Global Analysis - October 1999
Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective September 2012, the GHCN-M version 3.2.0 dataset of monthly mean temperature replaced the GHCN-M version 3.1.0 monthly mean temperature dataset. Beginning with the August 2012 Global monthly State of the Climate Report, released on September 17, 2012, GHCN-M version 3.2.0 is used for NCDC climate monitoring activities, including calculation of global land surface temperature anomalies and trends. For more information about this newest version, please see the GHCN-M version 3.2.0 Technical Report.
*The GHCN-M version 3.1.0 Technical Report was revised on September 5, 2012 to accurately reflect the changes incorporated in that version. Previously that report incorrectly included discussion of changes to the Pairwise Homogeneity Algorithm (PHA). Changes to the PHA are included in version 3.2.0 and described in the version 3.2.0 Technical Report. Please see the Frequently Asked Questions to learn more about this update.
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.
|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.|
larger image 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 .
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