainfall, and La Nia related to higher rainfall, due to large-scale atmospheric circulation changes. 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. (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.) (2011)PLoS ONE3(7): e2791(Creative Commons Attribution license, image reorganized and resized). The monsoon's intensity waned by the early Jurassic, and the rivers and floodplains were replaced by even larger deserts. Copyright 2021 Paleontological Research Institution. This mortality is attributed to higher temperatures, drought, and the eruption of bark beetles that are able to survive through warmer winter weather. Pangaea was completed when North America finally collided with Gondwana. Warmer temperatures also make it easier for insect pests to overwinter and produce more generations. As the Triassic period began, the Southwest moved north from the equator. Light precipitation travels eastward over the Sierra Nevada and Cascade mountains after dropping heavy snowfall in areas of high elevation. The globe about 485 million years ago, near the Cambrian-Ordovician boundary. MacDonald, G.M. Changes include formatting and revisions to the text and images. Storms form when there is strong convection in the atmosphere. Cycads are a group of seed plants that look superficially similar to palms, but are not closely related to them and do not produce flowers. This chapter builds on assessments of climate change in the Southwest region from the three previous U.S. National Climate Assessments. The Southwest, already the driest region in the United States, has become even drier since the mid-20th century, particularly on the hottest days . Climate change in the Southwest The global rise in temperatures will affect different locations on earth in unique ways. 4. Shiprock is part of the San Juan volcanic field and dates to the Oligocene (about 27 million years ago). Mesohippusmeasured up to 70 centimeters (2 feet) at shoulder height. Drier conditions occurred through the 1920s/1930s, again in the 1950s, and since 1990, when the Southwest has seen some of the most persistent droughts on record (see Figure 3). The new dry-land isthmus blocked the warm ocean currents that had been flowing east-to-west from the Atlantic to the Pacific for more than 100 million years, diverting them into the Gulf of Mexico and ultimately into the western Atlantic Gulf Stream. 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. 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. Precipitation, while sparse, peaks in the summer during the monsoonal storms, and again in the winter from storms originating in the Pacific Ocean. The coldest periods will be in late November, mid- and late December, and mid-January. The average precipitation for the United States is 85.6 centimeters (33.7 inches). Notice that North America has separated from Africa and there is a spreading center in the Central Atlantic Ocean. Left (1):Leaves of a seedling. Today, most of the Southwest experiences about 17 fewer freezing days than it did over the last century. The first letter of each zone in the key indicates its major classification. The state's mountainous areas, however, have climate characteristics that more closely follow those found in the Colorado Rockies. North America's position near the equator kept its climate relatively warm. During the winter, moisture travels from the west, as storms from the Pacific Ocean move east. Summer temperatures on the South Rim, at 7000 feet (2134 meters), are especially pleasant from 50 to about 85 F (10s to 20s C). PRI is a registered 501(c)(3) nonprofit organization. Zack and Mike mention that last year was an extremely dry monsoon, and this year is extremely wet. Maps modified from maps by Wade Greenberg-Brand, originally published inThe Teacher-Friendly Guide to the Earth Science of the SouthwesternUS, after figure 3 in L. Grande (2013) The Lost World of Fossil Lake. In the Southwest, climate change may impact a variety of resources, including water availability in the form of snowpack and spring streamflow, the distribution and composition of plant communities, and fire regimes. Snowpack helps keep the ground and soil moist by covering it longer into the spring and summer, which delays the onset of the fire season and influences the prevalence and severity of wildfires. The Southwest's Triassic to Jurassic dune deposits are some of the most extensive in the world, and the dune field that existed during the Jurassic may be the largest in Earth history. Introduction The overall climate of the Southwestits weather patterns over a long period of timetends to be warm and dry. But El Nio leads to more tropical storms than average, youre saying, because youre not new here. Another factor besides latitude and elevation that influences temperature in the Southwest is its arid climate. Some of these thunderstorms can be strong, delivering heavy rain and frequent lightning. 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. In New Mexico, for example, the average difference between the daily high and low temperatures ranges from 14 to 19C (25 to 35F). Credits for individual images are given in figure captions. Fossils of a cycad (Dioonopsis praespinulosa) from the Paleocene Castle Rock Flora, Colorado. Stages in the formation of a thunderstorm. 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). By comparison, the average high and low temperatures for the entire United States are 17C (63F) and 5C (41F), respectively. All rights reserved. One especially alarming detail about the Calf Canyon fire is that it was originally set in January 2022. The average annual temperature in most of the Southwest is predicted to rise 2.2 to 5.5C (4 to 10F) by 2100. Answer: Winter, June, July, and August. Data for Figures 1 and 3 were obtained from the National Oceanic and Atmospheric Administrations National Centers for Environmental Information, which maintains a large collection of climate data online at: www.ncdc.noaa.gov/cag. This led to global cooling and dropping global sea levels. Since the early 1900s, the Southwest has experienced wetter conditions during three main periods: the 1900s, 1940s, and 1980s. Increased heat in the Pacific Ocean has altered the weather patterns of Pacific storms, decreasing snowfall in the mountains of western Utah and Arizona. These warmer temperatures and increased precipitation have helped bring on longer growing seasons. Precipitation forms. Las Cruces is located in the Basin and Range region of New Mexico. 