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This report provides highlights, recent evolution, and current conditions of the South American Monsoon System. It includes rainfall patterns, temperature and wind anomalies, and bias-corrected precipitation forecasts.
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The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 4 September 2012 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, below-average precipitation was observed to the north of the equator and over western and southern Brazil. • During the last 30 days, below-average precipitation was observed over most regions to the north of 30S. Above-average precipitation was found over eastern Argentina and central Colombia.
Rainfall Total & Anomaly Patterns:Last 7 Days Total Anomaly During the last 7 days, below-average precipitation was observed to the north of the equator and over western and southern Brazil.
Rainfall Totals & Anomaly Patterns:Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over most regions to the north of 30S. Above-average precipitation was found over eastern Argentina and central Colombia.
BP Recent Evolution: RainfallLast 90 Days BP: Brazilian Plateau • 90-day rainfall totals are below average over the southern Amazon basin and the Brazilian Plateau.
Tropical Pacific and Atlantic SST Anomalies Above-average SSTs are observed in much of the equatorial Pacific Ocean especially the central Pacific. (For more details concerning El Niño – La Niña, go to the link below.) A weekly PowerPoint 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 27 August – 2 September 2012, in the upper troposphere, a weak anomalous cyclonic pattern (red C) was observed over Brazil. • Lower panels: Anomalous sinking motion (positive omega) was observed over most of the South America. C 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-hPa Wind &Temperature Recent 30 Days Recent 7 Days • During the 7-day period of 27 August – 2 September 2012, temperatures were above average over central-northern Brazil and below average over southeastern Bolivia. 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-hPa are usually similar to surface observations. Note: Areas with surface pressure below 925-hPa are masked out.
NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 4 September 2012 – Days 1-7 Total Anomaly Unavailable Note: Bias correction based on last 30-day forecast error.
NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 4 September 2012 – Days 8-14 Total Anomaly Unavailable Note: Bias correction based on last 30-day forecast error.
ClimatologyRainy Season Dates ONSET DEMISE
