Nevada's Weather and Climate

Fact Sheet-17-04 Nevada’s Weather and Climate Kerri Jean Ormerod, Assistant Professor/Extension Program Leader Stephanie McAfee, Assistant Professor/Deputy State Climatologist

Introduction different seasons. Every place has its own normal Weather and climate are related, but they are climate. For example, Las Vegas typically gets not the same. The difference between weather thunderstorms in the summer. Much of Nevada and climate is time. Practically speaking, weather gets winter rain or snow when large storms that determines which clothes you decide to put on form over the Pacific head eastward. today, but climate determines the type of clothes Weather and climate are influenced and defined that are in your closet. by a number of factors, including atmospheric pressure, winds, ocean currents, temperature and Weather and Climate Basics topography. Atmospheric pressure (the weight Weather describes the variation of the atmo- of the atmosphere, also known as barometric sphere in a particular place over a short period of pressure) is an important driver of weather and time. Weather conditions include changes in air climate. Weather maps indicate areas of similar pressure, temperature, humidity, clouds, wind and atmospheric pressure with lines called isobars precipitation – rain, hail and snow. Weather can (see Figure 1). Areas with high pressure are change over the course of minutes, hours, days marked H and are typically associated with sun- or weeks. Climate is the usual or expected weather for a particular place or region, which is typically evalu- ated over a 30-year time period referred to as a normal. The timescale for climate is months, seasons, years, decades, centuries and even mil- lenia. Climate is often thought of as just the long-term average temperature and precipitation, but it also includes vari- ability and the likelihood of extreme events. Cli- mate is an assessment of the types of weather that Figure 1. Surface weather analysis map for the U.S., Oct. 27, 2016. The isobars (brown are expected – or may- lines marked with numbers) distinguish constant pressure areas. The lines with symbols depict frontal boundaries. (Source: National Weather Service (NWS) Weather Prediction be not unexpected – in Center, http://www.wpc.ncep.noaa.gov/html/sfc2.shtml.)

A partnership of Nevada counties; University of Nevada, Reno; and U.S. Department of Agriculture 1 ny weather. Areas of low pressure are marked L Nevada Weather and Climate and are more likely to receive precipitation. At the Although Nevada is the driest state in the nation, surface, air moves from areas of higher pressure it is also a mountainous state. In the mountains toward areas of lower pressure, producing wind. the climate tends to be colder and wetter. In Larger differences in pressure generate stron- fact, Nevada means “snow-capped” in Spanish, ger winds. Therefore, closer isobar lines indicate and much like other Westerners, Nevadans rely windy conditions. heavily on mountain snow for their water supplies Fronts develop when air masses of different den- (Green, 2015). sity and temperature come in contact. You may Differences in climate from one place to another be familiar with this in the form of cold and warm reflect Nevada’s size and rugged topography, fronts. Fronts, whether cold or warm, typically which ranges from over 13,000 feet in the White mean increased wind, rapid changes in tempera- Mountains to just 500 feet above sea level at the ture, and often precipitation for the local area. Colorado River (Green, 2015). The fact that elevation is a particularly important driver of weather Meteorology and Climatology and climate is no surprise to high-country travel- Meteorology is the scientific study of the atmo- ers familiar with the increased likelihood of high sphere. A meteorologist describes the current winds and wet or snowy weather on mountain weather conditions and makes short-term fore- passes. casts (typically no more than seven to 10 days). To produce forecasts, meteorologists rely on real-time observations and computer models of the atmosphere. In addition to weather station and rain gauge observations, satellite and radar technologies and weather-balloon-based measurements are used to track storm systems and air masses across the U.S. Climatology evaluates the large-scale and long- term drivers of weather. It includes the study of past climate and projected future climate. Clima- tologists use a variety of instruments, technologies and observations to document aspects of past and current climates and to model past and future conditions. Climate information is im- mensely useful for mid-term and long-term plan- ning and is frequently used by farmers, ranchers, the military, land and water managers, and the shipping and construction trades, among others. Climate conditions are mapped in many different ways by numerous local, regional and national entities. For example, gardeners who utilize the United States Department of Agriculture (USDA) plant hardiness zones (see Figure 2) to select plants from a nursery are already acquainted with Figure 2. The U.S. Department of Agriculture climate. These growing zones are based on aver- (USDA) Plant Hardiness Zones are based on extreme minimum temperatures, 1976–2005. The aging 30 years of minimum winter temperatures. color variation indicates the broad range of climate conditions in Nevada. (Source: USDA, http://planthardiness.ars.usda.gov.)

