Weather Extremes

World’s Largest Hailstones

By: weatherhistorian, 5:44 AM GMT on April 30, 2011

World’s Largest Hailstones

Large hail has accompanied the recent spate of tornado outbreaks across the U.S. including stones 4.5” in diameter in the Abilene, Texas area on April 24 and possible state records for largest hailstone on record in Mississippi, South Carolina, Tennessee, and Virginia during just this past month. This blog is a revue of the greatest hailstorms on record and the largest individual stones yet measured.

Hailstorms and Hailstone Size in the U.S.A.


There have been a handful of hailstorms that resulted in $1 billion or more in damages in the U.S. The costliest storm appears to be that of April 10, 2001 which cut a swath along the I-70 corridor from eastern Kansas to southwestern Illinois and pounded the St. Louis area. Property damage was in excess of $2.4 billion in 2010 dollars. The hailstorm that struck the Dallas/Ft. Worth, Texas metro area on May 5, 1995 also caused an estimated $2 billion in damage (adjusted to current dollars). The only other $1 billion dollar hailstorm on record was that which pummeled the Front Range of Colorado between Colorado Springs and Fort Collins on July 11, 1990 causing $1.6 billion damage in 2010 inflation-adjusted dollars.


In spite of the enormous crop and property damage that hailstorms have caused only three people have ever been killed by falling hailstones in the United States: 1) a farmer caught in his field near Lubbock, Texas on May 13, 1930 2) a baby struck by large hail in Fort Collins, Colorado on July 31, 1979, and 3) a boater on Lake Worth, Texas on March 29, 2000.

Largest Stones

Mr. and Ms. Clarence Costner proudly display baseball-sized hail that fell on their farm near Norbonne, Missouri date unknown. Photo from Weatherwise Magazine, August 1976.

The largest officially recognized hailstone on record to have been ‘captured’ in the U.S. was that which fell near Vivian, South Dakota last summer (2010) on July 23rd. It measured 8.0” in diameter, 18 ½” in circumference, and weighed in at 1.9375 pounds. Mr. Lee Scott, who collected, the monster stone originally planned to make daiquiris out of the hailstone but fortunately thought better and placed it in a freezer before turning it over to the National Weather Service for certification.

The largest official hailstone ever collected in the U.S. An eight-inch monster that fell at Vivian, South Dakota on July 23, 2010.

Other instances of 8-inch hail have been reported in the past but not certified. The U.S. Weather Bureau’s Climatological Data by Sections Vol. 22, Part 2 April-June, 1935 mentions a hailstorm producing 8-inch diameter hailstones at Ponca City, Oklahoma on April 17, 1935 (see p. 18 in the Oklahoma section).

Below is a list by state of the largest hailstones ever measured. Only a few states maintain an ‘official’ list of such records which I have listed first and then followed up with a list of ‘unofficial’ sizes by state that I have gathered from various sources. If any readers could add to this list or correct it, I would be much appreciative!

Bart McCarthy inspects a 5.5”-diameter hailstone that fell near Wisconsin Rapids on June 7, 2007. It is the 2nd largest hailstone on record for the state of Wisconsin. Photo from NWS Green Bay, Wisconsin archives.

Hail Accumulations

Some hailstorms train over the same area (or stationary thunderstorms develop) producing massive hail accumulations. Hail accumulated to over 12” deep on level in El Dorado, Kansas on June 23, 1951 and a storm at Seldon, in northwest Kansas, left an 18”-deep accumulation of hail over a 54 square mile area on June 3, 1959.

An aerial view of a deep hail swath accumulation over Seldon, Kansas. The 18” of hail fell on the town on June 3, 1959. Photo from the Norton Telegram newspaper archives, Norton, Kansas.

Heavy rainfall following a hailstorm causes the hail accumulations to wash into ditches or creek beds and enormous piles of hail accumulate. This was the case during a storm south of Clayton, New Mexico on August 13, 2004 when a 12-inch hail accumulation was swept into a draw by 5” of rainfall. A culvert in the draw became clogged by the flow and the hail piled up to 15 feet deep behind it!

