The above figure shows October 1999 temperature
anomalies calculated from available in-situ stations using a
1961-1990 base period. Temperatures were above normal in many
regions of the world during October. A dominant ridge of high
pressure over central Russia produced temperatures that were more
than 4C above average throughout much of the West Siberian Plain.
(See the October
atmospheric circulation pattern for the Northern Hemisphere.)
Above average temperatures also stretched throughout Europe and the
Mediteranean, where temperatures were more than 2 C above average
in most areas. Much of India, China and southeast Asia recorded
temperatures that were slightly above the long term mean. Western
areas of the United States also experienced above average
temperatures as an area of high pressure persisted throughout the
month. A persistent low pressure trough over eastern Canada
produced temperatures 1 to 2 C below average in northeastern
sections of the United States and southeastern areas of Canada.
Temperatures were also cooler than average throughout much of
Alaska and parts of the Yukon and Inuvik regions of western
Canada.
Temperature
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image
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Preliminary mean
monthly temperature anomalies (using a base period 1880-1998) for
October are shown in the figure to the left. Both land and ocean
temperatures were above their respective long term means but below
the record values recorded during the 1997/1998 El Nino episode.
Ocean temperature anomalies were 0.26 C above average, but they
were 0.29 C below the record value recorded in 1997. Land
temperatures continued to be historically warm in October as the
global temperature averaged 0.67 C above the long term mean. |
Precipitation
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As shown on the
adjacent map of precipitation anomalies calculated from reporting
in-situ stations (1961-1990 base period), several regions of the
world received much above average precipitation in October. Wetter
than average conditions persisted across much of Spain for the
third month in a row. October precipitation was as much as 100 mm
above average in some areas. October was also another wetter than
average month in the Sahel region of Africa as precipitation was
more than 25 mm above average across a large part of the
region. |
| Devastating flooding
occurred in India as two strong typhoons brought torrential rains
to eastern sections of the country. (Anomalies are not shown due to
an absence of reporting stations in this region of the country.)
Precipitation was also much above average in northern sections of
South America. Stations in Venezuela averaged 79 mm above the
1961-1990 normal. However, southeast coastal areas of South America
were extremely dry in October. Drier than average conditions were
also experienced across much of North America as a ridge of high
pressure was a dominate feature over central sections of the
continent for much of the month. (See the U.S. national
page for a complete discussion.) Drier than average conditions
prevailed across the Mediteranean, parts of Northern Europe, the
West Siberian Plain, and parts of Southeast Asia. For additional
details on precipitation and temperatures in October see the
Global
Regional page . |
References:
Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global
Historical Climatology Network Database. Bull. Amer. Meteorol.
Soc., 78, 2837-2849.
NOAA's National Centers for Environmental Information