2 Climographs provide a snapshot of “normal” When wind pushes moist air up steep hills or weather conditions by representing average mountains, such as the Sierra Nevada Range, temperature and precipitation in a specific loca- precipitation occurs. The steep rise in the to- tion over a 30-year time frame. Figure 3 shows pography blocks air flow and forces air mass- climographs for Ely and Boulder City that quickly es upward; this is known as orographic lifting. illustrate how two basic climate parameters differ Orographic lifting wrings moisture out of the air in these locations. The blue lines indicate the on the windward slope of the mountain, leaving average monthly temperatures, and green bars dry air to descend along the leeward side of the indicate average monthly precipitation. As the mountain range. The area in the lee of a moun- climographs illustrate, Ely experiences more pre- tain range, where precipitation is blocked, is cipitation and lower temperatures than Boulder known as the rain shadow. City. Ely is a mountain community that sits at over 6000 feet above sea level. Boulder City is located El Niño and La Niña roughly 225 miles to the south at an elevation of The El Niño Southern Oscillation (ENSO for 2500 feet. short) refers to large-scale changes in the winds and sea surface temperatures in the tropical 100 1.4 Pacific Ocean. El Niño, referred to as the warm Ely, 1971 - 2000 phase, and La Nina, also called the cool phase, 90 1.2 are ENSO’s two extremes. During El Niño, a 80 large expanse of unusually warm water in the 70 1.0 eastern tropical Pacific Ocean can drive changes (in) on 60 in the wintertime storm track into North Ameri- 0.8 ca. During a typical El Niño winter, more storms 50 ec ipitati cross southern California, Arizona, and southern 0.6 40 Nevada, while fewer storms than usual hit the Pa- 30 0.4 cific Northwest. El Niño has little relationship with ve rageTemperature(°F)

ve ragePr wintertime precipitation in the Sierra and northern

A 20 0.2 A Nevada. Since the 1930s, northern Nevada has 10 had dry El Niño winters and wet ones. La Niña, 0 0.0 when the ocean is colder than normal in the east- ay ug Jul ep Apr Oct Jun Jan Feb Mar Nov Dec ern tropical Pacific, also impacts the winter storm A S M 100 1.4 track. While there have been both wet and dry La Boulder City, 1971- 2000 Niña winters in northern Nevada and the northern 90 1.2 Sierra, southern Nevada is usually dry during La 80 Niña years (see Figure 4). 70 1.0 (in) on 60 0.8 Atmospheric Rivers Atmospheric rivers are narrow bands of concen- 50 0.6 ec ipitati trated water vapor in the atmosphere associated 40 with strong winds and heavy precipitation. Atmo- 30 0.4 spheric rivers can contain more water than seven ve ragePr ve rageTemperature(°F) to 15 Mississippi Rivers combined (Ralph and A A 20 0.2 Dettinger, 2011). In the western U.S., atmospher- 10 ic rivers are responsible for extreme precipitation 0 0.0 events as well as destructive flooding and mud- Jul Apr Oct Jun Jan Feb Mar Nov Dec Aug Sep May slides. Although they can be destructive, atmo- Figure 3. Climographs for Ely (top) and Boulder City spheric rivers are particularly important drivers of (bottom), 1971–2000. (Source: Data from Western precipitation in the Sierra and western Nevada. Regional Climate Center (WRCC), http://www.wrcc. dri.edu/.) 3 100% Elko 50%

