Photo by James St. John (flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized). Left:Warm air rises. Moisture condenses out of the warm air as it comes into contact with cool air, forming clouds. 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. 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. Data from the Northeast Regional Climate Center Applied Climate Information System; 2079-2099 image shows the weighted mean of downscaled CMIP5 models in the LOCA dataset. A major contributing factor to this event was a geological change that occurred far to the south. In fact, this monsoon may turn out to be the wettest on record for some places! This chapter builds on assessments of climate change in the Southwest region from the three previous U.S. National Climate Assessments. 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. Global temperatures during the Cretaceous were very warm, as much as 10C (18F) above those at present. Colorado has a generally cool and continental climate with low humidity. Map made by Elizabeth J. Hermsen usingSimplemapprand modified in Photoshop. Copyright 2021 Paleontological Research Institution. The Southwest relies on the slow melt of mountain snowpack throughout the spring and summer, when water demands are highest. All the weather intel you need for summer 2021 is here -- including what's in store for wildfire season . Since then carbon dioxide emissions have been on a downward trend. This chart shows annual values of the Palmer Drought Severity Index, averaged over six states in the Southwest (Arizona, California, Colorado, Nevada, New Mexico, and Utah). Source:FEMA National Risk Index. The satellite loop in this post shows Gulf of Mexico moisture moving west into the monsoon region. Left photoandright photoby NPS/Michael Quinn (Grand Canyon National Park via flickr,Creative Commons Attribution 2.0 Generic license, images cropped and resized). However, the Southwest is located between the mid-latitude and subtropical atmospheric circulation regimes, and this positioning relative to shifts in these . The climate remained warm, despite large southern ice sheets, but it had grown much drier. Credits for individual images are given in figure captions. Nighttime winter temperatures in the desert can drop slightly below freezing. Modified from illustrations by Wade Greenberg-Brand originally published inThe Teacher-Friendly Guide to the Earth Science of the SouthwesternUS. Download related technical information PDF, https://droughtmonitor.unl.edu/DmData/DataTables.aspx, A Closer Look: Temperature and Drought in the Southwest. Although on the western edge of the North American Monsoon, California plant geography indicates it makes a large contribution to the states southern flora. Precipitation also varies widely. The Palmer Index is calculated from precipitation and temperature measurements at weather stations, and has been used widely for many years. 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. Light precipitation travels eastward over the Sierra Nevada and Cascade mountains after dropping heavy snowfall in areas of high elevation. JavaScript appears to be disabled on this computer. As of 2010, bark beetles in Arizona and New Mexico have affected more than twice the forest area burned by wildfires in those states. Photo by Stefan Klein (Wikimedia Commons, Creative Commons Attribution-ShareAlike 4.0 International license, image cropped and resized). The long-range forecast team breaks down region by region what to expect during the summer. Photo by Dr. David Goodrich, NOAA (NOAA Photo Library ID wea04192, NOAA's National Weather Service, via flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized). 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. Based on the long-term Palmer Index, drought conditions in the Southwest have varied since 1895. An ancient horse (Mesohippus),Eocene Florissant Fossil Beds, Teller County, Colorado. 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. The formation of precipitation also causes electrical charging of particles in the atmosphere, which in turn produces lightning. 830 AM EST Thu Feb 16 2023. Before the Isthmus closed, the Atlantic and Pacific oceans were connected. Digital Encyclopedia of Earth Science: Why talk about climate change? Temperatures in the southwest region average greater than states up North, because there isn't as much water vapor in upper level winds to screen direct sunlight. A blog about monitoring and forecasting El Nio, La Nia, and their impacts. Wetter-than-average monsoons (green dots) are slightly more common during La Nia years, while drier-than-average monsoons (brown dots) are slightly more common during El Nio years. Fossil mammals adapted to colder temperatures are found in the Pleistocene of Colorado. 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. What is the weather like in the Southwest region in summer? Water is already scarce in the Southwest, so every drop is a precious resource. 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. As of June 2022, it was more than 90% contained. Glaciers covered most of the world's southern landmasses, which were located over the South Pole. Photo by Daniel Mayer (Wikimedia Commons, Creative Commons Attribution-ShareAlike 3.0 Unported license, image resized). . The better known of these wet seasons is the summer monsoon, which lasts from about mid-June to early September. 