The South American Monsoon System Recent Evolution and

The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 30 May 2016 For more information, visit: http: //www. cpc. ncep. noaa. gov/products/Global_Monsoons/American_Monsoons

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

Highlights • Long-term rainfall deficits continue over the Amazon Basin and central Brazil. The rainy season has ended over central Brazil. • During the last 7 days (23 -29 May 2016), below-average precipitation was observed over southern Venezuela, northern Brazil, southern Brazil and southern Chile. Above-average precipitation was observed over portions of Colombia, extreme northern Peru, central Paraguay and southwest Brazil. • For 30 May-5 June 2016, below-average precipitation is predicted portions of northern South America, extreme southern Brazil, Uruguay, northeastern Argentina and southern Chile. Above-average precipitation is predicted for Ecuador and Brazil, between 20 S and 25 S. • Note: This is the last SAMS update for the 2015 -2016 wet season. A summary of the season will be available on 6 June.

Rainfall Total & Anomaly Patterns: Last 7 Days Total Anomaly During the last 7 days, below-average precipitation was observed over southern Venezuela, northern Brazil, southern Brazil and southern Chile. Above-average precipitation was observed over portions of Colombia, extreme northern Peru, central Paraguay and southwest Brazil.

Rainfall Totals & Anomaly Patterns: Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over most of the Amazon Basin, northeastern Argentina, Uruguay, southern Brazil, and southern Chile. Above-average precipitation was observed over portions of Paraguay, Ecuador, central Colombia, and central Venezuela.

Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau BP • 90 -day rainfall deficits are present over the southern Amazon Basin (>250 mm) and the Brazilian Plateau (~120 mm). • 90 -day rainfall is near average over southern Brazil.

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

Atmospheric Circulation Recent 7 days C • Upper panels: During the period of 22 -28 May 2016, anomalous cyclonic flow (center noted by red C) was observed over subtropical South America. • Lower panels: Anomalous rising motion was observed over central Chile, western Argentina, and Paraguay. Anomalous sinking motion was observed over northern Northeast Brazil, extreme southern Brazil, Uruguay, eastern Argentina and southern Chile. • Rising motion (negative omega, yellow/red shading), usually associated with wetter- thannormal conditions. • Sinking motion (positive omega, blue shading), usually associated with drier-than-normal conditions.

925 -h. Pa Wind &Temperature Recent 30 Days Recent 7 Days During the 7 -day period 22 -28 May 2016, below-average temperatures were observed over southern Brazil, eastern Bolivia, Paraguay, Uruguay and Argentina. 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 -h. Pa are usually similar to surface observations. Note: Areas with surface pressure below 925 -h. Pa are masked out.

NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 30 May 2016 – Days 1 -7 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 30 May 2016 – Days 8 -14 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS MODEL FORECASTS • For Days 1 -7 (30 May-5 June 2016), below-average precipitation is predicted portions of northern South America, extreme southern Brazil, Uruguay, northeastern Argentina and southern Chile. Above-average precipitation is predicted for Ecuador and Brazil, between 20 S and 25 S. • For Days 8 -14 (6 -12 June 2016), below-average precipitation is predicted for most of the Amazon Basin, extreme southern Brazil, Uruguay, northeastern Argentina and southern Chile. Above-average precipitation is predicted for portions of southeastern Brazil.

Forecast Verification Forecast from 16 May 2016 Valid for 23 -29 May 2016 Forecast from 23 May 2016 Valid for 23 -29 May 2016 Observed 23 -29 May 2016

Climatology Rainy Season Dates ONSET DEMISE

Precipitation Climatology

Precipitation Climatology Animation