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National Oceanic and Atmospheric Administration

Climate-Watch, April 2001


National Climatic Data Center - (last update May 23, 2001

Oldest known tornado photo

Oldest known tornado photograph - August 28th, 1884
22 miles southwest of Howard, South Dakota
(Courtesy of NOAA Photo library
Click on the image for a larger view )

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Tornadoes are one of nature's most violent storms. In an average year, 800 tornadoes are reported across the United States, resulting in 80 deaths and over 1,500 injuries. What is a tornado? According to the Glossary of Meteorology (AMS 2000), a tornado is "a violently rotating column of air, pendant from a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud." In order for a vortex to be classified as a tornado, it must be in contact with the ground and the cloud base. Weather scientists haven't found it so simple in practice, however, to classify and define tornadoes. For example, the difference is unclear between a strong mesocyclone (parent thunderstorm circulation) on the ground, and a large, weak tornado. Tornadoes come in all shapes and sizes and can occur anywhere in the U.S at any time of the year. Intensities are ranked by the Fujita (F) Tornado Scale . In the southern states, peak tornado season is March through May, while peak months in the northern states are during the summer. Additional information on tornadoes, their origins, causes and other information are available from:
NOAA's Storm Prediction Center.
NCDC's Tornado Page
NCDC's Technical Report on Tornadoes

Tornadoes Take Many Shapes and Sizes

Weak Tornadoes (F0 -F1) Strong Tornadoes (F2 - F3) Violent Tornadoes (F4 - F5)
69% of all tornadoes 29% of all tornadoes Only 2% of all tornadoes
Less than 5% of tornado deaths Nearly 30% of all tornado deaths 70% of all tornado deaths
Lifetime 1-10 + minutes May last 20 minutes or longer Lifetime can exceed 1 hour
Winds less than 110 mph Winds 110 - 205 mph Winds greater than 205 mph

10th Anniversary -Historical Tornado Event- April 1991 -

Severe thunderstorms in the central U.S. spawned fifty-five tornadoes from northeastern Texas to Iowa and eastern Nebraska killing twenty-one persons. During the early evening on the 26th of April 1991, thunderstorms over south central Kansas spawned a violent (F-5) tornado which traveled 45 miles from southwest of Wichita to north of El Dorado. It killed seventeen persons, including thirteen at the Golden Spur Mobile Home Park in Andover. The tornado also caused 62 million dollars damage to McConnell Air Force Base as it crossed the south side of Wichita.

Weather Log - April 1 - 10, 2001

Media reports indicate that the small rivers of the Altai Republic in southern Siberia were melting in early April 2001 due to abnormally warm weather. Water levels in the rivers are on the rise, and homes in Gomo-Altaisk are suffering from short-term flooding.

Flooding is also causing problems in parts of the Upper Midwest in the United States. The Red River and others streams across the Dakotas and Minnesota were rising fast due to rapidly melting snow and heavy rain dumped by a storm that swept across the region on April 7th, 2001. Media reports indicated that Watertown, South Dakota received 2.27 inches of rain on April 7th, and about 250 families left their homes as a precaution against high water on the Big Sioux River. They were allowed back on the 8th as the river started receding. National Guard members also had been sent to help out there.

Other rivers in eastern South Dakota were still rising, including the James River, which was 6 feet over flood stage at Huron. The focus of attention Sunday was the Red River, which flows northward between North Dakota and Minnesota and caused devastating flooding four years ago in Grand Forks, North Dakota. New dikes and flood control systems are expected to spare many areas from a repeat of its Northern Plains 1997 flood.

Grand Forks officials issued a new flood warning on April 8th, as the Red River rose past 36 feet there, up more than 4 feet since Saturday morning and on its way to a forecasted crest of 43 to 45 feet. However, the city had already been shoring up its dike system, which protects to a river level of 50 feet, said city spokeswoman Christine Page Diers.

Weather Log - April 11 - 20, 2001

Media reports indicate that reported that Cuba’s eastern and central regions have been suffering from one of the worst droughts in a decade for months. The on-going drought has forced authorities to adopt a series of measures to protect water supplies as well as crops and livestock. According to the Granma newspaper, the drought has brought reservoirs in the province of Camaguey to their lowest levels in 5 years. The provinces of Tunas and Guantanamo have registered below-average rain levels for the region, and currently only 9% of the cultivated farmland is being irrigated.

