935
FXSA20 KWBC 081957
PMDSA

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 PM EST WED JAN 08 2025

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

SOUTH AMERICAN FORECAST BULLETIN FOR 08 JAN 2025 AT 2000 UTC:

IN THE CENTRAL PORTION OF THE CONTINENT...THE SOUTH ATLANTIC
CONVERGENCE ZONE (SACZ) IS LOCATED FROM RIO DE JANEIRO TO CENTRAL
BOLIVIA ON WEDNESDAY. THE PRESENCE OF THE SACZ IS EXPECTED TO
REMAIN IN THE REGION OVER THE NEXT THREE DAYS AND PROMOTE HEAVY
PRECIPITATION IN CENTRAL BRASIL. IN THE 700 HPA LEVEL THE TROUGH
ASSOCIATED WITH THE SACZ IS VERY PROMINENT AND THE AMOUNT OF
AVAILABLE MOISTURE WILL CONTINUE OVER THE AMAZON BASIN. IN
ADDITION TO THE SACZ AND THE MOISTURE IN THE AMAZON
BASIN...TROUGHS IN THE TRADE WINDS ARE CONVERGING IN NORTHEAST
BRASIL...ENHANCED BY THE MID TO UPPER LEVEL DIFFLUENCE FROM THE
INTERACTION BETWEEN BOLIVIAN HIGH AND THE UPPER TROUGH WITH ITS
BASE IN SOUTH MINAS GERAIS AND SAO PAULO. THIS MID TO UPPER LEVEL
TROUGH WILL STRENGTHEN ON THURSDAY AND FRIDAY BY THE UPPER JET
OVER PARAGUAY AND SOUTH BRASIL. AS THE UPPER TROUGH MOVES
NORTHWARD...THE SACZ IS EXPECTED TO ALSO PROPAGATE NORTH AND THE
DIVERGENCE IS EXPECTED FURTHER NORTH IN BRASIL. THIS WILL ASSIST
WITH THE VENTILATION OF DEEP CONVECTION IN NORTH AND EAST
BRASIL...WHERE HEAVY PRECIPITATION IS EXPECTED ON THURSDAY AND
FRIDAY. IN TERMS OF PRECIPITATION...ON WEDNESDAY...EXPECT MAXIMA
OF 50-100MM IN RIO DE JANEIRO AND SOUTH ESPIRITO SANTO. MAXIMA OF
40-80MM IN MINAS GERAIS AND SAO PAULO. MAXIMA OF 35-70MM ARE
EXPECTED IN CENTRAL BRASIL...WHILE MAXIMA OF 25-50MM ARE EXPECTED
IN CENTRAL BOLIVIA/MATO GROSSO AND CENTRAL PERU. ON THURSDAY...THE
PRESENCE OF THE SACZ WILL FAVOR MAXIMA OF 50-100MM IN ESPIRITO
SANTO...AND MAXIMA OF 35-70MM FROM MINAS GERAIS...TO MATO GROSSO.
TO THE NORTH FROM PARA TO NORTH BAHIA...A TROUGH WILL FAVOR MAXIMA
OF 30-60MM. ON FRIDAY...THE SACZ WILL FAVOR MAXIMA OF 30-60MM IN
MINAS GERAIS...RIO DE JANEIRO...AND ESPIRITO SANTO. MAXIMA OF
20-45MM ARE EXPECTED FROM CENTRAL MATO GROSSO THROUGH GOIAS. FROM
NORTH BAHIA TO THE NORTHERN STATES...AN AREA OF MOISTURE
CONVERGENCE IN THE LOWER LEVELS IS EXPECTED TO BE ENHANCED BY
UPPER DIVERGENCE FROM THE MID TO UPPER LEVEL TROUGH IN EAST
BRASIL. MAXIMA OF 50-100MM ARE EXPECTED. AS THE SACZ IS WEAKENING
IN THE WESTERN SECTOR BY BOLIVIA AND WEST BRASIL...MOISTURE IS
BEING TRANSPORTED ALONG THE ANDES MOUNTAINS IN BOLIVIA. OROGRAPHIC
LIFT WILL FAVOR MAXIMA OF 30-60MM IN CENTRAL BOLIVIA.

ON WEDNESDAY AND THURSDAY...A MID LEVEL TROUGH IS PRESENT FROM
SOUTH PERU INTO CENTRAL BOLIVIA...WHERE DEEP CONVECTION IS
DEVELOPING AND EXPECTED TO FAVOR HEAVY PRECIPITATION FOR THE
MOUNTAIN REGIONS OF SOUTH PERU AND CENTRAL BOLIVIA. IN ADDITION
MOISTURE IN THE REGION WILL FAVOR PRECIPITATION TOTALS RANGING
FROM 15-35MM IN THE MOUNTAIN REGION OF PERU AND BOLIVIA FOR
WEDNESDAY AND THURSDAY. A SLIGHT DECREASE IS EXPECTED ON FRIDAY AS
THE TROUGH IN THE MID LEVEL WEAKENS...YET DEEP CONVECTION IS
EXPECTED IN EAST POTOSI-BOLIVIA...WHERE EXPECT MAXIMA OF 30-60MM.

IN THE SOUTHERN CONE OF THE CONTINENT DRIER CONDITIONS ARE
EXPECTED TO CONTINUE OVER THE FORECAST PERIOD. A FRONTAL BOUNDARY
CURRENTLY OVER SOUTHERN ARGENTINA WILL STRENGTHEN ON WEDNESDAY
INTO THURSDAY WITH THE ASSISTANCE OF A MID TO UPPER TROUGH
PROPAGATING OVER THE REGION. DUE TO THE INSTABILITY EXPECTED IN
ASSOCIATED WITH THE UPPER TROUGH...CENTRAL AND SOUTH ARGENTINA CAN
EXPECT A SLIGHT RISK OF SEVERE WEATHER. PRECIPITATION AMOUNTS ARE
EXPECTED TO REMAIN BELOW 25MM. AS THE FRONTAL BOUNDARY PROPAGATES
NORTH AND EAST...THROUGH BUENOS AIRES...AND INTO
MENDOZA-ARGENTINA...EXPECT A SLIGHT RISK OF SEVERE WEATHER FROM
BUENOS AIRES TO LA PAMPA. MAXIMA OF 20-45MM ARE EXPECTED IN
MENDOZA AND SAN LUIS-ARGENTINA. ON FRIDAY...A DECREASE IN AMOUNT
OF AVAILABLE MOISTURE WILL FAVOR A DECREASE IN PRECIPITATION IN
CENTRAL ARGENTINA. EXPECT MAXIMA OF 15-20MM FROM BUENOS AIRES TO
MENDOZA WITH THE PRESENCE OF THE FRONTAL BOUNDARY BECOMING
STATIONARY DUE TO THE PRESENCE OF A DEVELOPING UPPER RIDGE OVER
THE REGION.

CASTELLANOS...(WPC)
$$