969
FXSA20 KWBC 132012
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
312 PM EST MON JAN 13 2025
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 13 JAN 2025 AT 2000 UTC:
ACROSS THE SOUTH AMERICAN CONTINENT...THE MOST SIGNIFICANT
RAINFALL IS EXPECTED TO BE OBSERVED OVER BRASIL OVER THE FIRST
HALF OF THE WORKWEEK. THE MODEL GUIDANCE IS IN GENERAL AGREEMENT
THAT AREAS FROM MATO GROSSO TO THE EAST AND NORTH WILL RECEIVE
SIGNIFICANT RAINFALL OVER THE NEXT 3 DAYS. THAT BEING SAID...THE
ECMWF MODEL ALSO SUGGESTS SIGNIFICANT RAINFALL OVER PORTIONS OF
NORTHERN BOLIVIA. OUT OF THE NEXT 3 DAYS...WEDNESDAY INTO THURSDAY
IS EXPECTED TO BE THE PERIOD WITH THE SMALLEST COVERAGE OF
SIGNIFICANT RAIN.
IN THE UPPER LEVELS...THE BOLIVIAN HIGH IS EXPECTED TO ACTUALLY BE
CENTERED NORTH OF BOLIVIA...NEAR RONDONIA IN BRASIL THIS
EVENING...AS IT WEAKENS. HOWEVER...ANOTHER HIGH PRESSURE WILL
DEVELOP NEAR MINAS GERAIS BY WEDNESDAY EVENING. A LOW PRESSURE
WILL APPROACH THE NORTHEASTERN COAST OF BRASIL ON WEDNESDAY. A LOW
PRESSURE IN THE WESTERN ATLANTIC IS HELPING THE DEVELOPMENT OF
STRONG WINDS ALOFT OVER SOUTHERN BRASIL INTO SOUTHERN PARAGUAY.
WESTERLY WINDS ARE FORECAST OVER SOUTHERN SOUTH AMERICA...PEAKING
AT AROUND 135 KT ON WEDNESDAY.
IN THE MID LEVELS THERE IS A SHORTWAVE TROUGH THAT WILL QUICKLY
MOVE INTO SOUTHERN SOUTH AMERICA TONIGHT...EXITING ARGENTINA AND
INTO THE ATLANTIC BY TUESDAY AT 12Z. OTHERWISE...MAINLY WESTERLY
WINDS ARE FORECAST OVER SOUTHERN SOUTH AMERICA...WITH SPEEDS NEAR
40-65 KT...BUT PEAKING NEAR 75 KT IN THE SOUTHERNMOST AREA OF
SOUTH AMERICA. A MID-LEVEL LOW OVER THE WESTERN ATLANTIC IS
CAUSING SOME DIVERGENCE OVER EASTERN BRASIL...THOUGH THE LOW
PRESSURE SYSTEM IS MOVING EAST AND AWAY OF THE AREA. LIGHT
MID-LEVEL WINDS ARE EXPECTED OVER MOST OF CENTRAL TO NORTHERN
SOUTH AMERICA...WITH A HIGH PRESSURE OVER PARA AND A LOW PRESSURE
OVER NORTHERN ARGENTINA.
IN THE LOW LEVELS...THE WINDS WILL BE FROM THE NORTH TO NORTHWEST
OVER NORTHERN SOUTH AMERICA...WHICH WILL CONTRIBUTE TO THE
CONTINUED DEVELOPMENT OF A SACZ EXTENDING FROM BAHIA TO
NORTHEASTERN MATO GROSSO. THAT SAID...THE LOW LEVEL WIND
CONVERGENCE AND CONTINUATION INTO THE ATLANTIC COAST OF BRASIL
STARTS TO BECOME A BIT MORE DISORGANIZED AND WEAKER WITH EACH
PASSING DAY INTO WEDNESDAY...AND THUS WE HAVE A TROUGH IN OUR
ANALYSIS FOR WEDNESDAY INTO THURSDAY. STRONG LOW-LEVEL WINDS WILL
MOVE INTO SOUTH CENTRAL CHILE LATE TUESDAY INTO WEDNESDAY...WITH
AS MUCH AS 2 STANDARD DEVIATIONS HIGHER THEN NORMAL PRECIPITABLE
WATER. HIGHER THAN NORMAL MOISTURE WILL CONTINUE INTO
ARGENTINA...REACHING BUENOS AIRES...THOUGH NOT AS ANOMALOUSLY HIGH
AS WHEN IT REACHES CHILE. EASTERN BRASIL WILL ALSO HAVE HIGHER
THAN NORMAL PRECIPITABLE WATER VALUES FROM TODAY THROUGH
WEDNESDAY.
THE OVERALL RAINFALL PATTERN WILL FAVOR BRASIL AND ESSENTIALLY THE
TROPICAL REGION OF SOUTH AMERICA. EACH DAY THERE COULD BE
SIGNIFICANT SHOWERS AND THUNDERSTORMS OVER BRASIL. DAILY RAINFALL
OVER MANY AREAS ALONG THE SACZ COULD BE AS HIGH AS 15-30MM WITH
MAX VALUES AS HIGH AS 80MM...THOUGH SOME AREAS ALONG THE SACZ ARE
FORECAST SLIGHTLY LESS RAINFALL. OTHER AREAS OF NORTHEASTERN
BRASIL ARE ALSO EXPECTED TO OBSERVE SIGNIFICANT RAIN...WITH MAX
VALUES BEING NEAR 30-60MM NEAR CEARA...AND AS MUCH AS 40-80MM OVER
AREAS NEAR AND AROUND PERNAMBUCO. FURTHER WEST IN
BRASIL...GENERALLY OVER PORTIONS OF PARA...WESTERN MATO GROSSO AND
WESTWARD...THE AVAILABLE MOISTURE IS EXPECTED TO BE NEAR
NORMAL...SO THE AMOUNTS OF RAIN ARE ALSO EXPECTED TO BE A BIT MORE
MODEST. ALTHOUGH ISOLATED AREAS COULD RECEIVE SIGNIFICANT
RAINFALL...MOST AREAS WOULD OBSERVE RAINFALL TOTALS PEAKING NEAR
15-35MM. THE EXCEPTION IS THIS AFTERNOON INTO TONIGHT OVER PARA
AND AMAZONAS...WHERE THE MODEL GUIDANCE AND SATELLITE IMAGERY
INDICATES CONVECTION ALONG THE ITCZ/NET. SOUTHERN SOUTH AMERICA IS
FORECAST TO OBSERVE SOME RAINFALL ACTIVITY...THOUGH GENERALLY INT
HE ORDER OF MAX AMOUNTS NEAR 15-35MM IN SOUTHERN CHILE...EACH DAY
INTO THURSDAY MORNING.
ALAMO...(WPC)
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