1. The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 21 November 2011 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 rainfall was observed over much of Brazil, southeastern Bolivia, Guyana, Suriname, and French Guiana. Above-average rainfall was observed over northwestern South America, southern Brazil (20ºS-25ºS), central Paraguay, and portions of northern Argentina. For 21-27 November, above-average rainfall is predicted for southern Peru, western Bolivia, and eastern Brazil. Below-average rainfall is predicted over northern Peru, western and extreme southern Brazil, Uruguay, and northeastern Argentina. For 28 November – 4 December, above-average rainfall is predicted for northern and northeastern South America including Colombia, Venezuela, Guyana, and northeastern Brazil. Below-average rainfall is predicted mainly over western Brazil and central Peru. Highlights

4. Rainfall Total & Anomaly Patterns: Last 7 Days During the last 7 days, below-average rainfall was observed over much of Brazil, southeastern Bolivia, Guyana, Suriname, and French Guiana. Above-average rainfall was observed over northwestern South America, southern Brazil (20ºS-25ºS), central Paraguay, and portions of northern Argentina. TotalAnomaly

5. Rainfall Totals & Anomaly Patterns: Last 30 Days During the last 30 days, below-average rainfall was mainly observed to the west of 60ºW (except for portions of Colombia and northern Peru) and south of 15ºS (except for Paraguay). Above-average rainfall was found over central and eastern Brazil and Guyana. 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. Below-average rainfall has been observed over the Brazilian Plateau as well. 90-day totals are also below average in southern Brazil.

7. Tropical Pacific and Atlantic SST Anomalies Below-average SSTs are present in the tropical Pacific Ocean, and above-average SSTs are found in most of the tropical Atlantic. (For more details concerning El Niño – La Niña go to the link below.) 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

8. Atmospheric Circulation Recent 7 days 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. Upper panels: During 12-18 November 2011, a weak anomalous upper tropospheric anti-cyclonic circulation (A) was located over northwestern South America. Lower panels: Anomalous rising motion (negative omega) was found over northwestern South America, southern Brazil, and Argentina, and anomalous sinking motion was observed over northeastern Brazil and northwestern Argentina. A

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 12-18 November 2011, below-average temperatures were observed over southern Brazil and Paraguay, and above-average temperatures were found over southeastern Argentina.

10. NCEP/GFS Model Forecasts Bias-Corrected Precipitation Total Forecasts from 21 Nov 2011 – 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 21 Nov 2011– Days 8-14 Anomaly Note: Note: Bias correction based on last 30-day forecast error.

12. For Days 1-7 (21-27 November), above-average rainfall is predicted for southern Peru, western Bolivia, and eastern Brazil. Below- average rainfall is predicted over northern Peru, western and extreme southern Brazil, Uruguay, and northeastern Argentina. For Days 8-14 (28 November – 4 December), above-average rainfall is predicted for northern and northeastern South America including Colombia, Venezuela, Guyana, and northeastern Brazil. Below- average rainfall is predicted mainly over western Brazil and central Peru. NCEP/GFS MODEL FORECASTS

13. Forecast Verification Forecast from 7 Nov 2011 Valid 14-20 Nov 2011 Forecast from 14 Nov 2011 Valid 14-20 Nov 2011 Observed 14-20 Nov 2011

14. Climatology Rainy Season Dates ONSETDEMISE

15. Precipitation Climatology

16. Precipitation Climatology Animation