Photo of USNM 166396 from the Cretaceous Atlas of Ancient Life(Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license, image cropped). Satellite photo showing smoke from the Calf Canyon-Hermit Creek Fire on May 10, 2022. 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. Left:Lake Bonneville's maximal extent during the Pleistocene. National Drought Mitigation Center. Data: U.S. Energy Information Administration. 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. Sprawling development of Phoenix, Arizona, a city in the Sonoran Desert, 2009. 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. Photo by Udo S. Title: Monument Valley - Arizona / USA. The Southwest Region climate in the United States is often associated with extremes. 2010. Trees killed by bark beetles at Cameron Pass, Colorado, 2011. As the Cambrian progressed, North America moved northward, and what would become much of the southwestern U.S. was located near the Tropic of Capricorn. Temperature and drought data come from a network of thousands of weather stations overseen by the National Weather Service. 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. Figure by climate.gov; data from CPC Unified data. Since then carbon dioxide emissions have been on a downward trend. Regarding changes that have already occurred, the report finds modest evidence that the monsoon rainfall has intensified since the 1970s, and this has been partly attributed to greenhouse gas emissions. 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. Positive values represent wetter-than-average conditions, while negative values represent drier-than-average conditions. For example, parts of the Colorado Rockies experience cool annual temperatures and over 8 meters (25 feet) of snowfall every year, while the dry deserts in southwestern Arizona receive only about 8 centimeters (3 inches) of precipitation a year and can experience as much as a 15C (60F) degree temperature difference between night and day. Since the early 1900s, the Southwest has experienced wetter conditions during three main periods: the 1900s, 1940s, and 1980s. Shiprock, a volcanic monadnock in San Juan County, New Mexico, rises roughly 483 meters (1583 feet) above the desert plain. The rainfall generally has a strong diurnal cycle, meaning a daily pattern of mostly dry mornings, storms developing through the day, and most rainfall occurring in the afternoon and evening. Figure by Ingrid Zabel for PRI's [emailprotected] project (CC BY-NC-SA 4.0 license). The warming conditions alone can be impactful, drying out soils quicker during breaks in monsoon rainfall, for example (2). A lock (LockA locked padlock) or https:// means youve safely connected to the .gov website. 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. Monsoon region averaged over all land gridpoints, 20N37N, 102W115W. Figures 2 and 3 show two ways of measuring drought in the Southwest: the Drought Monitor and the Palmer Drought Severity Index. Where the land was exposed, deposits of dust (loess) accumulated and were blown across much of the Southwest. SW Precipitation Precipitation in the Southwest has two distinct seasons. Southwest Asia is a region of diverse climates and is generally divided into three main climate types: arid, semiarid, and temperate. Monsoon rainfall activity tends to be grouped into bursts, with periods of rainy days interspersed with drier periods, rather than rain every day. Summer- The summer in the Southwest region is hot and desert-like. This circulation brings thunderstorms and rainfall to the monsoon region, providing much of their annual total precipitation. Also, the occasional eastern Pacific tropical storm can increase monsoon moisture and rainfall. Right (2):Crown of leaves from a mature plant. One recent study explored the relationship between the monsoon and wildfires in the Southwest and northern Mexico, finding that monsoon rains were important for ending wildfires. The elevation of Bear Lake is about 2880 meters (9450 feet). 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. Credits: Most of the text on this page comes from "Climate of the Southwestern US" by Ingrid H. H. Zabel, Judith T. Parrish, and Andrielle N. Swaby, chapter 8 in The Teacher-Friendly Guide to the Earth Science of the Southwestern US, edited by Andrielle N. Swaby, Mark D. Lucas, and Robert M. Ross (published in 2016 by the Paleontological Research Institution; currently out of print). For temperature, the 2020 monsoon was the hottest on record for the Southwest with an average temperature of 77.1 F, significantly beating the previous record of 76.8 F in 2011 (average is 74.3 F). Glaciers covered most of the world's southern landmasses, which were located over the South Pole. Fossils of a cycad (Dioonopsis praespinulosa) from the Paleocene Castle Rock Flora, Colorado. The average annual temperature in most of the Southwest is predicted to rise 2.2 to 5.5C (4 to 10F) by 2100. :https://earthathome.org/de/talk-about-climate/, Digital Encyclopedia of Earth Science: What is climate? Map by NOAA(public domain) modified for the[emailprotected]project. Onion Creek salt diapir, a salt dome exposed at the surface at Fisher Towers, Utah. The March-April-May (MAM) 2023 temperature outlook favors below-normal. Spring- The spring in the Southwest region is cool. The Southwest has a very unique culture, climate, and geography. Pangaea began to break up during the Jurassic, rifting apart into continents that would drift toward their modern-day positions. However, the Southwest is located between the mid-latitude and subtropical atmospheric circulation regimes, and this positioning relative to shifts in these . NWS Climate Prediction Center College Park MD. Photos by Lauren Dauphin, NASA Earth Observatory (used following NASA's image use policy). The formation of precipitation also causes electrical charging of particles in the atmosphere, which in turn produces lightning. The continued growth of Pangaea created an intense monsoonal climate, similar to that of Asia today, that affected large parts of the continent. Although there has so far been little regional change in the Southwests annual precipitation, the areas average precipitation is expected to decrease in the south and remain stable or increase in the north. The average precipitation for the United States is 85.6 centimeters (33.7 inches). | View Google Privacy Policy. Earth 300 million years ago, during the end of the Carboniferous Period (Pennsylvanian). Precipitation, while sparse, peaks in the summer during the monsoonal storms, and again in the winter from storms originating in the Pacific Ocean. 