554  
FXSA20 KWBC 111917  
PMDSA  
 
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
317 PM EDT TUE MAR 11 2025  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/DATA/NCCF/COM/GFS/PROD/  
 
SOUTH AMERICA FORECAST BULLETIN 11 MAR 2025 AT 1915 UTC:  
 
ACROSS THE SOUTH AMERICAN CONTINENT THE GENERAL RAINFALL PATTERN  
OVER THE NEXT 3 DAYS WILL HAVE SIGNIFICANT RAINFALL COVERAGE NORTH  
OF LATITUDE 15S. HOWEVER, TODAY AND WEDNESDAY, THE COMBINATION OF  
A FEW FACTORS WILL CAUSE SHOWERS AND THUNDERSTORMS ACROSS  
PORTIONS OF NORTHERN ARGENTINA INTO SOUTHERN BOLIVIA TODAY AND  
WEDNESDAY BUT DRYING SIGNIFICANTLY FOR THURSDAY. SOUTH OF LATITUDE  
35S, THE GENERAL PATTERN WILL BE DRY WITH THE EXCEPTION OF THE  
SOUTHERNMOST TIP OF CHILE OR A FEW SHOWERS ARE POSSIBLE FOR THE  
NEXT COUPLE OF DAYS WITH MINIMAL RAINFALL ACCUMULATION.  
 
THERE IS AN UPPER TROUGH WITH AXIS FROM EAST OF THE FALKLAND  
ISLANDS INTO NORTH CENTRAL ARGENTINA. ALTHOUGH THE ASSOCIATED LOW  
PRESSURE WILL CONTINUE MOVING EAST, A PORTION OF THE TROUGH WILL  
BECOME POSITIVELY TILTED AND WILL HAVE AN AXIS THAT WILL EXTEND  
FROM AROUND LA PAMPA AND BUENOS AIRES INTO CORDOBA AND SANTA FE  
OF ARGENTINA ON WEDNESDAY. THIS TROUGH WILL GRADUALLY DEEPEN,  
BECOMING A LOW PRESSURE BY THURSDAY NIGHT, WITH ITS CENTER NEAR  
URUGUAY AND SOUTHEASTERN BRASIL. THERE IS ALSO AN UPPER RIDGE IN  
THE SOUTHEAST PACIFIC THAT WILL MOVE INTO SOUTHERN CHILE AND  
ARGENTINA BY WEDNESDAY MORNING. BY THURSDAY MORNING THE RIDGE WILL  
EXTEND FROM THE NORTHERN PATAGONIA TO JUST EAST OF THE FALKLAND  
ISLANDS AS IT CONTINUES TO MOVE EAST. MEANWHILE, A SHORT WEIGHT  
TROUGH IN THE UPPER LEVELS WILL MOVE INTO AUSTRAL CHILE AND  
ARGENTINA LATE WEDNESDAY INTO THURSDAY. ACROSS NORTHERN SOUTH  
AMERICA THERE WILL BE AN UPPER HIGH PRESSURE ENTERING NORTHEAST  
BRASIL AND EXTENDING WEST INTO WESTERN BRASIL TODAY. THAT SAID,  
MOST OF NORTHERN SOUTH AMERICA, PARTICULARLY BRASIL, WILL BE UNDER  
A HIGH PRESSURE IN THE UPPER LEVELS. IT IS ALSO WORTH MENTIONING  
THAT THERE WILL BE A NEARLY STATIONARY LOW PRESSURE IN THE EAST  
PACIFIC NEAR 28S/75W. HAVING A HIGH PRESSURE OVER BRASIL AND THE  
LOW ACROSS THE EASTERN PACIFIC, AS WELL AS THE DEEPENING TROUGH  
OVER NORTHEAST ARGENTINA WILL TIGHTEN THE PRESSURE GRADIENT IN THE  
UPPER LEVELS ACROSS NORTH TO NORTHEAST ARGENTINA, URUGUAY AND  
SOUTHEAST BRASIL, PRODUCING AN UPPER LEVEL JET WHICH WILL SUPPORT  
THUNDERSTORM POTENTIAL.  
 
THE MID AND UPPER LEVELS ARE FAIRLY VERTICALLY STACKED, MEANING  
THAT THE MID LEVELS WILL ALSO HAVE A HIGH PRESSURE OVER BRASIL,  
WHICH WILL PROVIDE SOME STABILITY OVER MOST OF THE COUNTRY.  
HOWEVER, AREAS IN THE PERIPHERY SUCH AS SOUTHERN BOLIVIA TO THE  
SOUTHEAST INTO URUGUAY AND SOUTHEASTERN BRASIL WILL HAVE STRONGER  
MID-LEVEL WINDS WHICH WILL PROVIDE SUPPORT FOR SHOWER AND  
THUNDERSTORM DEVELOPMENT.  
 