Hail cliffs 15 feet high line the bottom of a creek near Clayton, New Mexico following a deluge on August 13, 2004. Photo by Barbara Podzemny.

Some Notes on Large Hail Around the World


A map of world hail incidence. The most hail prone spot on the planet is Kericho, Kenya that averages about 50 days of hail each year and, in 1965, recorded 113 days of hail. Map by Mark Stroud and from my book ‘Extreme Weather: A Guide and Record Book’ p. 162.

Bangladesh and India

The deadliest hailstorms, and perhaps the largest hailstones, in the world occur on the Deccan Plateau of northern India and in Bangladesh. The heaviest authenticated hailstone ever measured was one of 2.25 pounds that fell in the Gopalganj district of Bangladesh on April 14, 1986. The stones size was not measured although anecdotal reports claimed the stones were the size of “pumpkins”. Ninety-two people perished as a result of the storm although how many of these can be attributed to the hail is uncertain. A hailstorm in the Moradabad and Beheri districts of India killed 246 people on April 30, 1888, the deadliest hailstorm on record in modern history.


In China 25 were killed by hail in Henan Province on July 19, 2002 and a possibly reliable report claims 200 were killed by hail in Hunan Province on June 19, 1932.


In Europe a hailstone weighing 2.14 pounds was measured following a storm in Strasbourg, France on August 11, 1958. The size was not noted. Europe’s most catastrophic hailstorm was that which struck Munich, Germany on July 12, 1984. Some 70,000 homes (and 190 aircraft!) were damaged and 400 people injured by hail the size of baseballs. Property damage was estimated at over US$2 billion.


Perhaps the single costliest hailstorm in world history was that which struck the Sydney, Australia area on April 14, 1999. Hailstones up to 3½” in diameter fell for almost 60 minutes damaging 20,000 structures and 40,000 vehicles. The total damage came to US$3 billion in inflation-adjusted dollars and remains Australia’s costliest natural disaster.

A hailstorm bears down on Sydney, date unknown. Photo by Carl Ord.


Canada’s largest hailstone of record was that collected at Cedoux, Saskatchewan on August 27, 1973. It measured 114 mm in diameter (4.5”) and weighed 290 grams (10.2 ounces). Probably the costliest hailstorm was that which affected 130 sq. kilometers in the Calgary, Alberta area on September 7, 1991. It caused $400 million in Canadian dollars damage.

Unsubstantiated Reports

There are many apocryphal or unsubstantiated stories of giant hailstones from many corners of the world including a stone weighing 4.18 pounds in Kazakhstan in 1959; an 11-pound stone in Guangxi Province, China in 1986; and, best of all, a hailstone the size of an “elephant” in Seringapatam, India sometime in the late 18th century! Many of these events are more likely not hailstones but hydrometeors, large chunks of ice that fall from the sky for some unknown reason or source.

REFERENCES: The only book I am aware that is solely devoted to hail is Snowden D. Flora’s classic Hailstorms of the United States published by the Univ. of Oklahoma Press back in 1956. It is still a great reference.

The best hail-related web site is


Record Late Season Snowfalls

By: weatherhistorian, 9:58 PM GMT on April 22, 2011

Record Late Season Snowfalls

While most of the extreme weather attention (deservedly!) has been on the phenomenal tornado outbreaks this month, I thought I’d buck the trend and discuss record late season snowfalls. In fact while the Midwest was being hammered by violent thunderstorms and tornadoes April 19-20, Green Bay, Wisconsin was ‘enjoying’ its greatest late season snowfall on record with a 10” accumulation. Ironically the snow impacted the same area that was struck by a tornado outbreak just nine days earlier.

The fact is that the greatest snowfalls ever experienced in the world have occurred during the month of April and that for portions of the High Plains and Rocky Mountains April and May usually produce the heaviest accumulating snowstorms.