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. Is the tropical storm season done for this part of the country? Flows in late summer are correspondingly reduced, leading to extra pressure on the states water supplies. 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). Photo by James St. John (flickr,Creative Commons Attribution 2.0 Generic license, image cropped and resized). During the Paleocene to Eocene, the Southwests climate was warm and wet, and large mammals roamed the forested landscape. Average annual temperatures for the southwestern U.S. Changes in atmospheric pressure during the late fall and winter can lead to an accumulation of haze. 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. After the end-Cretaceous bolide impact, the climate may have cooled briefly, but it soon rebounded to a warmer state. That timeworn classic is only partially true--May and September can also be great summer months. However, while the effect of warming on the storms is uncertain, temperatures have been increasing. 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. Historic data from Livneh et al. July 1August 22, 2021 precipitation shown as a percent of the average July 1August 22, based on 19792020. And yet another element of the monsoon system that needs more study to resolve. 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. It is the largest wildfire that New Mexico has ever witnessed. 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 reasons for this are complex and involve a combination factors. SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS. Map modified from amap by Chiche Ojeda (Wikimedia Commons,Creative Commons Attribution-ShareAlike 4.0 International license, image cropped and modified). Precipitation also varies widely. This map shows how the average air temperature from 2000 to 2020has differed from the long-term average (18952020). Photo by Jeffrey Beall (Wikimedia Commons,Creative Commons Attribution 4.0 International license, image resized). 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. | View Google Privacy Policy. In the middle Cretaceous, oceans covered most of the Southwest, with the exception of parts of Arizona and New Mexico. 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. An ancient horse (Mesohippus),Eocene Florissant Fossil Beds, Teller County, Colorado. This movement of air in different directions is also the reason for the high incidence of powerful tornados that occur along "Tornado Alley" in the Great Plains, which affect eastern New Mexico and especially eastern Colorado. Lake Mead, the lake created by the Hoover Dam, at two points in time about 21 years apart. Left (1):Leaves of a seedling. Soils associated with these floodplains testify to the extreme seasonality of rainfall during that time. Of the southwestern states, Arizona emits the most greenhouse gases, releasing 92.5 million metric tons of energy-related carbon dioxide (CO2) in 2019. Source:Figure 1 from Erdei et al. The supercontinent was split by spreading along the mid-Atlantic ridge, initiating the formation of the Atlantic Ocean. (2015) . The pyrocumulonimbus cloud shown at the arrow was created by heat from the fire. 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. Right: As the vertical column of air turns over, with warm air at the top and cool air at the bottom, the storm begins to dissipate. In the early Carboniferous (Mississippian), ice capped the South Pole and began to expand northward. Copyright 2021 Paleontological Research Institution. Glaciers in the Colorado Rockies are sustained largely by avalanches and wind-blown snow. Modified from a map by Adam Peterson (Wikimedia Commons,Creative Commons Attribution-ShareAlike 4.0 International license). Submitted by rebecca.lindsey on Thu, 09/30/2021 - 10:13. See you then! The American Southwest, here defined as the area between 95W and 125W and 25N and 40N, 9 covers over four million square kilometers. During this time, the only exposed areas were islands in western Colorado and parts of New Mexico. The location of the Southwest and the topographical extremes across this area strongly influence its weather. The warmer the air near the surface is relative to the air above it, the more potential energy it has to move up. Bear Lake and Glacier Gorge, Rocky Mountain National Park, Colorado, 2011. P. Natl. One especially alarming detail about the Calf Canyon fire is that it was originally set in January 2022. 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. Recent warming within the Southwest has been among the most rapid in the United States, and models predict that the area's climate will continue to warm. 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. At this time, the Southwest was still submerged. All rights reserved. Photo by Eltiempo10 (Wikimedia Commons, Creative Commons Attribution-ShareAlike 4.0 International license, image resized). 