Title: The South American Monsoon System: Recent Evolution and Current Status
1The South American Monsoon System Recent
Evolution and Current Status
Update prepared by Climate Prediction Center / NC
EP
12 April 2009
For more information, visit http//www.cpc.ncep.
noaa.gov/products/Global_Monsoons/American_Monsoon
s
2Outline
- Highlights
- Recent Evolution and Current Conditions
- NCEP/GFS Model Forecasts
- Climatology
3Highlights
- Rainfall deficits continue to be observed over
Paraguay, southern Brazil and northeastern
Argentina.
- The GFS predicts below normal rainfall to
continue over Paraguay, northeastern Argentina
and southern Brazil for the next two weeks.
4Rainfall Total Anomaly PatternsLast 30 Days
During the last 30 days (13 Mar 11 Apr 2009),
rainfall deficits were observed over portions of
the Amazon basin, central and Northeast Brazil,
Southern Brazil, Paraguay, Uruguay and
northern/northeastern Argentina. Above-normal
rainfall was observed over portions of the Amazon
basin, southeastern Brazil and most of Bolivia.
5Rainfall Total Anomaly PatternsLast 7 Days
During the last 7 days above-to-near-normal
rainfall occurred over most of Brazil, with the
exception of the northeastern Amazon basin and
southwestern/southern Brazil. Above-normal
rainfall was also observed over central/southern
Colombia, northern Peru and northern Bolivia.
Below-normal rainfall was observed over southern
Paraguay, northeastern Argentina and Uruguay.
6Recent Evolution Rainfall
- 90-day rainfall totals are near-normal over
Northeast Brazil, and below normal over the
Brazilian Planalto (BP) (deficits near 180 mm).
7Recent Evolution Rainfall
- During the last 90 days, rainfall has been below
normal over southern Brazil (deficits near 150
mm), and over southern Paraguay and northeastern
Argentina (deficits near 180 mm).
8Atmospheric Circulation Recent 7 days
- During 4-10 April 2009 an enhanced 200-hPa trough
was located over the western Atlantic Ocean,
accompanied by enhanced downward motion (positive
omega) and below-normal precipitation over
Paraguay, southern Brazil, northeastern Argentina
and Uruguay (west of the trough axis). - Upward motion (negative omega) and above-normal
rainfall was observed over central and
southeastern Brazil.
A
9925-hPa Temperature
Recent 90 Days
Recent 30 Days
Recent 7 Days
- During the last 7 days (4-10 Apr 2009)
above-normal temperatures were observed over
Paraguay, northeastern Argentina, Southern Brazil
(red oval) and along the coast of Northeast
Brazil.
10NCEP/GFS Model Forecasts Bias-Corrected
Precipitation
Forecasts from 12 April 2009 Week 1
Anomaly
Total
Note Bias correction based on last 30-day
forecast error.
11NCEP/GFS Model Forecasts Bias-Corrected
Precipitation
Forecasts from 12April 2009 Week 2
Anomaly
Total
Note Bias correction based on last 30-day
forecast error.
12NCEP/GFS MODEL FORECASTS
- For week 1 (12-18 Apr 2009), below-normal
rainfall is predicted for eastern Colombia and
Venezuela, central and southern Brazil, Paraguay,
northeastern Argentina and Uruguay. - For week 2 (19-25 Apr 2009), Above-normal
rainfall is predicted for Colombia, Ecuador,
northern Peru, and Brazil over an area between
3S-10S. Below-normal rainfall is predicted over
the northern Amazon basin, central/southeastern/so
uthern Brazil, Paraguay, Uruguay, northeastern
Argentina southern Peru and western Bolivia.
NOTE See forecast verification in the next slide.
13Forecast Verification
Observed 5-11 Apr 2009
Forecast from 5 April 2009 Valid 5-11 Apr 2009
Forecast from 29 Mar 2009 Valid 5-11 Apr 2009
14ClimatologyRainy Season Dates
ONSET
DEMISE
15Precipitation Climatology