This blog is a bookend to the blog I posted on November 3, 2010 “Record Early Season Snowfalls”.

Below is the same table I produced last November in the aforementioned blog (then for earliest record snowfalls) but here for the latest on-record-snowfalls:

Latest Measureable Snowfall for Selected Cities in the USA

World-record Snowfalls During April

World Record 24-hour Snowfall at Silver Lake, Colorado

The greatest 24-hour snowfall officially measured in the world was the 75.8” that fell at Silver Lake, Colorado (in the mountains just west of Boulder) on April 14-15, 1921. The storm total was an amazing 95.0” over a 32½ hour period.

Storm precipitation (melted—in inches) total for Silver Lake event from April 1-15, 1921 Map from ‘Monthly Weather Review’, Feb. 1953, p. 39.

World-record Single Greatest Snowfall in the Sierra Nevada

The greatest single-storm snowfall on record in the world was 194” (over 16 feet!) that fell during a massive spring blizzard at the Sierra Nevada railway summit station of Norden over the four day period of April 20-23, 1880. Sacramento, California’s capital city, received a record two-day rainfall of 8.37” during this event.

An historic photo of the Norden station during the winter of 1887.

World-record 19-hour Snowfall and European Record

Europe’s greatest 24-hour snowfall happened at Bessans in the French Alps on April 5-6, 1959 when 67.8” accumulated in just 19 hours (a world record for a 19 hour period).

Bessans, France is a popular ski resort in the French Alps.

Some All-time Single-Greatest Storm Snowfall Records in the U.S.A. that occurred during April and May

The Southern Appalachians have also recorded some phenomenal late season snowfalls including a reported 60.0” accumulation at Newfound Gap, North Carolina on April 2-5, 1987 and, even more incredible, another 60.0” accumulation at Mount Pisgah, North Carolina on May 5-8, 1992!

Some Historic Pre-NWS Late Season Snowstorms

The May 4th Snowstorm in 1774

A general snowfall of around 4” occurred from northern Virginia to southern New England. Both Philadelphia and New York City reported “a considerable quantity of snow”. Thomas Jefferson and George Washington both noted the event in their diaries.

The Great April Fools Day Snow of 1807

Probably the deepest April snowfall in modern history occurred on April 1, 1807 from Illinois to the Mid-Atlantic. The track of the storm was not the usual coastal nor’easter variety that normally produces great snows but rather the low moved northeast from the lower Tennessee Valley and across the mid-Atlantic states and offshore around New York City. To the north of the storm path incredible snowfalls were reported. The westernmost report we have came from Vincennes on the Illinois-Indiana border with an 11” accumulation but it was in Pennsylvania, New York and New England that astonishing snowfall was reported including: 52” at Montrose, Pennsylvania near Scranton; 54” at Utica, New York, 52” at Lunenburg, Vermont; 60” at Danville, Vermont; 48” at Montpelier, Vermont; and 42-48” at Norfolk, Connecticut.

The June 1816 Snows of the ‘Year without Summer’

Most famous of all cold and snowy late season events would have to be the infamous 1816 ‘Year without Summer’ and the snowfall in June that occurred in the eastern U.S. and Canada. On June 6th accumulating snow was observed as far south as the Catskills in New York (where one inch was reported) and highlands of central and northwest Pennsylvania. Snowflakes were seen at sea level as far south as ten miles north of tidewater on the Hudson River just north of New York City. The deepest accumulations were reported in the mountains of Vermont where drifts of 12-18” were measured. Quebec City in Canada reported 12” on level with drifts up to two feet deep.

The even Greater Snow of June 1842

It should be noted that June snowfall in the Northeast is not a unique event to 1816. On June 11, 1842 widespread snow fell over northern New York and New England and snowflakes were observed in Cleveland, Ohio; Boston, Massachusetts; and even Harrisburg, Pennsylvania (a low elevation site). Accumulations of 10-12” were common in Vermont, so this event was actually more extreme than the more famous snow of June 1816.

