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Climate of 2001 - April
Global Regional Analysis

National Climatic Data Center, 11 May 2001

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Global Analysis / Global Regional / U.S. National / U.S. Regional / U.S. Drought / Extreme Events
Use these links to access detailed analyses of the Global and U.S. climate of April 2001.
 a satellite image of the Mongolian sandstorm Mongolia/China Sandstorm Contents of This Section:

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Regional Highlight

A strong mid-latitude storm system moved across Mongolia and northeastern China during April 6-8 and produced a massive sandstorm as it crossed the Gobi Desert. Northwest China's Ningxia Hui Autonomous Region and the neighboring province of Gansu experienced the most severe conditions with near zero visibility in some areas. In the Russian Far East provinces, the regions of Khabarovsk, Amur and Chita were impacted as both air and land travel were hampered and streets covered with brown dust. During a NOAA polar orbiting satellite pass on April 6 , the geographic area covered by dust and sand was estimated at 675,000 square miles (1.75 million km²) or nearly the size of the state of Alaska. This was one of the biggest sandstorms to occur in this part of world in up to 30 years. The enormous mass of dust was carried by strong westerlies across the Pacific Ocean and arrived in North America a week later resulting in very hazy skies as far east as the Eastern Seaboard by the 17th. Additional global regional information is available below.

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Top of Page European/Asian Wetness

A contributing factor to the severity of the Mongolia/China sandstorm was the abnormally dry conditions that have prevailed across eastern Asia since mid-March. Below average precipitation, with moisture deficits exceeding 100 mm (3.94 inches), continued this month from China's Sichuan province eastward through the Korean Peninsula. In China's Inner Mongolian Autonomous Region, nearly 530,000 people and 4.5 million cattle have been affected by a shortage of drinking water. Farther north in Mongolia, the storm system that was responsible for generating the sandstorm produced very heavy snowfall across much of the country. According to the Mongolian News Agency, at least 7 people died from the storm with communications and travel disrupted as the system moved eastward into China.  European/Asian Wetness map larger image
Elsewhere, negative wetness anomalies of 3-5 percent covered a large area from eastern Romania through southern parts of the former Soviet Union.

Top of Page North American Wetness

During the month, the upper level circulation pattern across the United States was characterized by ridging in the eastern states with troughing in the West. This translated to cooler than average conditions along the West Coast with unusually warm weather for the eastern two-thirds of the nation. An active storm track through the upper Mississippi Valley teamed with melting snow cover to produce significant flooding along the Mississippi and adjoining tributaries. Much needed rain and snow fell on parched areas of the Pacific Northwest.
 North American Wetness map
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Extreme drought conditions continued to plague Florida south into central and eastern Cuba. Reservoir levels in the Cuban provinces of Guantanamo, Runas and Camaguey fell to their lowest levels in 5 years. The dry weather resulted in numerous fires across Cuba that were noted in satellite imagery. Unusually dry weather also affected much of the Canadian prairie provinces of Alberta and Saskatchewan, where dry soil conditions caused uncertainty regarding what to seed this spring.

Top of Page South American Wetness

 South American Wetness map
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Torrential flooding rains affected western Brazil during the week of the 23rd, killing at least 13 people. The Associated Press reported that several neighborhoods in Cuiaba, about 700 miles northwest of Brasilia, were flooded and many residents had to be rescued by helicopter. The same storm system also brought heavy rains and subsequent flooding along the Cuvaru and Camavari Rivers in the Junin province of central Peru, where 9 people were reported missing. In Argentina, a storm system that affected several northwestern provinces on the 4th and 5th with strong winds and heavy rain resulted in at least 6 deaths. In the province of Jujuy, 2,000 people were left homeless in Palma Sola due to flooding along the Santa Rita River. Farther east across central Argentina, wet weather that began in March continued through the first half of April. Rainfall surpluses during the past 8 weeks exceeded 200 mm (7.87 inches) across portions of Cordoba, San Luis and southern Santiago Del Estero provinces.
Much drier conditions prevailed farther east in Argentina with little precipitation observed from Buenos Aires northward.

Top of Page African Wetness

 African wetness map larger image Heavy rains hit the coastal provinces of Angola with 11 deaths reported due to flooding and landslides. Reuters reported that over 20,000 people had been displaced from their homes in Benguela and Namibe provinces, with some of the worst flooding along the Bero River in the provincial capital of Namibe. In stark contrast, severe drought conditions continued in the interior of Angola, where dry weather that began earlier this year continued across the provinces of Cunene and Kwanza-Sul.