The 2001 Atlantic hurricane is still several months away but as of early April, the Colorado State University (CSU) hurricane forecasting team led by William Gray has upped the numbers for 2001 just slightly, suggesting a normal season. For the June 1-Nov. 30, 2001 season, the scientists are calling for 10 named storms, six hurricanes and two intense (Saffir-Simpson category 3 or higher) hurricanes. That's one tropical storm and one hurricane more than predicted in the initial 2001 season forecast released last December by Gray. Fore more details, see the CSU complete hurricane forecast and related research and press releases.

According to media reports, as of April 17th, 2001, the Mississippi River kept residents in river basin areas on alert as it slowly swept out of its banks and threatened to become the highest flood crest on record in spots. A 403-mile stretch of the river from Muscatinem, Iowa, to Minneapolis was closed to boat and barge traffic, and nine counties in western Wisconsin were under a state of emergency. The National Guard in St. Paul needed civilian help again Monday (16th) to build up a dike protecting their headquarters at St. Paul's flooded downtown airport. More than 350 Guardsmen are on active duty in Minnesota because of flooding across the state, but most are deployed on the Red and Minnesota rivers, forcing the Guard to rely on volunteers to battle the Mississippi. The river was expected to crest at 20 to 22 feet early next week at Davenport, Iowa, where the record was 22.6 feet in 1993. It was predicted to crest near La Crosse at 17 feet Wednesday, just short of the record 17.9 feet set in 1965. See the latest NWS Minneapolis Flood statement for more information. River levels are expected to remain very high for an extended period of 2-4 weeks in the region which will place added stress on dikes and dams. Some additional Flood information and photo's are available from the NWS LaCrosse, WI web site .

In Zimbabwe, media reports indicate a total of 109 lives have reportedly been lost as a result of the floods - 71 in the province of Zambezia, 28 in Tete, 6 in Sofala and 4 in Manica. According to OCHA the number of people now in accommodation centers is estimated at 225,075, and the total number of affected people is 461,811. Provincial authorities in Sofala have reportedly estimated that 1.5 million dollars is needed to rehabilitate roads and bridges damaged by the floods. An estimated 900km of road and at least 3 bridges are reportedly in need of rehabilitation. The FAO reported that the area of crops lost is approximately 67,300 hectares, and the Ministry of Health reported an outbreak of cholera in Mutarara district, Tete province. The direct cause for the outbreak is reportedly consumption of untreated water from the Zambezi River.

In the U.S., Reuters reported that Florida’s drought - the worst in a century in some parts - has cost farmers 574 million dollars in the last four years. Even the state’s citrus industry has suffered from the drought, losing 82 million dollars over the past 4 years. The Florida Department of Agriculture survey from this year reportedly found serious losses across the state’s farming industries. The largest losses - 295 million since 1997 - were reportedly to row crops, like corn, peanuts, cotton, soybeans and hay in northern Florida, and the panhandle.

Satellites again this spring have tracked a huge sand/dust storm that started in Mongolia earlier in April, then picked up industrial pollution from China and spread eastward across the Pacific. NCDC has processed three impressive satellite images of the event. The first image shows the sandstorm caused by powerful Siberian low pressure - NOAA-16 multi-spectral image on April 6th, 2001 at 0615 UTC (Z). The second image is a closeup shot of the same event. The third image shows the eastward progression of the duststorm across eastern China moving toward the Yellow Sea. Satellite remote sensors tracked vast clouds of dust /sand and anthropogenic aerosols en route from Asia to North America. The haze which was reported over various parts of the United States and Canada this week (third week of April 2001) was traced to Asian origins between the sixth and ninth of April. The storm spread a haze across parts of the U.S. and Canada. The whitish haze has reportedly been seen from Calgary, Alberta to Arizona, to the East Coast, and levels of particulate matter in some places quadrupled.

Media reports indicated that 4 individuals died, buildings were badly damaged, trees uprooted and cars overturned when numerous tornados hit the Midwest around the 11th of the month. Two individuals reportedly died in Agency, Iowa where 2 houses were destroyed and 9 others were severely damaged after a tornado touched down in the southeastern Iowa town. Three other twisters reportedly hit southern Iowa on Wednesday April 11th. See the NWS Des Moines Storm Surveys web page for more information. Other tornadoes hit parts of Oklahoma and Missouri causing several deaths.

Weather Log - April 21 - 30, 2001

Earth Day, which occurs annually on April 22, involves tens of thousands of events, from rallies and teach-outs to concerts and earth fairs. The goal is to be good stewards of the earth and environmentally responsible. Check out some of the activities here . NOAA celebrates Earth Day 2001 by participating in community based activities across the country and recognizing environmental heroes with an agency award. See Earth Day - 2001 for more information.