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. Annual Weather SummaryNovember 2022 to October 2023. Calf Canyon-Hermit Creek Fire near Holman, New Mexico, on May 8, 2022. All rights reserved. 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. 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. 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. Monsoon rainfall activity tends to be grouped into bursts, with periods of rainy days interspersed with drier periods, rather than rain every day. Percent of total annual precipitation occurring during JulySeptember, based on 19792020 using CPC Unified rain-gauge-based data. Sprawling development of Phoenix, Arizona, a city in the Sonoran Desert, 2009. Average temperatures range from about 60 to 80 F in Paris, while in Nice and on the south coast they range from around 80 to 90 F. In recent years, heatwaves in Paris and elsewhere have brought record-breaking temperatures, sometimes exceeding 100 degrees F. Summer storm systems are common. Global temperatures fell further in the late Miocene thanks to the formation of the Himalayas. Where the land was exposed, deposits of dust (loess) accumulated and were blown across much of the Southwest. Modified fromFigure 11 in Kirby et al. Notice that North America has separated from Africa and there is a spreading center in the Central Atlantic Ocean. Warmer temperatures also make it easier for insect pests to overwinter and produce more generations. Left photoandright photofrom NPS, courtesy David Bustos (public domain). July 1August 22, 2021 precipitation shown as a percent of the average July 1August 22, based on 19792020. Shallow seaways spread over many of the continents, including South America, Africa, Eurasia, and North America. Ordovician deposits across the Southwest indicate warm, shallow seas rich in invertebrate life. (3) There is a whole lot of interesting detail in this reportabout everything, but about the North American Monsoon specifically. Left (1):Leaves of a seedling. 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. 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. During the Paleocene to Eocene, the Southwests climate was warm and wet, and large mammals roamed the forested landscape. Summer temperatures in this region rarely rise above 60 F during the day, while winter temperatures hover around 30 F due to the temperate . 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. ; 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 . 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. 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. Some areas were more than2F warmer than average (see Figure 1). SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS. 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. All of these plants, animals, and people need water to survive. Zack also mentioned our good friend El Nio! 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. Bark beetles, which normally die in cold weather, have been able to survive through the winter and reproduce, increasing tree mortality. The recent Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report covers observed and potential future changes in the North American Monsoon. Climate change is affecting the Southwest's water resources, terrestrial ecosystems, coastal and marine environments, agriculture, and energy supply. Mesohippusmeasured up to 70 centimeters (2 feet) at shoulder height. Well those extra storms probably just go somewhere else because of the change in wind pattern that the El Nino brings, eh? 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. According to the Kppen classification system, a system of climate classification using latitude band and degree of continentality as its primary forcing factors, Central Asia is a predominantly B-type climate regime. 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. We can see some hints of this relationship in my scatter-plot here. The Wave, a series of intersecting U-shaped troughs eroded into Jurassic NavajoSandstone within the Paria Canyon-Vermilion Cliffs Wilderness, Arizona. Right:Dolichometoppus productus. The final ingredient is wind. The oceans between Gondwana and North America began to close. The thicker line is a nine-year weighted average. NASA Earth Observatory image by Lauren Dauphin (NASA Earth Observatory,used following NASA's image use policy). 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. Its remnant exists today as the Great Salt Lake. 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. Page snapshot:Introduction to the climate of the southwestern United States, including present, past, and future climate. Yet this landscape actually supports a vast array of plants and animals, along with millions of people who call the Southwest home. It's made up of the states of Arizona, New Mexico, Oklahoma, and Texas. Brown indicates areas where experts forecast drought will persist or worsen. On the other hand, New Mexico and northern Mexico are near or a bit below average. 2. Taken on August 15, 2016. Frequent showers and thunderstorms continue well into the summer. 