Tornado outbreak of April 30 – May 2, 1967
A destructive severe weather episode affected portions of the Midwestern and Southern United States from April 30–May 2, 1967. It consisted of two consecutive tornado outbreaks that generated at least 38 tornadoes, causing 13 fatalities and 90 injuries. All of the deaths occurred on April 30, which is known as the 1967 Iowa–Minnesota tornado outbreak, or Black Sunday, to residents of Iowa and southern Minnesota. That day spawned a total of 21 tornadoes, devastating the towns of Albert Lea and Waseca, Minnesota.[6][7][nb 2][nb 3]
Type | Tornado outbreak |
---|---|
Duration | April 30–May 2, 1967 |
Highest gust | 70 kn (81 mph; 130 km/h) in Louisiana on May 1[3] |
Tornadoes confirmed | 38 confirmed[1][2] |
Max. rating1 | F4 tornado |
Duration of tornado outbreak2 | 2 days, 2 hours, and 55 minutes |
Largest hail | 2+3⁄4 in (7.0 cm) in diameter in Pittsburgh County, Oklahoma, on April 30[4] |
Fatalities | 13 fatalities, 90 injuries |
Damage | $286.982 million (1967 USD)[nb 1][5] $2.62 billion (2024 USD) |
Areas affected | Midwestern and Southern United States (particularly Iowa and Minnesota) |
Part of the tornado outbreaks of 1967 1Most severe tornado damage; see Fujita scale 2Time from first tornado to last tornado |
Background
editBeginning on April 30, 1967, a potent mid-latitude cyclone generated severe weather, including blizzards and severe thunderstorms, across a broad region extending from the northernmost High Plains and Rocky Mountains to the Mississippi and Ohio River valleys. These conditions occurred within a seventy-two-hour-long span.[18] By 1:00 p.m. CDT (12:00 p.m. CST; 18:00 UTC) on April 30, a low-pressure area of at most 984 millibars (29.06 inHg) was centered near Pierre, South Dakota, with a stationary front superimposed from north of Sioux Falls to near LaCrosse, Wisconsin. Nearby, a warm front also attended from south of Sioux Falls to near Des Moines, Iowa, and St. Louis, Missouri.[19] As the warm sector advanced into northernmost Iowa and southern Minnesota, surface air temperatures rose into the 60s and low 70s °F, while dew points reached the 60s °F. Winds at the surface ranged from 15 to 25 miles per hour (24 to 40 km/h) out of the east-southeast.[19] By 7:00 p.m. CDT (6:00 p.m. CST; 00:00 UTC), the warm front migrated to near the Minnesota-Iowa border, while the mid-level trough associated with the surface cyclone acquired a negative tilt. At the same time, a strong jet stream brought deep-layer wind shear over portions of northern Iowa and southern Minnesota—indicating favorable conditions for tornadogenesis.[20]
Daily statistics
editFU | F0 | F1 | F2 | F3 | F4 | F5 | Total |
---|---|---|---|---|---|---|---|
0 | 1 | 8 | 21 | 4 | 4 | 0 | 38 |
"FU" denotes unclassified but confirmed tornadoes. |
Date | Total | Fujita scale rating | Deaths | Injuries | Damage | Ref. | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
FU | F0 | F1 | F2 | F3 | F4 | F5 | ||||||
April 30 | 21 | 0 | 0 | 4 | 10 | 3 | 4 | 0 | 13 | 81 | ≥$11,000,000 | [5][21][22][23] |
May 1 | 15 | 0 | 1 | 5 | 8 | 1 | 0 | 0 | 0 | 9 | ≥$25,000 | [5][14][24] |
May 2 | 2 | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 0 | 0 | $25,000 | [5][14][24] |
Total | 38 | 0 | 1 | 8 | 21 | 4 | 4 | 0 | 13 | 90 | $286,962,000 | [5][14][22][24] |
State | Total | County | County total |
---|---|---|---|
Minnesota | 13 | Freeborn | 7 |
Waseca | 6 | ||
Totals | 13 | ||
All deaths were tornado-related |
Confirmed tornadoes
editApril 30 event
editF# | Location | County / Parish | State | Start coord. |
Time (UTC) | Path length | Max. width | Summary |
---|---|---|---|---|---|---|---|---|
