1. The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 23 March 2015 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. Large long-term (90-day) rainfall deficits continue over central and southeastern Brazil. During the last 7 days (16-22 March 2015), below-average precipitation was observed over eastern Bolivia, Paraguay, eastern Argentina, Uruguay and southern Brazil. Above-average precipitation was observed over Colombia, and portions of the western Amazon Basin and central Brazil. For 23-29 March 2015, above-average precipitation is predicted for portions of the northern and western Amazon Basin. Below-average precipitation is indicated for southern Bolivia, most of central Brazil, eastern Argentina, Uruguay and southern Brazil. Highlights

4. Rainfall Total & Anomaly Patterns: Last 7 Days During the last 7 days, below-average precipitation was observed over eastern Bolivia, Paraguay, eastern Argentina, Uruguay and southern Brazil. Above-average precipitation was observed over Colombia, and portions of the western Amazon Basin and central Brazil. TotalAnomaly

5. Rainfall Totals & Anomaly Patterns: Last 30 Days During the last 30 days, below-average precipitation was observed over portions of the eastern and southern Amazon Basin, Bolivia, Uruguay, and portions of southern and southeastern Brazil. Above- average precipitation was observed over Suriname, Guiana, southern Colombia and portions of the western Amazon Basin. TotalAnomaly

6. BP Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau 90-day rainfall deficits are present over the southern Amazon Basin (>300 mm) and the Brazilian Plateau (~300 mm). 90-day rainfall is slightly below average over 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 SSTs are above average in the central equatorial Pacific and near average in the eastern equatorial Pacific. SSTs are near average in the equatorial Atlantic. (For details concerning El Niño – La Niña, go to the link below.)

8. Atmospheric Circulation Recent 7 days Upper panels: During the period of 15-21 Mar. 2015, anomalous cyclonic flow (center indicated by red C) was located over central Brazil and anomalous anticyclonic circulation (center indicated by red A) was located over central Chile. Lower panels: Anomalous rising motion occurred over the Amazon Basin and central Brazil. Anomalous sinking motion occurred over Paraguay, central Argentina and Uruguay. 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. C A

9. 925-hPa Wind &Temperature Recent 30 DaysRecent 7 Days Low-level (~600 m above sea level) 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 15-21 Mar. 2015, above-average temperatures were observed over central Chile, eastern Argentina, Paraguay and Uruguay.

10. NCEP/GFS Model Forecasts Bias-Corrected Precipitation Total Forecasts from 23 March 2015 – Days 1-7 Anomaly Note: Bias correction based on last 30-day forecast error.

11. NCEP/GFS Model Forecasts Bias-Corrected Precipitation Total Forecasts from 23 March 2015 – Days 8-14 Anomaly Note: Bias correction based on last 30-day forecast error.

12. For Days 1-7 (23-29 March 2015), above-average precipitation is predicted for portions of the northern and western Amazon Basin. Below-average precipitation is indicated for southern Bolivia, most of central Brazil, eastern Argentina, Uruguay and southern Brazil. For Days 8-14 (30 March -5 April 2015), near-average precipitation is predicted for most of central Brazil. Below-average precipitation is predicted for portions of western Brazil, Bolivia, northeastern Argentina, Uruguay and southern Brazil. NCEP/GFS MODEL FORECASTS

13. Forecast Verification Forecast from 9 March 2015 Valid for 16-22 Mar 2015 Forecast from 16 March 2015 Valid for 16-22 Mar. 2015 Observed 16-22 Mar. 2015

14. Climatology Rainy Season Dates ONSETDEMISE

15. Precipitation Climatology

16. Precipitation Climatology Animation