REFERENCE: Early American Winters: Vol 1: 1604-1820 and Vol 2: 1821-1870 by David M. Ludlum, American Meteorological Society, 1966, 1968.

Winter Weather

March 2011 Global Weather Extremes Summary

By: weatherhistorian, 7:40 PM GMT on April 15, 2011

March 2011 Global Weather Extremes Summary

Extreme weather highlights for this past March include a stormy month in California, wild temperature swings in Asia with record rainfall in Thailand and relief from the prolonged drought in China.

Below are some of the month’s highlights.


A series of powerful storms slammed California during the month resulting in 21 days of measureable precipitation in San Francisco and bringing the Sierra snowpack to its highest level since 1995. Seasonal snowfall at Donner Summit approached 740” by the end of the month (the record seasonal snowfall was 819” in 1937-1938). The 3-year-long drought emergency in California was officially rescinded.

Up to ten feet of snow buried the Soda Springs General Store and Post Office near California’s Donner Summit the week ending March 28th. Photo by Rich Pedroncelli.

A sharp cold front passed over the Northeast on March 5-7 resulting in some wild temperature swings and heavy precipitation. In Houlton, Maine the temperature rose from -24°F on March 4 to 47°F on March 7 (an amazing 71°F rise!) and then dropped back to -4°F by March 9. One of the city’s heaviest 3-day precipitation accumulations also resulted when 3.24” were measured March 5-7, mostly in the form of rain.
The Tampa-St. Petersburg metro area reported heavy flooding at the end of the month when 8.19” of rain fell March 28-31.

The coldest temperature in the Northern Hemisphere for the month was measured at Summit Station, Greenland on March 17 with a -77.8°F (-61.0°C) reading.


Torrential rain in the southern Brazilian states of Parana, Rio do Sul, and Santa Catarina resulted in severe flooding and mudslides March 11-14. At least 12 lives were lost and 2700 homes were destroyed leaving 8000 homeless.


Unusually warm weather towards the end of the month (15°F above normal) resulted in a deadly avalanche in the Swiss canton of Valais on March 25. Five skiers were killed while traversing a high altitude piste near the Great St. Bernard Pass.


An all-time national heat record was set for the Republic of Congo when the temperature reached 102.6°F (39.2°C) at Mpouya on March 8. The previous record was 102.2°F (39.0°C) at Impfondo on May 14, 2005. The capital city of Kinshasa may also have broken its all-time heat record with a 98.6°F (37.0°C) reading on March 28. The hottest temperature in the Northern Hemisphere and also for the whole world for the month of March was recorded at Kiffa, Mauritania on March 30th with a 114.8°F (46.0°C) reading. The hottest temperature for the month in the Southern Hemisphere was measured at Vioolsdrif, South Africa on March 1 when 111.9°F (44.4°C) was recorded.


Perhaps the most anomalous weather event of the month was the series of invasions of cold air into Southeast Asia during what is normally one of their hottest months of the year. On March 17th Bangkok recorded its coolest daytime high on record for any month when the temperature failed to rise above 68°F (normal high for the date was 93°F) at the Don Maung Airport location. Another cold blast at the end of the month brought a high of just 71°F on March 29th. The month ended up being the coldest March on record for the city. The invasion of cold air into the Gulf of Thailand resulted in phenomenal rainfall on the resort island of Ko Samui where 43.92” of rain fell during the single week of March 23-30. Of this, 16.33” fell on just March 28th possibly a national 24-hour record for rainfall for Thailand (another 7.72” fell the following day!). The worst flooding in many years killed at least 25 in the south of the country and hundreds of tourists had to be evacuated by air from some island resorts.

This NASA composed image of accumulated rainfall for the week ending March 30 indicates up to 48” of rainfall fell over Thailand’s Kra Isthmus.

A flooded street on the tourist resort of Ko Samui on March 28th following the fall of 20” of rain in the previous 24 hours. Photo by Rungroj Yongrit.