State run Radio Ethiopia reported dry weather was causing water shortages in the Somali state in southeastern Ethiopia as ponds and water points had run dry. In neighboring Kenya, the BBC reported that long term drought and a series of crop failures had increased the threat for widespread starvation in that country. The All Africa Global Media reported that the worst flooding in memory struck along the Gwayi River in the Matabeleland province of Zimbabwe, washing away hundreds of houses in Tsholotsho and leaving 1,500 homeless. Farther east, over 200,000 people remain displaced from their homes due to severe flooding that culminated in March across central Mozambique. Across North Africa, warm and dry weather prevailed across Morocco, Algeria and Tunisia where 2-month moisture deficits exceeded 100 mm (3.94 inches) in some areas. Positive temperature anomalies exceeding +5°C (9°F) were found from Morocco northward through the Iberian peninsula.

Top of Page Asian Wetness

April was a dry month across much of Afghanistan and Pakistan where severe long-term drought conditions continued. The Associated Press reported that the western Indian states of Gujarat and Rajasthan are in the midst of a drought resulting from nearly 2 years of light monsoon rains. The drought is hindering economic recovery in the region that was devastated by an earthquake in January. Across Bangladesh, an otherwise dry month was interrupted by severe thunderstorms during the weekend of the 28th-29th. Strong winds, heavy rains and lightning caused at least 21 deaths and over 100 injuries. Across southeast Asia and Indonesia, wet conditions during the first half of the month from the Malay Peninsula eastward to the Philippines resulted in precipitation surpluses of 200 mm (7.87 inches) over the past 2 months.

 Asian Wetness map
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Top of Page Australian Wetness

 Australian Wetness map larger image April rainfall was average to below average across much of the country, with two notable exceptions: the northeast Northern Territory (N.T.) and southern Victoria. An active monsoon trough brought heavy rains to the N.T. during the first half of the month, and westward moving tropical cyclone Alistair affected the coastal fringe of the N.T. and northern Western Australia between the 16th and 20th . A slow moving low pressure system brought heavy rains to southern Victoria beginning on the 21st, with a 4-day total of 506 mm (19.9 inches) atop Mt. Sabine in the Otway Range. Negative wetness anomalies persisted across southwestern Western Australia (W.A.) and southeastern Queensland. The period of severe rainfall deficiencies in W.A. has now extended to 13 months after April rainfall was less than 20 percent of the long-term average.

Tropical cyclone Sose affected the islands of Vanuatu, passing within 40 km (25 miles) of Santo on April 7 with sustained winds of 100 km/hr (62 mph). One person was swept away by a swollen river on Santo and 59 houses were completely destroyed.

Top of Page Global Blended Temperature

Across the globe, some of the largest positive temperature anomalies this month occurred in the central and eastern United States as temperatures were more than 4°C (7.2°F) above average in areas of the Midwest. Other warm anomalies of 1-3°C (1.8-5.4°F) were observed over parts of North Africa and into the Middle East, as well as western parts of the former Soviet Union. Cooler than average temperatures were found over western North America, western Europe, the South African nations as well as central Australia. Anomalies of -1 to -3°C (-1.5 to -5.4°F) were common in these areas.  Global blended temperature map larger image

Top of Page European Temperature

Much of Scandinavia and the northwestern corner of Russia experienced cold weather during the first half of the month with negative temperature anomalies of 2 to 4°C (3.6 to 7.2°F). The temperature dipped to -29°C (-20°F) on the 13th at Siccajavre, Norway. This cold anomaly spread southward across much of central Europe by mid-month with temperatures ranging from 3 to 6°C (5.4 to 10.8°F) below average. Subfreezing low temperatures dominated the entire region from southern Scandinavia to the Alps.

Across northern France, heavy rains caused flooding along the Somme River where as many as 1,200 houses were flooded, according to the Associated Press. The city of Paris received over 100 cm (39.4 inches) of rain since April 2000, nearly double the average annual rainfall.

 European blended temperature map
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Top of Page References:

Basist, A., N.C. Grody, T.C. Peterson and C.N. Williams, 1998: Using the Special Sensor Microwave/Imager to Monitor Land Surface Temperatures, Wetness, and Snow Cover. Journal of Applied Meteorology, 37, 888-911.

Peterson, Thomas C. and Russell S. Vose, 1997: An overview of the Global Historical Climatology Network temperature data base. Bulletin of the American Meteorological Society, 78, 2837-2849.

For all climate questions other than questions concerning this report, please contact the National Climatic Data Center's Climate Services Division:

Climate Services Division
NOAA/National Climatic Data Center
151 Patton Avenue, Room 120
Asheville, NC 28801-5001
fax: 828-271-4876
phone: 828-271-4800

For more information, refer also to ...
SSMI Derived Products
Global Historical Climatology Network (GHCN)
The Blended GHCN - SSM/I Product
The Global Temperature Anomalies

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For further information on the historical climate perspective presented in this report, contact:

Scott Stephens
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328


Jay Lawrimore
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
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