Global Analysis - April 1999



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Top of Page Temperature

Global Temp Anomalies, April
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Mean monthly temperature anomalies for April (using a base period 1880-1998) are shown in the figure to the left. Global temperatures were considerably cooler in April 1999 than in the record warm April 1998 but continued to be higher than the long term mean. The average temperature over land and ocean was 0.44 C above the 1880-1998 mean, 0.32 C less than the record anomaly recorded in 1998. Although the drop in temperature was due to cooler conditions over both land and ocean, the most significant cooling occurred over the oceans. The average sea surface temperature anomaly dropped almost in half from 0.54 C in April 1998 to 0.28 C in 1999. April land surface temperatures averaged 0.84 C above the long term mean in 1999, down from 1.28 C in 1998.
The drop in both land and ocean temperatures is a continuation of the trend toward cooler temperatures that began last year with the transition from El Niño to La Niña conditions. This figure shows the difference in land surface temperatures between the mature El Niño conditions in April 1998 and La Niña in April 1999. (These are NOT temperature anomalies. They are simply April 1999 temperatures minus April 1998 temperatures. Blue dots indicate cooler temperatures in 1999.) Some areas were warmer in 1999, but blue dots extend across a large area of the world, indicating that temperatures were cooler throughout most areas.
GlobalTemp Anomalies, Apr99
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GlobalTemp Anomalies, Apr99
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Although temperatures are generally lower in 1999 when compared with 1998's extremely warm temperatures, this figure of global anomalies shows that temperatures were still well above average in large parts of the world. The largest positive anomalies occurred throughout Canada and areas of western Russia. Above average temperatures were also widespread throughout Europe and Asia. Large positive anomalies have been recorded in Canada for the past several months while below average temperatures have been measured in northern sections of Russia.
Although Russian data is limited, cooler than average temperatures are shown in northeast and northwest areas of Russia again in April. The western third of the United States and southern areas of South America also experienced below average temperatures in April. See the U.S. Regional / Statewide Analyses pages and the Global Regional Analyses pages for more details on regional climate in the United States and throughout the world.

Top of Page Precipitation

As shown in the adjacent figure, preliminary global precipitation (land only) averaged 5.0 mm (0.20 inches) above the long term mean (1900-1998) in April. This continues a pattern of above average precipitation in 1999 with above average values every month this year.
Global Precip, April 99
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However, in April the areal coverage of anomalies greater than 100 mm was less than in previous months. The areal coverage of negative anomalies less than -100 mm was also lower in April, indicating that precipitation in many areas was closer to average this month. Precipitation departures less than 25 mm are shown in the figure below for many regions of the world, particularly much of Asia, Africa and a large part of Europe. Anomalies greater than 100 mm were scattered throughout several areas of the world, e.g. portions of southeastern China, the South Pacific islands and parts of South America and the central United States.

Global Precip Anomalies, April 99
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Much of Europe was slightly wetter than average in April, while near normal precipitation fell across the Asian continent. Some areas in southern and eastern China that had been experiencing drought conditions the past several months were wetter than average in April. As they have in recent months, most islands in the South Pacific continued to receive above average rainfall in April. Above average precipitation also fell across the central plains and Midwest areas of the United States. Venezuela, much of Argentina and isolated areas of Brazil also received precipitation amounts above their long term averages.

Top of Page Global Surface Wetness


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Surface wetness was above average in large areas of the central United States, Manchuria, northern Argentina, and Indochina. There were small positive anomalies in central Russia, northern South America, central Africa and Baltic Sea area. The largest negative anomalies occurred in southern Russia, Ukraine, and southeastern China, while scattered negative values covered portions of central Russia, the horn of Africa, eastern Argentina, and eastern India.

Citing This Report

NOAA National Climatic Data Center, State of the Climate: Global Analysis for April 1999, published online May 1999, retrieved on September 2, 2014 from http://www.ncdc.noaa.gov/sotc/global/1999/4.