1. The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 1 October 2012 For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons

2. Outline Highlights Recent Evolution and Current Conditions NCEP/GFS Model Forecasts Climatology

3. During the last 7 days, below-average precipitation was observed over most regions north of the Equator, and over southern Brazil, Uruguay and northeastern Argentina. Above-average rainfall was found over northern Peru and northern Bolivia. During 1-7 Oct 2012, above-average precipitation is predicted for Bolivia, Paraguay, extreme southern Brazil, Uruguay and northeastern Argentina. Below-average precipitation is predicted for central and southeastern Brazil and most of northern South America. During 8-14 Oct 2012, above-average precipitation is predicted for northwest South America, Bolivia, Paraguay, and southern Brazil. Below-average precipitation is predicted for central Brazil and Uruguay. Highlights

4. Rainfall Total & Anomaly Patterns: Last 7 Days During the last 7 days, below-average precipitation was observed over most regions north of the Equator, and over southern Brazil, Uruguay and northeastern Argentina. Above-average rainfall was found over northern Peru and northern Bolivia. TotalAnomaly

5. Rainfall Totals & Anomaly Patterns: Last 30 Days During the last 30 days, below-average precipitation was observed over most regions north of 28S. Above-average precipitation was found over portions of eastern Argentina and extreme southern Brazil. TotalAnomaly

6. BP Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau 90-day rainfall totals are clearly below average over the southern Amazon basin, Brazilian Plateau, and southern Brazil.

7. Tropical Pacific and Atlantic SST Anomalies A weekly PowerPoint summarizing the ENSO Cycle: Recent Evolution, Current Status and Predictions is available at: http://www.cpc.noaa.gov/products/precip/CWlink/MJO/enso.shtml Above-average SSTs are observed in much of the equatorial Pacific Ocean. (For more details concerning El Niño – La Niña, go to the link below.)

8. Atmospheric Circulation Recent 7 days Upper panels: During the period of 22-28 September 2012, anomalous upper-tropospheric cyclonic circulation (center indicated by red C) was observed over southern Brazil and northeastern Argentina. Lower panels: Anomalous sinking motion (positive omega) was observed over southern Brazil, Uruguay and northeastern Argentina to the south of the cyclonic circulation center, consistent with the drier- than-average conditions over this region (see slide 4). Rising motion (negative omega, yellow/red shading), usually associated with wetter- than- normal conditions. Sinking motion (positive omega, blue shading), usually associated with drier-than-normal conditions. A C

9. 925-hPa Wind &Temperature Recent 30 DaysRecent 7 Days Low-level (~600 m) wind and temperature anomalies based on the NCEP Climate Data Assimilation Systems (CDAS) analysis. The patterns of anomalous temperature and wind at 925-hPa are usually similar to surface observations. Note: Areas with surface pressure below 925-hPa are masked out. During the 7-day period of 22-28 September 2012, temperatures were below average over western and southern Brazil, Paraguay, Uruguay and eastern Argentina.

10. NCEP/GFS Model Forecasts Bias-Corrected Precipitation Total Forecasts from 1 Oct. 2012 – Days 1-7 Anomaly Note: Note: Bias correction based on last 30-day forecast error.

11. NCEP/GFS Model Forecasts Bias-Corrected Precipitation Total Forecasts from 1 Oct. 2012 – Days 8-14 Anomaly Note: Note: Bias correction based on last 30-day forecast error.

12. For Days 1-7 (1-7 Oct 2012), above-average precipitation is predicted for Bolivia, Paraguay, extreme southern Brazil, Uruguay and northeastern Argentina. Below-average precipitation is predicted for central and southeastern Brazil and most of northern South America. For Days 8-14 (8-14 Oct 2012), above-average precipitation is predicted for northwest South America, Bolivia, Paraguay, and southern Brazil. Below-average precipitation is predicted for central Brazil and Uruguay. NCEP/GFS MODEL FORECASTS

13. Climatology Rainy Season Dates ONSETDEMISE

14. Precipitation Climatology

15. Precipitation Climatology Animation