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. The large ice sheets in the Northern Hemisphere did not extend into the Southwest, even at their maximum area. PRI's free resource to help you learn about the Earth and its history. These changes include the following: The seasonality and transmission frequency of insect-borne diseases and other infectious diseases prevalent in the Southwest, including plague, valley fever, and Hanta, are influenced by warming trends. During the winter, moisture travels from the west, as storms from the Pacific Ocean move east. (41-60 degrees.) Check out Toms recent post on the drought in Arizona to understand more about how drought works in this region. 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. Official websites use .gov Photograph by Bill Morrow (Flickr;Creative Commons Attribution 2.0 Generic license). Page snapshot:Introduction to the climate of the southwestern United States, including present, past, and future climate. Warm, moist air from the south occasionally but infrequently moves into Colorado during the summer. 4. Photo by Lane Pearman (flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized). At the very end of the Cretaceous, the Gulf Coast experienced an enormous disruption when a large asteroid or bolide collided with Earth in what is now the northern Yucatn Peninsula in Mexico. So is climate change increasing monsoon variability? For example San Diego county has a population of azalea otherwise not seen for hundreds of miles to the north. Drought outlook for the Lower 48 U.S. states in August 2022. Zack and Mike described this years monsoon for southern Arizona as generational, meaning once in a generation. People in the Southwest are particularly dependent on surface water supplies like Lake Mead, which are vulnerable to evaporation. Arizona's climate is influenced by three main topographical areas: the high Colorado Plateau (about 15202130 meters or 50007000 feet in elevation), the rugged mountains to the west (27403660 meters or 900012000 feet high), and the low southwestern mountains with desert valleys (as low as 30 meters or 100 feet above sea level). The southwestern desert is hot, with winter daytime temperatures in the lower 60s and average summer daytime temperatures between 105 and 115F. 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. Brown indicates areas where experts forecast drought will persist or worsen. In Utah, areas below 1200 meters (4000 feet) receive less than 25 centimeters (10 inches) per year, while higher elevations in the Wasatch Mountains receive more than 100 centimeters (40 inches). (1) The North American Monsoon, published in the Bulletin of the American Meteorological Society by David Adams and Andrew Comrie, provides a comprehensive overview of the North American Monsoon and related research through the late 20th century. Photo by James St. John (flickr,Creative Commons Attribution 2.0 Generic license, image cropped and resized). Warmer temperatures also make it easier for insect pests to overwinter and produce more generations. 94, 95, 96 Each assessment has consistently identified drought, water shortages, and loss of ecosystem integrity as major challenges that the Southwest confronts under climate change. Likewise, its not yet clear how the monsoon is changing in the warming climate, or how it will in the future. Scale bar = 1 centimeter (about 0.4 inches). The white arrow is pointing to one of the leaflets of a compound leaf. Regional overview Southwest. 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. The long-range forecast team breaks down region by region what to expect during the summer. Source:FEMA National Risk Index. 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. Large glaciers were found at higher elevations, and temperatures were cool. Fossil ammonoid (Nigericeras scotti) from the Late Cretaceous Greenhorn Limestone, Baca County, Colorado. NOAA (National Oceanic and Atmospheric Administration). Roadcut exposing lake sediments of the Eocene Green River Formation, Duchesne County, Utah. 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 also an important relationship between rainfall and temperature: usually, more rain leads to cooler conditions, and less rain leads to hotter conditions. 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. Despite the monsoon rainfall this year, much of the region is still in a precipitation deficit. In New Mexico, for example, average annual precipitation ranges from less than 25 centimeters (10 inches) within the Great Plains and Basin and Range regions to more than 50 centimeters (20 inches) at the higher elevations to the northwest. Some of these thunderstorms can be strong, delivering heavy rain and frequent lightning. Sci. Earth 150 million years ago, near the end of the Jurassic Period. Thanks for visiting the North American Monsoon region with me! Allmon, W. D., T. A. Smrecak, and R. M. Ross. Scale bar = 5 centimeters (about 2 inches). A couple of field campaigns, including the Arizona-based South-West Monsoon Project (SWAMP, 1993) and the international North American Monsoon Experiment (NAME, 2004), provided a lot of observational data and resulted in a better understanding of the mechanics of the monsoon. Introduction The overall climate of the Southwestits weather patterns over a long period of timetends to be warm and dry. Winter will be warmer than normal, with above-normal precipitation. 