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The South American Monsoon System: Recent Evolution and Current Status. Update prepared by Climate Prediction Center / NCEP 29 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 29 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 precipitation was observed over portions of Colombia, northern Peru, Paraguay, and southern Brazil. Below-average rainfall occurred over northern and extreme southern Brazil, Uruguay, and northeastern Argentina. • For 29 Apr – 5 May 2012, above-average precipitation is predicted for north of the equator, northern Peru, and portions of northwestern Brazil. Below-average precipitation is predicted for most of northern, western and extreme southern Brazil, southern Peru, Bolivia, Paraguay, and northeastern Argentina. • For 6-12 May 2012, above-average precipitation is predicted for northwestern South America (including northern Peru and portions of northwestern Brazil) and portions of northeastern Argentina. Below-average precipitation is predicted 0-20S and southern Brazil.
Rainfall Total & Anomaly Patterns:Last 7 Days Total Anomaly During the last 7 days, above-average precipitation was observed over portions of Colombia, northern Peru, Paraguay, and southern Brazil. Below-average rainfall occurred over northern and extreme southern Brazil, Uruguay, and northeastern Argentina.
Rainfall Totals & Anomaly Patterns:Last 30 Days Total Anomaly During the last 30 days, above-average rainfall was observed over Colombia, Ecuador, northern Peru, portions of northwestern Brazil, and Paraguay. Below-average rainfall occurred over most of the remainder of South America especially Brazil.
BP Recent Evolution: RainfallLast 90 Days BP: Brazilian Plateau • 90-day rainfall totals are clearly below average over the southern Amazon basin, the Brazilian Plateau (core monsoon region), and 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-western Pacific and the 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 20-26 April 2012, an anomalous upper-tropospheric anticyclonic circulation (red A) was located over southern Brazil. • Lower panels: Anomalous rising motion (negative omega) occurred over northwestern and western South America and southern Brazil. Anomalous sinking motion was observed over eastern Brazil and eastern and southern Argentina. A 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 20-26 April 2012, temperatures were above average over central-southern Brazil (10S-25S) and below average over eastern 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 29 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 29 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 (29 Apr – 5 May 2012), above-average precipitation is predicted for north of the equator, northern Peru, and portions of northwestern Brazil. Below-average precipitation is predicted for most of northern, western and extreme southern Brazil, southern Peru, Bolivia, Paraguay, and northeastern Argentina. • For Days 8-14 (6-12 May 2012), above-average precipitation is predicted for northwestern South America (including northern Peru and portions of northwestern Brazil) and portions of northeastern Argentina. Below-average precipitation is predicted 0-20S and southern Brazil.
Forecast Verification Forecast from 16 April 2012 Valid 22-28 Apr 2012 Forecast from 22 Apr 2012 Valid 22-28 Apr 2012 Observed 22-28 Apr 2012 Not available
ClimatologyRainy Season Dates ONSET DEMISE