F1 | NW of De Smet | Kingsbury | SD | 44°24′N 97°34′W / 44.40°N 97.57°W | 21:15–? | 0.1 miles (0.16 km) | 10 yards (9.1 m) | A brief tornado struck unpopulated countryside, resulting in no material damage.[26] |
F2 | NW of Vincent to ENE of Thor | Webster | IA | 42°36′N 94°02′W / 42.60°N 94.03°W | 21:50–? | 6.8 miles (10.9 km) | 200 yards (180 m) | Tornado researcher Thomas P. Grazulis did not list this tornado as an F2 or stronger.[14] |
F2 | ESE of Gruver to SE of Huntington | Emmet | IA | 43°23′N 94°41′W / 43.38°N 94.68°W | 22:00–? | 8.2 miles (13.2 km) | 300 yards (270 m) | This tornado struck six barns, one of which was destroyed. Damage was also reported in Dolliver.[27][28] |
F2 | Emmetsburg to WNW of Ringsted | Palo Alto, Emmet | IA | 43°07′N 94°40′W / 43.12°N 94.67°W | 22:10–? | 14 miles (23 km) | 300 yards (270 m) | This tornado struck the western portion of the community of Halfa, tearing the roofs off several homes. While passing east of Gridley, it also destroyed barns.[27] |
F2 | WSW of Crystal Lake | Hancock, Winnebago | IA | 43°13′N 93°48′W / 43.22°N 93.80°W | 22:30–? | 4.3 miles (6.9 km) | 300 yards (270 m) | This tornado struck eight farmsteads, three of which were nearly destroyed, except for the farmhouses.[27] |
F2 | NNE of Gruver | Emmet | IA | 43°25′N 94°41′W / 43.42°N 94.68°W | 22:33–? | 1 mile (1.6 km) | 200 yards (180 m) | Grazulis did not list this tornado as an F2 or stronger.[14] |
F3 | Clear Lake | Cerro Gordo | IA | 43°06′N 93°25′W / 43.10°N 93.42°W | 23:05–? | 7.7 miles (12.4 km) | 250 yards (230 m) | This tornado destroyed barns, agricultural machinery, and one home. Observers reported three distinct funnel clouds. Grazulis listed the tornado as an F2.[27][28] |
F2 | Fort Madison | Lee | IA | 40°38′N 91°19′W / 40.63°N 91.32°W | 23:20–? | 2.3 miles (3.7 km) | 400 yards (370 m) | Grazulis did not list this tornado as an F2 or stronger.[14] |
F4 | ENE of Manly to SSE of Otranto | Worth | IA | 43°18′N 93°10′W / 43.30°N 93.17°W | 23:28–? | 13.3 miles (21.4 km) | 400 yards (370 m) | This violent tornado caused extensive damage to approximately ten farms.[27] |
F3 | SSE of Kensett, IA to N of London, MN | Worth (IA), Freeborn (MN) | IA, MN | 43°20′N 93°12′W / 43.33°N 93.20°W | 23:30–? | 17.2 miles (27.7 km) | 800 yards (730 m) | This tornado caused extensive damage to six farmsteads and destroyed a few homes.[29] |
F2 | W of Lemond to NE of Waseca | Waseca | MN | 43°59′N 93°25′W / 43.98°N 93.42°W | 00:00–? | 9.2 miles (14.8 km) | 67 yards (61 m) | This tornado destroyed barns as it passed near Lemond and west of Meriden. The total path length may have been 30 miles (48 km).[27] |
F1 | WSW of Union | Steele | MN | 43°52′N 93°12′W / 43.87°N 93.20°W | 00:05–? | 0.2 miles (0.32 km) | 10 yards (9.1 m) | Unknown |
F3 | Alden to ESE of Matawan | Freeborn, Waseca | MN | 43°40′N 93°35′W / 43.67°N 93.58°W | 00:05–? | 14 miles (23 km) | 100 yards (91 m) | 2 deaths – Near the start of its path, this tornado neared the threshold of F4-level intensity, based on structural damage to farms. Additionally, the tornado destroyed barns. Twenty-three people sustained injuries.[27][30] |
F4 | ENE of Northwood, IA to ENE of Myrtle, MN | Worth (IA), Freeborn (MN) | IA, MN | 43°27′N 93°10′W / 43.45°N 93.17°W | 00:20–? | 7.6 miles (12.2 km) | 500 yards (460 m) | This powerful tornado destroyed ten farms in Minnesota, three of which sustained borderline-F5-level damage. One injury was reported.[27][31] |
F4 | NNW of Twin Lakes to Albert Lea to Owatonna | Freeborn, Steele | MN | 43°34′N 93°26′W / 43.57°N 93.43°W | 00:23–? | 38.7 miles (62.3 km) | 100 yards (91 m) | 5 deaths – This destructive, long-tracked tornado caused $2 million in damages in Albert Lea alone. The tornado ravaged the western portion of the town; there, it significantly damaged 55 homes, and "completely leveled" 10 others. In all, the tornado destroyed 26 homes and severely damaged an additional 64 in Albert Lea. Along its entire path, the tornado flattened farms at six different locations. The tornado also destroyed many structures on farms near Owatonna. The tornado injured a total of 35 people.[29][32][33] |
