IRI Climate Information Digest - March 1999
Issued 14 April 1999, Next
Issue 14 May 1999
NOAA CPC temperature percentile |
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NOAA CPC precipitation percentile |
Highlights The La Niña (cold episode) continues
to evolve as expected. Colder than average water continues to characterize
the equatorial Pacific. A patch of warmer water in the eastern Pacific
that briefly caused some concern along the west coast of South America
during February had all but disappeared by the end of March. The
magnitude of the La Niña has been slowly decreasing but the equatorial
sea surface temperatures remain 1 to 2 degrees Celsius below average from
160 East through approximately 150 West longitude. Numerical computer models
and statistical forecast tools are in general agreement for the continued
slow demise of this La Niña over the next four to five months.
Precipitation Patterns Rainfall in the tropical Pacific continues
to be strongly influenced by the current La Niña. Typical of the
La Niña phenomena, there is a sharp dividing line between the areas
of heavier than average rainfall in the far west Pacific and the areas
of drier conditions further to the east. During January to March this dividing
line was near 140 E longitude, with satellite estimates showing most of
the area from Papua New Guinea eastward to be dry and much of Indonesia
to be wet. Much of the southern tier of the United states and Northern
Mexico were also dry, a typical La Niña pattern. Not typical
of La Niña was the above average rainfall along most of the South
America's West Coast and also in northern Argentina. Dry conditions in
eastern Brazil were likely associated with Atlantic sea surface temperatures.
In eastern Africa wetter than average rainfall was observed from Ethiopia
southward through Tanzania, also not a typical La Niña pattern.
Temperature Above average temperatures characterized most of
the land areas of the world for the January through March period 1999.
Virtually all of Africa experienced above average temperatures.
Small pockets of below average temperatures included far eastern Siberia
through Alaska, central Brazil and the coastal sections of north Western
Australia.
Forecasts - Seasonal Temperature and Precipitation
Impacts - On Fisheries, Agriculture, Health and Hazards.
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