263
FXSA20 KWBC 091921
PMDSA

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
221 PM EST THU JAN 09 2025

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

SOUTH AMERICAN FORECAST BULLETIN FOR 09 JAN 2025 AT 1920 UTC:

THE BOLIVIAN HIGH IS CENTERED IN NORTHERN BOLIVIA AND EXTENDS INTO
CENTRAL BRASIL...SOUTH COLOMBIA/SOUTH VENEZUELA...OVER PERU...AND
AS FAR SOUTH AS NORTH ARGENTINA ON THURSDAY. TO THE EAST IN EAST
BRASIL...AN UPPER TROUGH EXTENDS FROM SOUTH EAST BRASIL INTO
CENTRAL BAHIA AND SOUTH TOCANTINS-BRASIL. THIS INTERACTION BETWEEN
THE UPPER LEVEL TROUGH AND THE BOLIVIAN HIGH IS FAVORING A
DIFFLUENT REGION IN PORTIONS OF CENTRAL AND EAST BRASIL WHERE
HEAVY PRECIPITATION HAS BEEN OBSERVED THIS WEEK AND IS EXPECTED TO
CONTINUE OVER THE NEXT THREE DAYS AS THE PRESENCE OF THE SOUTH
ATLANTIC CONVERGENCE ZONE IS EXPECTED IN CENTRAL AND EAST BRASIL.
IN ADDITION TO THE SACZ...TROUGHING IN THE LOWER LEVELS IN THE
TRADE WINDS ARE INTERACTING WITH THE OROGRAPHY AS WELL AS THE
DIVERGENT PATTERN IN NORTHERN BRASIL. THIS REGION IS ALSO SEEING
AVAILABLE MOISTURE THAT WILL ASSIST IN PRODUCING MODERATE TO HEAVY
PRECIPITATION DURING THE FORECAST PERIOD. IN TERMS OF
PRECIPITATION...ON THURSDAY...EXPECT MAXIMA OF 40-80MM IN ESPIRITO
SANTO AND EXTREME EAST MINAS GERAIS. MAXIMA OF 35-70MM ARE
EXPECTED FROM NORTH MINAS GERAIS THROUGH SOUTH MARANHAO AND
TOCANTINS. MAXIMA OF 30-60MM ARE EXPECTED IN FROM SOUTH
BAHIA...THROUGH MINAS GERAIS...AND INTO SOUTH TOCANTINS/NORTH
GOIAS. PARA AND MATO GROSSO CAN EXPECT MAXIMA OF 20-45MM AS THE
MOISTURE IN THE REGION REMAINS TO THE NORTH OF THE SACZ. ON
FRIDAY...THE SACZ IS EXPECTED TO BEGIN WEAKENING IN WESTERN BRASIL
AND MOISTURE IS CONTINUING INTO BOLIVIA AND NORTH ARGENTINA.
AVAILABLE MOISTURE IS DECREASING IN EASTERN BRASIL...HOWEVER THE
UPPER LEVEL DYNAMICS ARE STILL PRESENT TO FAVOR HEAVY
PRECIPITATION. EXPECT MAXIMA OF 40-80MM FROM ESPIRITO SANTO INTO
SOUTH BAHIA...AND EAST MINAS GERAIS. THE REST OF
BAHIA...TOCANTINS...AND NORTH GOIAS CAN EXPECT MAXIMA OF 30-60MM.
ELSEWHERE IN CENTRAL BRASIL...GENERALIZED MAXIMA OF 20-45MM. ON
SATURDAY...THE EXPECT SIMILAR AMOUNTS TO BE SPREAD OUT OVER
NORTHERN REGIONS OF BRASIL. BAHIA AND NORTH MINAS GERAIS CAN
EXPECT MAXIMA OF 40-80MM...WHILE FROM SOUTH PARA TO
TOCANTINS/PIAUI CAN EXPECT MAXIMA OF 30-60MM.