Meanwhile, west of Southeast Asia, March was one of the hottest such on record for portions of Bangladesh and India. Mumbai (Bombay) recorded its all-time hottest temperature on record for any month when a reading of 106.9°F (41.6°C) at the downtown site of Colaba. Records at this site go back to 1846.

In northern China welcome rains and snow alleviated what was on the verge of becoming one of the most catastrophic droughts in history for the country’s wheat growing regions in and around Shandong Province.


Abnormally wet weather continued to plague Australia as the past March became the wettest such in the country's recorded history. It was the 6th wettest month of any month on record (this following February which was the 4th wettest month on record). Bambaroo, Queensland recorded 51.20” (1300.6mm) of precipitation during the month, one of 41 stations with at least 50 years of record to report their wettest March on record.

Rainfall in Australia during March as a percentage of the historical average for the month. Image courtesy of the Australian Bureau of Meteorology.

It was a very cool month as well, in fact the coolest March on record so far as average maximum temperature were concerned. The national maximum for the month was just 106.0°F (41.1°C) at Roebourne, Western Australia on March 19th, the lowest absolute maximum for a March in at least 50 years.

Departure from normal for the average maximum temperature during the month of March. Image courtesy of the Australian Bureau of Meteorology.


The lowest temperature recorded in the Southern Hemisphere and anywhere in the world during the month was -90.0°F (-67.8°C) at Vostok Station on March 15th.

KUDOS Thanks to Maximiliano Herrera for temperature data, Blair Trewin for Australian records.

Extreme Weather

The World’s Deadliest Tornadoes

By: weatherhistorian, 11:11 PM GMT on April 06, 2011

The World’s Deadliest Tornadoes

The tornado ‘season’ got off to a roaring start this April when a powerful line of storms moving across the eastern half of the U.S. on April 4-5 produced as many as 20 tornadoes and an unprecedented 1300 severe storm warnings. Unfortunately, eight people died as a result. It could, however, been much worse.

I thought this might be a good time to look back at what the deadliest tornadoes on record have been.

The United States and Canada are the only countries in the world to have verified reports of the most violent tornadoes: those with a classification of F-5 or EF-5 (wind speeds estimated to be in excess of 260mph/417kph and measured as high as 318mph/512kph on the old Fujita Scale or over 200mph/320kph on the new Enhanced Fujita scale). See this link for details about the Fujita and Enhanced Fujita Scales and the differences between the two.

Since 1900 there have only been a total of 97 such storms, all but one in the United States. In all but 10 cases these storms resulted in fatalities. This table is from my book Extreme Weather: A Guide and Record Book.

The table above covers just those tornadoes rated as F-5’s on the former Fujita Scale. The following EF-5 tornadoes have since occurred (the EF scale went into effect on February 1, 2007; there were no F-5 or EF-5 tornadoes reported between the May, 1999 event in Oklahoma and the May 2007 event in Greensburg, Kansas):

May 4, 2007: Kansas 11 killed
June 22, 2007: Manitoba, Canada 0 killed
May 25, 2008: Iowa 9 killed

The reason the heart of the North American continent bears the brunt of these most powerful of twisters lies with its unique topography. Only in North America does a solid land mass stretch from the sub-tropics to the arctic with no mountain barriers to inhibit the mixture of air masses originating from these two regions.


Most of you probably already know that the ‘single’ deadliest tornado in U.S. history was the famous ‘Tri-state’ twister of March 25, 1925 when 695 died in Missouri, Illinois, and Indiana when a F-5 mile-wide monster carved a course some 219 miles through the three states. However, modern research suggests that this may well have been a series (or at least two) tornadoes developing from a single super cell traversing the area. Eight other violent (F-2 or stronger) tornadoes killed an additional 52 people in Alabama, Tennessee, and Kentucky over the course of the day bringing the total killed to 747 and making this also the deadliest tornado outbreak in American history.

Griffin, Indiana lies devastated following the passage of the Tri-state tornado on March 18, 1925. 71 people perished in the vicinity of Griffin. Photo from the National Archives.

