636   
FXSA20 KWBC 271951  
PMDSA   
  
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
250 PM EST MON JAN 27 2025  
  
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
  
SOUTH AMERICAN FORECAST BULLETIN FOR 27 JAN 2025 AT 1930 UTC:  
  
THE SOUTH AMERICAN CONTINENT IS SEEING THE EFFECTS OF A CONVERGENT  
PHASE OF THE MADDEN-JULIAN OSCILLATION ON MONDAY AND INTO TUESDAY.  
AS THE WORK WEEK PROGRESSES THE CSF MODEL IS SUGGESTING A  
POTENTIAL ATMOSPHERIC KELVIN WAVE ENTERING THE REGION BY  
MIDWEEK...POTENTIALLY ASSISTING IN ENHANCED CONVECTION. ALTHOUGH  
THE POTENTIAL FOR DEEP CONVECTION COULD EXIST WITH THE PRESENCE OF  
A KELVIN WAVE...SYNOPTIC CONDITIONS WILL CONTINUE TO BE THE  
DRIVERS FOR ANY HEAVY PRECIPITATION OVER THE CONTINENT.  
  
ON MONDAY...A PROMINENT UPPER LEVEL TROUGH EXTENDS INTO PORTIONS  
OF CENTRAL ARGENTINA AND CHILE...WHICH THE BASE IS EXPECTED TO  
INTERACT WITH THE BOLIVIAN HIGH CENTERED JUST WEST OF NORTH CHILE  
AND SOUTH PERU...AND EXTENDS FROM NORTH CHILE EASTWARD THROUGH  
SOUTH BRASIL. AN UPPER LEVEL TROUGH WITH A REDUCED AMPLITUDE IS  
EXPECTED TO MOVE SLOWER OVER NORTH-CENTRAL CHILE INTO THE CUYO  
REGION OF ARGENTINA. AHEAD OF THIS TROUGH...A SHORTWAVE TROUGH IS  
EXPECTED TO REACH THE AFOREMENTIONED REGION AND PROVIDE LIFT FROM  
THE CUYO REGION TO CENTRAL ARGENTINA BY TUESDAY  
MORNING...ELEVATING THE POTENTIAL FOR SEVERE WEATHER ON THE EARLY  
HOURS ON TUESDAY. FURTHER ON TUESDAY...THE UPPER LEVEL TROUGH IS  
EXPECTED TO MAKE IT TO WEST AND CENTRAL ARGENTINA FAVORING DEEP  
CONVECTION AND SEVERE WEATHER...AS WELL AS HEAVY  
PRECIPITATION...FROM CENTRAL ARGENTINA INTO THE CHACO REGION. THIS  
SYSTEM WILL HAVE FAVORABLE AMOUNT OF AVAILABLE MOISTURE WITH THE  
SALLJ TRANSPORTING MOISTURE INTO THE REGION WITH PRECIPITABLE  
VALUES EXCEEDING 50MM AS WELL AS ENHANCING THE MOISTURE  
CONVERGENCE AGAINST THE ANDEAN MOUNTAIN RANGE. AS THIS TROUGH  
CONTINUES PROPAGATING EASTWARD INTO WEDNESDAY...THE AREA OF  
DIVERGENCE EXTENDS EASTWARD OVER SOUTH PARAGUAY...SOUTH  
BRASIL...AND URUGUAY. IN TERMS OF PRECIPITATION...ON  
MONDAY...NORTH CENTRAL ARGENTINA CAN EXPECT MAXIMA OF 25-50MM WITH  
A MODERATE RISK OF SEVERE WEATHER. ON TUESDAY...THE CHACO REGION  
OF ARGENTINA CAN EXPECT MAXIMA OF 30-60MM...WHILE ALONG THE  
CORDILLERA...EXPECT MAXIMA OF 40-80MM. A RISK OF MCS FORMATION IS  
EXPECTED. ON WEDNESDAY...EXPECT MAXIMA OF 30-60MM IN NORTHEAST  
ARGENTINA...WITH A RISK OF MCS FORMATION. PARAGUAY CAN EXPECT  
MAXIMA OF 20-40MM.  
  
IN THE SOUTHERN CONE OF THE CONTINENT...SOUTH CHILE IS EXPECTED TO  
SEE MODERATE PRECIPITATION IN THE AUSTRAL REGION OF CHILE OVER THE  
NEXT THREE DAYS. THAT IS DUE TO THE CONTINUOUS PRESENCE OF THE  
POLAR JET OVER THE REGION...PROVIDING VENTILATION IN THE LOWER  
LEVELS AS A SERIES OF FRONTAL BOUNDARIES WITH AN ASSOCIATED  
ATMOSPHERIC RIVER WILL FAVOR MOISTURE CONVERGENCE ALONG THE  
MOUNTAIN REGION IN AUSTRAL CHILE...PRIMARILY ON TUESDAY AND  
WEDNESDAY. ON MONDAY...EXPECT A FRONTAL BOUNDARY TO ENTER  
MAGALLANES-CHILE BY LATE MONDAY EVENING WITH A POTENTIAL FOR  
MAXIMA OF 20-35MM IN MAGALLANES. AYSEN AND SOUTH MAGALLANES CAN  
EXPECT MAXIMA BELOW 25MM. ON TUESDAY...THE ATMOSPHERIC RIVER  
ENTERS THE AUSTRAL REGION WITH CONTINUOUS MOISTURE TRANSPORT.  
SOUTH AYSEN AND NORTH MAGALLANES CAN EXPECT MAXIMA OF  
25-50MM...WITH A POTENTIAL FOR LOCALLY HIGHER AMOUNTS. SOUTH  
MAGALLANES CAN EXPECT MAXIMA OF 15MM. ON WEDNESDAY...MOISTURE  
CONTINUES TO ENTER THE REGION AND WILL FAVOR MOISTURE CONVERGENCE  
IN MAGALLANES-CHILE. A POTENTIAL FOR MAXIMA OF 50-100MM ARE  
EXPECTED FOR THE REGION. THE UPPER LEVEL JET WILL FAVOR  
VENTILATION FOR THE HEAVY PRECIPITATION OVER SOUTH CHILE.  
  
IN THE NORTHERN REGION OF THE CONTINENT...THE BOLIVIAN HIGH  
EXTENDS OVER PERU...BOLIVIA...AND WEST BRASIL. THE VENTILATION AT  
THE PERIPHERY OF THE UPPER LEVEL HIGH PRESSURE SYSTEM WILL  
INTERACT WITH THE UPPER TROUGH OVER NORTHERN BRASIL. THIS REGION  
WILL CONTINUE TO SEE SHOWERS AS LOWER LEVEL TROUGHS TRIGGER MAXIMA  
OF 15-25MM ON MONDAY OVER NORTH BRASIL. THE CENTRAL REGIONS OF  
PERU CAN EXPECT MAXIMA OF 20-35MM ON MONDAY. ON TUESDAY...THE  
AFOREMENTIONED REGIONS CAN EXPECT MAXIMA OF 20-35MM. BY  
WEDNESDAY...EXPECT MAXIMA OF 20-40MM IN NORTH AND CENTRAL BRASIL.  
  
CASTELLANOS...(WPC)  
  
 
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