The above figure shows September 1999 temperature
anomalies calculated from available in-situ stations using a 1880 -
1998 base period. Two persistent high pressure areas, one over
Europe and one over eastern Canada and the northeast U.S., resulted
in temperatures well above the long term mean in these areas. (See
the September
atmospheric circulation pattern for the Northern Hemisphere.)
Mean temperatures were more than 5 C above average in some
locations. Above average temperatures were also recorded in the Far
East, much of the southern half of South America, the Mediteranean
and western areas of the United States. The largest area of cooler
than average temperatures is shown throughout the central and
southeastern areas of the U.S. No other area of widespread below
average temperatures are shown in this figure; however, it is
possible that cooler than average temperatures were more extensive,
but not shown in this figure due to unreported data.
Temperature
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image
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Preliminary mean
monthly temperature anomalies (using a base period 1880-1998) for
September are shown in the figure to the left. September 1999 ocean
temperatures were much lower than the 1997 and 1998 values and were
the 3rd coolest this decade. However, land temperature anomalies
continued to be very warm. The average global land temperature was
0.65 C above the long term mean, the second warmest anomaly on
record. |
Precipitation
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image
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As shown on the
adjacent map, precipitation anomalies were highly variable in
September. Flooding rains fell in northern areas of India and
Bangladesh, while areas in the south and west were much drier than
average. Eastern areas of the U.S. received record rainfall in
September primarily due to hurricanes Dennis and Floyd. Areas to
the west continued to be much drier than the long term mean. (See
the U.S.
national page for a complete discussion.) |
Western Europe was wetter than average as a low pressure trough in
the eastern Atlantic brought abundant moisture to Iceland and
western areas of the European continent. An area of high pressure
limited precipitation throughout much of eastern Europe. Tropical
cyclones affected parts of Korea and southwestern Japan, producing
much above average rainfall in these areas. For additional details
on precipitation and temperatures in September 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