-50% El Nino Neutral La Nina -100% 1950 1960 1970 1980 1990 2000 2010 100% 100% 100% Reno Elko 50% 50% 50%

0% 0% 0%

-50% -50% -50%

-100% El Nino Neutral La Nina -100% -100% 1950 1960 1970 1980 1990 2000 2010 1950 1960 1970 1980 1990 2000 2010 1950 1960 1970 1980 1990 2000 2010 300% 300% Las Vegas Figure100% 4. Percent of normal October – March precipitation Las Vegas for Elko, RenoReno and Las Vegas (1950–2016). El Niño years are orange, and La Niña years are turquoise. In Las Vegas, 200% essentially50% all La Niña years have below normal precipitation, and all El Niño years have above normal precipitation. 100% 100% The 0%pattern is not as clear in Elko or Reno, which have had wet and dry El Niño and La Niña years. (Source: Data from 0% Western Regional Climate Center (WRCC), http://drought- 0% monitor.unl.edu/,-50% and Earth System Research Laboratory (ESRL), http://www.esrl.noaa.gov/psd/people/gary.bates/ -100% -100% water/index.html.)-100% 1950 1960 1970 1980 1990 2000 2010 1950 1960 1970 1980 1990 2000 2010 1950 1960 1970 1980 1990 2000 2010 Snow Hazardous300% Weather in Nevada Mountain snow serves as a natural “water tower,” Nevada’sLas weather Vegas and climate are both varied storing water for downstream communities and and200% extreme. These include extremes in tem- releasing it slowly in the form of snowmelt. The perature, amount of precipitation, and wind. While timing of snowmelt (and consequently of peak any100% individual flood, heat wave, or snowstorm is flows in streams) is critically important for sus- a weather event, the fact that they occur and their taining habitat and providing adequate water for frequency0% are aspects of Nevada’s climate. wildlife, and rural, suburban and urban residents. Floods 20000 -100% 1950 1960 1970Floods1980 can1990 be2000 sudden2010 and cause a significant amount 16000 of damage. Intense rains, rapidly melting snowpacks 12000 and heavy rain onto a snowpack contribute to 8000 flood events. Landscapes scarred by fire are also 4000 prone to landslides during heavy rain events. Truckee River Reno (cfs) 0 Scientists use stream gaug- 91 93 95 97 99 01 03 05 07 09 11 13 15 ------es to measure and monitor

an an an an surface water. Hydrographs Jan Jan Jan Jan Jan Jan Jan Jan Jan J J J J are used to plot the flow of surface waters (see Figure Figure 5. Hydrograph illustrating the cubic feet of water flow per second of the 5). Hydrographs provide a Truckee River in Reno, 1991–2015. Increased stream flow can be a result of simple means to represent rainfall or snowmelt. (Source: Data from U.S. Geological Survey, http://waterda- the measured volume of ta.usgs.gov/nwis/.) 4 U.S. Drought Monitor January 5, 2016 (Released Thursday, Jan. 7, 2016) Nevada Valid 7 a.m. EST Drought Conditions (Percent Area) U.S. Drought Monitor January 5, 2016 None D0-D4 D1-D4 D2-D4 D3-D4 D4 U.S. Drought Monitor - Nevada (Released Thursday, Jan. 7, 2016) Nevada Valid 7 a.m. EST Current 1.34 98.66 90.76 64.40 31.40 9.35 January 5, 2016 Drought Conditions (Percent Area)

