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The South American Monsoon System: Recent Evolution and Current Status. Update prepared by Climate Prediction Center / NCEP 28 April 2014. 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 28 April 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 • Large rainfall deficits persist over the SAMS core region (Brazilian Plateau). • During the last 7 days (21-27 April 2014), below-average precipitation was observed over coastal areas of northeastern South America, southern Brazil, Uruguay and eastern Argentina, and above-average precipitation was observed over northern Paraguay, eastern Bolivia and portions of the western Amazon Basin. • For 28 April-4 May 2014, below-average precipitation is predicted for the southern Amazon Basin and southeastern Brazil, and above-average precipitation is southern Chile, Paraguay, extreme northeastern Argentina and portions of southern Brazil.
Rainfall Total & Anomaly Patterns:Last 7 Days Total Anomaly During the last 7 days, below-average precipitation was observed over coastal areas of northeastern South America, southern Brazil, Uruguay and eastern Argentina, and above-average precipitation was observed over northern Paraguay, eastern Bolivia and portions of the western Amazon Basin.
Rainfall Totals & Anomaly Patterns:Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over the eastern and southern Amazon Basin, Venezuela, western Colombia and Ecuador. Above-average precipitation was observed over southern Paraguay and most of Argentina.
BP Recent Evolution: RainfallLast 90 Days BP: Brazilian Plateau • 90-day rainfall deficits (100-300 mm) continue over the Brazilian Plateau and the southern Amazon Basin. • 90-day rainfall totals are near average over southern Brazil.
Tropical Pacific and Atlantic SST Anomalies SSTs are above average in most of the equatorial Pacific. SSTs are near average in most of the equatorial Atlantic. (For 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 19-25 April 2014, anomalous cyclonic circulation was observed over the western Atlantic near 35S (red C). • Lower panels: Areas of anomalous rising motion were found over Bolivia, northern Paraguay and southern Brazil, while anomalous sinking motion, a proxy for suppressed precipitation, was observed over Chile, most of Argentina, and Uruguay. 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 19-25 April 2014, below-average temperatures were observed over eastern Argentina, Uruguay, and southern Brazil. 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-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 28 Apr 2014– Days 1-7 Total Anomaly Note: Bias correction based on last 30-day forecast error.
NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 28 Apr 2014– Days 8-14 Total Anomaly Note: Bias correction based on last 30-day forecast error.
NCEP/GFS MODEL FORECASTS • For Days 1-7 (28 Apr-4 May 2014), below-average precipitation is predicted for the southern Amazon Basin and southeastern Brazil, and above-average precipitation is southern Chile, Paraguay, extreme northeastern Argentina and portions of southern Brazil. • For Days 8-14 (5-11 May 2014), below-average precipitation is predicted for the southern Amazon Basin and southeastern Brazil, and above-average precipitation northern Northeast Brazil, southern Paraguay, and eastern Argentina.
Forecast Verification Forecast from 14 Apr 2014 Valid for 21-27 Apr 2014 Forecast from 21 Apr 2014 Valid for 21-27 Apr 2014 Observed 21-27 Apr 2014
ClimatologyRainy Season Dates ONSET DEMISE