Editing Utah (section)

===Climate===
[[File:Köppen Climate Types Utah.png|left|thumb|300x300px|[[Köppen climate classification|Köppen climate types]] of Utah, using 1991–2020 [[Climatological normal|climate normals]].]]
Utah features a dry, [[semi-arid climate|semi-arid]] to [[desert climate]],<ref>{{Cite web |date=2021-12-14 |title=Why is Utah so dry? - 2022 |url=https://theflatbkny.com/united-states/why-is-utah-so-dry/ |access-date=2022-06-10 |website=The Flat |language=en-US}}</ref> although its many mountains feature a large variety of climates, with the highest points in the [[Uinta Mountains]] being above the [[Tree line|timberline]]. The dry weather is a result of the state's location in the [[rain shadow]] of the [[Sierra Nevada (U.S.)|Sierra Nevada]] in California. The eastern half of the state lies in the rain shadow of the [[Wasatch Mountains]]. The primary source of precipitation for the state is the Pacific Ocean, with the state usually lying in the path of large Pacific storms from October to May. In summer, the state, especially southern and eastern Utah, lies in the path of [[monsoon]] moisture from the [[Gulf of California]].

Most of the lowland areas receive less than {{convert|12|in|mm|0}} of precipitation annually, although the [[Interstate 15 in Utah|I-15]] corridor, including the densely populated [[Wasatch Front]], receives approximately {{convert|15|in|mm|0}}. The Great Salt Lake Desert is the driest area of the state, with less than {{convert|5|in|mm|0}}. Snowfall is common in all but the far southern valleys. Although St. George receives only about {{convert|3|in|mm|0}} per year, Salt Lake City sees about {{convert|60|in|mm|0}}, enhanced by the [[lake-effect snow]] from the Great Salt Lake, which increases snowfall totals to the south, southeast, and east of the lake.

Some areas of the [[Wasatch Range]] in the path of the lake effect receive up to {{convert|500|in|cm|0}} per year. This micro climate of enhanced snowfall from the Great Salt Lake spans the entire proximity of the lake. The cottonwood canyons adjacent to Salt Lake City are located in the right position to receive more precipitation from the lake.<ref>{{cite book|last1=Steenburgh|first1=Jim|title=Secrets of the Greatest Snow on Earth|date=November 14, 2014|publisher=Utah State University Press|isbn=978-0874219500|edition=1}}</ref> The consistently deep powder snow led Utah's ski industry to adopt the slogan "the Greatest Snow on Earth" in the 1980s. In the winter, [[temperature inversion]]s are a common phenomenon across Utah's low basins and valleys, leading to thick haze and fog that can last for weeks at a time, especially in the [[Uintah Basin]]. Although at other times of year, its air quality is good, winter inversions give Salt Lake City some of the worst wintertime pollution in the country.

Previous studies have indicated a widespread decline in snowpack over Utah accompanied by a decline in the snow–snow-precipitation ratio while anecdotal evidence claims have been put forward that measured changes in Utah's snowpack are spurious and do not reflect actual change. A 2012 study<ref>[http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00084.1 2012 study] {{Webarchive|url=https://web.archive.org/web/20170512142725/http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00084.1 |date=May 12, 2017 }}, journals.ametsoc.org.</ref> found that the proportion of winter (January–March) precipitation falling as snow has decreased by nine percent during the last half century, a combined result of a significant increase in rainfall and a minor decrease in snowfall. Meanwhile, observed snow depth across Utah has decreased and is accompanied by consistent decreases in snow cover and surface albedo. Weather systems with the potential to produce precipitation in Utah have decreased in number with those producing snowfall decreasing at a considerably greater rate.<ref>Gillies et al. (2012) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00084.1 {{Webarchive|url=https://web.archive.org/web/20170512142725/http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00084.1 |date=May 12, 2017 }}</ref>
[[File:RoseParkStreets.jpg|thumb|Snow in [[Rose Park, Salt Lake City]]]]

Utah's temperatures are extreme, with cold temperatures in winter due to its elevation, and very hot summers statewide (except mountain areas and high mountain valleys). Utah is usually protected from major blasts of cold air by mountains lying north and east of the state, although major Arctic blasts can occasionally reach the state. Average January high temperatures range from around {{convert|30|F|C|0}} in some northern valleys to almost {{convert|55|F|C|0}} in St. George.