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. Map of the modern Yucatn Peninsula region showing the location of the Chicxulub impact crater. At the close of the Mesozoic, global climatealthough warmer than todaywas cooler than at the start of the era. Pangaea began to break up during the Jurassic, rifting apart into continents that would drift toward their modern-day positions. The white arrow is pointing to one of the leaflets of a compound leaf. Brown indicates where precipitation has been less than average; green is greater than average. 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. 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 impacts of the monsoon go beyond just rainfall amounts. The cycling layers in thesandstone represent changes in the direction of prevailing winds as large sand dunes migratedacross the desert. Soil moisture, ground water, and streamflow are part of Drought Monitor calculations (Figure 2), and they are all sensitive to human activities. Has hurricanes and tornadoes. 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. Because higher temperatures mean greater evaporation and warmer air can hold more water, precipitation will occur in greater amounts at a time, but less frequently. 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. In general, it is expected that high alpine glaciers in the Colorado Rockies will disappear as the climate continues to warm. 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. PRI's free resource to help you learn about the Earth and its history. 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. There is some variability in the onset and demise of the monsoon. The average amount of precipitation for the United States is 85.6 centimeters (33.7 inches). In winter, rising temperatures have increased the number of frost-free days. Large lakes covered parts of northern Utah and Colorado. 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. This led to global cooling and dropping global sea levels. 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.. 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. Shiprock, a volcanic monadnock in San Juan County, New Mexico, rises roughly 483 meters (1583 feet) above the desert plain. 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. Photo by Gregory Smith (flickr, Creative Commons Attribution-ShareAlike 2.0 Generic license, image cropped and resized). (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. Every part of the Southwest experienced higher average temperatures between 2000 and 2020 than the long-term average (1895-2020). Data for Figure 2 were provided by the National Drought Mitigation Center. A value between -2 and -3 indicates moderate drought, -3 to -4 is severe drought, and -4 or below indicates extreme drought. Wind moves the air, promoting mixing. Maps showing the progressive closure of the Isthmus of Panama at 20 million years ago (A) and 15 million years ago (B). 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). Summer- The summer in the Southwest region is hot and desert-like. 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. (2011)PLoS ONE3(7): e2791(Creative Commons Attribution license, image reorganized and resized). Elevation does, however, play a key role in precipitation received throughout the Southwest. Tornado Alley is identified. The Cretaceous-Paleogene boundary at Trinidad Lake State Park, Las Animas County, Colorado. Image fromCretaceous Atlas of Ancient Life: Western Interior Seaway(Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Internationallicense). Kppen climate map of the 48 contiguous states of the continental United States. The monsoon starts to develop in Mexico in June, and moves into the U.S. Southwest in July. The Southwest is typically dry, hot, and humid. The average annual temperature in most of the Southwest is predicted to rise 2.2 to 5.5C (4 to 10F) by 2100. 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. Large portions of the Southwest have experienced drought conditions since weekly Drought Monitor records began in 2000. Unless otherwise indicated, text and images on this website have Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International licenses. The Southwest, already the driest region in the United States, has become even drier since the mid-20th century, particularly on the hottest days . So is climate change increasing monsoon variability? A strong temperature difference at different heights creates instability. Onion Creek salt diapir, a salt dome exposed at the surface at Fisher Towers, Utah. 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 first letter of each zone in the key indicates its major classification. In the middle Cretaceous, oceans covered most of the Southwest, with the exception of parts of Arizona and New Mexico. Paleontological Research Institution Special Publication 38, Ithaca, NY, 200 pp. Left:Jaw with teeth. Precipitation accumulation over the past 12 months, shown as a percent of the average mid-August through mid-August total. Southwest Increased heat, drought, and insect outbreaks, all linked to climate change, have increased wildfires.
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