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 28 October 2013 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 • During the last 7 days (21 -27 October 2013), below-average precipitation was observed over northwestern Brazil, southeastern Brazil, and portions of Venezuela and Colombia. Above-average precipitation was observed over southern Brazil and Uruguay. • For 28 October-3 November, below-average precipitation is predicted for portions of southeastern Brazil and the western Amazon Basin. Above-average precipitation is predicted for portions of Venezuela, Colombia, Bolivia, southwestern Brazil, Paraguay, Uruguay and eastern Argentina.

Rainfall Total & Anomaly Patterns: Last 7 Days Total Anomaly During the last 7 days, below-average precipitation was observed over northwestern Brazil, southeastern Brazil, and portions of Venezuela and Colombia. Above-average precipitation was observed over southern Brazil and Uruguay.

Rainfall Totals & Anomaly Patterns: Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over northwestern Brazil, southern Paraguay, northeastern Argentina, and southern Chile. Above-average precipitation was found over northern Paraguay and in spotty locations elsewhere in South America.

Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau BP • 90 -day rainfall totals are below average over the southern Amazon Basin, and the Brazilian Plateau. • Rainfall is near average over southern Brazil.

Tropical Pacific and Atlantic SST Anomalies SSTs are near average in most of the equatorial Pacific and equatorial 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 • Upper panels: During the period of 19 -25 October 2013, anomalously strong westerlies extended from northern Chile east-southeastward to Uruguay and eastern Argentina. • Lower panels: Anomalous rising motion was found over northern Argentina and Paraguay. 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 19 -25 October 2013, above-average temperatures were observed over portions of southern and southeastern 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 28 Oct 2013– Days 1 -7 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 28 Oct 2013– Days 8 -14 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS MODEL FORECASTS • For Days 1 -7 (28 Oct-3 Nov), below-average precipitation is predicted for portions of southeastern Brazil and the western Amazon Basin. Above-average precipitation is predicted for portions of Venezuela, Colombia, Bolivia, southwestern Brazil, Paraguay, Uruguay and eastern Argentina. • For Days 8 -14 (4 -10 Nov), above-average precipitation is predicted for southern Venezuela, eastern Colombia, and central and southeastern Brazil. Below-average precipitation is predicted for the extreme western Amazon Basin and portions of southern Brazil.

Forecast Verification Forecast from 14 Oct 2013 Valid for 21 -27 Oct 2013 Forecast from 21 Oct 2013 Valid for 21 -27 Oct 2013 Observed 21 -27 Oct 2013

Climatology Rainy Season Dates ONSET DEMISE

Precipitation Climatology

Precipitation Climatology Animation