Temperature
| As shown in the above
figure, global temperatures were much warmer than average in May.
Although temperatures remained below those measured near the end of
the 1997/1998 warm phase of El Nino, May 2000 land surface
temperatures once again approached record levels as the cold phase
of El Nino (La Nina)
weakened in the equatorial Pacific. Average land surface
temperatures were 0.67C above the 1880-1999 long-term mean, 0.30C
cooler than in 1998 while the average sea surface temperature was
0.26C above average, the eighth warmest May sea surface temperature
anomaly. The extremely warm land surface temperatures combined with
above average sea surface temperatures resulted in a land/sea
average anomaly of 0.38C above the long-term mean, 0.31C below the
1998 value, the third warmest May on record. |
| The adjacent plot
shows the spatial distribution of temperature anomalies throughout
the world based on a 1961-1990 base period. May temperatures were
much warmer than average throughout much of the Northern
Hemisphere, while cooler than average temperatures prevailed over
many land areas south of the equator. Strong positive anomalies
covered much of Western Europe, Siberia, China and the United
States with values in excess of 3C in many areas. |
larger image |
| The only widespread
areas of below normal temperatures in the Northern Hemisphere can
be found in the western half of Canada, Alaska, Central Russia and
India. Temperatures were more than 4C below normal in many areas
north of the Caspian sea as a low pressure trough persisted
throughout much of the month. In the Southern Hemisphere, two areas
of widespread below-normal temperatures are evident. Temperatures
were cooler than normal in all areas of Australia with the
exception of eastern coastal sections. Below normal temperatures
also covered much of the southern half of South America as storms
and continued cloudiness kept temperatures down throughout the
month. |
| Although the cold
phase of El Nino (La Nina) is beginning to
weaken, temperatures in the tropics (20N-20S) remained well
below average in May. The anomaly in this region was -0.36C, while
temperatures were above average elsewhere. An anomaly of +0.28C was
measured in the 20N-90N latitude band, while temperatures south of
20S were +0.08C above average. |
Precipitation
larger image |
As shown in the figure
to the left, May precipitation anomalies were highly variable. The
largest negative anomalies (indicating drier than normal
conditions) occurred in the Ryukyu Islands of Japan and Taiwan with
some areas more than 150mm (6 inches) below normal. Other notable
areas of below normal rainfall include the Southeastern United
States, much of Eastern Europe, Australia and Brazil. Notable areas
receiving much above-normal precipitation include much of
Argentina, Columbia, and Bangladesh. |
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
