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IRI Climate Digest   August 2006

July Global Climate Summary

Climatological Background

In July, heating of the continents in the northern hemisphere results in strengthened monsoon systems which bring rains to West Africa, South Asia, and southwestern North America. In the southern hemisphere, winter has set in, with stronger north-south temperature gradients fueling active mid-latitude storm tracks.

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 continued to dominate over much of the northern hemisphere. Record and near-record July temperatures were recorded in Western Europe and much of the United States. Lower-than-average temperatures to the east of the Urals provided the only major change in the previous month’s temperature pattern (Temperature Persistence Map). Above-average temperatures dominated the tropics and sub-tropics as well as most of the southern hemisphere. An exception, however, was northern Australia which has experienced below-average temperatures since May.

Temperature Difference from the 1961-1990 mean, with data from NCEP Climate Prediction Center, CAMS.
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Greater-than-average monsoon rainfall amounts were received in northern India and parts of Pakistan in July. Heavy rains were also experienced in eastern China northward into Korea and Japan. Generally drier-than-average conditions were observed over the Maritime Continent. Rainfall in the Sahel was mixed with both dry and wet regions. Less-than-average rainfall was recorded in northern South America, Western Europe and the central United States and Canada.

Precipitation Difference from 1979-2000 mean, with data from NCEP Climate Prediction Center, CAMS-OPI.
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Oceanic Conditions

A small area of positive sea surface temperature (SST) anomalies was observed near the dateline in the equatorial Pacific. Otherwise, SSTs during July were near average across most equatorial regions. In the Atlantic, the relatively small areal extent and magnitude of the July SST anomalies were in stark contrast to the large positive SST anomalies observed in June. In the mid and high latitudes of the northern hemisphere, SST anomaly patterns were very similar to those observed in June.

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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