None D0-D4 D1-D4 D2-D4 D3-D4 D4 Last Week Floods can occur suddenly. 1.34 98.66 93.08 65.49 31.74 9.35 12/29/2015 Current 1.34 98.66 90.76 64.40 31.40 9.35 Be prepared to react to floods by 3 Months Ago Last Week 0.01 99.99 94.76 75.92 37.52 15.93 1.34 98.66 93.08 65.49 31.74 9.35 visiting Nevada Floods, 10/6/2015 12/29/2015 3 Months Ago Start of 0.01 99.99 94.76 75.92 37.52 15.93 10/6/2015 www.nevadafloods.org, Calendar Year 1.34 98.66 93.08 65.49 31.74 9.35 12/29/2015 Start of Calendar Year 1.34 98.66 93.08 65.49 31.74 9.35 for flood awareness information. Start of 12/29/2015 Water Year 0.00 100.00 94.76 76.08 37.52 15.93 Start of Water Year 0.00 100.00 94.76 76.08 37.52 15.93 9/29/2015 water in a river or stream, and they can be used 9/29/2015 One Year Ago One Year Ago 0.00 100.00 96.98 68.25 48.38 11.89 to represent past river conditions as well as fore- 0.00 100.00 96.98 68.25 48.38 11.89 1/6/2015 1/6/2015 casted future flows. In addition, hydrographs help Intensity: illustrate seasonal changes, extreme events and Intensity: D0 Abnormally Dry D3 Extreme Drought D1 Moderate Drought D4 Exceptional Drought trends, and can be used to identify weather and D0 Abnormally Dry D3 Extreme Drought climate conditions associated with floods. D2 Severe Drought D1 Moderate Drought D4 Exceptional Drought The Drought Monitor focuses on broad-scale conditions. Local conditions may vary. See accompanying text summary D2 Severe Drought for forecast statements. Drought The Drought Monitor focuses on broad-scale conditions. Author: Meteorological drought occurs when abnormally Local conditions may vary. See accompanying text summary Brian Fuchs for forecastD0 Abnormally statements. Dry National Drought Mitigation Center dry weather persists. The absence of precipita- D1 Moderate Drought tion can be classified by the severity and dura- Author: BrianD2 Fuchs Severe Drought tion of the shortfall. People may wonder whether NationalD3 Extreme Drought MitigationDrought Center Nevadans even notice drought, since the av- D4 Exceptional Drought http://droughtmonitor.unl.edu/ erage precipitation is already so low. However, below normal precipitation can impact certain sectors quite heavily, including recreation, water management and agriculture. The warm temperatures that often accompany dry spells amplify the http://droughtmonitor.unl.edu/ impacts of protracted drought and pose additional hardships on affected communities. Figure 6. January 5, 2016 Drought Monitor map. Drought Status and current conditions are Drought was exceptional and prolonged in the west- mapped weekly in the U.S. Drought Monitor, ern part of Nevada, while there were normal condi- which is produced by the National Oceanic and tions in a very small area in the northeastern part of Atmospheric Administration, the U.S. Department Elko County (indicated in white). (Source: National Drought Mitigation Center (NDMC) U.S. Drought of Agriculture, and the National Drought Mitiga- Monitor (USDM), http://droughtmonitor.unl.edu/.) tion Center at the University of Nebraska-Lincoln. The map in Figure 6 is based on measurements Fire of climatic, hydrological and soil conditions, as Available fuels, topography and weather all in- well as reported impacts and observations from fluence wildland fires. Low humidity, warm tem- more than 350 contributors across the country. peratures and high winds are ripe conditions for The extent and intensity of drought is color-cod- wildfire, especially when there is dry lightning. ed, ranging from Abnormally Dry (D0), to Moder- Cloudbursts and thunderstorms bring lightning ate (D1), Severe (D2), Extreme (D3) and Excep- that causes wildland fire, but people spark many tional (D4) Drought. fires in the western U.S. as well. High winds, which are not unusual in Nevada, quickly spread wildland fires. For information about university programs and regional expertise, visit Living With Drought, www.unce.unr.edu/programs/sites/ drought/. 5 Volunteer Weather Observers Be better prepared for fire. Local weather observers provide data that play Visit Living With Fire, an important role in water and land management www.livingwithfire.info, across the western U.S. In Nevada, reports of for more information on how to zero precipitation for days – or months – is not live more safely with the threat of uncommon. However, it is just as important for meteorologists and climatologists to know when wildland fires. and where it did not rain or snow, as it is to know how much it rained or snowed. Heat Waves A heat wave is an extended period of higher than The oldest weather network is the National normal temperatures. Exposure to several days Weather Service’s Cooperative Observer Pro- of hotter than average temperatures can have gram (COOP), which was established by an act lasting environmental and social effects. Extreme of Congress in 1890. Each day, COOP volunteers heat puts stress on plants and animals and poses report minimum temperature, maximum tempera- significant health risks for vulnerable people. ture, precipitation and other weather information Extreme heat can be fatal. During a heat wave it to the National Weather Service. is important to find a place to cool down and stay The Community, Collaborative, Rain, Hail and hydrated by drinking lots of water. Snow (CoCoRaHS) network provides a platform for volunteers to measure and report daily precip-

