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 6 May 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 (29 April-5 May 2013), above-average precipitation was observed over portions of Colombia, Venezuela, Guyana, Suriname, Paraguay, Uruguay, eastern Argentina and extreme southern Brazil. Below-average precipitation was observed over Peru, the western and central Amazon Basin, and the northern portions of southern Brazil. • • For 6 -12 May, above-average precipitation is predicted for most of Colombia, northern Peru and the western Amazon Basin. Belowaverage precipitation is predicted for most of Venezuela and Southeast Brazil. • For 13 -19 May, above-average precipitation is predicted for southern Colombia, northern Peru and portions of Paraguay, and below-average precipitation is predicted for Venezuela, Guyana, the central Amazon Basin, and central Chile.

Rainfall Total & Anomaly Patterns: Last 7 Days Total Anomaly During the last 7 days, above-average precipitation was observed over portions of Colombia, Venezuela, Guyana, Suriname, Paraguay, Uruguay, eastern Argentina and extreme southern Brazil. Below-average precipitation was observed over Peru, the western and central Amazon Basin, and the northern portions of southern Brazil.

Rainfall Totals & Anomaly Patterns: Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over southern Venezuela, Peru, portions of northern Northeast Brazil, southern Brazil and northern Argentina. Above-average precipitation was found over Paraguay, and portions of central and southeastern Brazil.

Recent Evolution: Rainfall Last 90 Days BP: Brazilian Plateau BP • 90 -day rainfall totals are near average over the Brazilian Plateau and the southern Amazon Basin. • 90 -day rainfall totals are slightly below average over southern Brazil, and much below average over Northeast Brazil (deficits more than 150 mm).

Tropical Pacific and Atlantic SST Anomalies SSTs are near average in most of the equatorial Pacific, and above average in the western and eastern equatorial Atlantic. (For more 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: not updated. • Lower panels: not updated. C A 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 : not updated. 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 6 May 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 6 May 2013– Days 8 -14 Total Note: Bias correction based on last 30 -day forecast error. Anomaly

NCEP/GFS MODEL FORECASTS • For Days 1 -7 (6 -12 May), above-average precipitation is predicted for most of Colombia, northern Peru and the western Amazon Basin. Below-average precipitation is predicted for most of Venezuela and Southeast Brazil. • For Days 8 -14 (13 -19 May), above-average precipitation is predicted for southern Colombia, northern Peru and portions of Paraguay, and below-average precipitation is predicted for Venezuela, Guyana, the central Amazon Basin, and central Chile.

Forecast Verification Forecast from 22 April 2013 Valid for 29 Apr-5 May 2013 Forecast from 29 April 2013 Valid for 29 Apr-5 May 2013 Observed 29 April-5 May 2013

Climatology Rainy Season Dates ONSET DEMISE

Precipitation Climatology

Precipitation Climatology Animation