F4 | W of Hartland to NNE of Waseca | Freeborn, Waseca | MN | 43°48′N 93°31′W / 43.80°N 93.52°W | 00:52–? | 20.1 miles (32.3 km) | 267 yards (244 m) | 6 deaths – This tornado was the last violent event of the entire outbreak sequence. It paralleled Minnesota State Highway 13, known then as Highway 67, and damaged farms on each side of the highway. In Waseca, the tornado leveled six homes, destroyed 16, and extensively damaged 25. The tornado injured 22 people.[29][34] |
F1 | NW of Littleton | Buchanan | IA | 42°33′N 92°03′W / 42.55°N 92.05°W | 01:00–? | 0.1 miles (0.16 km) | 50 yards (46 m) | Unknown |
F1 | NW of Montezuma | Poweshiek | IA | 41°36′N 92°33′W / 41.60°N 92.55°W | 01:00–? | 0.1 miles (0.16 km) | 10 yards (9.1 m) | Unknown |
F2 | SE of Austin to E of Nicolville | Mower | MN | 43°38′N 92°56′W / 43.63°N 92.93°W | 01:15–? | 3.8 miles (6.1 km) | 10 yards (9.1 m) | This short-lived tornado destroyed a few barns and unroofed a home on a farmstead.[29] |
F2 | S of Marion to N of Eyota | Olmsted | MN | 43°56′N 92°21′W / 43.93°N 92.35°W | 02:10–02:15 | 6.8 miles (10.9 km) | 10 yards (9.1 m) | This tornado destroyed a barn and a trailer.[29] |
F2 | SSE of Epworth | Dubuque | IA | 42°24′N 90°54′W / 42.40°N 90.90°W | 03:00–? | 2 miles (3.2 km) | 400 yards (370 m) | Grazulis did not list this tornado as an F2 or stronger.[14] |
May 1 event
editF# | Location | County / Parish | State | Start Coord. | Time (UTC) | Path length | Max. width | Summary |
---|---|---|---|---|---|---|---|---|
F2 | E of North Zulch | Madison | TX | 30°55′N 96°05′W / 30.92°N 96.08°W | 12:00–? | 0.6 miles (0.97 km) | 33 yards (30 m) | A brief tornado destroyed a barn and a livestock pen. Fencing was wrenched from the ground as well. Grazulis did not list this tornado as an F2 or stronger.[14][35] |
F1 | NNW of Lambert | Hot Spring | AR | 34°21′N 93°14′W / 34.35°N 93.23°W | 13:20–? | 0.1 miles (0.16 km) | 10 yards (9.1 m) | A brief tornado felled many trees and damaged one home.[36] |
F2 | WSW of Ebenezer | Camp | TX | 32°57′N 94°55′W / 32.95°N 94.92°W | 13:30–? | 1 mile (1.6 km) | 50 yards (46 m) | A brief tornado destroyed a pair of chicken coops and damaged a number of large livestock feeders. Trees were downed as well. Grazulis did not list this tornado as an F2 or stronger.[14][35] |
F1 | Mount Pleasant | Wood | TX | 33°10′N 94°58′W / 33.17°N 94.97°W | 16:00–? | 0.1 miles (0.16 km) | 10 yards (9.1 m) | A brief tornado damaged several buildings and a farmhouse on up to six farmsteads. Trees were uprooted as well.[35] |
F2 | NNE of Corsicana | Navarro | TX | 32°10′N 96°27′W / 32.17°N 96.45°W | 16:00–? | 2 miles (3.2 km) | 33 yards (30 m) | A brief tornado, coincident and possibly in conjunction with downbursts, flipped a mobile home and damaged or destroyed a few houses and several barns. A large pecan was prostrated as well. Grazulis did not list this tornado as an F2 or stronger.[14][35] |
F0 | SSE of Avinger | Cass | TX | 32°53′N 94°33′W / 32.88°N 94.55°W | 17:00–? | 0.5 miles (0.80 km) | 300 yards (270 m) | A brief tornado sheared and uprooted trees beside a church.[35] |
F1 | W of Negreet | Sabine | LA | 31°28′N 93°36′W / 31.47°N 93.60°W | 18:50–? | 1 mile (1.6 km) | 33 yards (30 m) | A tornado was observed but did not produce damage.[37] |