The 2nd deadliest single tornado was that which struck Natchez, Mississippi on May 7, 1840 killing 317, many of the fatalities being along the town’s waterfront when the twister traversed the Mississippi River. The 2nd deadliest tornado outbreak was that of April 5-6, 1936 when 454 were killed across the Southeast from Arkansas to South Carolina. Tupelo, Mississippi was the worst affected where 216 were killed by a tornado on March 5th and Gainesville, Georgia where 203 lost their lives the following day on March 6, 1936.

Below are tables listing the 20 deadliest U.S. tornado outbreaks and 20 deadliest single tornadoes in U.S. history. Some of these figures are, to some degree, disputable and simply represent the best available information to date:

Tables reproduced from ‘Extreme Weather: A Guide and Record Book. Note that on the ‘deadliest single tornadoes’ table No. 4 and No.5 positions are transposed. Sorry, but hard to fix at the moment.

A F-5 tornado completely swept away the town of Glazier, Texas on April 9, 1947. The same tornado killed 181 in Woodward, Oklahoma (see table above) and so ranks as the 6th deadliest tornado in U.S. history. Glazier was never rebuilt. Photo courtesy of the ‘Amarillo Globe-News’.


Environment Canada has concluded that the tornado that formed near Elie, Manitoba on June 22, 2007 was of EF-5 strength making it the only such storm of this violent nature to occur outside of the United States. Canada’s deadliest tornado event was that of June 30, 1912 when 28 were killed in the city of Regina, Saskatchewan. More recently, 27 died in and around Edmonton, Alberta on July 31, 1987 when a F-4 slammed the city.

The second deadliest tornado in Canadian history bears down on Edmonton, Alberta on July 31, 1987. Twenty-seven lives were lost. Photo by Robert Carlton, University of Alberta.


Other regions of the world that also experience very violent tornadoes (EF2-4 strength) fairly regularly (but to date no EF-5s) include the following:


Bangladesh has suffered the deadliest tornadoes on record and several of these have been estimated to be in the F-4 category of strength. The reason Bangladesh receives violent tornadoes is because during the beginning of the wet monsoon season (usually April and May) cold dry air spilling south over the Himalayan massif encounters deep tropical moisture streaming north from the Bay of Bengal. The ensuing violent thunderstorms produce not only tornadoes but also some of the largest hail ever observed (the heaviest single hailstone ever measured on earth weighed in at 2.25 pounds on April 14, 1986 during a storm in the Gopalanj District—unfortunately, the diameter of the stone was not noted).

A synoptic chart illustrating a day a tornado formed in Bangladesh during the spring of 2003.

The deadliest tornado in Bangladesh, and thus world, history (at least in modern records) was that which occurred on April 26, 1989. At least 1,300 deaths were reported from flattened villages in a region just north of the city of Dacca. On May 13, 1995 another 700 lives were lost in the city of Tangail as the result of a violent tornado. Four other tornado events have killed 500 or more people in Bangladesh since 1964 (on April 11, 1964, April 14, 1969, April 17, 1973, and April 1, 1977). In fact, at least 6,500 people have died from tornadoes in Bangladesh in the past 50 years. This list provides more details about these events.


Although tornadoes are relatively rare in South America Argentina has recorded some violent twisters that may have reached the F3-4 level of intensity as was the case on January 10, 1973 when 50-70 people were killed in the town of San Justo, Santa Fe State northwest of Buenos Aires.


Tornado expert Thomas Grazulis has speculated that Russia might receive the largest absolute number of tornadoes each year, following the United States, due to its vast size and “potential for small tornadoes”. Violent tornadoes, however, have been known to occur as was the case on June 9, 1984 when as many as 400 people were reported killed during an outbreak in a region 150-200 miles north of Moscow.


