The South American Monsoon System: Recent Evolution and Current Status

1. The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 11 February 2019 For more information, visit: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. Highlights • Long-term rainfall deficits are present over the Amazon Basin and the Brazilian Plateau, as well as the extreme southern Brazil. • During the last 7 days, below-average precipitation was observed over much of west-central and southern Brazil, northern Argentina, Uruguay, Paraguay and Bolivia. Above-average precipitation was observed over portions of northwestern and eastern Brazil, northern Peru and eastern Ecuador. • For Days 1-7 (11 – 17 Feb 2019), below-average precipitation is predicted for much of northern and central Brazil, Uruguay, central Argentina, southern Peru and northern Ecuador. Above-average precipitation is predicted for southern Brazil, southern Paraguay, southern Bolivia and southern Ecuador.

4. Rainfall Total & Anomaly Patterns:Last 7 Days Total Anomaly During the last 7 days, below-average precipitation was observed over much of west-central and southern Brazil, northern Argentina, Uruguay, Paraguay and Bolivia. Above-average precipitation was observed over portions of northwestern and eastern Brazil, northern Peru and eastern Ecuador.

5. Rainfall Totals & Anomaly Patterns:Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over much of Brazil, eastern Bolivia, Paraguay, central Argentina and southern Chile. Above-average precipitation was observed over portions of northern Brazil, Uruguay, northern Argentina, western Bolivia and northern Peru.

6. BP Recent Evolution: RainfallLast 90 Days BP: Brazilian Plateau • 90-day rainfall deficits are present over the Amazon Basin (> 100 mm), the Brazilian Plateau (> 250 mm) and the extreme southern Brazil.

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

8. Atmospheric Circulation Recent 7 days • Upper panels: During the period of 03-09 Feb 2019, anomalous anticyclonic flow (center noted by red A) was observed over northern Argentina. • Lower panels: Anomalous sinking motion was observed over much of western Brazil and central Argentina. Anomalous rising motion was observed elsewhere. A • 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.

9. 925-hPa Wind &Temperature Recent 30 Days Recent 7 Days During the 7-day period 03-09 Feb 2019, above-average temperature was seen over eastern Brazil. 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.

10. NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 11 February 2019–Days 1-7 Total Anomaly Note: Bias correction based on last 30-day forecast error.

11. NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 11 February 2019– Days 8-14 Total Anomaly Note: Bias correction based on last 30-day forecast error.

12. NCEP/GFS MODEL FORECASTS • For Days 1-7 (11 – 17 Feb 2019), below-average precipitation is predicted for much of northern and central Brazil, Uruguay, central Argentina, southern Peru and northern Ecuador. Above-average precipitation is predicted for southern Brazil, southern Paraguay, southern Bolivia and southern Ecuador. • For Days 8-14 (18 -24 Feb 2019), below-average precipitation is predicted over much of northwestern and southern Brazil, Uruguay, northern Argentina, Paraguay, northern Bolivia, eastern Peru and northern Ecuador. Above-average precipitation is predicted for portions of central Brazil, southern Chile, northeastern Argentina and southern Ecuador.

13. ClimatologyRainy Season Dates ONSET DEMISE

14. Precipitation Climatology

15. Precipitation Climatology Animation