Temperatures dropping below {{convert|0|F|C|0}} should be expected on occasion in most areas of the state most years, although some areas see it often (for example, the town of [[Randolph, Utah|Randolph]] averages about fifty days per year with temperatures that low). In July, average highs range from about {{convert|85|to|100|F|C|0}}. However, the low humidity and high elevation typically lead to large temperature variations, leading to cool nights on most summer days. The record high temperature in Utah was {{convert|118|F|C|0}}, recorded south of St. George on July 4, 2007,<ref>{{cite news |last= Fidel |first= Steve |url= http://www.deseretnews.com/article/680196797/Utahns-feeling-hot-hot-hot.html |title= Utahns feeling hot, hot, hot |newspaper= [[Deseret Morning News]] |date= July 6, 2007 |archive-url= https://web.archive.org/web/20141104175045/http://www.deseretnews.com/article/680196797/Utahns-feeling-hot-hot-hot.html |archive-date= November 4, 2014 }}</ref> and the record low was {{convert|-69|F|C|0}}, recorded at [[Peter Sinks]] in the [[Bear River Mountains]] of northern Utah on February 1, 1985.<ref>{{cite news|url=http://www.ksl.com/index.php?nid=341&sid=148094|title=Utah Cold Weather Facts—Snow and Winter Storms|work=[[KSL-TV]] |access-date=October 19, 2014|archive-url=https://web.archive.org/web/20141022004925/http://www.ksl.com/index.php?nid=341&sid=148094|archive-date=October 22, 2014|url-status=live}}</ref> However, the record low for an inhabited location is {{convert|-49|F|C|0}} at [[Woodruff, Utah|Woodruff]] on December 12, 1932.<ref>{{cite web|url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ut9595|title=WOODRUFF, UTAH (429595)|website=wrcc.dri.edu|access-date=October 19, 2014|archive-url=https://web.archive.org/web/20150630174716/http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ut9595|archive-date=June 30, 2015|url-status=live}}</ref>

Utah, like most of the western United States, has few days of thunderstorms. On average, there are fewer than 40 days of thunderstorm activity during the year, although these storms can be briefly intense when they do occur. They are most likely to occur during [[North American Monsoon|monsoon]] season from about mid-July through mid-September, especially in southern and eastern Utah. Dry lightning strikes and the generally dry weather often spark wildfires in summer, while intense thunderstorms can lead to [[flash flood]]ing, especially in the rugged terrain of southern Utah. Although spring is the wettest season in northern Utah, late summer is the wettest period for much of the south and east of the state. Tornadoes are uncommon in Utah, with an average of two striking the state yearly, rarely higher than EF1 intensity.<ref>[http://www.ncdc.noaa.gov/img/climate/research/tornado/small/avgt5304.gif Annual Average Number of Tornadoes, 1953–2004] {{Webarchive|url=https://web.archive.org/web/20111016174155/http://www.ncdc.noaa.gov/img/climate/research/tornado/small/avgt5304.gif |date=October 16, 2011 }}. [[NOAA]] [[National Climatic Data Center]]. Retrieved March 20, 2008.</ref>

One exception of note, however, was the unprecedented [[Salt Lake City Tornado]] that moved directly across downtown Salt Lake City on August 11, 1999. The [[F2 tornado]] killed one person, injured 60 others, and caused approximately $170&nbsp;million in damage;<ref name="1999_tornado">{{cite web |last1=Brough |first1=Clayton |last2=Brown |first2=Dan |last3=James |first3=David |last4=Pope |first4=Dan |last5=Summy |first5=Steve |title=Salt Lake City Tornado - August 11, 1999 |url=http://www.wrh.noaa.gov/slc/climate/tornado.php |website=NOAA |archive-url=https://web.archive.org/web/20120614191624/http://www.wrh.noaa.gov/slc/climate/tornado.php |archive-date=June 14, 2012}}</ref> it was the second strongest tornado in the state behind an F3 on August 11, 1993, in the Uinta Mountains.<ref name="1999_tornado"/><ref>{{cite web |last1=Dunn |first1=Larry |last2=Alder |first2=William |last3=McClung |first3=Tim |title=Western Region Technical Attachment No. 94-20: The High Uinta Tornado |url=https://www.weather.gov/media/wrh/online_publications/TAs/ta9420.pdf |website=NOAA |access-date=October 7, 2021 |date=June 21, 1994}}</ref> The only other reported tornado fatality in Utah's history was a 7-year-old girl who was killed while camping in [[Summit County, Utah|Summit County]] on July 6, 1884.<ref name="1999_tornado"/>