SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 PM EDT TUE AUG 27 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 27 AUG 2024 AT 1955 UTC:

THE AREAS WITH POSSIBLE SIGNIFICANT PRECIPITATION ARE EXPECTED TO
BE OVER THE NORTHERN AND TROPICAL SECTIONS OF SOUTH
AMERICA...CENTRAL PERU...THE EAST COAST OF EAST CENTRAL BRAZIL
FROM RIO DE JANEIRO DE BAHIA...AND SOUTHERN CHILE FROM AYSEN TO
MAGALLANES. THERE IS ALSO SOME SNOW FORECAST ACROSS THE
MOUNTAINOUS SECTIONS OF SAN JUAN AND MENDOZA IN ARGENTINA ALONG
THE BORDER WITH CHILE...AS WELL AS SOME RAIN ALONG A LINE FROM
CORDOBA TO ENTRE RIOS IN ARGENTINA INTO SOUTHERN URUGUAY.

BASED ON THE LATEST GUIDANCE...IN TERMS OF LIQUID
PRECIPITATION...NORTHERN SOUTH AMERICA IS EXPECTED TO HAVE THE
MOST AMOUNT OF RAIN. THE 3-DAY PRECIPITATION TOTALS ACROSS
NORTHERN SOUTH AMERICA COULD RANGE BETWEEN 25 AND 75MM WITH
ISOLATED HIGHER AMOUNTS...POSSIBLY REACHING 100MM ACROSS ISOLATED
PORTIONS OF NORTHERN VENEZUELA AND NORTHERN COLOMBIA. THIS WOULD
BE DUE TO A COMBINATION OF FACTORS...INCLUDING DEEP TROPICAL
MOISTURE...TROPICAL WAVES PASSING BY AND SURFACE TROUGHS...ALL
THAT INTERACTING WITH THE LOCAL OROGRAPHIC AND DIURNAL EFFECTS.

EASTERN BRAZIL...ESPECIALLY OVER BAHIA COULD OBSERVE UP TO 60MM
OVER THE 3-DAY PERIOD...AS A FRONTAL BOUNDARY THAT MOVES OVER THE
ATLANTIC AND SKIRTS THE EAST COAST OF BRAZIL. THIS FRONTAL
BOUNDARY WILL BEGIN AS A COLD FRONT TODAY AND WILL GRADUALLY
WEAKEN AND BECOME STATIONARY BY LATE WEDNESDAY. THE DEEPER
MOISTURE AHEAD OF THE FRONTAL BOUNDARY WILL BE PUSHED IN BY THE
SOUTHEASTERLY WIND FLOW AND THEN INTERACT WITH THE LOCAL
TERRAIN...CAUSING A LOCALLY HIGHER AMOUNT OF RAINFALL OVER
PORTIONS OF THE BAHIA STATE IN BRAZIL. MEANWHILE...SOUTHERN CHILE
COULD OBSERVE A RAIN AND SNOW MIX...WITH THE HIGHER ELEVATIONS OF
MAGALLANES POSSIBLY OBSERVING AS MUCH AS 50CM OF SNOW OVER THE
3-DAY PERIOD. THE SNOWFALL EXPECTED ACROSS SAN JUAN AND MENDOZA IN
ARGENTINA CAN BE UP TO 40CM FOR THE 3-DAY PERIOD...BUT ALMOST ALL
OF THE PRECIPITATION IN THE AREA IS EXPECTED TO BE OBSERVED FROM
THURSDAY INTO FRIDAY.

AT THE SURFACE...THERE ARE SEVERAL LOW AND HIGH PRESSURE SYSTEMS
OVER THE WATERS. HOWEVER...ONE TO NOTE IS A LOW PRESSURE ACROSS
THE SOUTHERN PACIFIC...WHICH IS MOVING EAST INTO THE DRAKE
PASSAGE. THIS LOW PRESSURE HAS AN ASSOCIATED COLD FRONT THAT WILL
BE PASSING THROUGH SOUTHERN SOUTH AMERICA STARTING TONIGHT THROUGH
WEDNESDAY. THE PASSAGE OF THIS COLD FRONT WILL ALSO BRING
PRECIPITATION TO SOUTHERN SOUTH AMERICA IN THE FORM OF RAIN AND
SNOW MIX NEAR THE COAST TO SNOW FURTHER INLAND.

IN THE MID LEVELS...THERE IS A TROUGH THAT IS ALSO PASSING THROUGH
THE SOUTHERN PORTIONS OF SOUTH AMERICA ON WEDNESDAY...AND A MID
LEVEL LOW THAT IS APPROACHING THE WEST COAST OF NORTH CENTRAL
CHILE...WHICH WILL EVENTUALLY CROSS OVER CHILE INTO ARGENTINA ON
FRIDAY. HOWEVER...A MID LEVEL HIGH PRESSURE ACROSS SOUTHEASTERN
BRAZIL WILL CREATE A BLOCKING PATTERN...WHICH WILL KEEP THE OTHER
SYSTEMS AND FRONTS FROM MOVING FURTHER NORTH WHILE CREATING
SUBSIDENCE OVER THE AREA. FOR THIS REASON...MOST OF BRAZIL AND
BOLIVIA WILL REMAIN DRY FOR THE NEXT SEVERAL DAYS.


ALAMO...(WPC)
LOPEZ...(DMH PARAGUAY)