Figure 7. These photos display the same landscape, a portion of Cottonwood Ranch’s Bureau of Land Management grazing allotment. The image on the left was taken in 2000 after the 11,000- acre Camp Creek Fire. The image on the right was taken in 2015 and illustrates the successful recovery of several native grasses. (Source: Hottle, 2016.) 6 itation and other environmental conditions using cate the severity of drought impacts directly with low-cost equipment and an interactive website. the Climate Office. Observations made by participants are imme- diately available to State Climate Offices, the If drought is impacting you, please let National Weather Service, research scientists the Climate Office know at and others. www.unr.edu/climate/drought-impact. Want to track and map weather? It is easy to do as part of CoCoRaHS. For information, visit References www.cocorahs.org. Green, M. S. (2015). Nevada: a history of the Silver State. Las Vegas; Reno, University of Landscape Condition Monitoring Nevada Press. People with knowledge of local landscapes can Hottle, Dan (2016, 9/21) Nevada’s ‘Shoesole’ help monitor environmental conditions. Regular Ranchers Grazing Cattle For Sustainable Re- monitoring using repeat photography, as in Figure sults, Not For Federal Regulations. US Fish and 7, helps land and water managers identify normal Wildlife Service Pacific Southwest Region. https:// conditions and communicate abnormal conditions www.fws.gov/cno/newsroom/featured/2016/ (e.g., pests, wildlife, weeds, streamflow). Consis- shoesole_ranchers/?utm_medium=email&utm_ tent and locally relevant on-the-ground reports source=govdelivery regarding environmental or agricultural health are Ralph, F. M., and M. D. Dettinger. Storms, floods, extremely helpful for communicating short-term and the science of atmospheric rivers. Eos 92.32 impacts to stakeholders, as well as for long-term (2011): 265-266. monitoring. Resources Want to monitor local landscapes? What is Climatology? National Drought Mitigation Using a cell phone with GPS makes Center (NDMC), the U.S. Department of Agricul- photographing the landscape and ture (USDA) and the National Oceanic and Atmo- spheric Administration (NOAA). http://drought.unl. sharing these images with others edu/DroughtBasics/WhatisClimatology.aspx easy. Report information to the State U.S. Drought Monitor. National Drought Mitigation Climate Office or via CoCoRaHS to Center (NDMC), the U.S. Department of Agricul- help improve the quality of the data ture (USDA) and the National Oceanic and At- used to make management and policy mospheric Administration (NOAA). http://drought- decisions in Nevada. monitor.unl.edu/ Cooperative Observer Program. National Weath- er Service (NWS). http://www.nws.noaa.gov/om/ Drought Impact Reporting coop/Publications/coop_factsheet.pdf Identifying and documenting drought impacts is difficult. The Nevada State Climate Office under- El Niño and La Niña. National Oceanic and Atmo- stands that changes in weather and climate have spheric Administration. https://www.climate.gov/ wide-ranging impacts. Nevadans can communi- enso

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