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This update provides information on the recent evolution and current conditions of the South American Monsoon System, including rainfall patterns, long-term deficits, and forecast predictions.
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The South American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 06 May 2019 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 • Long-term rainfall deficits are present over the western Brazilian Plateau. • During the last 7 days, below-average precipitation was observed over portions of northern and the extreme southern Brazil, northern Uruguay, as well as much of Colombia and Venezuela. Above-average precipitation was observed over portions of central and southern Brazil, Paraguay and southern Chile. • For Days 1-7 (06 - 12 May 2019), below-average precipitation is predicted over much of northern Brazil, northern Peru and southern Chile. Above-average precipitation is predicted for the extreme southern Brazil and Paraguay, as well as portions of central Bolivia, central Colombia and southern Venezuela.
Rainfall Total & Anomaly Patterns:Last 7 Days Total Anomaly During the last 7 days, below-average precipitation was observed over portions of northern and the extreme southern Brazil, northern Uruguay, as well as much of Colombia and Venezuela. Above-average precipitation was observed over portions of central and southern Brazil, Paraguay and southern Chile.
Rainfall Totals & Anomaly Patterns:Last 30 Days Total Anomaly During the last 30 days, below-average precipitation was observed over much of northern South America as well as Uruguay, southeastern Argentina and southern Chile. Above-average precipitation was observed over portions of central and southern Brazil, northern Argentina, Paraguay, northern Peru and central Colombia.
BP Recent Evolution: RainfallLast 90 Days BP: Brazilian Plateau • 90-day rainfall deficits are present over the Amazon Basin (~ 50 mm), the western Brazilian Plateau (~ 200 mm).
Tropical Pacific and Atlantic SST Anomalies SSTs are above-average across much of the tropical Pacific. (For details concerning El Niño – La Niña, go to the link below.) A weekly PowerPoint summarizing the ENSO Cycle: Recent Evolution, Current Status and Predictionsis available at: http://www.cpc.noaa.gov/products/precip/CWlink/MJO/enso.shtml
Atmospheric Circulation Recent 7 days • Upper panels: During the period of 28 Apr – 04 May 2019, weak anomalous anticyclonic flow (center noted by red A) was observed over southeastern Brazil. • Lower panels: Anomalous sinking motion was observed over northern and central Brazil and southeastern Argentina, and anomalous rising motion was observed elsewhere. 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 28 Apr - 04 May 2019, above-average temperature was seen over much of Brazil and central Argentina. 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 06 May 2019–Days 1-7 Total Anomaly Note: Bias correction based on last 30-day forecast error.
NCEP/GFS Model Forecasts Bias-Corrected Precipitation Forecasts from 06 May 2019– Days 8-14 Total Anomaly Note: Bias correction based on last 30-day forecast error.
NCEP/GFS MODEL FORECASTS • For Days 1-7 (06 - 12 May 2019), below-average precipitation is predicted over much of northern Brazil, northern Peru and southern Chile. Above-average precipitation is predicted for the extreme southern Brazil and Paraguay, as well as portions of central Bolivia, central Colombia and southern Venezuela. • For Days 8-14 (13 – 19 May 2019), below-average precipitation is predicted over portions of northern Brazil, Uruguay, southern Chile, Peru and Venezuela. Above-average precipitation is predicted for much of northern Peru, Ecuador and southern Colombia.
ClimatologyRainy Season Dates ONSET DEMISE