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IRI Climate Digest   November 2004

October Global Climate Summary

Climatological Background

During October, the Northern Hemisphere mid-latitude storm tracks increase in strength, while monsoon systems in West Africa, South Asia, and southwestern North America continue their retreat southward following the maximum solar heating. Late season tropical storm activity continues in the North Atlantic, the North Pacific, and northern Indian Oceans. Spring is underway in the Southern Hemisphere, with mid-latitude storm tracks losing strength.

Monthly Mean Temperature (1961-1990), data from the Climate Research Unit, University of East Anglia
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Monthly Mean Precipitation (1961-1990), data from the Climate Research Unit, University of East Anglia
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Above-average temperatures were observed in Africa, Europe and South America with only small changes in the overall anomaly patterns in these regions over the past three months. Below-average temperatures appeared in Siberia during October and continued in western and central Canada. Eastern North America from Canada through most of the eastern and southeastern United States experienced above-average temperatures, as did most of the Australian continent.

Temperature Difference from the 1961-1990 mean, with data from NCEP Climate Prediction Center, CAMS.
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During October dry conditions continued to dominate the far western Pacific from Indonesia and New Guinea through Southeast Asia and northward into China. However, the overall dryness was punctuated by pockets of short-lived rainfall events in Sumatra and into the Mekong Delta. Heavy rains were reported in Bangladesh. The southern islands of Japan experienced heavy rainfall events associated with tropical storm activity. In Africa dry conditions continued to prevail from Chad and Sudan through western Ethiopia and southward through much of southern Africa. Somalia and parts of eastern Ethiopia experienced above average rainfall. In South America, drier-than-average conditions prevailed from Rio de Janeiro north westward through Venezuela and Colombia and into much of Central America. Episodic rains, however, were reported in Panama and the Colombia Pacific coast. Except for the eastern coastal areas much of North America experienced above-average rainfall.

Precipitation Difference from 1979-1995 mean, with data from NCEP Climate Prediction Center, CAMS-OPI.
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Oceanic Conditions

There were very few changes in the sea surface temperatures in the tropical Pacific during October. Above-average sea surface temperatures continued to be experienced in the central equatorial Pacific with relatively small anomalies over the rest of the basin. See the latest IRI ENSO Update for a detailed summary and outlook for the tropical Pacific. Slightly above-average temperatures were also experienced in parts of the central and eastern Indian Ocean. Sea surface temperature anomalies in the equatorial Atlantic and tropical North Atlantic changed little during the month with above-average temperatures characterizing most of the region from northeastern South America to the west coast of Saharan Africa.

Monthly Sea Surface Temperature Difference from the 1971-2000 mean, with data from the Environmental Modeling Center, NCEP/NOAA.
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Material for this Global Climate Summary has been extracted from the IRI Climate Data Library, the NOAA NCEP Climate Prediction Center, the Climate Diagnostics Center, and the NOAA ERL Pacific Marine Environmental Laboratories. Additional information has been obtained from the Bureau of Meteorology, Australia, and CPTEC, Brazil.

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