Violent tornadoes are extremely rare anywhere in Western Europe although many weak ones occur every year. The deadliest tornado in Western Europe’s history struck three textile and paper mills near Monville, France on August 19, 1845 killing at least 70 people. Sketchy reports of waterspouts coming ashore in the Mediterranean claim fatalities of 500 in Sicily in December 1851 and 600 killed in the Grand Harbour at Valetta, Malta on September 2, 1551. There seems to be few details concerning these events and uncertainty as to the actual dates of occurrence.


The only country in Africa to occasionally report a violent tornado is South Africa where powerful thunderstorms often erupt during the summer months of November through February. The deadliest tornado outbreak in the nation’s history was that of November 30-December 2, 1952 when 31 people were killed in the towns of Albertynesville and Paynesville near Johannesburg.


In Japan about 20 tornadoes, or tatsumaki (dragon whirls), are reported annually. These are most often associated with super cell thunderstorms that develop along the Pacific Coastline during the summer months. Weaker winter tornadoes (similar to those that affect the U.S. West Coast during winter storms) are also known to form. However, the strongest tornado in Japanese history was one of these winter ones which hit the coastal city of Mobara (20 miles southeast of Tokyo) on December 1, 1990. It was rated as a F-4 and destroyed over 1000 buildings and injured 100 people. There were no fatalities. The deadliest tornado in modern Japanese records killed 16 at an elementary school in Miyazaki city on September 26, 1881.


Australia reports about 20-25 tornadoes a year, the same number as New Zealand, and in both cases they are usually relatively weak. Occasionally they become strong enough to warrant an EF-3 rating. New Zealand’s deadliest tornado was that which struck the towns of Frankton and Hamilton in August 1948 killing three and injuring dozens. It was rated as a F-2 in intensity.

Australia’s deadliest twister was that of August 14, 1971 when three were killed at Kin Kin (a small community between Gympie and Noosa) in southern Queensland.

The Bucca, Queensland tornado of November 29,1992. The only F4 tornado so far officially reported in Australia (photo courtesy of “Emergency Management Australia”).


The Top Ten Deadliest Tornado Outbreaks on Record in the World Since 1900

1. 1,300 fatalities in Bangladesh on April 26, 1989
2. 747 fatalities in the USA on March 18, 1925
3. 700 fatalities in Bangladesh on May 13, 1996
4. 681 fatalities in Bangladesh on April 17, 1973
5. 660 fatalities in Bangladesh on April 14, 1969
6. 500 fatalities in Bangladesh on April 4, 1964
7. 500 fatalities in Bangladesh on April 1, 1977
8. 454 fatalities in USA on April 5-6, 1936
9. 400 fatalities in Russia on June 9, 1984
10. 330 fatalities in USA on March 21-22, 1932

Deadliest Tornado Outbreaks on Record by Continent Since 1900

1,300 fatalities in Bangladesh on April 26, 1989

747 fatalities in the USA on March 18, 1925

400 fatalities in Russia on June 9, 1984

70 fatalities in Argentina on January 10, 1973

3 fatalities on August 14, 1971

3 fatalities in New Zealand on August 25, 1948

REFERENCE: The single best reference work about tornadoes and tornado history is Thomas P. Grazulis’s masterpiece Significant Tornadoes: 1680-1991. A supplement to this was published bringing the data up to 1995. Unfortunately, no further editions have been published to cover the past 16 years although his web site has done so.


World Record Snowfall?

By: weatherhistorian, 4:24 AM GMT on April 01, 2011

World Record Snowfall?

Last Blog (Part 3), for now, About NCDC Possible Extreme Weather Record Errors

I’ve been reporting the last few weeks about some errors in the NCDC database of extreme temperature records for a selection of various states. This blog was going to be about precipitation errors but the NCDC COOP site for the COOP/IPS data is apparently down for the time being so I am only able to present a single document (that I happened to download some months ago) so far as possible precipitation errors.
According to the NCDC site a world record 24-hour snowfall occurred at a site in Alaska back in February 1963.

