IRI Climate Information Digest - July 1998

Issued 13 August 1998, Next Issue 14 September

Highlights - LA NINA conditions grew in the Central Equatorial Pacific as the area of colder than average sea surface temperatures continued to expand. By month's end an area of water 1°C to 2°C colder than average water stretched from 120°W to the dateline. The recent El NINO episode has been reluctant to leave the west coast of South America but a slow decline continued. Even though sea surface temperatures remained 1° to 2°C warmer than average along the coast of Ecuador and Peru, the characteristic LA NINA pattern of colder than average waters further to the west emerged as the dominant climate feature during July.

1979-1998 July Percentiles CAMS_OPI mean prcp

Global Monsoon Rainfall Despite some local and regional scale variability the overall progress of the summer monsoon rainy seasons has been near-average to good over India as well as in Western Africa. The North American Monsoon System got off to a slow start but was well underway by mid-July. The figure on the right presents rainfall in the lowest (highest) 10th and 20th (80th and 90th) percentiles for the month of July. [Data source Climate Prediction Center/NOAA].

Mid-Latitude Precipitation Summary - July was characterized by a number of extreme precipitation events in the Eastern Hemisphere most notably in Japan, Korea and into Central China. Western and Central Australia and the North Island of New Zealand also experienced well above their July average rainfall. Many locations in these regions experienced flooding in conjunction with record heavy rainfall. Meanwhile many locations in the Western Hemisphere (Central Chile through Northern Argentina, Uruguay and Southern Brazil; Northern Mexico through the Southern United States) experienced dry to drought or near drought conditions.

Record high July temperatures - Global mean temperatures reached record high levels during July. Positive temperature departures characterized most of the Northern Hemisphere land areas.

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, the IRI Experimental Forecast Division, the NOAA NCEP Climate Prediction Center, the Climate Diagnostic Center, and the NOAA ERL Pacific Marine Environmental Laboratories. Additional information has been obtained from the Bureau of Meteorology, Australia, and INPE, Brazil.