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South American Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1927Z Jan 23, 2025)
 
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SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
227 PM EST THU JAN 23 2025

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

SOUTH AMERICAN FORECAST BULLETIN FOR 23 JAN 2025 AT 1930 UTC:

THE NORTHER REGION OF SOUTH AMERICA IS EXPECTED TO SEE THE
BOLIVIAN HIGH EXTEND OVER PERU INTO BOLIVIA...NORTH
CHILE...PARAGUAY...AND WEST BRASIL BY THURSDAY EVENING. THIS WILL
PLACE THE PERIPHERY OF THE UPPER LEVEL SYSTEM OVER REGIONS OF WEST
AND NORTH BRASIL...AS WELL AS NORTH PERU. THE CENTRAL CORDILLERA
IN PERU IS EXPECTED TO SEE THE PRESENCE OF MOISTURE IN THE REGION
WHILE A MID LEVEL TROUGH WILL ENHANCE CONVECTION OVER CENTRAL PERU
AND INTO THE ALTIPLANO REGION INTO BOLIVIA. CENTRAL BOLIVIA CAN
EXPECT MAXIMA OF 20-45MM...WHILE SOUTH PERU CAN EXPECT MAXIMA OF
15-30MM WITH A CHANCE OF MOUNTAIN SNOW IN THE HIGHER ELEVATIONS.
SOUTH WEST BOLIVIA...AND THE WESTERN CENTRAL CORDILLERA IN PERU
CAN EXPECT MAXIMA OF 15MM. IN NORTHERN BRASIL...THE UPPER LEVEL
DIFFLUENCE WILL INTERACT WITH THE ITCZ/NET IN NORTH BRASIL AND
FAVOR GENERALIZED MAXIMA OF 20-45MM FROM AMAZONAS-BRASIL TO
PARA-BRASIL AND INTO SOUTHERN REGIONS OF
COLOMBIA...VENEZUELA...AND THE GUIANAS. ON FRIDAY...THE BOLIVIAN
HIGH BEGINS TO MEANDER TO THE EAST...WHERE IT EXTENDS FURTHER INTO
SOUTHEAST BRASIL. TO ITS NORTH AND EAST...AN UPPER LEVEL JET IS
RETROGRADING OVER EAST BRASIL AND INTERACT WITH THE BOLIVIAN HIGH.
THE AREA OF DIFFLUENCE FROM THIS INTERACTION IS EXPECTED OVER
NORTH BRASIL AND INTO SOUTH VENEZUELA AND THE GUIANAS. IN THE
LOWER LEVELS OVER PERU...WEST BRASIL...AND BOLIVIA...THE TRANSPORT
OF MOISTURE FROM THE NORTH CONTINUES WITH THE DEVELOPMENT OF THE
SALLJ IN BOLIVIA. THIS WILL FAVOR MOISTURE CONVERGENCE ALONG THE
ANDES MOUNTAINS ON FRIDAY. EXPECT MAXIMA OF 30-60MM IN SOUTH
VENEZUELA...RORAIMA-BRASIL...AND NORTH AMAZONAS. CENTRAL PERU CAN
EXPECT GENERALIZED MAXIMA OF 15-25MM. CENTRAL BRASIL CAN EXPECT
SIMILAR AMOUNTS ON FRIDAY. ON SATURDAY...THE UPPER LEVEL TROUGH
OVER EAST BRASIL CONTINUES TO RETROGRADE INTO THE NORTHERN AND
CENTRAL PORTIONS OF BRASIL...FAVORING DRIER CONDITIONS IN THE
REGION. THE BOLIVIAN HIGH STRENGTHENS FROM PERU INTO THE SOUTHERN
REGION OF BRASIL BY SATURDAY EVENING. AN INCREASE IN MOISTURE IS
BEGIN ADVECTED IN THE TRADE WINDS OVER THE
GUIANAS...AMAPA...PARA-BRASIL...EXTENDING INTO
AMAZONAS-BRASIL...WHERE MOISTURE CONVERGENCE IS EXPECTED. THIS
REGION WILL ALSO BE LOCATED IN THE AREA OF HIGHEST DIVERGENCE
ALOFT DUE TO THE INTERACTION BETWEEN THE UPPER LEVEL SYSTEMS. IN
TERMS OF PRECIPITATION EXPECT MAXIMA OF 30-60MM FROM SOUTH
COLOMBIA/VENEZUELA...INTO RORAIMA...WEST AMAZONAS-BRASIL AND INTO
WEST PARA. AMAPA AND THE GUIANAS CAN EXPECT MAXIMA OF 20-40MM. THE
SOUTHERN REGIONS OF PERU INTO WEST BOLIVIA CAN EXPECT MAXIMA OF
15-25MM.

IN THE CENTRAL PORTIONS OF THE CONTINENT...A FRONTAL BOUNDARY HAS
CROSSED THE CORDILLERA IN CENTRAL CHILE AND EXTENDS ACROSS CENTRAL
ARGENTINA THROUGH SOUTH BUENOS AIRES BY THURSDAY EVENING. THIS
SYSTEM IS INTERACTING WITH MID TO UPPER LEVEL SHORT WAVE TROUGHS
THAT ARE ENHANCING THE POTENTIAL FOR SEVERE WEATHER IN THE REGION
OVER THE NEXT THREE DAYS. ON THURSDAY...EXPECT MAXIMA OF 15-25MM
WITH A MODERATE RISK OF SEVERE WEATHER IN BUENOS AIRES AND EAST LA
PAMPA-ARGENTINA. TROUGHING IN THE LOWER LEVELS WILL FAVOR MAXIMA
OF 20-35MM FROM URUGUAY INTO NORTH EAST ARGENTINA WITH A SLIGHT
RISK OF SEVERE WEATHER AS MOISTURE ADVECTED INTO THE REGION. ON
FRIDAY...THE FRONTAL BOUNDARY IS EXPECTED OVER BUENOS AIRES AND
EXITS INTO THE ATLANTIC OCEAN. A TROUGH TO THE NORTH IN RIO GRANDE
DO SUL FROM THE DEEP CONVECTION THAT IS BEING GENERATED IN THE
REGION. THESE TWO FEATURES WILL INTERACT WITH SHORT WAVE TROUGHS
IN THE MID TO UPPER LEVEL...FAVORING A MODERATE RISK OF SEVERE
WEATHER FROM RIO GRANDE DO SUL TO SOUTH PARAGUAY AND A MAXIMA OF
30-60MM. FROM SOUTH URUGUAY INTO BUENOS AIRES EXPECT A MARGINAL
RISK OF SEVERE WEATHER WITH A MAXIMA OF 15-20MM. ON SATURDAY...A
DECREASE IN AVAILABLE MOISTURE IS REFLECTED FROM NORTH ARGENTINA
INTO SOUTH BRASIL. YET...THE MOISTURE THAT IS AVAILABLE IN THE
CHACO REGION IS EXPECTED TO CONVERGE ALONG THE ANDES WHERE THE
CHACO LOW DEVELOPS. AS THE FRONTAL BOUNDARY ADVANCES INTO CENTRAL
URUGUAY AND THROUGH CORDOBA-ARGENTINA...EXPECT A MAXIMA OF 15-30MM
WITH A SLIGHT RISK OF ISOLATED SEVERE WEATHER IN CORDOBA AND SANTA
FE-ARGENTINA. THE CHACO REGION IN NORTH ARGENTINA CAN EXPECT
MAXIMA OF 20-40MM...WHILE SOUTH BRASIL AND EAST PARAGUAY CAN
EXPECT MAXIMA OF 20-35MM.

CASTELLANOS...(WPC)