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The South American Monsoon System: Recent Evolution and Current Status. Update prepared by Climate Prediction Center / NCEP 2 April 2012. For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons. Outline. Highlights
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The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 2 April 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, above-average rainfall was mainly observed over southern Colombia and northern Brazil. Below-average rainfall was found over most of Brazil (esp. its east), Suriname, central Peru, northern Bolivia, Uruguay, and northeastern Argentina. • For 2-8 April 2012, above-average rainfall is predicted north of 4S and over northeastern Argentina and southern Paraguay. Below-average rainfall is predicted for the region 4S-22S, especially central and eastern Brazil. • For 9-15 April 2012, above-average rainfall is predicted over northeastern South America. Below-average rainfall is predicted over much of South America, especially western Colombia, western Peru, eastern Brazil and northeastern Argentina.
Rainfall Total & Anomaly Patterns:Last 7 Days Total Anomaly During the last 7 days, above-average rainfall was mainly observed over southern Colombia and northern Brazil. Below-average rainfall was found over most of Brazil (esp. its east), Suriname, central Peru, northern Bolivia, Uruguay, and northeastern Argentina.
Rainfall Totals & Anomaly Patterns:Last 30 Days Total Anomaly During the last 30 days, above-average rainfall was mainly observed over southern Colombia, Ecuador, and northwestern Brazil. Below-average rainfall was seen over much of the other South American regions especially eastern and southern Brazil.
BP Recent Evolution: RainfallLast 90 Days BP: Brazilian Plateau • 90-day rainfall totals are below average over the southern Amazon basin. They are also clearly below average over the Brazilian Plateau, the core monsoon region. • 90-day totals are significantly below average in southern Brazil.
Tropical Pacific and Atlantic SST Anomalies Above-average SSTs are observed in the tropical eastern Pacific and below-average SSTs are present in the equatorial central Pacific and equatorial Atlantic Ocean. (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 24-30 March 2012, anomalous upper-tropospheric cyclonic circulation occurred over southern Brazil and northern Argentina. • Lower panels: Anomalous rising motion (negative omega) was mainly seen over northwestern South America, and anomalous sinking motion was observed over eastern Brazil, Argentina, Uruguay, and southern Brazil. 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 24-30 March 2012, temperatures were above average in eastern Brazil and below average in southern Brazil, Paraguay, Uruguay and northeastern Argentina. 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 2 April 2012 – Days 1-7 Total Anomaly Note: Bias correction based on last 30-day forecast error.
NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 2 April 2012 – Days 8-14 Total Anomaly Note: Bias correction based on last 30-day forecast error.
NCEP/GFS MODEL FORECASTS • For Days 1-7 (2-8 April 2012), above-average rainfall is predicted north of 4S and over northeastern Argentina and southern Paraguay. Below-average rainfall is predicted for the region 4S-22S, especially central and eastern Brazil. • For Days 8-14 (9-15 April 2012), above-average rainfall is predicted over northeastern South America. Below-average rainfall is predicted over much of South America, especially western Colombia, western Peru, eastern Brazil and northeastern Argentina.
Forecast Verification Forecast from 19 March 2012 Valid 26 Mar – 1 Apr 2012 Forecast from 26 Mar 2012 Valid 26 Mar – 1 Apr 2012 Observed 25-31 Mar 2012
ClimatologyRainy Season Dates ONSET DEMISE