The 1965 Palm Sunday tornado outbreak was a historic severe weather event that affected the Midwestern and Southeastern United States on April 10–12, 1965. The tornado outbreak produced 55 confirmed tornadoes in one day and 16 hours. The worst part of the outbreak occurred during the afternoon hours of April 11 into the overnight hours going into April 12. The second-largest tornado outbreak on record at the time, this deadly series of tornadoes inflicted a swath of destruction from Cedar County, Iowa, to Cuyahoga County, Ohio, and a swath from Kent County, Michigan, to Montgomery County, Indiana. The main part of the outbreak lasted 16 hours and 35 minutes and is among the most intense outbreaks, in terms of tornado strength, ever recorded, including at least four "double/twin funnel" tornadoes. In all, the outbreak killed 266 people, injured 3,662 others, and caused $1.217 billion (1965 USD) in damage.
In 2023, tornado expert Thomas P. Grazulis created the outbreak intensity score (OIS) as a way to rank various tornado outbreaks. The 1965 Palm Sunday tornado outbreak received an OIS of 238, making it the fourth-worst tornado outbreak in recorded history.
Meteorological synopsis A vigorous extratropical cyclone centered over the northeastern High Plains, in the region of the Dakotas, was the primary catalyst for widespread severe weather on April 11, 1965. As early as the preceding day, a strong jet stream in the upper two-thirds of the troposphere traversed the southern Great Plains and was responsible for an outbreak of tornadoes from the Kansas–Missouri border to Central Arkansas, including a violent F4 tornado that struck the town of Conway in Faulkner County, Arkansas, killing six people and injuring 200. The following morning, at 7:00 a.m. CDT (12:00 UTC), data from radiosondes indicated wind speeds of between the altitudes of over the Sonoran–Chihuahua Deserts and the Arizona/New Mexico Mountains. Meanwhile, at , winds of impinged on the southern Great Plains. Retreating northward, a warm front interacted with a shortwave to produce isolated thunderstorms from northern Missouri and Central Illinois to the Lower Peninsula of Michigan.
The well-defined surface cyclone over the High Plains intensified as it headed into Iowa, its central pressure decreasing from by 1:00 p.m. CDT (18:00 UTC). As the warm front bisected central Iowa and stretched into Illinois and Indiana, a cold front and very dry air aloft—indicative of a potent elevated mixed layer—departed from eastern Kansas. Strong winds transported steep lapse rates within the elevated mixed layer eastward across the Great Plains. Concomitant destabilization of the atmosphere occurred over the warm sector due to abundant sunshine from the elevated mixed layer. High temperatures ranged from from Chicago to St. Louis. Simultaneously, a strong low-level jet stream brought a moistening air mass northward: dew points of at least reached southernmost Illinois and Indiana by 10:00 a.m. CDT (15:00 UTC). Meanwhile, a pronounced dry line-like boundary near the cold front moved into eastern sections of Arkansas and Missouri. Weather stations from Topeka, Kansas, to Peoria, Illinois, showed very strong vertical shear that favored intense low-level convergence—combined with a moist dew point in the warm sector, an environment favorable for supercell thunderstorms.
A weather balloon launched from Dodge City, Kansas recorded winds of aloft; another at Peoria, Illinois, subsequently measured . Minimum dew points of reached as far north as southern Michigan by mid afternoon. Volatile atmospheric conditions led to thunderstorm activity over eastern Iowa by 1:40–48 p.m. CDT (18:40–48 UTC), the first supercell of which produced the initial tornado of the day. By 6:00 p.m. CDT (23:00 UTC), instability reached record proportions for the time of year over a wide area, with convective available potential energy (CAPE) of at least 1,000 J/kg in the mixed layer over much of Indiana and southernmost Michigan. Record-breaking ambient vertical wind shear in the lowest of the atmosphere facilitated the explosive development of long-lived mesocyclones and thus long-tracked tornado families. The very strong shear and rapid forward speed of the storms—up to in some cases—may have enhanced the formation of cyclic supercells and could account for numerous reports of multiple mesocyclones and twin tornadoes, including the famous "twin tornadoes" near Elkhart, Indiana; similar conditions yielded the Tri-State Tornado, the longest-tracked and deadliest in U.S. history, on March 18, 1925.
At 11:45 a.m. CDT (16:45 UTC) on April 11, the Severe Local Storms Unit (SELS) in Kansas City, Missouri, issued an outlook that mentioned the possibility of tornadoes from northeastern Missouri to the northernmost two-thirds of Indiana. At 2:00 p.m. CDT (19:00 UTC)—fifteen minutes after the first tornado was spotted—the first tornado watch of the day was issued, covering portions of northern Illinois and southern Wisconsin. A total of four watches were issued on April 11–12. For the first time in the U.S. Weather Bureau's history, an entire Weather Bureau Office's jurisdiction, in Northern Indiana, was under a tornado warning; this was termed a "blanket tornado warning" and was later used by several National Weather Service (NWS) offices on April 3, 1974.
