This Date in Weather History

On July 21, 1861, a hot and dry summer Sunday, Union and Confederate troops clashed outside Manassas, Virginia, in the first major engagement of the Civil War, the First Battle of Bull Run. Union General McDowell hoped to march his men across a small stream called Bull Run in the vicinity of Manassas, Va. that was well-guarded by a force of Confederates under General Beauregard. McDowell needed to find a way across the stream and through the Southern line that stretched for over six miles along the banks of Bull Run. McDowell launched a small diversionary attack at the Stone Bridge while marching the bulk of his force north around the Confederates’ left flank. The march was slow, but McDowell’s army crossed the stream easily because the weather leading up the the battle had been dry and the stream was running at a low level. Some of Beauregard’s troops, recognizing that the attack at Stone Bridge was just a diversion, fell back just in time to meet McDowell’s oncoming force. The battle raged for several hours on top of Henry Hill, with each side taking control of the hill more than once. Slowly, more and more Southern men poured onto the field to support the Confederate defense, and Beauregard’s men pushed the Northerners back. At this point in the battle, Confederate General Barnard Bee attempted to rally his weary men by pointing to Brigadier General Thomas Jackson who stood his ground in the face of the Union assault. Bee cried, “There stands Jackson like a stone wall!” From that moment on, Thomas Jackson was known as “Stonewall” Jackson. As the day wore on, the strength of McDowell’s troops was sapped by the continuous arrival of fresh Southern reinforcements and the intense heat of the summer day with temperatures in the 90s and Union troops in heavy wool uniforms. Eventually, the Northerners began to retreat across Bull Run. The Union pullout began as an orderly movement. However, when the bridge over Cub Run was destroyed, cutting off the major route of retreat, it degenerated into a rout. The narrow roads and fords, clogged by the many carts, wagons, and buggies full of people who had driven out from Washington, D.C., to see the spectacle, hampered the withdrawal of the Union Army. The heat had done in the Union troops who had marched a greater distance to get to the battle and then choked in the dry, dusty roads as they made their way back to Washington City.

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On July 20, 1977 a flash flood devastated Johnstown, Pennsylvania, killing 84 people and causing millions of dollars in damages. This flood happened 88 years after the Horrible Flood of 1889 that was one of the worst weather-related disasters in US history that killed more than 2,000 people. Johnstown sits in a deep valley, hard against the Conemaugh river. In that earlier flood, the dams in the Conemaugh Valley failed, bringing disaster to Johnstown and as fate would have it the combination of the weather and those human make dams would once again bring catastrophe. The flood occurred when an extraordinary amount of rain came down in the Conemaugh Valley in a short period of time. Nearly 12 inches were measured in 10 hours. The National Weather Service later estimated that this amount of rain in that location should happen less than once every 1,000 years. Dams started bursting upstream from Johnstown. The largest dam that burst was at Laurel Run. This 10-year-old earthen dam held back 100 million gallons of water. Despite having a 42-foot-high spillway, the dam failed and the resulting flood devastated the town of Tanneryville. Five other dams in the area also burst, releasing another 30 million gallons of water. The failure of the dams was a shock. Johnstown had constructed an entire system designed to completely eliminate the flood risk after the devasting flood of 1889 and a destructive flood in 1936. Many safely measure were in place along with inspections. Still, the dams were no match for the thunderstorm that stalled over the area on July 20. In addition to the 84 people who lost their lives to the flood, $300 million or more than $1.2 Billion in 2020 dollars in damages were suffered and hundreds of people lost their homes. President Carter declared the region a federal disaster area and the National Guard was sent to assist in the relief efforts. Despite millions spent to rehabilitate the Johnstown area, the economy never recovered. The city’s population decreased nearly 15 percent in the aftermath of the flood, as people moved away.

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Over the course of a three-month period in the summer of 1993, a slow-moving and historic flooding disaster unfolded across the midwestern United States, leaving economic ramifications that would be felt for years to come. Over 17 million acres were flooded across nine states across the Midwest during the summer of 1993, starting in June and lasting through August. This is an area larger than the entire state of West Virginia. “The magnitude and severity of this flood event was simply overwhelming, and it ranks as one of the greatest natural disasters ever to hit the United States,” said Lee Larson, chief at the Hydrologic Research Laboratory. This long-duration river flooding caused hundreds of levees failures, 50 fatalities and an estimated $15 billion in damages. While the worst of the flooding occurred in the summer of 1993, impacts across the region lasted for years. Of the 17 million acres that were flooded, a majority was being used as farmland. This had a long-term impact on the industry as some of the land was not able to be used again for farming for several years after flood waters had receded. Shipping and transportation industries were also severely impacted during the height of the flooding. Barge traffic on the Missouri and Mississippi rivers was stopped for nearly two months. The inability for ships and barges to navigate the waters of these major waterways resulted in an economic loss of $2 million per day, according to the National Weather Service. High water also rendered some bridges that spanned across the Mississippi River unusable for weeks, disrupting travel across the region. In some cases, this meant taking a detour of over 100 miles just to make it to the other side of a flooded river. The historic flooding was not caused by one single rainfall event, but rather an extended period of above-normal rainfall across the same region. The stage was set in 1992 with a wet fall which resulted in above-normal soil moisture and reservoir levels in the Missouri and Upper Mississippi river basins. The wet autumn was followed by above-average snowfall during the winter. When all of this snow melted in the spring, it left the ground across the region saturated and prone to flooding. The focus of the flooding on July 19, 1993 was St Louis Mo, where the Mississippi river rose to 46.8 feet at were flood stage is only 30'. It was the high-water mark in St Louis and flooding extended from the Gateway Arch to the suburbs.

