The South American Monsoon System Recent Evolution and

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The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate

The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 24 January 2011 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 •

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

Highlights • During the last 7 days, below-average rainfall was observed over Suriname, French

Highlights • During the last 7 days, below-average rainfall was observed over Suriname, French Guiana, part of northern Peru, portions of southeastern and far western Brazil, and central Argentina. Above-average rainfall was observed over portions of northern and southwestern Brazil and eastern Bolivia. • The GFS predicts above-average rainfall over far northeastern and far southern Brazil and northern Argentina, and belowaverage rainfall over central-southeastern Brazil, Bolivia, and northern South America for the week of 24 -30 January. It also predicts above-average rainfall over portions of central and southern Brazil, Paraguay, and northern Argentina, and belowaverage rainfall over eastern and far western Brazil and northern South America for the week after that.

Rainfall Total & Anomaly Patterns: Last 7 Days Total Anomaly During the last 7

Rainfall Total & Anomaly Patterns: Last 7 Days Total Anomaly During the last 7 days, below-average rainfall was observed over Suriname, French Guiana, part of northern Peru, portions of southeastern and far western Brazil, and central Argentina. Above-average rainfall was observed over portions of northern and southwestern Brazil and eastern Bolivia.

Rainfall Totals & Anomaly Patterns: Last 30 Days Total Anomaly During the last 30

Rainfall Totals & Anomaly Patterns: Last 30 Days Total Anomaly During the last 30 days, below-average rainfall was observed over northern Peru, western Brazil, Bolivia, and northern Argentina. Above-average rainfall was observed over portions of central and southeastern Brazil, and parts of Colombia and northern Brazil.

Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau BP • 90 -day rainfall

Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau BP • 90 -day rainfall totals remain below average over the southern Amazon Basin. Also, slightly-above-average rainfall has been observed over the core monsoon region due to the January rainfall (BP). • 90 -day totals are near average in southern Brazil, where rainfall during December eliminated previous deficits.

Tropical Pacific and Atlantic SST Anomalies During the last week, equatorial SSTs were between

Tropical Pacific and Atlantic SST Anomalies During the last week, equatorial SSTs were between 0. 5° - 2. 0°C below average over most of the central and eastern Pacific Ocean. SSTs were 0. 5°-1. 0°C above average in the equatorial Atlantic. A La-Nina event is in progress in the tropical Pacific (for more details 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 • During 15 -21 Jan 2011, anomalous cyclonic circulation

Atmospheric Circulation Recent 7 days • During 15 -21 Jan 2011, anomalous cyclonic circulation (red C) was observed over eastern Brazil. C • Anomalous sinking motion (positive omega) and drier-than-average conditions (see slide 4, right panel) were observed over eastern Brazil. Rising motion (negative omega) and aboveaverage rainfall were observed over large portions of western and southern Brazil. 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.

925 -h. Pa Wind &Temperature Recent 30 Days Recent 7 Days • During the

925 -h. Pa Wind &Temperature Recent 30 Days Recent 7 Days • During the 7 -day period (15 -21 Jan 2011) near-average temperatures were observed over most of South America. Low-level (~600 m) 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 24 January 2011 – Days 1 -7

NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 24 January 2011 – Days 1 -7 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 24 January 2011– Days 8 -14 Total

NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 24 January 2011– Days 8 -14 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS MODEL FORECASTS • For Days 1 -7 (24 -30 Jan), above-average rainfall is

NCEP/GFS MODEL FORECASTS • For Days 1 -7 (24 -30 Jan), above-average rainfall is predicted over northern Northeast and extreme southern Brazil and northern Argentina, and below-average rainfall is predicted over central and southeastern Brazil, Bolivia, and northern South America. • For Days 8 -14 (31 Jan – 6 Feb), above-average rainfall is predicted over portions of central and southeastern Brazil, Paraguay, and northern Argentina, and below-average rainfall is predicted over eastern and far western Brazil and northern South America. NOTE: See forecast verification in the next slide.

Forecast Verification Forecast from 10 Jan 2011 Valid 17 -23 Jan 2011 Forecast from

Forecast Verification Forecast from 10 Jan 2011 Valid 17 -23 Jan 2011 Forecast from 17 Jan 2011 Valid 17 -23 Jan 2011 Observed 17 -23 Jan 2011

Climatology Rainy Season Dates ONSET DEMISE

Climatology Rainy Season Dates ONSET DEMISE

Precipitation Climatology

Precipitation Climatology

Precipitation Climatology Animation

Precipitation Climatology Animation