The South American Monsoon System: Recent Evolution and Current Status

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The South American Monsoon System Recent
Evolution and Current Status
Update prepared by Climate Prediction Center /
NCEP 22 October 2007
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Outline

• Recent Evolution and Current Conditions
• Summary
• Climatology

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Recent Evolution Rainfall

• The SAMS wet season has been slow to start over
  Central Brazil.
• During the last 90 days rainfall deficits over
  the Brazilian Plateau (BP) are between 70 mm and
  80 mm.

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Recent Evolution Atmospheric Circulation OLR

• Drier than normal conditions (positive OLR
  anomalies) dominated most of tropical and
  subtropical South America during 18 September-7
  October (top two panels).
• During the last 10 days (bottom panel)
  precipitation has increased (negative OLR
  anomalies) over southern Brazil, Paraguay and
  Bolivia.
• This increase in precipitation has been
  associated with cold fronts that have advanced
  northeastward over the region of eastern
  Argentina, Uruguay and southern Brazil.

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Summary

• The rainy season has been slow to start over
  central and southeastern Brazil.
• Rainfall deficits of 70 to 80 mm have been
  observed near the Brazilian Plateau.
• Recently, rainfall has increased over southern
  Brazil, Paraguay and Bolivia, as cold fronts
  began to advance northward over these areas.

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ClimatologyRainy Season Dates
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Precipitation Climatology