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IRI Climate Information Digest - September 1998

Issued 14 October 1998, Next Issue 13 November 
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percentile NOAA NCEP CAMS_OPI mean precipitation

Highlights Monsoon Rainfall Season

The 1998 summer monsoon was characterized by abundant rainfall in most areas over India.  In Bangladesh, tropical storm activity in combination with higher than normal sea levels produced severe flooding.  Abundant rainfall characterized the western African monsoon with drier than average conditions along the Gulf of Guinea.  The remnants of the 1997 - 1998 ENSO warm episode influenced the evolution of the North American Monsoon System but the season ended with near average with rains from the remains of tropical storm ISIS.

The ENSO cold episode La Niña

The La Niña episode continues to develop at about the predicted pace with most models calling for a peak early in 1999.  Relatively cold water is now in place from the East Pacific extending to the dateline.  However, relatively warm water, remnants of the El Niño warm episode, remain south of the equator in the east Pacific.

Rainfall - Southeastern Asia and eastern China

Myanmar through Vietnam and into eastern China experienced large rainfall deficits in July to September.  Dry condition extended eastward through the northern Philippines.  Dry conditions over Southeast Asia and the Philippines were somewhat alleviated by late season showers.  Heavy rains returned to Indonesia consistent with developing La Niña conditions.

September Atlantic TROPICAL STORM Activity

September saw eight named storms (Danielle, Earl, Frances, Georges, Hermine, Ivan, Jeanne and Karl) and for the first time this century, on September 24, four Atlantic hurricanes were active at the same time. Enhanced hurricane activity is consistent with developing La Niña conditions.  Tropical Storm Frances brought flooding rains to drought affected areas of Texas northward through Missouri. Hurricane Earl brought heavy rains to the dry southeastern United States. Hurricane George was a destructive influence from the Caribbean through the southeastern United States.

Global Temperatures

Averaged global temperatures remain at record high levels through September. Temperatures were notably above average levels over much of North America and Eurasia for the July through September period. The evolving La Niña is not expected to have a substantial effect on global temperatures until the end of the year.

Forecasts - for temperature and precipitation
Impacts - on fisheries, agriculture, and hazards.

Material for the IRI Climate Information Digest has been extracted from the IRI Climate Data Library - http://ingrid.ldeo.columbia.edu/, IRI Experimental Forecast Division - , the Climate Prediction Center, NCEP NOAA - http://www.cpc.ncep.noaa.gov, the Climate Diagnostic Center http://www.cdc.noaa.gov, and Pacific Marine Environmental Laboratories ERL/NOAA, http://www.pmel.noaa.gov . Additional information has been obtained from the Bureau of Meteorology, Australia, and INPE, Brazil.