Meteorological events that happened on May 21st:
A severe hailstorm occurred in parts of Virginia and was recorded by pioneer storm studiers Rolfe and Smith.
Gustave-Gaspard Coriolis was born on this date. Coriolis was a French engineer and mathematician who first described the Coriolis force, an effect of motion on a rotating body, which is of paramount importance to Meteorology. The Coriolis force on Earth is one factor that determines general wind directions and is responsible for the rotation of hurricanes and other low pressure systems.
The Dutch government wanted weather reports for its port cities. They approached meteorologist Christopher Buys-Ballot. The weatherman used a network of observing stations connected by telegraph. Although his network was sparse, Bays-Ballot had discovered a helpful weather maxim. To be named for him, the principle states that if an observer stands with the wind at his back in the northern Hemisphere, low pressure is to his or her left. Using this technique, an observer can detect and track the movement of low pressure systems even without a weather map.
A wide area of southern Ohio and northern Kentucky were struck by intense downburst winds and possible tornadoes. The affected area stretched 250 miles from Louisville, KY to Portsmouth, OH. Tornadoes struck the Ohio cities of Cincinnati, Chillicothe and Marietta & Louisville, KY causing a million dollars damage. Six people died in the Cincinnati area.
An unusually late season snowfall occurred at Cheyenne, WY with 3 inches measured.
The temperature at Norwalk, OH dipped to 19° to set a state record for the month of May.
The temperature at Salton, CA soared to 124°, the highest ever recorded in the United States during the month of May.
South central Illinois was affected by several tornadoes during the late afternoon hours. One affected areas around Mt. Sterling, destroying several barns and unroofing many homes. A violent tornado crossed the Mississippi River from the St. Louis area into Wood River, then to Roxanna. This tornado damaged or destroyed 300 homes in these two towns, killing 5 people. Another violent tornado in southeast Illinois caused significant damage in Palestine, before the storm moved into Indiana. Four people were killed in a destroyed restaurant in Palestine; one body was recovered from a tree.
A tornado causing F4 damage killed 5 people and injured 55 in St. Louis and St. Charles counties in Missouri and Madison County in Illinois. This tornado was part of an outbreak that produced 4 different tornadoes and was responsible for 5 deaths and 57 injuries.
A tornado touched down at Little London (Buckinghamshire), England and tracked 67 miles to Coveney (Cambridgeshire). From there it continued as a funnel cloud, another 33 miles to Shipham (Norfolk) where it dissipated over the North Sea.
Tornadoes raged across Lambton and Middlesex Counties in southwestern Ontario, Canada leaving five people dead and property damage was estimated at $8 million dollars in the Sarnia region.
An intense electrical storm that moved through Tecumseh, OK which resulted in lightning "fire balls ", running along the city's power lines. Only brief power outages and minor damage were reported, except for an abandoned home that burned down after being struck by the lightning.
Yankton, SD was blasted with a 103 mph wind gust. The strong winds uprooted many trees and toppled farm structures.
A strong upper level ridge brought record heat from parts of the Rockies to the Northern Plains. Williston, ND soared to 102° then soared to 106° the next day.
Locations that reported daily record highs included: Miles City, MT: 96°, Minot, ND: 96°, Dickinson, MT: 96°, Bismarck, ND: 96°, Great Falls, MT: 93°, Pierre, SD: 93°, Billings, MT: 91°, Boise, ID: 90°-Tied, Helena, MT: 89°, Bozeman, MT: 88° and Burley, ID: 88°-Tied.
Yankton, SD recorded 5.5 inches of rain in just 4 hours. The heavy rains and rapid runoff from the storms washed out many roads and flooded basements.
Lightning injured three men as they stood under a tree at the Fox Meadows Golf Course in Memphis, TN. The bolt evidently went through one man's neck, down his spine, and then came out a pocket.
Severe thunderstorms, developing along a sharp cold front crossing the central U.S., produced 60 mph winds and golf ball size hail at Sedalia, MO, and drenched Hagerstown, IN with 6 inches of rain in one hour.
Temperatures soared into the 90s ahead of the cold front. Paducah, KY hit 94° for the second day in a row.
Light snow blanketed parts of Montana, with three inches reported at Butte.
Severe thunderstorms swept across southern Louisiana during the morning hours spawning six tornadoes, and producing wind gusts to 88 mph at Jennings. Thunderstorms also produced 5 inches of rain in two hours at Lake Charles, causing local flooding.
Thunderstorms moving southeastward across the Central Plains Region into Oklahoma and Arkansas produced severe weather through the day and night. Thunderstorms spawned just 4 tornadoes, but there were 243 reports of large hail and damaging winds. Baseball size hail was reported at Augusta, KS, and thunderstorm winds gusted to 98 mph at Johnson, KS.
Thunderstorms produced severe weather across the southeastern U.S. for the second day in a row. Severe thunderstorms spawned 5 tornadoes, including one which injured a person at Richmond, KY. There were 87 reports of large hail or damaging winds, with hail 3 inches in diameter reported at Austin, TX. Thunderstorms produced up to 5 inches of rain in Macon County, Georgia, and heavy rains left nearly 8 feet of water over roads near Stepstone, KY.
Stationary thunderstorms dumped 8 inches of rain in 6 hours on Liberal, KS, causing the worst flood in 45 years. More than 35 homes were damaged and many people had to be temporarily relocated. The Red Cross provided assistance and some residents could only be reached by boat. Special pumping equipment was brought in to remove the water. Fish, mostly catfish, were being caught in the streets. The flood waters remained until early afternoon on the 23rd.
Canadian high pressure across the Mid-Atlantic brought record low temperatures to parts of the East. The morning low of 28° degrees in Atlantic City, NJ was the coldest ever for so late in season.
Locations that reported daily record lows for the date included: Martinsburg, WV: 35°, Salisbury, MD: 36°, Aberdeen, MD: 37°, Willow Grove, PA: 37°, Baltimore, MD: 38°, Groton, CT: 38°-Tied, Dover, DE: 41°, Wilmington, DE: 41°, Washington, D.C.: 43° and Arcadia, FL: 47°.
Nearly stationary thunderstorms dumped 5 to 7.5 inches of rain on the southwest side of Sioux Falls, SD causing major urban flooding. At least 200 basements were flooded by water and sewage as storm and sewer systems backed up. Water came up to the roofs of cars in the Empire Mall area. Nearly 3,000 customers in Sioux Falls lost power due to the flooding. Quarter sized hail fell for up to 1.5 hours continuously in some areas in southwest Sioux Falls causing considerable damage to hundreds of roofs, trees, and gardens. Thousands of cars received extensive hail damage. The storm seemed to serve as a precursor for the wet months and extensive flooding that occurred in the summer of 1993.
Golfers participating in a golf tournament on the Majestic Golf Course in Hartland, MI received an urgent message on the Global Positioning Units on their carts. The message, replayed from the clubhouse, was that a tornado was bearing down on the course. Most of the golfers made it to safety in the clubhouse, although some had to take shelter out on the course. Only one golfer suffered a minor injury. The F2 tornado damaged 70 cars in the parking lot along with numerous golf carts and a pontoon boat. The clubhouse received just minor damage.
A record warm weekend started across Oklahoma and northern Texas. Most of the area had warmed into the upper 90s to just over 100°, as a ridge of high pressure had built across the southwestern United States.
A cold front swept across South Africa setting 54 weather records. Most were for lowest maximum and minimum daily temperatures, with some locations reaching a low minimum temperature of 21° while in some other locations the lowest maximum temperature was 35°.
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