569   
FXSA20 KWBC 071946  
PMDSA   
  
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
246 PM EST TUE JAN 07 2025  
  
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
  
SOUTH AMERICAN FORECAST BULLETIN FOR 07 JAN 2025 AT 1945 UTC:  
  
THE BOLIVIAN HIGH IS EXPECTED TO MEANDER OVER THE CENTRAL PORTIONS  
OF SOUTH AMERICA...WHERE THE INTERACTION WITH OTHER UPPER LEVEL  
SYSTEMS IN ITS PERIPHERY WILL FAVOR VENTILATION FOR DEEP  
CONVECTION IN BRASIL...PERU...BOLIVIA AND AS FAR SOUTH AS NORTH  
ARGENTINA ON TUESDAY AND INTO THE WEDNESDAY AND THURSDAY. IN THE  
LOWER LEVELS...THERE IS SUPPORT FOR THE SOUTH ATLANTIC CONVERGENCE  
ZONE (SACZ) TO DEVELOP. THE TROUGH ASSOCIATED WITH THE FEATURE IS  
SEEN IN THE 700 HPA AND 850 HPA LEVELS...WITH A MOISTURE GRADIENT  
THAT IS SEEN IN CENTRAL BRASIL AND REACHING INTO CENTRAL BOLIVIA  
ON TUESDAY. THE SACZ IS EXPECTED TO MEANDER IN THE SAME REGION ON  
WEDNESDAY AND SHIFT SLIGHTLY NORTH INTO CENTRAL MATO GROSSO ON  
THURSDAY AS THE ASSOCIATED UPPER TROUGH IN SOUTHEAST BRASIL SHIFTS  
NORTHWARD ON THURSDAY INTO FRIDAY. AS SUCH...THE EAST AND CENTRAL  
REGIONS OF BRASIL ARE EXPECTED TO SEE HEAVY PRECIPITATION OVER THE  
FORECAST PERIOD. ON TUESDAY...RIO DE JANEIRO CAN EXPECT MAXIMA OF  
50-100MM. ESPIRITO SANTO...MINAS GERAIS AND EAST GOIAS CAN EXPECT  
MAXIMA OF 40-80MM. FROM WEST GOIAS-BRASIL THROUGH SOUTH MATO  
GROSSO/NORTH MATO GROSSO DO SUL...AND INTO EAST-CENTRAL  
BOLIVIA...EXPECT MAXIMA OF 30-60MM. THE REGIONS MENTION COULD SEE  
LOCALLY HIGHER TOTALS. ON WEDNESDAY...ADDITIONAL TROUGHS IN THE  
LOWER LEVELS ARE FAVORING HEAVY PRECIPITATION WITHIN A MOIST  
ENVIRONMENT IN THE AMAZON BASIN. WITH THE PRESENCE OF THE  
SACZ...RIO DE JANEIRO AND SOUTH ESPIRITO SANTO CAN EXPECT MAXIMA  
OF 50-100MM. NORTH ESPIRITO SANTO THROUGH GOIAS CAN EXPECT MAXIMA  
OF 40-80MM. EAST AMAZONAS...WEST PARA...MATO GROSSO...AND  
TOCANTINS CAN EXPECT MAXIMA OF 30-60MM. SIMILAR AMOUNTS ARE  
EXPECTED IN CENTRAL BOLIVIA WITH THE PRESENCE OF MOISTURE  
CONVERGING ALONG THE ANDES. ON THURSDAY...THE UNSTABLE AND MOIST  
ENVIRONMENT REMAINS OVER THE AMAZON BASIN AND FAVORS HEAVY  
PRECIPITATION AS THE SACZ MEANDERS IN THE REGION. ESPIRITO SANTO  
CAN EXPECT MAXIMA OF 50-100MM...WHILE MINAS GERAIS AND GOIAS CAN  
EXPECT MAXIMA OF 35-70MM. FROM AMAZONAS-BRASIL...EAST INTO  
BAHIA...EXPECT MAXIMA OF 30-60MM...WITH LOCALLY HIGHER TOTALS  
POSSIBLE.  
  
IN ARGENTINA AND CHILE...A WIDE TROUGHING PATTERN IS PRESENT THAT  
EXTENDS INTO THE CENTRAL PORTIONS OF THE COUNTRIES. WITHIN THIS  
WIDE TROUGH ARE SEVERAL SHORT WAVE TROUGHS THAT WILL PROGRESS  
EASTWARD INTO THE SOUTH AND CENTRAL REGIONS OF THE COUNTRIES OVER  
THE NEXT FEW DAYS. THESE ARE EXPECTED TO INCREASE THE INSTABILITY  
IN THE REGION...PARTICULARLY IN CENTRAL ARGENTINA WHERE A SMALL  
AMOUNT OF MOISTURE FROM THE NORTH IS BEING TRANSPORTED...AND  
ASSISTED BY THE PRESENCE OF FRONTAL BOUNDARIES ENTERING CENTRAL  
CHILE AND ARGENTINA OVER THE NEXT FEW DAYS. ON TUESDAY...MAXIMA OF  
15-25MM WITH A MODERATE RISK OF SEVERE WEATHER IS EXPECTED IN  
MENDOZA..LA PAMPA...AND NEUQUEN-ARGENTINA WITH THE PASSING OF A  
MID TO UPPER LEVEL TROUGH. A MID TO UPPER TROUGH IS ALSO  
PROPAGATING OVER SOUTHERN CHILE WHERE IT WILL FAVOR MAXIMA OF  
15-20MM WITH A RISK OF THUNDER ACTIVITY. ON WEDNESDAY...AN  
INCREASE IN MOISTURE IS EXPECTED IN NORTH AND CENTRAL REGIONS OF  
ARGENTINA...WHERE EXPECT MAXIMA OF 20-35MM AND A SLIGHT RISK OF  
SEVERE WEATHER AS ANOTHER SHORT WAVE TROUGH IN THE MID TO UPPER  
LEVELS PROPAGATES OVER THE REGION ON WEDNESDAY EVENING INTO EARLY  
THURSDAY MORNING. IN THE AUSTRAL REGION OF CHILE...FRONTAL  
BOUNDARIES ARE FAVORING PRECIPITATION BELOW 25MM IN SOUTH AYSEN  
AND NORTH MAGALLANES...AND BELOW 15MM IN SOUTH MAGALLANES. ON  
THURSDAY...A FRONTAL BOUNDARY PROPAGATING INTO CENTRAL ARGENTINA  
WILL TRIGGER MAXIMA OF 15-25MM WITH A MARGINAL RISK OF SEVERE  
WEATHER. THE CONTINUED PRESENCE OF SHORT WAVE TROUGHS IN CENTRAL  
ARGENTINA WILL FAVOR A MARGINAL RISK OF SEVERE WEATHER FROM LA  
RIOJA TO NORTH MENDOZA-ARGENTINA. MAXIMA OF 15-30MM ARE EXPECTED.  
  
CASTELLANOS...(WPC)  
  
 
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