Confirmed tornadoes
Crystal Lake–Burtons Bridge, Illinois
This devastating tornado was first detected at 3:27 p.m. CDT (21:27 UTC), but officially touched down seven minutes earlier, in Lakewood. At that time the tornado first produced visible damage at the Crystal Lake Country Club; two firs on the golf course were prostrated. Initially narrow, the tornado subsequently and rapidly widened to . Crossing Nash Street and McHenry Avenue in Crystal Lake, the tornado unroofed or severely damaged several houses. Alongside U.S. Route 14 the tornado claimed its first fatality, a man in a barn. Nearby gas stations and a strip mall were damaged. At the latter place, a roof sheltering a Piggly Wiggly and a Neisner's collapsed, trapping 20 or more people below. The tornado tossed cars about in the parking lot as well. Shortly afterward, the tornado struck the Colby subdivision, destroying or severely damaging 155 homes. F4-level damage occurred as several homes were completely swept off their foundations. Four deaths occurred in the neighborhood, including three in one family (the Holter family) whose home was obliterated. Their bodies were located two blocks distant and a pickup truck was found to have landed in the basement. The tornado scattered debris from the Colby subdivision up to a away.
After ravaging the Colby neighborhood, the tornado destroyed several warehouses and shattered windows. A diesel plant, a wallpaper factory, and a manufacturer sustained damage ranging from light to heavy. The tornado then extensively damaged the Orchard Acres subdivision, crossed Illinois Route 31, and apparently weakened before impacting farmland. A few barns and isolated trees were damaged. The tornado may have dissipated and reformed as a new tornado near the Fox River. The tornado also struck the community of Burtons Bridge. The tornado, now wide, then restrengthened and felled mature oak trees as it crested a precipitous hill before striking Bay View Beach. There the tornado badly damaged several homes and downed willow trees. Finally, the tornado intersected Illinois Route 176 and produced its final swath of significant damage in Island Lake. In Island Lake the tornado tossed boats ashore, wrecked piers, and caused homes to collapse, resulting in one additional death. The tornado also displaced several homes from their foundations. The tornado neared U.S. Route 12 as it dissipated at 3:42 p.m. CST (21:42 UTC). Damage estimates were set at about $1.5 million.Multiple sources:
Wakarusa–Midway–Middlebury, Indiana
This violent and destructive tornado was the most famous and well-publicized of the Palm Sunday tornadoes, often remembered as the first of two F4 tornadoes to hit the Dunlap (Elkhart)–Goshen area. It formed near the St. Joseph–Elkhart County border and tracked northeastward, striking Wakarusa, where it caused severe damage and killed a child. The tornado then intensified significantly as it moved toward northern Goshen and the Midway Trailer Court. As it neared the trailer park, Elkhart Truth reporter Paul Huffman, then reporting on severe weather, overheard a report of a tornado approaching his position on U.S. Route 33, about south of Midway. As Huffman and his wife Betty awaited the storm, he noticed the tornado approaching from the southwest, so he began taking a series of photographs, six in all. The photographs captured the evolution of the storm into twin funnels as it struck the trailer park, with each funnel gyrating around a central point yet only producing one damage swath. The tornado struck the trailer park at 6:32 p.m. CDT (23:32 UTC). (Roughly 45 minutes later, another F4 tornado passed just to the north of the Midway Trailer Court, splitting into yet another pair of funnels as it struck the Sunnyside neighborhood in Dunlap.) The tornado obliterated roughly 80% of the trailer park, with 10 deaths, and caused F4 damage to numerous other homes near Middlebury, some of which were swept clean. Three more people died in the Middlebury area before the tornado ended. Unofficial estimates of the death toll vary, with Grazulis listing 14 deaths instead of the 31 appearing in the official National Climatic Data Center/National Centers for Environmental Information (NCDC/NCEI) database. An airplane wing from Goshen Airport was found away in Centreville, Michigan.Multiple sources:
Ted Fujita lists this event as two tornadoes.
Orland, Indiana/Coldwater Lake–southern Hillsdale–Manitou Beach–Devils Lake–southern Tecumseh, Michigan (two tornadoes)
With the telephone lines down, emergency services in Elkhart County, Indiana, could not warn Michigan residents that the tornadoes were headed their way. From the Detroit Metropolitan Airport, the radar operator at the U.S. Weather Bureau Office (WBO) observed that the thunderstorms over Northern Indiana and western Lower Michigan were moving east-northeastward at . Of the southernmost counties of Michigan, all but three—Berrien, Cass, and St. Joseph—were hit.
These deadly and enormous tornadoes all formed in Michigan, with one of the 2 supercells forming just south of the Indiana-Michigan state line. With the first, being the deadliest, and strongest of the two tornadoes forming near Orland, debarking trees and leveling homes on the shoreline of Lake Pleasant in Steuben County. Crossing into Branch County, Michigan, the tornado damaged more homes in East Gilead. The tornado was up to wide as it obliterated homes on Coldwater Lake; 18 deaths occurred there. Debris from the empty foundations was strewn over the surface of the lake and deposited in a small cove. The tornado destroyed 200 homes and caused one additional death as it traversed Branch County. After striking Coldwater Lake, the tornado widened even further, up to across, destroying a century-old farmhouse and killing a family of six near Reading. The tornado then narrowed back to as it struck Baw Beese Lake, near the southern edge of Hillsdale. The tornado hurled a New York Central Railroad freight train into Baw Beese Lake. Across Hillsdale County the tornado killed 11 or more people and destroyed 177 homes.