AS FAR AS AVAILABLE MOISTURE, ACROSS THE NORTHERN HALF OF SOUTH  
AMERICA, THAT IS NORTH OF ARGENTINA CHILE AND URUGUAY, THE  
PRECIPITABLE WATER WILL BE NEAR TO ABOVE NORMAL, EXCEPT FOR  
PORTIONS OF CENTRAL TO EASTERN BRASIL FROM MATO GROSSO TO THE EAST  
AS WELL AS NORTHEASTERN BRASIL, WHICH WILL HAVE BELOW NORMAL  
PRECIPITABLE WATER TODAY AND WEDNESDAY. MOISTURE WILL INCREASE  
ACROSS MATO GROSSO ON THURSDAY BUT MOST OF THE NORTHEAST QUADRANT  
OF BRASIL WILL REMAIN WITH NEAR TO BELOW NORMAL MOISTURE ON  
THURSDAY. SOUTHERN SOUTH AMERICA, MAINLY ARGENTINA, CHILE AND  
URUGUAY AS WELL AS THE RIO GRANDE DO SUL STATE OF BRASIL, WILL  
OBSERVE MAINLY NEAR TO BELOW NORMAL MOISTURE FOR THE NEXT 3 DAYS.  
THAT BEING SAID, THERE IS A NARROW BAND OF MOISTURE EXTENDING FROM  
CENTRAL ARGENTINA INTO URUGUAY TODAY AND WEDNESDAY BUT IT WILL DRY  
FOR THURSDAY. ANOTHER NARROW BAND OF MOISTURE WILL MOVE FROM SOUTH  
OF NORTH THROUGH THE PATAGONIA ON THURSDAY.  
 
IN TERMS OF RAINFALL ACCUMULATION AMOUNTS TODAY, NORTHERN BRASIL  
AS WELL AS PORTIONS OF SOUTHERN BOLIVIA, PARAGUAY, AND  
SOUTHEASTERN BRASIL CAN OBSERVE RAINFALL MAXIMA UP TO 50MM, BUT  
POSSIBLY HIGHER ACROSS ISOLATED PORTIONS OF BOLIVIA AND PARAGUAY.  
ANOTHER SECTION NEAR CORDOBA AND SANTA FE OF ARGENTINA MAY RECEIVE  
UP TO 50MM OF RAIN. OTHER AREAS NORTH OF 20S CAN RECEIVE MAXIMUM  
RAINFALL OF UP TO 25 TO 35MM. ON WEDNESDAY, THERE IS A LOCAL  
MAXIMUM OF RAIN EXPECTED ACROSS SOUTHERN BOLIVIA INTO NORTHERN  
PARAGUAY WHERE THE DAILY MAXIMUM RAINFALL CAN REACH 70MM, WHILE  
THERE IS ALSO A SMALL SECTION OF COASTAL SOUTHEASTERN BRASIL THAT  
MAY RECEIVE UP TO 60MM. ELSEWHERE, NORTH OF 28S THE DAILY RAINFALL  
IS EXPECTED TO MAX OUT BETWEEN 25 AND 45MM, WITH NORTHERN BRASIL  
AND NORTHERN PERU BEING ON THE HIGHER END OF THE RANGE.  
ESSENTIALLY, THE VAST MAJORITY OF EASTERN BRASIL, EXCEPT FOR AREAS  
ALONG THE EAST COAST OF BRASIL, ARE EXPECTED TO RECEIVE LITTLE TO  
NO RAIN. THURSDAY IS EXPECTED TO BE A LITTLE BIT DRIER, WITH NO  
AREA IN THE CONTINENT BEING FORECAST OVER 45MM, ALTHOUGH ISOLATED  
AMOUNTS OVER THAT ARE POSSIBLE. THAT BEING SAID, MOST AREAS NORTH  
OF 20S ARE EXPECTED TO HAVE DAILY RAINFALL MAXIMA BETWEEN 25 AND  
45MM, WITH CENTRAL TO SOUTHERN PERU INTO BOLIVIA AND PORTIONS OF  
NORTHWESTERN BRASIL BEING ON THE HIGHER END OF THE RANGE. MOST OF  
EASTERN BRASIL WILL OBSERVE LITTLE TO NO RAIN. ELSEWHERE, SOME  
AREAS ARE EXPECTED TO RECEIVE RAIN WITH MAXIMUM AMOUNTS SOMEWHERE  
IN THE MIDDLE NEAR 25 TO 35MM. MOST AREAS SOUTH OF 35S ARE  
EXPECTED TO RECEIVE LITTLE TO NO RAIN OVER THE NEXT 3 DAYS.  
 
ALAMO...(WPC)  
 

 
 
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