F2 | E of Symonds | Bolivar | MS | 33°50′N 90°51′W / 33.83°N 90.85°W | 19:45–? | 1 mile (1.6 km) | 200 yards (180 m) | A brief tornado affected a 600-acre (240 ha) conservation area as it tossed and sank forty motorboats, some of which were wrapped around trees. Additionally, the tornado tore a section from a 200-foot-long (61 m) pier, severely damaged several trees, and tilted a concession stand. Grazulis did not list this tornado as an F2 or stronger.[14][38] |
F2 | Onalaska to W of Leggett | Polk | TX | 30°48′N 95°07′W / 30.80°N 95.12°W | 20:00–20:10 | 8 miles (13 km) | 67 yards (61 m) | This tornado may have first begun in Point Blank, on the opposite shore of the Trinity River. In and near Point Blank, trees sustained damage, a church was destroyed, and homes were damaged. However, official data indicate that the tornado first impacted Onalaska, on the eastern side of Lake Livingston. In Onalaska, the tornado unroofed a combined store and post office; the building itself also lost its rear wall. The tornado injured two people, and losses reached $25,000.[29][39][40][41] |
F1 | W of Hazel | Calloway | KY | 36°30′N 88°21′W / 36.50°N 88.35°W | 20:15–? | 1 mile (1.6 km) | 50 yards (46 m) | A brief tornado destroyed one house and minimally damaged a few others. Some outbuildings and trees were levelled as well.[42] |
F2 | NNE of Dayton | Liberty | TX | 30°04′N 94°53′W / 30.07°N 94.88°W | 23:45–00:00 | 1.5 miles (2.4 km) | 33 yards (30 m) | A brief tornado caused sizeable damage to trees, splintered utility poles, and partly unroofed a building. Several other structures were substantially damaged, one of which had its steel doors knocked down. Additionally, a horse died as a barn collapsed during the tornado. Grazulis did not list this tornado as an F2 or stronger.[14][43] |
F3 | Mittie | Allen | LA | 30°40′N 92°56′W / 30.67°N 92.93°W | 00:15–? | 5.2 miles (8.4 km) | 750 yards (690 m) | An intense tornado damaged or destroyed homes, sheds, barns, and trees. Two people sustained injuries, one of which was critical.[29][37][44] |
F2 | S of Geronimo | Guadalupe | TX | 29°39′N 97°58′W / 29.65°N 97.97°W | 02:45–? | 0.5 miles (0.80 km) | 20 yards (18 m) | A brief tornado tore the roof off a home and destroyed a barn nearby.[29][43] |
F2 | Kaplan | Vermilion | LA | 30°00′N 92°17′W / 30.00°N 92.28°W | 04:40–? | 2 miles (3.2 km) | 50 yards (46 m) | A brief tornado affected 35 homes and businesses as it passed through Kaplan. Four people were injured. Grazulis did not list this tornado as an F2 or stronger.[14][37][45] |
May 2 event
editF# | Location | County / Parish | State | Start Coord. | Time (UTC) | Path length | Max. width | Summary |
---|---|---|---|---|---|---|---|---|
F2 | E of Bayou Pigeon | Iberville | LA | 30°05′N 91°13′W / 30.08°N 91.22°W | 05:30–? | 1 mile (1.6 km) | 50 yards (46 m) | A brief tornado destroyed a mobile home and a delicatessen. A nearby home and a pilothouse also incurred damage. One person was injured.[29][37][46] |
F2 | SSE of Lucedale | George | MS | 30°54′N 88°35′W / 30.90°N 88.58°W | 07:25–? | 0.1 miles (0.16 km) | 10 yards (9.1 m) | A brief tornado dislodged a house, flipped a nearby mobile home, and downed a large tree. A utility room and a carport were torn loose as well. Grazulis did not list this tornado as an F2 or stronger.[14][38] |
F2 | Dunean | Greenville | SC | 34°50′N 82°25′W / 34.83°N 82.42°W | 00:10–? | 1 mile (1.6 km) | 67 yards (61 m) | A brief tornado significantly damaged three homes and slightly damaged about forty others. Windows, signage, and canopy-forming vegetation were broken. Grazulis did not list this tornado as an F2 or stronger.[14][47] |
See also
edit- Tornado outbreak of April 22–23, 2020 – Produced an even stronger EF3 tornado in Onalaska that killed three and injured 33 others
- Climate of Minnesota
- List of North American tornadoes and tornado outbreaks
Notes
edit- ^ All losses are in 1967 USD unless otherwise noted.