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July 18, 1942: Late in the evening of Friday, July 17, 1942 heavy rain began falling in southern New York. The weather system producing the heavy rain and thunderstorms intensified and moved into Pennsylvania. The weather system stalled out over Smethport and Port Allegany PA, on Saturday, July 18th. Most of the rain, incredibly feel in just a 5-hour period. People living in the region reported in the local press after the storm that the electrical storm was the worst they had ever witnessed. Water quickly began to accumulate and rise rapidly, many thought that they would drown. In the Austin, PA, many people were quoted as saying that “the rain did not come down in drops, it came down in streams.” The dam at the Williamson Pulp and Paper Company at Austin was breached and immediately flooded the town of Austin. There were reports of massive quantities of gravel and rock being washed down small gullies and even reports of bedrock being ripped out and carried downstream as the relentless rain continued. In Emporium, Pennsylvania, the estimated rainfall rate was more than 10 inches per hour. There was massive flooding over a short period of time. There were many accounts of an “almost instantaneous rise” in the water from 5 to 8 or 10 feet. Buildings in Austin were being knocked off their foundations and the water was 4 to 5 feet deep on the main street. The heaviest rain fell in Smethport, Pennsylvania. Some locations received an incredible 34.50 inches of rain from the event. A rainfall total of 30.7 inches of rain in a 4 1/2-hour period set a world record at Smethport.

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Heavy rain on July 17, 1996, produced several rainfall records and was the second most costly weather disaster in Illinois history. The 16.94 inches recorded at Aurora still stands as the statewide record for the most rain from a single 24-hour period. The 10.99 inches on the west side of the Chicago metro area was the most ever recorded in the Chicago urban area. Just as impressive as the point values was the size of the area covered by heavy rainfall. It was estimated that 16.3 inches fell over the wettest 100 square mile area of the storm, 12.6 inches over the wettest 1000 square mile area, and 5.2 inches over the wettest 10,000 square mile area. Another way to look at it is that an area of 1350 square miles exceeded the expected 100-year, 24-hour storm while 4650 square miles exceeded the expected 10-year, 24-hour storm for northeast Illinois. The widespread heavy rains led to excessive flooding. Damage estimates were on the order of 700 million dollars or more than 1.1B in 2020 dollars. FEMA estimated that more than 35,000 residences were flooded.

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On July 16, 1945 the first nuclear device ever detonated in Earth history occurred at the Trinity site near Alamogordo, New Mexico. From a weather perspective, scientists wanted good visibility, low humidity, light winds at low altitude, and westerly winds at high altitude for the test. The best weather was predicted between July 18 and 21, but the Potsdam Conference near the end of WWII between the Allies was due to start on July 16 and President Truman wanted the test to be conducted before the conference began. It was therefore scheduled for July 16, the earliest date at which the bomb components would be available. The detonation was initially planned for 4am Mountain War Time but was postponed because of rain and lightning from early that morning. It was feared that the danger from radiation in the form of fallout would be increased by rain, and lightning had the scientists concerned about a premature detonation. A crucial favorable weather report came in at 4:45am and the final countdown began at 5:10. By 05:20 the rain had gone. At 5:29am the device exploded with an energy equivalent to around 22 kilotons of TNT. The desert sand, largely made of silica, melted and became a radioactive light green glass. At the time of detonation, the surrounding mountains were illuminated "brighter than daytime" for one to two seconds, and the heat was reported as "being as hot as an oven" at the base camp. The roar of the shock wave took 40 seconds to reach the observers. It was felt over 100 miles away, and the mushroom cloud reached 7.5 miles in height. John Lugo was flying a U.S. Navy transport at 10,000 feet, 30 miles east of Albuquerque en route to the west coast. "My first impression was, the sun was coming up in the south. What a ball of fire! It was so bright it lit up the cockpit of the plane." Lugo radioed Albuquerque. He got no explanation for the blast but was told, "Don't fly south." Because the rain cleared and the test went off successfully Truman was able to tell Soviet leader Stalin then ally, of a terrible new weapon the US had in its possession as it became the only nuclear power in the world. After the blast and the initial euphoria of witnessing the explosion had passed, Bainbridge one of those working on the project told Robert Oppenheimer, the director of the project, "Now we are all sons of bitches." Oppenheimer later recalled that, while witnessing the explosion, he thought of a verse from a Hindu holy book, the Gita, 'Now I am become Death, the destroyer of worlds.”

