IRI Climate Digest
May Global Climate Summary
Climatological Background In May, the sun
is well into its march north of the equator (the maximum northward location
will be achieved in June at 23.6 degrees north). Surface heating of the
continents are setting the stage for summer monsoonal systems or northern
hemisphere warm season rains. The lack of direct solar heating in the southern
hemisphere creates a north-south temperature difference which strengthens
mid-latitude storm tracks and the approach of winter.
Monthly Mean Temperature (1961-1990), data from the Climate Research
Unit, University of East Anglia
|Monthly Mean Precipitation (1961-1990), with data from
the Climate Research Unit, University of East Anglia
Temperatures Over Land
Europe: Above-average temperatures were observed
across much of west-central sections for the fourth consecutive month.
Asia: Temperatures continued above average in a broad
west-east band extending from Iran in the west to coastal China in the
east as well as in north-central sections of the Former Soviet Union.
In contrast, temperatures were as much as 4 C below average across much
of south-central Russia. Temperatures were near to slightly below average
across India and most of southeast Asia.
Africa: With the exception of southern Africa - southward
of Botswana and Zimbabwe - which had near-average conditions, most of the
remainder of the continent experienced above average temperatures.
Australia: Eastern Queensland and New South Wales experienced
near-average conditions for the month but temperatures were well below
average elsewhere. In fact, (maximum) temperatures for the month
were the lowest recorded for Australia as a whole.
South America: Uneventful as far as temperatures were
concerned, near average conditions prevailed across most of the continent.
North and Central America: Most of the south-central United
States and north-central Mexico observed above average temperatures.
Temperatures averaged 1 to 2C below average across the Canadian Prairies
as well as north-central Alaska. Conditions were close to average
|Temperature Difference from the 1961-1990 mean, with
data from NCEP Climate Prediction Center, CAMS.
Africa: Below-average rainfall persisted over much of
eastern Africa from southern Ethiopia southward into Kenya, southern Somalia
and much of Tanzania. Above average precipitation was observed in
western Zaire and northwest Angola as well as portions of eastern South
Africa and Zimbabwe. The rainy season began
in western Africa with above average rainfall across western
Ghana, southern Mali and Burkina Faso and unusually dry conditions farther
east from Nigeria into northern Cameroon.
Australia: Exceptionally dry conditions were observed
in southern portions of Western Australia. Although the spatial coverage of
the real-time observations below
are limited, analysis by the Australian Bureau of Meteorology indicates unusually heavy rains
fell in south-central Queensland southward through New South Wales to Tasmania.
Heavy rains also occurred in northern sections of the Northern Territory.
Philippines / Indonesia: Above average rainfall
was observed throughout the region with localized very heavy rains in Timor
and New Guinea.
Southeast Asia: Precipitation was above average from Bangladesh
southeastward through Burma and Thailand and into Cambodia.
China: Below average rainfall was observed across
the North China Plain. Locally heavy rains in west central sections
resulted in above average rainfall for the month.
South America: Uruguay and eastern Argentina saw
above average rainfall during May. Above average precipitation was
also observed in Ecuador, Colombia and along the northern border of Brazil
and neighboring areas. Below average rainfall occurred over south-central
Brazil. Extremely dry conditions were seen in the area around Sao
Paulo with the start of the dry season there just beginning.
Middle East: Rainfall continued to be below average across much
of the Middle East eastward to Afghanistan and Pakistan.
Central and North America: Heavy
rainfall was observed across southern Mexico southward into Guatemala.
Below average rainfall continued
in the southeastern US and along the Gulf coast. Heavy rains
in the midwestern US brought some temporary relief to drought conditions
there while the northeast also had above average rainfall.
Europe: Northern and western Europe had above average
precipitation for the month while unusually dry weather was observed across
eastern and southern Europe from southern Poland southward to the Mediterranean
|Precipitation Difference from 1961-1990 mean, with
data from NCEP Climate Prediction Center, CAMS-OPI.
Tropics: Weak La Niña (colder than average)
conditions continue in the central equatorial Pacific. The large positive
anomalies of last month in
the eastern equatorial Pacific have weakened. Neither oceanic
observations nor model predictions suggest a transition towards warmer than
average contions (El Niño) in the coming months.
Extratropics: The most notable feature of the extratropical
oceans continues to be the large positive anomalies in the Northern
Hemisphere mid-latitudes (e.g., +4 C off the northern coast of Japan).
Monthly Sea Surface Temperature Difference from the 1950-1979 mean,
with data from the Environmental Modeling Center, NCEP/NOAA.