- ^ An outbreak is generally defined as a group of at least six tornadoes (the number sometimes varies slightly according to local climatology) with no more than a six-hour gap between individual tornadoes. An outbreak sequence, prior to (after) the start of modern records in 1950, is defined as a period of no more than two (one) consecutive days without at least one significant (F2 or stronger) tornado.[8][9][10][11][12][13]
- ^ The Fujita scale was devised under the aegis of scientist T. Theodore Fujita in the early 1970s. Prior to the advent of the scale in 1971, tornadoes in the United States were officially unrated.[14] While the Fujita scale has been superseded by the Enhanced Fujita scale in the U.S. since February 1, 2007,[15] Canada utilized the old scale until April 1, 2013;[16] nations elsewhere, like the United Kingdom, apply other classifications such as the TORRO scale.[17]
- ^ a b c All dates are based on the local time zone where the tornado touched down; however, all times are in Coordinated Universal Time and dates are split at midnight CST/CDT for consistency.
- ^ a b c Prior to 1994, only the average widths of tornado paths were officially listed.[25]
References
edit- ^ National Weather Service (30 September 2019). Grazulis, Thomas P.; Grazulis, Doris (eds.). Tornado History Project: Maps and Statistics. Tornado History Project (Report). The Tornado Project of Environmental Films. Retrieved 2 January 2021.
- ^ National Weather Service (30 September 2019). Grazulis, Thomas P.; Grazulis, Doris (eds.). Tornado History Project: Maps and Statistics. Tornado History Project (Report). The Tornado Project of Environmental Films. Retrieved 2 January 2021.
- ^ National Weather Service (May 2019). Events reported between 04/30/1967 and 05/02/1967 (3 days). Storm Events Database (Report). National Centers for Environmental Information. Retrieved 18 November 2019.
- ^ National Weather Service (May 2019). Events reported between 04/30/1967 and 05/02/1967 (3 days). Storm Events Database (Report). National Centers for Environmental Information. Retrieved 18 November 2019.
- ^ a b c d e f g h i National Weather Service (May 2019). Events reported between 04/30/1967 and 05/02/1967 (3 days). Storm Events Database (Report). National Centers for Environmental Information. Retrieved 24 September 2019.
- ^ Hatfield, Karen (2007). "Black Sunday April 30, 1967". National Weather Service Weather Forecast Office Twin Cities, MN. Minneapolis–Saint Paul: National Weather Service. Archived from the original on 12 October 2012. Retrieved 23 September 2019.
- ^ Hatfield 2017, pp. 3–4.
- ^ Schneider, Russell S.; Brooks, Harold E.; Schaefer, Joseph T. (2004). Tornado Outbreak Day Sequences: Historic Events and Climatology (1875-2003) (PDF). 22nd Conference on Severe Local Storms. Hyannis, Massachusetts: American Meteorological Society. Retrieved 17 September 2019.
- ^ Hagemeyer 1997, p. 400.
- ^ Grazulis 2001, p. 206.
- ^ Hagemeyer 1997, p. 401.
- ^ Hagemeyer, Bartlett C.; Spratt, Scott M. (2002). Written at Melbourne, Florida. Thirty Years After Hurricane Agnes: the Forgotten Florida Tornado Disaster (PDF). 25th Conference on Hurricanes and Tropical Meteorology. San Diego, California: American Meteorological Society. Archived from the original (PDF) on 16 October 2008. Retrieved 24 November 2019.
- ^ Grazulis, Thomas P. (2001). The Tornado: Nature's Ultimate Windstorm. Norman: University of Oklahoma Press. p. 206. ISBN 978-0-8061-3538-0.
