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 29 December 2014 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 • Rainfall deficits continue over the core monsoon region of central Brazil and the southern Amazon Basin. • During the last 7 days (22 -28 December 2014), below-average precipitation was observed over the central and eastern Amazon Basin, portions of central and southeastern Brazil, southern Bolivia and northern Argentina. Above-average precipitation was observed over the northwestern Amazon Basin, and portions of southern Brazil and northeastern Argentina. • Forecasts are not available.

Rainfall Total & Anomaly Patterns: Last 7 Days Total Anomaly During the last 7 days, below-average precipitation was observed over the central and eastern Amazon Basin, portions of central and southeastern Brazil, southern Bolivia and northern Argentina. Above-average precipitation was observed over the northwestern Amazon Basin, and portions of southern Brazil and northeastern Argentina.

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, southern Venezuela, and portions of southeastern Brazil. Above-average precipitation was observed over southern Colombia, northern Peru, northeastern Argentina, Uruguay, and portions of southern Brazil.

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 (100 -250 mm). • 90 -day rainfall is below average (~60 mm) over southern Brazil.

Tropical Pacific and Atlantic SST Anomalies SSTs are above average in the equatorial Pacific and below average in the 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 C A • Upper panels: During the period of 20 -26 Dec. 2014, anomalous cyclonic flow (center indicated by red C) was located along the coast of Northeast Brazil and anomalous anitcyclonic flow (center indicated by red A) dominated the mid-latitudes over the South Atlantic Oceanl. • Lower panels: Anomalous rising motion occurred over Paraguay and southern Brazil, and anomalous sinking motion occurred over Northeast and portions of Southeast Brazil. • 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 20 -26 Dec. 2014, below-average temperatures occurred over central and southern Chile, Argentina, Uruguay, Paraguay and eastern Bolivia. 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 29 December 2014 – Days 1 -7 Total Anomaly Not Available Note: Bias correction based on last 30 -day forecast error.

NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 29 December 2014 – Days 8 -14 Total Anomaly Not Available Note: Bias correction based on last 30 -day forecast error.

NCEP/GFS MODEL FORECASTS • For Days 1 -7 (29 December 2014 -4 January 2015), forecasts are not available. • For Days 8 -14 (5 -11 January 2015), forecasts are not available.

Forecast Verification Forecast from 15 December 2014 Valid for 22 -28 Dec. 2014 Forecast from 22 December 2014 Valid for 22 -28 Dec. 2014 Observed 22 -28 Dec. 2014

Climatology Rainy Season Dates ONSET DEMISE

Precipitation Climatology

Precipitation Climatology Animation