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July 15, 1643: Weather reporting up until the mid-1700’s was sketchy at best across North America. Colonial leaders who formed the path to independence of our country were avid weather observers. Thomas Jefferson purchased a thermometer from a local Philadelphia merchant while in town for the adoption of the Declaration of Independence. He also purchased a barometer — one of the only ones in America at the time — a few days later from the same merchant. Jefferson made regular observations at Monticello from 1772-78, and participated in taking the first known simultaneous weather observations in America. George Washington also took regular observations; the last weather entry in his diary was made the day before he died. During the early and mid-1800's, weather observation networks began to grow and expand across the United States. Although most basic meteorological instruments had existed for over 100 years, it was the telegraph that was largely responsible for the advancement of operational meteorology during the 19th century. With the advent of the telegraph, weather observations from distant points could be "rapidly" collected, plotted and analyzed at one location in real time. In 1870 a Joint Congressional Resolution required the Secretary of War "to provide for taking meteorological observations at the military stations in the interior of the continent”. And so, a national weather service had been born within the U.S. Army Signal Service’s Division of Telegrams and Reports for the Benefit of Commerce. The first systematic weather observations didn't start in colonial America until 1644 in what would become the state of Delaware. Occasional observations of the weather were reported a bit before that and on July 15, 1643, John Winthrop’s from Newberry, MA entered in his in diary; “There arose a sudden gust at NW; so violent for half an hour as it blew down multitudes of trees. It lifted up their meeting house at Newberry, the people being in it, but only killed (one person) with the fall of a tree”. It was one of the first ever reports of weather’s impact in America.

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July 14, 1886: Rainfall in Southern California in the summertime is almost non-existent. In fact, the climate takes on desert-like conditions. The average rainfall in June, July and August in Los Angles is less than a quarter of an inches of rainfall – 2 tenths of an inch to be exact. July is the driest month with barley more than a spritz of rain at an average of one hundredth of an inch – the lowest measurable total of rainfall that is officially observed. In contrast New Orleans is generally regarded as the rainiest big-city in the US and averages more than 6 inches of rain for the month of July. It’s not always dry in LA with the months of January, February and March all averaging more than 3 inches of rain each month. Certainly, though there are two distinct seasons in LA a wet season and a dry season. To give you an idea of just how dry it is in Southern California in July, on this date in weather history on July 14, 1886, twenty-four hundredths of an inch of rain – just shy of a quarter of an inch fell in LA, the most ever on a single day in the region in recorded history. Not much impact was felt in the region – today of course a rainfall like that on a July day would result in slippery freeways because the accumulated oil dripping off of cars and onto the highway would mix with the water and cause the roads to become slippery.

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July 13, 1816: The year 1816 featured unprecedented cold conditions throughout the United States and Europe. The key cause was the eruption of Indonesia’s Mount Tambora in April 1815, the largest volcanic explosion in recorded. “Mount Tambora ejected so much ash and aerosols into the atmosphere that the sky darkened and the sun was blocked from view in many places around the world that year. The eruptions killed up to 100,000 people – some immediately from the blasts – and tens of thousands of others as a result of starvation and the resulting crop failures and disease. “It might have been millions who died in total, across the globe in the next year” said AccuWeather Founder and CEO Dr. Joel Myers. The smaller particles spewed by the volcano were light enough to spread into the stratosphere and eventually had a worldwide impact on the climate by reflecting solar radiation back into space. The Earth’s average global temperature dropped 5 degrees Fahrenheit, according, and in some areas, the drop was more than 10 degrees.  The uncharacteristic cold ruined agricultural production in the United States, Europe and China, which led to drastic increases in food prices, as well as famine and epidemics of cholera and other diseases.  The U.S. consisted of just 18 states in 1816 and five were in New England, which was devastated by the frigid temperatures and the lack of food. Frost throughout May killed crops in several Northeast states, snow fell in June in wide areas from New York to Maine, and heavy frosts and ice storms occurred as late as July in parts of New England.  There were freezing temperatures in all 12 months of the year in New England, many of the crops failed, causing famine and triggering a western migration from New England where there was a depression and starvation. In 1815, before the effects of the volcano were known, the typesetter of the Old Farmer's Almanac jokingly printed America "snow, and hail" across eastern North America for this date of July 13, 1816. The editor missed it, and the publication went to print. But because of the severe climate change; snow, and hail did fall across parts of New England on July 13. Even though later editions of the Almanac had the "correct" forecast in place, those who received the earlier editions "swore" by the Almanac the rest of their lives. 

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On July 12, 1984 a rapidly developing storm pounded the Munich area with hailstones the size of tennis balls, high winds and heavy rains, injuring 300 people and causing extensive damage. The Red Cross said the storm injured about 200 people in Munich and 100 in surrounding south-east Bavaria, most of them hit on the head by ice balls, cut by glass shattering from windows, or hurt in car crashes. One person was killed and damages reached nearly $100 million.

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