434  
FXSA20 KWBC 101906  
PMDSA  
 
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
306 PM EDT MON MAR 10 2025  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/DATA/NCCF/COM/GFS/PROD/  
 
SOUTH AMERICA FORECAST BULLETIN 10 MAR 2025 AT 1900 UTC:  
 
FROM TODAY UNTIL EARLY THURSDAY ACROSS THE SOUTH AMERICAN  
CONTINENT, THE MOST SIGNIFICANT RAINFALL COVERAGE AND THUNDERSTORM  
POTENTIAL IS EXPECTED TO BE ACROSS THE NORTHERN HALF, MAINLY NORTH  
OF ARGENTINA. THERE ARE SEVERAL REASONS WHY THAT WILL HAPPEN,  
THOUGH FOR THE MOST PART, THE AVAILABLE MOISTURE WILL BE NEAR TO  
ABOVE NORMAL OVER MOST OF NORTHERN SOUTH AMERICA. THAT SAID,  
EASTERN BRASIL WILL HAVE BELOW NORMAL MOISTURE FOR THE NEXT FEW  
DAYS. THE SOUTHERN HALF OF THE CONTINENT WILL HAVE BELOW NORMAL  
MOISTURE FOR THE MOST PART, EXCEPT FOR A NARROW AREA ACROSS  
CENTRAL ARGENTINA ON TUESDAY INTO WEDNESDAY, THEN DEEP MOISTURE  
WILL MOVE INTO AUSTRAL CHILE AND ARGENTINA LATE WEDNESDAY INTO  
THURSDAY. MOST OF THE AREAS WITH RAINFALL CAN BE EXPECTED IN AREAS  
WITH HIGHER THAN NORMAL MOISTURE, WHILE LITTLE TO NO RAINFALL IS  
FORECAST FOR PORTIONS OF EASTERN BRASIL.  
 
OVER THE 3-DAY PERIOD FROM TODAY INTO THURSDAY MORNING, THE  
NORTHWESTERN QUADRANT OF SOUTH AMERICA IS FORECAST TOTAL RAINFALL  
THAT MAY EXCEED 75MM ACROSS ISOLATED AREAS. THAT SAID, ALTHOUGH  
MOST AREAS WILL OBSERVE DAILY MAX TOTALS NEAR 15-35MM, PORTIONS OF  
NORTH CENTRAL TO NORTHWESTERN BRASIL MAY OBSERVE MAX RAINFALL  
TODAY AND TUESDAY REACHING 50MM. CENTRAL PERU, EAST OF THE  
MOUNTAIN RANGE IS FORECAST UP TO 50MM TODAY, WITH LOWER AMOUNTS OF  
RAIN EVERY OTHER DAY. AS FAR AS BOLIVIA INTO NORTHWESTERN  
PARAGUAY, WEDNESDAY LOOKS TO BE THE DAY WITH MOST RAINFALL, WITH A  
DAILY MAX FORECAST OF 25-50MM. NORTHERN ARGENTINA INTO URUGUAY  
WILL OBSERVE A GENERALLY DRY DAY FOR THE REST OF TODAY, BUT A COLD  
FRONT WILL MOVE NORTH AND BECOME STATIONARY OVER THE REGION BY  
TUESDAY NIGHT. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP  
ALONG THE FRONTAL BOUNDARY, MAINLY AFFECTING NORTHERN ARGENTINA ON  
TUESDAY AFTERNOON AND EVENING, THEN URUGUAY AND EXTREME SOUTHEAST  
BRASIL HAVING AN ENHANCED CHANCE OF SHOWERS AND THUNDERSTORMS ON  
WEDNESDAY.  
 
IN THE UPPER LEVELS, THERE IS A TROUGH WITH AXIS JUST EAST OF  
SOUTHERN SOUTH AMERICA, ITS BASE BEING OVER CENTRAL ARGENTINA.  
THERE WILL BE AN UPPER JET OVER SOUTHERN SOUTH AMERICA THROUGH  
WEDNESDAY MORNING AS AN UPPER RIDGE SLOWLY MOVES IN, THEN ANOTHER  
UPPER TROUGH MOVES INTO AUSTRAL SOUTH AMERICA ON WEDNESDAY NIGHT.  
THAT SAID, AN UPPER TROUGH WITH BASE OVER NORTHERN ARGENTINA AND  
URUGUAY WILL PERSIST THROUGH THURSDAY MORNING. FURTHER NORTH,  
THERE WILL BE A PERSISTENT AND BROAD HIGH PRESSURE OVER BRASIL.  
 
IN THE MID LEVELS, THE OVERALL PATTERNS ARE FORECAST TO BE SIMILAR  
TO THE UPPER LEVELS, MEANING THAT THE TROUGHS AND RIDGES, AS WELL  
AS THE HIGH PRESSURE OVER NORTHERN SOUTH AMERICA ARE FAIRLY  
VERTICALLY STACKED. THIS PATTERN WILL ALSO PROVIDE A MID-LEVEL JET  
IN THE SOUTHERN PERIPHERY OF THE HIGH PRESSURE, WHICH WILL PROVIDE  
VENTILATION ALONG A LOW-LEVEL TROUGH, ENHANCING SHOWER AND  
THUNDERSTORM POTENTIAL FROM SOUTHERN BOLIVIA THROUGH PARAGUAY AND  
INTO SOUTHEAST BRASIL, MAINLY ON WEDNESDAY INTO EARLY THURSDAY.  
THE MID-LEVEL TROUGH WILL ALSO BE A CONTRIBUTOR TO THE ENHANCED  
SHOWER AND THUNDERSTORM POTENTIAL OVER NORTHERN ARGENTINA INTO  
URUGUAY AND EXTREME SOUTHEAST BRASIL, ALONG THE STATIONARY FRONT  
EXPECTED ON TUESDAY AND WEDNESDAY.  
 
ALAMO...(WPC)  
 
 
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