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 03 October 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 are present over Brazilian Plateau and southern Brazil. • During the last 7 days (26 Sept. – 02 Oct. 2016), below-average precipitation was observed over Venezuela, much of the western and southern Brazil. Above-average precipitation was observed over portions of Colombia, northern Peru, southern Amazon Basin and much of central Brazil. • For 03 - 09 October 2016, below-average precipitation is predicted over portions of northern South America and southern Brazil. Above-average precipitation is predicted over much of central South America and central Argentina.

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

Rainfall Totals & Anomaly Patterns: Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over much of the northern South America, western and southern Brazil, central Argentina and southern Chile. Above-average precipitation was observed over southern Amazon Basin, northern Peru, eastern Ecuador and central Colombia.

Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau BP • 90 -day rainfall deficits are present over the Brazilian Plateau (~40 mm) and southern Brazil (~100 mm).

Tropical Pacific and Atlantic SST Anomalies SSTs are below average cross central and east-central 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 A • Upper panels: During the period of 25 Sept. – 01 Oct. 2016, anomalous anticyclonic flow (center noted by red A) was observed over northern Chile, with slightly weaker-than-average westerlies over subtropical South America. • Lower panels: Anomalous sinking motion was observed over much of western and southern Brazil, northern Argentina and northern 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 25 Sept. – 01 Oct. 2016, slightly above-average temperatures were observed over much of 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 -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 03 Oct 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 03 Oct 2016 – Days 8 -14 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS MODEL FORECASTS • For Days 1 -7 (03 - 09 October 2016), below-average precipitation is predicted over portions of northern South America and southern Brazil. Above-average precipitation is predicted over much of central South America and central Argentina. • For Days 8 -14 (10 October– 16 October 2016), below-average precipitation is predicted for southern Venezuela, northern and central Brazil. Aboveaverage precipitation is predicted over central Colombia and much of Peru.

Forecast Verification Forecast from 19 Sept 2016 Valid for 26 Sept-02 Oct 2016 Forecast from 26 Sept 2016 Valid for 26 Sept-02 Oct 2016 Observed 26 Sept-02 Oct 2016

Climatology Rainy Season Dates ONSET DEMISE

Precipitation Climatology

Precipitation Climatology Animation