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! These changes to rain and snow-pack are already stressing water sources and affecting agriculture. The number of days with temperatures above 35C (95F) and nights above 24C (75F) has been steadily increasing since 1970, and the warming is projected to continue. Photo of USNM 166396 from the Cretaceous Atlas of Ancient Life(Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license, image cropped). :https://earthathome.org/de/what-is-climate/, Digital Encyclopedia of Earth Science: Evidence for and causes of recent climate change:https://earthathome.org/de/recent-climate-change/, Digital Encyclopedia of Earth Science: Climate change mitigation: https://earthathome.org/de/climate-change-mitigation/, Digital Encyclopedia of Earth Science: Climate change adaptation: https://earthathome.org/de/climate-change-adaptation/, [emailprotected]: Quick guides & FAQ: Climate and Energy:https://earthathome.org/quick-faqs/#climate, [emailprotected]: Here on Earth: Introduction to Climate: https://earthathome.org/hoe/climate/. Wildfire risk map for the United States. Wind moves the air, promoting mixing. Figures 2 and 3 show two ways of measuring drought in the Southwest: the Drought Monitor and the Palmer Drought Severity Index. Southwest Increased heat, drought, and insect outbreaks, all linked to climate change, have increased wildfires. A major contributing factor to this event was a geological change that occurred far to the south. Higher atmospheric moisture content has also been correlated with an increased incidence of tornados and winter storms. . Figure by Climate.gov. Its remnant exists today as the Great Salt Lake. Figure by Emily Becker. These are blog posts, not official agency communications; if you quote from these posts or from the comments section, you should attribute the quoted material to the blogger or commenter, not to NOAA, CPC, or Climate.gov. As the summer heat builds over North America, a region of high pressure forms over the U.S. Southwest, and the wind becomes more southerly, bringing moisture from the Pacific Ocean and the Gulf of California. Please click here to see any active alerts. . The formation of precipitation also causes electrical charging of particles in the atmosphere, which in turn produces lightning. That timeworn classic is only partially true--May and September can also be great summer months. Climate at a glance. Glaciers covered most of the world's southern landmasses, which were located over the South Pole. In the early Carboniferous (Mississippian), ice capped the South Pole and began to expand northward. I listened to the Southwest Climate Podcast from CLIMAS, the Climate Assessment for the Southwest, to learn more about what affects the monsoon and its rainfall, and how Monsoon 2021 is shaping up, and reached out to the podcast co-hosts, Zack Guido and Mike Crimmins, for help with this post. | View Google Privacy Policy. The Sonoran Desert is located in southwestern Arizona and adjacent regions of California and Mexico. See you then! This map shows how the average air temperature from 2000 to 2020has differed from the long-term average (18952020). Check out Toms recent post on the drought in Arizona to understand more about how drought works in this region. It is the largest wildfire that New Mexico has ever witnessed. Rugose corals or horn corals (Turbophyllum) from the Mississippian Great Blue Limestone, Cache Canyon, northern Utah, near the border between the Basin and Range and Rocky Mountain physiographic provinces. Its largely too soon to tell. 2010. Summer- The summer in the Southwest region is hot and desert-like. Based on the long-term Palmer Index, drought conditions in the Southwest have varied since 1895. Winter is the driest season in New Mexico, because precipitation from eastward-traveling Pacific storms is left behind in the western mountains of Arizona and Utah. 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. Shelly sandstones in Utah represent vast tidal flats. PRI's free resource to help you learn about the Earth and its history. The North American monsoon, variously known as the Southwest monsoon, the Mexican monsoon, the New Mexican monsoon, or the Arizona monsoon is a pattern of pronounced increase in thunderstorms and rainfall over large areas of the southwestern United States and northwestern Mexico, typically occurring between June and mid-September.During the monsoon, thunderstorms are fueled by daytime heating . Lower latitudes receive more heat from the sun over the course of a year; for each degree increase in latitude, there is approximately a 1C (2F) decrease in temperature. The Cretaceous-Paleogene boundary at Trinidad Lake State Park, Las Animas County, Colorado. Official websites use .gov Fall- The fall in the Southwest region is warm. Photo source:National Park Service (public domain). All rights reserved. (3) There is a whole lot of interesting detail in this reportabout everything, but about the North American Monsoon specifically. Climate at a glance. Title: Arizona Monsoon Thunderstorm. 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. Average yearly tornado watches in each county of the United States between 1993 and 2012. Here at the ENSO Blog, were always curious about the role of ENSO (El Nio/Southern Oscillation, the entire El Nio/La Nia system). 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. Summer rains fall almost entirely during brief but intense thunderstorms on the Great Plains, although the occasional hurricane in the Gulf of Mexico may push heavier precipitation inland. This project was made possible in part by the Institute of Museum and Library Services (ARPML-250637-OMLS-22).The views, findings, conclusions or recommendations expressed in this website do not necessarily represent those of the Institute of Museum and Library Services. 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. Today nearly all the glaciers in the Southwest are gone, and the climate is in an arid state. [7] Pion pines are very drought tolerant and have survived dry periods in the past. An official website of the United States government. Accessed March2021. www.ncdc.noaa.gov/cag. By the late Carboniferous, North America had collided with Gondwana, leading to the formation of Pangaeaa supercontinent composed of nearly all the landmass on Earth. The summer precipitation total for the CONUS was 9.48 inches, 1.16 inch above average, ranking eighth wettest in the historical record. however, the monsoons provide life-giving moisture in a region that is always dry. The main features that influence the areas climate are latitude, regional topography, and a low atmospheric moisture content that leads to quick evaporation. Thanks for visiting the North American Monsoon region with me! During the Paleocene to Eocene, the Southwests climate was warm and wet, and large mammals roamed the forested landscape.