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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