The Great 78-inch snowfall of February 7, 1963 at Mile 47 Camp, Alaska

The official world record 24-hour snowfall, according to the WMO Climate Extremes Committee, was an accumulation of 75.8” at Silver Lake, Colorado on April 14-15, 1921. This record has been scrutinized in great detail, especially since an observer in Montague, New York reported a 77” fall during a 24-hour period on January 11-12, 1997 . The NCDC sent a team to investigate that report and published 50-page report refuting it. It was refuted as a result of one too many observations being made during the course of the 24 hours of accumulation. This in spite of the fact that the accumulation itself was not questioned, simply the method of the observation of such.

Remarkably, the NCDC now seems to accept without question a 78” snow accumulation on February 7, 1963 at a remote site located on the mile 47 marker of the Richardson Highway in Alaska (to its credit the WMO Climate Extremes Committee has, as of now, not published this as a new world record weather extreme). Here is the COOP form associated with the Alaska event:

The COOP form for Mile 47 Camp, Alaska showing the 78” single-day snow accumulation of February 7, 1963. Note the melted precipitation figure of 6.02” and the daily temperature range of 0°-8°F (or perhaps -4° to +8°F, it appears the '0°' is crossed out and replaced with a -4°F figure, hard to tell).

Of particular interest is the melted precipitation figure of 6.02” on February 7, 1963 along with the day’s temperature range of 0°F (low) to 8°F (high) for that day. A fall of some 6 inches of precipitation with a temperature of zero to 8°F strains the boundary of physical possibility. I would challenge anyone to conceive of how a situation could possibly evolve to create 6 inches of precipitation while the temperature at the surface was this cold. The observer’s comment for this extraordinary day simply states “overcast”.


Camp Mile 47 on the Richardson Highway is located, obviously, 47 miles along the route heading north from the port of Valdez.

A photograph of the Richardson Highway near the site of Mile Camp 47. Photo by “TFO” from Google Earth map site.

It was a highway maintenance station associated with the construction of the oil pipeline from the North Slope of Alaska to the port of Valdez. This highway crosses over the Thompson Pass (elevation 2,800’) 27 miles north of Valdez. Thompson Pass for the period of 1952-1974 maintained a weather station (at a site located at 2,500’) which indeed did record the heaviest snowfalls ever reported from Alaska, and, in some cases, reported the most intense snow accumulations ever measured on earth. To wit:

62.0” in 24 hours on December 29, 1955
120.6” in 2 days on Dec. 29-30, 1955 (world record)
147.0” in 3 days on Dec. 28-30, 1955 (world record)
163.0” in 4 days on Dec. 27-30, 1955
175.4 in 5 days on Dec. 27-31, 1955
186.9” in 7 days on Feb. 18-24, 1953
346.1” in one calendar month in February 1964
974.1” in one winter season in 1952-1953

However, a modest 53.5” fell for the ENTIRE month of February 1963 at Thompson Pass. Kenney Lake was the only other site in the area to have records for February 1963 and it reported 17.0” for the month. Sheep Mountain, also in the area reported 7.0” for that month and Cordova Airport had 10.1” with Valdez reporting 36.0” (a relatively low value for the site for a February that averages around 50” for the month). In other words, there was no extraordinary or unusual storm associated with the snowfalls of February 1963.

The Thompson Pass COOP weather site was operational during the winter of 1963 and recorded a snowfall of 12” on February 7, 1963. Mile 47 is 20 miles beyond the pass along the Richardson Highway and some 750 feet lower. It is hard to imagine that the Mile 47 site reported a snowfall some six to seven times greater than the summit just 20 miles further down the road.


The NCDC has obviously been using the IPS COOP form database to create its extreme weather summaries as per their new web site without actually fact checking the accuracies of these forms. Although it is conceivable that some microclimate pattern was at work (a strong moist easterly flow packing the snowfall up the backside of the Thompson Pass for instance) it seems that as thorough an investigation should be made of this event as was done at Montague in New York, being a potential world weather record.

Winter Weather

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Weather Extremes

About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.

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