Title: The South American Monsoon System: Recent Evolution and Current Status
1The South American Monsoon System Recent
Evolution and Current Status
Update prepared by Climate Prediction Center /
NCEP 14 December 2007
2Outline
- Recent Evolution and Current Conditions
- Summary
- Climatology
3Rainfall Patterns Last 90 Days
During the last 90 days rainfall has been below
normal over most of Brazil, with rainfall
deficits between 175-250 mm in portions of
central and southeastern Brazil. Deficits of up
to 100 mm are found in north-central Argentina.
Above-normal rainfall was observed over portions
of eastern Bolivia, Paraguay and southern Brazil.
4Rainfall Patterns Last 30 Days
During the last 30 days rainfall has been near
normal over most of Brazil, except for the
central and southeastern portions of the country.
Above-normal rainfall was observed over Paraguay
and eastern Bolivia, and below-normal over
Uruguay and the northern half of Argentina.
5Rainfall Patterns Last 7 Days
During the last 7 days rainfall has been slightly
above normal over northern Brazil, while
below-normal rainfall was observed over the
southern Amazon, central and southeastern Brazil,
and northern Argentina.
6Atmospheric Circulation Last 7 days
- During the last 7 days a strong 200-hPa
anticyclonic circulation was centered over
Brazil, just east of Bolivia. - Stronger-than-normal low-level northwesterly flow
extended from the western Amazon southeastward to
the coast of Southeast Brazil.
A
7Recent Evolution Rainfall
- The SAMS wet season was delayed in many areas.
- Since October, rainfall has increased over
western Brazil. - Rainfall deficits continue over the Brazilian
Plateau (BP), with deficits greater than 130 mm
during the last 3 months. - -
8Summary
- Rainfall has been slightly above normal in
western Brazil and much below normal in central
and southeastern Brazil during the last 90 days. - The rainy season was slow to start over central
and southeastern Brazil, where rainfall deficits
of 100-200 mm (locally up to 250 mm) have been
observed during the last 90 days. - During the last 7 days rainfall has been above
normal over the northern Amazon Basin and below
normal over southern Amazon, central and
southeastern Brazil.
9ClimatologyRainy Season Dates
ONSET
DEMISE
10Precipitation Climatology