- ^ a b c d e f g h i j k l m n o p Grazulis 1993, p. 141.
- ^ Edwards, Roger (5 March 2015). "Enhanced F Scale for Tornado Damage". The Online Tornado FAQ (by Roger Edwards, SPC). Storm Prediction Center. Retrieved 25 February 2016.
- ^ "Enhanced Fujita Scale (EF-Scale)". Environment and Climate Change Canada. 6 June 2013. Archived from the original on 3 March 2016. Retrieved 25 February 2016.
- ^ "The International Tornado Intensity Scale". Tornado and Storm Research Organisation. 2016. Archived from the original on 5 March 2016. Retrieved 25 February 2016.
- ^ Hatfield 2017, p. 7.
- ^ a b Hatfield 2017, p. 10.
- ^ Hatfield 2017, p. 15.
- ^ Grazulis 1993, pp. 1089–1090.
- ^ a b USWB 1967a, pp. 27, 30, 36.
- ^ Hatfield 2017, p. 14.
- ^ a b c USWB 1967b, pp. 42, 45–47, 52, 54–55.
- ^ Brooks 2004.
- ^ USWB 1967a, p. 36.
- ^ a b c d e f g h Grazulis 1993, p. 1089.
- ^ a b USWB 1967a, p. 27.
- ^ a b c d e f g h i Grazulis 1993, p. 1090.
- ^ Storm Data Publication 1967a, #10052249
- ^ Storm Data Publication 1967a, #10013117
- ^ Hatfield 2017, p. 22.
- ^ Storm Data Publication 1967a, #10052251
- ^ Storm Data Publication 1967a, #10052255
- ^ a b c d e USWB 1967b, p. 54.
- ^ USWB 1967b, p. 42.
- ^ a b c d USWB 1967b, p. 46.
- ^ a b USWB 1967b, p. 47.
- ^ USWB 1967b, pp. 54–55.
- ^ "NWS Damage Survey for April 22 2020 Polk County Tornado Event". Iowa Environmental Mesonet. National Weather Service Weather Forecast Office in Houston, Texas. April 24, 2020. Retrieved April 24, 2020.
- ^ Storm Data Publication 1967a, #10132367
- ^ USWB 1967b, p. 45.
- ^ a b USWB 1967b, p. 55.
- ^ Storm Data Publication 1967a, #10033059
- ^ Storm Data Publication 1967b, #10033060
- ^ Storm Data Publication 1967b, #10033061
- ^ USWB 1967b, p. 52.
Sources
edit- Brooks, Harold E. (April 2004). "On the Relationship of Tornado Path Length and Width to Intensity". Weather and Forecasting. 19 (2). Boston: American Meteorological Society: 310–319. Bibcode:2004WtFor..19..310B. doi:10.1175/1520-0434(2004)019<0310:OTROTP>2.0.CO;2.
- Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991: A Chronology and Analysis of Events. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. ISBN 1-879362-03-1.
- Hagemeyer, Bartlett C. (September 1997). "Peninsular Florida Tornado Outbreaks". Weather and Forecasting. 12 (3). Boston: American Meteorological Society: 399–427. Bibcode:1997WtFor..12..399H. doi:10.1175/1520-0434(1997)012<0399:PFTO>2.0.CO;2.
- Hatfield, Karen (2017) [2007]. Krause, Tom (ed.). The April 30, 1967 Tornadoes in Southern Minnesota: A Retrospective (PDF) (Report) (Revised ed.). National Weather Service. Archived from the original (PDF) on 12 September 2017. Retrieved 23 September 2019.
- U.S. Weather Bureau (April 1967a). "Storm Data and Unusual Weather Phenomena". Storm Data. 9 (4). Asheville, North Carolina: National Climatic Data Center.
- U.S. Weather Bureau (May 1967b). "Storm Data and Unusual Weather Phenomena". Storm Data. 9 (5). Asheville, North Carolina: National Climatic Data Center.
- National Weather Service (April 1967a). Storm Data Publication (Report). National Centers for Environmental Information – via Storm Events Database.
- National Weather Service (May 1967b). Storm Data Publication (Report). National Centers for Environmental Information – via Storm Events Database.
External links
edit- "Introduction to Black Sunday". National Weather Service–Chanhassen, Minnesota. Retrieved 2007-03-23.