According to news reports, the Iowa National Guard battled to keep downtown Davenport from the advancing Mississippi River as flooding reached the city's riverfront baseball stadium. Concerns remain ahead of Tuesday's (24th) projected river crest of 22 to 22.5 feet, just short of the 1993 record of 22.63 feet. Residents, volunteers and Guard troops have labored for days, filling sandbags to protect area businesses. See the NWS Central Region - North Central River Forecast Center for the latest information.

The AP reported that a tornado hit Hoisington, Kansas late Saturday night (20th), ripping the roof off a hospital just after it was evacuated, and damaging several blocks of homes. At least one individual reportedly died, and 32 individuals were injured, including 4 critically. See the NWS/Storm Prediction Center for preliminary tornado information for April 2001.

Media reports also indicate that half a million residents of Afghanistan are living as refugees in their own country as a result of the on-going drought, deep poverty and war. Afghanistan has reportedly been ravaged by 2 decades of war and the worst drought in 30 years. Also, two years of drought and record low snowfalls are severely affecting northern Pakistan. The previously abundant Indus River is reportedly now only a trickle in some places, causing fishing to be decimated and farmland to become parched.

In contrast, media reports indicated that an 18-mile stretch of U.S. 1 - the main highway between Florida City and Key Largo - and an alternate route were closed periodically from Monday to Thursday (23rd - 26th) because smoke was causing severely reduced visibility. Through Wednesday (25th) , 2,252 fires in Florida charred 178,138 acres since January 1st. . However, much needed rainfall brought relief to parts of the state over the last seveal days.

Heavy rains and flooding have caused extensive damage in southern Angola, particularly the provinces of Benguela, Cunene, Huila and Namibe. Bridges over the Beiro and Giraul Rivers in the Namibe province collapsed and the railroad connection between part of Namibe and Huila province has been cut, severely affecting the transportation of humanitarian assistance. Meanwhile, Mozambique is still assessing the damages from recent flooding, the death toll has reached 113 individuals, and that 223,000 people still remain displaced as a result of the flooding in Mozambique.

Heavy rains and flooding also affected parts of South America at months end. Media reports indicated that flooding caused by heavy rains across western Brazil caused the deaths of at least 13 individuals and left more than 10 others missing in the town of Cuiaba. In Peru, according to local authorities, 9 people are missing and 10 are injured in Junin because heavy rains caused the Cuvaru and Camavari Rivers to overflow on the 25th. More than 300 people from 6 native communities in the Mazamari district were reportedly affected, approximately 80 dwellings were washed away, and 400 hectares of cultivated land were destroyed.

Spring has brought back forest fires to Russia’s Far East, where according to the regional center of the Russian Ministry for Emergency Situations, more than 1,600 hectares of taiga are engulfed in flames. Approximately 14,000 hectares of taiga are reportedly on fire in the Jewish Autonomous District and new wildfires were spotted in Khabarovsk and Amur regions. The Khabarovsk administration reported that over the past 3 years approximately 2.5 million hectares of forest have been burned.

Reuters reported that at least 21 individuals died, more than 100 were injured and many are missing following a series of storms that hit parts of Bangladesh on the weekend (28th & 29th). The tropical storms with winds up to 80kmph (50mph) also damaged homes and paddy crops.

Other global highlights for the month can be found at NOAA/OGP Special Global Summary for April 2001.

Note: Hazard event satellite images available courtesy of NOAA OSEI Satellite Images WWW site.
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Top of Page Selected U.S. City and State Extremes

The Selected U.S. City and State Extremes provides a list of new monthly or unusual records that were set across the U.S. during April 2001.

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Top of Page Additional Resources

Storm Prediction Center Tornado FAQ page
NCDC Tornado Page
NCDC's Tornado Technical Report
NCDC Satellite's Eye Art Galleries
FEMA for Kids - Tornadoes
NWS Tornadoes Page and Preparedness Guide
Midwest Climate Watch
Southeast Climate Watch
Northeast Climate Watch
Southern Climate Watch
NNDC Climate Data Online (for long-term climate data)
NOAA Historical Visible Imagery Library
NCDC Climatic Extremes and Weather Events
NOAA Office of Global Programs (OGP) Rapid Response Project WWW Site
Additional NOAA OSEI Satellite Images
NCDC Storm Event Database
Links to Numerous Natural Disaster Web Sites

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Tom Ross
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
Specific requests for climatic data should be addressed to:

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NOAA Bullet NCDC / Climate Research / Climate-2001 / April / Climate-Watch / Search / Help
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