Extreme Weather and Climate EventsWhy Look at Extreme Events?BlizzardsFeatures Associated with BlizzardsProblems Associated with BlizzardsA Few ExamplesThunderstormsSome Features in ThunderstormsSlide 9A Few More ExamplesFloodsCauses of FloodsRillito River (July 2006)Slide 14Problems Associated with FloodsSlide 16DroughtDrought (cont’d)Slide 19Slide 20Slide 21Slide 22Extreme Weather and Extreme Weather and Climate EventsClimate EventsBlizzards, Thunderstorms, Hurricanes, Blizzards, Thunderstorms, Hurricanes, Floods, and DroughtFloods, and DroughtWhy Look at Extreme Events?Why Look at Extreme Events?Can harm human and natural systems both Can harm human and natural systems both during and after eventduring and after eventEconomic lossesEconomic lossesOccurrence may be affected by human Occurrence may be affected by human activity according to various studies, activity according to various studies, including IPCC, 2001including IPCC, 2001BlizzardsBlizzardsA strong winter storm with cold temperatures, A strong winter storm with cold temperatures, strong winds, and intense falling or blowing snowstrong winds, and intense falling or blowing snowRarely experienced in US below ~ 35Rarely experienced in US below ~ 35°N°NTypesTypes–Longwave cycloneLongwave cyclone: low pressure centers both at surface : low pressure centers both at surface and in upper atmosphere; move very slowly; affect and in upper atmosphere; move very slowly; affect northern portions of US; northern portions of US; usuallyusually in spring in spring–Trough cycloneTrough cyclone: develops in association with trough in : develops in association with trough in jet stream; then upper-air features strengthen low jet stream; then upper-air features strengthen low pressure at surface; move faster; typically along eastern pressure at surface; move faster; typically along eastern coast of US (nor’easters); any time during wintercoast of US (nor’easters); any time during winterFeatures Associated Features Associated with Blizzardswith BlizzardsLow pressure, frontsLow pressure, frontsCold temperatures (usually < Cold temperatures (usually < 2020°C (-6°F))°C (-6°F))Strong winds (Strong winds (>> 35 mph) 35 mph)Intense falling or blowing Intense falling or blowing snowsnowSleet and freezing rain south Sleet and freezing rain south of snowof snowSometimes rain even farther Sometimes rain even farther southsouthLow visibility due to Low visibility due to falling/blowing snowfalling/blowing snow““Whiteout” conditionsWhiteout” conditionsProblems Associated Problems Associated with Blizzardswith BlizzardsEconomic loss – Economic loss – businesses closedbusinesses closedDeath – due to exposure, Death – due to exposure, accidents, etc.accidents, etc.Other health problems – Other health problems – hypothermia, frostbitehypothermia, frostbiteUtility complicationsUtility complicationsStructural damage – Structural damage – weight of snowweight of snowTravel inconvenience – Travel inconvenience – closed airports, closed closed airports, closed highways, accidentshighways, accidentsA Few ExamplesA Few ExamplesMontana (March 1969)Montana (March 1969)–20+” (45+cm) of snow20+” (45+cm) of snow–Trough cycloneTrough cycloneEastern US (January 1978)Eastern US (January 1978)–Lowest central pressure = 958 mb, winds to ~ 90 mph, almost 100 deathsLowest central pressure = 958 mb, winds to ~ 90 mph, almost 100 deaths–Longwave cycloneLongwave cycloneStorm of the Century – eastern US (March 1993)Storm of the Century – eastern US (March 1993)–Lowest central pressure = 960 mb, up to 56” of snow (Tenn.), 24” in Mtn. Lowest central pressure = 960 mb, up to 56” of snow (Tenn.), 24” in Mtn. City, Georgia, winds > 75 mphCity, Georgia, winds > 75 mph–Every major East Coast airport closed, 3 million customers with no Every major East Coast airport closed, 3 million customers with no electricity, roofs collapseselectricity, roofs collapses–In Florida – 27 tornadoes, 3 m storm surgeIn Florida – 27 tornadoes, 3 m storm surge–In total, ~ 270 deaths and > $3 billion in damageIn total, ~ 270 deaths and > $3 billion in damageThunderstormsThunderstormsA strong local storm that A strong local storm that contains intense updrafts contains intense updrafts and downdrafts, lightning, and downdrafts, lightning, and thunderand thunderCapable of producing Capable of producing flooding, strong winds, flooding, strong winds, hail, and tornadoeshail, and tornadoesSevereSevere if produces any/all if produces any/all of followingof following–Hail Hail >> 0.75” (1.9 cm) 0.75” (1.9 cm)–Wind Wind >> 57 mph (50 knots, 57 mph (50 knots, 92 km/hr)92 km/hr)–TornadoTornadoSome Features in ThunderstormsSome Features in ThunderstormsOvershooting topOvershooting top – intense updrafts push cloud into – intense updrafts push cloud into stratosphere (top > 70 000 ft)stratosphere (top > 70 000 ft)HailHail – chunks of ice that grow inside a storm due to internal – chunks of ice that grow inside a storm due to internal circulation; most common in Great Plainscirculation; most common in Great PlainsMicroburstMicroburst – strong winds at surface produced when precip – strong winds at surface produced when precip pulls air with it (leading edge at surface called pulls air with it (leading edge at surface called gust frontgust front))LightningLightning – series of huge “sparks” caused by differing – series of huge “sparks” caused by differing electrical chargeselectrical chargesThunderThunder – sound waves produced by rapid expansion of air – sound waves produced by rapid expansion of air due to heat from lightningdue to heat from lightningTornadoesTornadoes......A Few ExamplesA Few ExamplesTri-State Outbreak (March Tri-State Outbreak (March 18, 1925)18, 1925)–Missouri, Illinois, and IndianaMissouri, Illinois, and Indiana–7 tornadoes over ~ 440 mi 7 tornadoes over ~ 440 mi (700km), 695 deaths(700km), 695 deathsPalm Sunday Outbreak Palm Sunday Outbreak (1965)(1965)–Midwest USMidwest US–30 tornadoes in 5 states, 256 30 tornadoes in 5 states, 256 deathsdeathsTopeka, KS (June 8, 1966)Topeka, KS (June 8, 1966)–16 deaths, hundreds of houses 16 deaths, hundreds of houses destroyed or damaged, destroyed or damaged, Washburn University badly Washburn University badly