IN SOUTHERN PERU AND CENTRAL BOLIVIA...THE PRESENCE OF A MID LEVEL
TROUGH IS ASSISTING IN PRODUCING DEEP CONVECTION ALONG THE ANDES
REGION IN PERU AND BOLIVIA. THIS EXTENDS INTO NORTH ARGENTINA AS
MOISTURE IS ADVECTED TO THE REGION FROM THE NORTH. WITH THE
PRESENCE OF THIS SOUTHWARD TRANSPORT OF MOISTURE CONVERGING ALONG
THE MOUNTAINS...HEAVY PRECIPITATION IS EXPECTED OVER THE NEXT
THREE DAYS. ON THURSDAY...IN SOUTH BENI-BOLIVIA EXPECT MAXIMA OF
30-60MM...WHILE FROM SOUTH PERU...THROUGH WEST BOLIVIA...INTO THE
NORTHWEST ARGENTINA EXPECT MAXIMA OF 15-25MM. ON FRIDAY..SIMILAR
CONDITIONS CONTINUE...WHERE MAXIMA OF 30-60MM ARE EXPECTED IN FROM
SOUTH BENI THROUGH SANTA CRUZ-BOLIVIA. MAXIMA OF 15-25MM ARE
EXPECTED FROM SOUTH-CENTRAL BOLIVIA TO NORTH ARGENTINA. ON
SATURDAY...THE MOISTURE TRANSPORT IS ENHANCED BY LONG FETCH
MOISTURE ADVECTION INTO CENTRAL BOLIVIA WITH VALUES OF
PRECIPITABLE WATER MAY REACH OVER 60MM WILL CONVERGE IN THE
REGION. ASSISTED BY THE MID LEVEL TROUGH...DEEP CONVECTION AND
HEAVY PRECIPITATION IS EXPECTED. FROM SOUTHERN PERU INTO SOUTH
BENI...AND WEST SANTA CRUZ-BOLIVIA EXPECT MAXIMA OF 25-50MM. THE
COCHABAMBA-BOLIVIA REGION CAN EXPECT MAXIMA OF 50-100MM.

TO THE SOUTH...THURSDAY AND FRIDAY ARE EXPECTED TO REMAIN
RELATIVELY DRY DUE TO THE RIDGING THAT HAS DEVELOPED OVER CENTRAL
PORTIONS OF CHILE AND SOUTH ARGENTINA. HOWEVER...THE PASSING OF A
FRONTAL BOUNDARY IN CENTRAL ARGENTINA...ASSISTED BY SHORT WAVE
TROUGHS IN THE UPPER LEVELS WILL ENHANCE SEVERE WEATHER IN CENTRAL
ARGENTINA. THE REGION CAN EXPECT MAXIMA OF 15-20MM WITH SLIGHT
RISK OF SEVERE WEATHER ON THURSDAY...AND MAXIMA OF 15-25MM WITH A
MARGINAL RISK OF SEVERE WEATHER ON FRIDAY. DRY CONDITIONS ARE
EXPECTED IN CENTRAL ARGENTINA ON SATURDAY. HOWEVER...IN SOUTHERN
CHILE...THE ENTRANCE OF AN ATMOSPHERIC RIVER...WITH HEAVY
WINDS...AND ASSISTANCE FROM A POTENT MID TO UPPER LEVEL TROUGH AND
THE UPPER JET WILL FAVOR HEAVY PRECIPITATION IN THE REGION. THE
POTENTIAL FOR MAXIMA OF 20-40MM ARE EXPECTED IN SOUTH AYSEN AND
NORTH MAGALLANES. PRECIPITABLE WATER VALUES ARE EXPECTED TO BE
HIGHER THAN 30MM AS THE ATMOSPHERIC RIVER ENTERS THE REGION. THE
POTENTIAL FOR HIGHER TOTALS IS POSSIBLE.

CASTELLANOS...(WPC)
$$