# Presentation: 164071

## The South American Monsoon System: Recent Evolution and Current Status

**Update prepared by**
**Climate Prediction Center / NCEP**
**8 February 2009**

**For more information, visit:****  **_[http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons](http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons)_

## Outline

** ****Highlights**
** ****Recent Evolution and Current Conditions**
** ****NCEP/GFS Model Forecasts**
** ****Climatology**

## Highlights

** ****Beneficial rains also occurred over portions of Northeast Brazil.**
** ****The GFS predicts above-normal rainfall over Southeast Brazil during week 1, and below-normal rainfall over the northern half of Argentina during both week 1 and week 2. **

**Highlights**

## Rainfall Total & Anomaly Patterns:Last 90 Days

**Rainfall Total & Anomaly Patterns:****Last 90 Days**

**During the period 10 November 2008 – 7 February 2009 rainfall was below normal over most of the monsoon core region. **

## Rainfall Anomaly Patterns:

**Last 30 Days**

**Last 7 Days**

**Rainfall deficits during the last 30 days persist over the southern Amazon basin and portions of central Brazil and the northern half of Argentina. Much above normal rainfall was observed over the northwestern Amazon basin. During the last 7 days below-normal rainfall occurred over portions of the southern Amazon, central, southeastern and southern Brazil, while above normal rainfall was observed over the northwestern Amazon basin, Northeast Brazil and portions of northeastern Argentina.**

## Recent Evolution: Rainfall

** ****90-day rainfall totals are below normal in the central Amazon (deficits near 150 mm) and over portions of the Brazilian Planalto (BP) (deficits near 100 mm).**

## Recent Evolution: Rainfall

** ****During the last 90 days, rainfall totals have been below normal in southern Brazil (deficits near 150 mm)  and in northeastern Argentina and southern Paraguay (deficits near 150 mm).**
** ****The rainfall during the last 7 days has helped to reduce the 90-day rainfall deficits over northeastern Argentina and southern Paraguay.**

## Atmospheric Circulation Recent 7 days

**Atmospheric Circulation ****Recent 7 days**

**Anomalous rising motion (negative omega) and above-normal rainfall (see slide 5) were observed over portions of northeastern Brazil, associated with trough along the coast (dashed red line in upper-left hand panel). Enhanced rising motion and above normal rainfall were also observed over southern Paraguay, northeastern Argentina and portions of southern Brazil. **

**A**

**C**

## 925-hPa Temperature 

**During the 7 days 31 January-6 February 2008 slightly above-normal temperatures were observed over central and southwestern Brazil, Paraguay and northern Argentina associated with anomalous northerly winds over those areas.**

**Recent 90 Days**

**Recent 30 Days**

**Recent 7 Days**

## NCEP/GFS Model Forecasts  Bias-Corrected Precipitation

**Total**

**Forecasts from 8 February 2009 – ****Week 1**

**Anomaly**

_**Note:**_** Bias correction based on last 30-day forecast error. **

## NCEP/GFS Model Forecasts  Bias-Corrected Precipitation

**Total**

**Forecasts from 8 February 2009 – ****Week 2**

**Anomaly**

_**Note:**_** Bias correction based on last 30-day forecast error. **

## For week 1 (8-14 Feb 2009), above-normal rainfall is predicted for southeastern and southern Northeast Brazil, while below-normal rainfall is predicted for the central and eastern Amazon basin, southern Brazil, and northern Argentina.
For week 2 (15-21 Feb 2009) near-normal rainfall is predicted over most of Brazil, and below-normal rainfall is predicted for the northern half of Argentina.

**For week 2 (15-21 Feb 2009) near-normal rainfall is predicted over most of Brazil, and below-normal rainfall is predicted for the northern half of Argentina.**

**NCEP/GFS MODEL FORECASTS**

_**NOTE**_**:**** See forecast verification in the next slide.**

## Forecast Verification

**Forecast from  1 Feb 2009 **
**Valid 1-7 Feb 2009**

**Observed**
**1-7 Feb 2009**

**Forecast from  23 Jan 2009 **
**Valid 30 Jan – 5 Feb 2009**

_**NOTE**_**:**** There is a slight difference in dates between the week 2 forecast and observations.**

## ClimatologyRainy Season Dates

**ONSET**

**DEMISE**

## Precipitation Climatology