# Presentation: 175951

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

**Update prepared by**
**Climate Prediction Center / NCEP**
**9 January 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 for southern Brazil, Paraguay and northern Argentina are predicted by the GFS during 9-15 January 2009 . **

**Highlights**

## Rainfall Total & Anomaly Patterns:1 July 2008 to Present

**During the period 1 July 2008 – 8 January 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 in an area from about 10-40S and 65-50W (red oval). Much above normal rainfall was observed over coastal southeastern Brazil. During the last 7 days above-normal rainfall occurred over Southeast Brazil and below-normal rainfall was observed over Bolivia and portions of western and central Brazil.**

## Recent Evolution: Rainfall

** ****90-day rainfall totals are below normal in the central Amazon with deficits near 150 mm**
** ****Near normal rainfall has been observed over the Brazilian Planalto (BP) since 1 December 2008.**

## Recent Evolution: Rainfall

** ****90-day rainfall totals are below normal in southwestern Brazil (deficits near 130 mm) **
** ****90-day rainfall totals are also below normal over eastern Argentina and Uruguay (deficits near 170 mm).**

## Atmospheric Circulation Recent 7 days

**During 1-7 January, an anomalously strong 200-hPa trough was located near the coast of Southern Brazil, and an anomalously strong ridge was centered over the northeast Brazil coast. This pattern was associated with anomalously strong northwest 200-hPa flow, upward motion (negative omega), and above-normal rainfall (see slide 5) over coastal Southeast Brazil.**

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## 925-hPa Temperature 

**During the last 7 days (1-7 January 2008), below-normal temperatures and anomalously strong southeast flow were observed over eastern Bolivia, Paraguay and southern Brazil. These features are consistent with a quasi-stationary front (enhanced South Atlantic Convergence Zone) near the coast of Southeast Brazil.**

**Recent 90 Days**

**Recent 30 Days**

**Recent 7 Days**

## NCEP/GFS Model Forecasts  Bias-Corrected Precipitation

**Total**

**Forecasts from 9 January 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 January 2009 – ****Week 2**

**Anomaly**

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

## For week 1 (9-15 Jan 2009), below-normal rainfall is predicted for the eastern Amazon basin, central and Southeast Brazil, most of Bolivia and eastern Argentina, while above-normal rainfall is predicted for Peru, the northwestern Amazon basin and southern Brazil.
For week 2 (15-21 Jan 2009) below-normal rainfall is predicted over portions of central eastern Brazil, and above-normal rainfall is predicted for the western Amazon basin and southeastern Brazil.

**For week 2 (15-21 Jan 2009) below-normal rainfall is predicted over portions of central eastern Brazil, and above-normal rainfall is predicted for the western Amazon basin and southeastern Brazil.**

**NCEP/GFS MODEL FORECASTS**

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

## Forecast Verification

**Forecast from  2 Jan 2009 **
**Valid 2-8 Jan 2009**

**Observed**
**2-8 Jan 2009**

## ClimatologyRainy Season Dates

**ONSET**

**DEMISE**

## Precipitation Climatology