IRI Climate Information Digest - November 1999
Issued 6 December 1999
Temperature in Percentiles (1961-1990 Base
Climatological Background In November, the transition
from the Northern Hemisphere warm to cold season and the Southern Hemisphere
cold to warm season is complete. In the Northern Hemisphere, mid-latitude
storms begin to acquire wintertime strength and produce accumulating snowfall,
while nearer the equator the monsoonal precipitation systems continue to
weaken. In the Southern Hemisphere, the monsoonal systems in
subtropical Africa, Indonesia, and South America are gaining strength,
while the mid-latitude storms have greatly weakened.
Tropics: November marked a strengthening of La Niña
(below average sea surface temperatures (SSTs) in the equatorial
Pacific) as the magnitude of below average SSTs intensified to the east
of the dateline. Elsewhere in the tropics SSTs remained above average
in the western Pacific, Indian and Atlantic basins.
Extratropics: Above average SSTs persisted in a broad band
extending from Japan to the west-central North Pacific. Warmer than
average SSTs strengthened to the west of Australia and to the east of southern
South America during the month.
Europe and Asia: After a warm start November brought a dramatic
shift to below average temperatures in Europe and western Russia.
In contrast, temperatures were well above average in China, Manchuria,
North America: Temperatures were significantly above average
across most of the US and central Canada while below average conditions
continued across Alaska.
Australia: In a reversal from October conditions, temperatures
were below average across most of the continent.
South America: Cooler than average conditions prevailed from
northern Argentina northward into western Paraguay and Bolivia while northeastern
coastal regions recorded temperatures much warmer than average.
Africa: Temperatures were above average across much of northern
Africa from the Sahel eastward to Ethiopia. Southern Africa also
saw a warm November as temperatures were well above average from the Cape
of Good Hope northward into Zambia.
Forecasts - Seasonal Temperature and Precipitation
Southeast Asia: Above average rainfall was observed across
southern China, Vietnam and Cambodia primarily due to very heavy rains
which occurred during the first part of November.
North America: Precipitation was well below average
across much of the central US northward into south-central Canada.
Australia: Rainfall was well above average from north-central
Queensland into northeastern regions of the Northern Territory. A
noticeable lack of precipitation was reported along southeast coastal sections
of New South Wales.
South America: Below average precipitation was observed in
Uruguay and Paraguay as well as extreme southern Brazil and northeast Argentina.
Opposite conditions were observed across north-central Argentina where
precipitation was well above average for the month.
Africa: Heavy rainfall was observed in a band extending from
the Congo basin southeastward to coastal Mozambique.
Impacts - On Fisheries, Agriculture, Health and Hazards.