IRI Climate Information Digest - August 1999
Issued 13 September 1999
The equatorial Pacific saw a resurgence
of La Niña during August as below-average sea surface temperatures
(SSTs) strengthened to the east of the dateline. Weak above-average
SSTs persisted in the western tropical Pacific. Elsewhere, warmer than
average conditions eased in the Gulf of Guinea, the North Atlantic and
the Indian Ocean while below average SSTs slackened in the eastern North
Pacific. A healthy west African monsoon produced widespread
rains throughout the Sahel while the Asian monsoon circulation weakened
in intensity. Dry conditions persisted in portions of the North China
Plain and the North American monsoon became irregular during the month.
Lower temperatures and increased rainfall eased the heat wave/drought conditions
over much of the eastern US. And although slow to develop, the tropical
cyclone season in the North Atlantic became well established during August
with the naming of four systems and three hurricanes which is close
to average for the region and the month.
NOAA NCEP Sea Surface Temperature Anomaly
La Niña conditions
were evident in rainfall patterns in the tropical Pacific with reduced
precipitation over central and eastern sections and enhanced rainfall over
the southern Philippines and nearby islands. Tropical storms brought
heavy rainfall to the Korean peninsula but did little to alleviate drought
in the North China Plain. Heavy rains associated with the west African
Monsoon were observed in the Sahel while precipitation was noticeably absent
along coastal sections near the Gulf of Guinea. The Indian
monsoon circulation weakened in August with precipitation over the subcontinent
below-average and noticeable rainfall deficits in northwestern India
into Pakistan. Much of the eastern US received beneficial rains to
ease drought conditions while dry conditions developed over the southern
states. Dry conditions also prevailed over central South America.
temperatures were observed throughout southern Europe, the Middle East
and southwest Asia. In the eastern US cooler conditions developed
while cool conditions persisted along the west coast. Above-average
temperatures were observed in the southern US and northern Mexico while
cooler than average conditions prevailed in central South America from
Bolivia into Paraguay and western Brazil.
Forecasts - Seasonal Temperature and Precipitation
Impacts - On Health, Agriculture, Hazards, Water Resources and Fisheries.