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! Other elements involved in the ignition and growth of fires and the risks they pose to people living in the Southwest include (but are not limited to) forest management practices, development patterns, and human behavior (intentionally or unintentionally starting fires). New Mexico, Utah, and Colorado have also reduced their carbon dioxide emissions between 2008 and 2019. Image by The High Fin Sperm Whale, created from images by NOAA National Weather Service training material (Wikimedia Commons, public domain). The Sonoran Desert is located in southwestern Arizona and adjacent regions of California and Mexico. Reconstruction created using basemap from thePALEOMAP PaleoAtlas for GPlatesand the PaleoData Plotter Program, PALEOMAP Project by C. R. Scotese (2016); map annotations by Jonathan R. Hendricks and Elizabeth J. Hermsen for PRI's[emailprotected]project (CC BY-NC-SA 4.0license). Las Cruces, New Mexico, 2006. Thanks thats a big pool of warm water larger than the gulf of California and warmer than the greater Pacific Ocean. 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. At the close of the Mesozoic, global climatealthough warmer than todaywas cooler than at the start of the era. Climate at a glance. Some areas were more than 2F warmer than average (see Figure 1). Scientists first noted the seasonal rainfall patterns in the Southwest in the early 20th century, with the circulation pattern being understood as monsoonal by midcentury. Ive summarized their conclusions above, and include the quotes here, but I suggest you head over to the full science report if youre in the mood for some specifics. North America's position near the equator kept its climate relatively warm. Convective mixing forces the moisture in warm air to condense as it comes into contact with cool air, forming vapor (clouds) and precipitation (for example, rain or hail). During the Permian, shallow marine waters gave way to lowland coastal areas across portions of the Southwest. Today nearly all the glaciers in the Southwest are gone, and the climate is in an arid state. 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. NOAA (National Oceanic and Atmospheric Administration). 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.. 2021. Northwestern Mexico receives upwards of 75% of its average annual precipitation from it, and Arizona and New Mexico more than 50%, during JulySeptember. Nighttime winter temperatures in the desert can drop slightly below freezing. Maps showing the progressive closure of the Isthmus of Panama at 20 million years ago (A) and 15 million years ago (B). We can see some hints of this relationship in my scatter-plot here. Photo by Bigmikebmw (Wikimedia Commons, Creative Commons Attribution-ShareAlike 3.0 Unported license, image cropped). Notice that North America has separated from Africa and there is a spreading center in the Central Atlantic Ocean. NASA Earth Observatory image by Lauren Dauphin (NASA Earth Observatory,used following NASA's image use policy). Photo by Bob Wick, Bureau of Land Management (flickr, public domain). 2010. 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). 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. Shelly sandstones in Utah represent vast tidal flats. Tornado Alley is identified. Photograph by "Cathy" (Flickr;Creative Commons Attribution-NonCommerical 2.0 Generic license). Another player is land-surface feedbackswetter soils provide more moisture to the air through evaporation. Storms form when there is strong convection in the atmosphere. The summer precipitation total for the CONUS was 9.48 inches, 1.16 inch above average, ranking eighth wettest in the historical record. This feature focuses on six states that are commonly thought of as southwestern and characterized at least in part by arid landscapes and scarce water supplies: Arizona, California, Colorado, Nevada, New Mexico, and Utah. Accessed March2021. www.ncdc.noaa.gov/cag. Fossil plants, Late Cretaceous Fruitland Formation, San Juan Basin, New Mexico. (2) In fact, comparing 1955, a year with very similar total rainfall in Tucson as this year, to this year shows temperature between July 1 and August 23 were on average more than 2 degrees F warmer. Sun and storm in Weld County, in the Great Plains region of Colorado, 2015. Photo source:National Park Service (public domain). . Climate change is affecting the Southwest's water resources, terrestrial ecosystems, coastal and marine environments, agriculture, and energy supply. The Central American Isthmus, which today makes up most of Panama and Costa Rica, rose out of the ocean at approximately this time, formed by undersea volcanoes. Map made by Elizabeth J. Hermsen usingSimplemapprand modified in Photoshop. The distance between Santa Fe and Las Vegas, New Mexico, is about 65 kilometers (about 40.5 miles). 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. (Going forward, to avoid having to say northwestern Mexico, Arizona, and New Mexico over and over, Ill refer to this area as the monsoon region.). Photo by Kenneth Carpenter (Wikimedia Commons,Creative Commons Attribution-ShareAlike 4.0 International license, image cropped and resized). 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. Andrews Glacier in Rocky Mountain National Park, Colorado, at two points in time. The cities of Aspen and Lafayette, Colorado, as well as the state of New Mexico, were early adopters of the 2030 Challenge, an effort to reduce fossil fuel use in buildings so that both new and renovated buildings would qualify as carbon neutral by the year 2030. 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. 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. Did La Nia drench the Southwest United States in early winter 2022/23? Although the mountain building that occurred during this event was mostly far to the east, the Southwest was influenced by both fluctuating sea levels and a few significant tectonic changes. Photo of USNM P 38052 by Frederic Cochard (Smithsonian National Museum of Natural History, public domain). 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. 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.