Climate Assessment for 1999

Abstract The global climate during 1999 was impacted by Pacific cold episode (La Nina) conditions throughout theyear, which resulted in regional precipitation and atmospheric circulation patterns across the Pacific Ocean and theAmericas that are generally consistent with those observed during past cold episodes. The primary La Ninaᵣelatedprecipitation anomalies included 1) increased rainfall across Indonesia, and a nearly complete disappearance of rainfall acrossthe east-central and eastern equatorial Pacific; 2) above-normal rains across northwestern and northern Australia; 3) increased monsoon rains across the Sahel region of western Africa; 4) above-average rains over southeastern Africa, 5) above-average rains over the Caribbean Sea and portions of Central America, and 6) below-average rains in southeastern South America. The La Nina also contributed to persistent cyclonic circulation anomalies in the subtropics of bothhemispheres, which flanked the area of suppressed convective activity over the easte. . .