SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
336 PM EDT FRI JUL 12 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 12 JUL 2024 AT 1930 UTC:
ON FRIDAY...THE OVERALL PATTERN OVER MOST OF THE CONTINENT IS
EXPECTED TO REMAIN DRY. WITH THE POTENT BLOCKING PATTERN OVER THE
SOUTHERN CONE OF SOUTH AMERICA...FRONTAL BOUNDARIES ARE REMAINING
TO THE SOUTH OVER THE DRAKE PASSAGE AND TIERRA DEL FUEGO REGION.
THIS REGION IS EXPECTED TO SEE LITTLE PRECIPITATION OVER THE NEXT
THREE DAYS. AN UPPER LEVEL TROUGH IS LOCATED OVER SOUTHERN PERU
AND EXTEND INTO ARGENTINA AND URUGUAY...WHILE THE SUBTROPICAL JET
AND NORTHERN POLAR JET ARE COUPLING OVER SOUTHERN BRASIL AND EAST
PARAGUAY. ALTHOUGH THE DYNAMICS ARE PRESENT FOR CONVECTION OVER
THE REGION...THE AMOUNTS OF PRECIPITABLE WATER IN THE REGION IS
LIMITING THE POTENTIAL FOR HEAVIER PRECIPITATION FROM PARAGUAY
INTO SOUTHERN BRASIL. FROM SOUTHEAST PARAGUAY INTO PARANA AND
SANTA CATARINA BRASIL...EXPECT MAXIMA OF 20-35MM. ON
SATURDAY...THE UPPER LEVEL RIDGE OVER THE EAST PACIFIC IS EXPECTED
TO WEAKEN...WHILE AN UPPER LEVEL TROUGH TO THE WEST BEGINS
PROPAGATING EASTWARD. THE UPPER LEVEL TROUGH OVER THE CENTRAL
PORTION OF THE CONTINENT ALSO BEGINS TO WEAKEN AND THE SUBTROPICAL
JET BECOMES MORE ZONAL FROM NORTHERN CHILE INTO SOUTHERN BRASIL. A
SHORT WAVE TROUGH IN THE MID LEVELS IS EXPECTED TO PROPAGATE FROM
PARANA...SANTA CATARINA...AND INTO RIO GRANDE DO SUL. THESE
CONDITIONS FAVOR ASCENT OVER THE REGION FOR DEEP
CONVECTION...HOWEVER AVAILABLE MOISTURE REMAINS LOW OVER THE
REGION. A MAXIMA OF 30-60MM IS EXPECTED FROM PARANA INTO SANTA
CATARINA...WHILE A MAXIMA OF 20-45MM IS EXPECTED OVER RIO GRANDE
DO SUL. LOCALIZED HIGHER AMOUNTS ARE POSSIBLE AS THE REGION IS
EXPECTED TO BE IN THE CYCLONIC SIDE OF A LOW LEVEL JET ACROSS RIO
GRANDE DO SUL. ON SUNDAY...THE MID TO UPPER TROUGH IS MOSTLY
LOCATED OVER THE ATLANTIC OCEAN JUST EAST OF URUGUAY...WHERE IT
WILL FAVOR CYCLOGENESIS OVER THE OCEAN WATERS. ONSHORE FLOW FROM
THE EAST ASSOCIATED WITH THE CYCLOGENESIS IS EXPECTED INTO RIO
GRANDE DO SUL...WHERE EXPECT MAXIMA OF 30-60MM. THE COASTAL
REGIONS OF PARANA AND SANTA CATARINA...INTO CENTRAL RIO GRANDE DO
SUL COULD EXPECT GENERALIZED MAXIMA OF 15-25MM.

THE TROPICAL SOUTH AMERICAN REGION WILL CONTINUE TO SEE THE
PROPAGATION OF TROUGHS AND TROPICAL WAVES THAT WILL FAVOR
PRECIPITATION OVER THE FORECAST PERIOD. THE HEAVIEST PRECIPITATION
IS EXPECTED ON FRIDAY...WITH THE PASSING OF A WAVE AND SOUTHERLY
FLOW OVER COLOMBIA...CONVERGING AT THE NORTHERN ANDES MOUNTAINS.
THIS WILL FAVOR MAXIMA OF 30-60MM FROM CENTRAL COLOMBIA INTO
NORTHEAST ECUADOR. FROM NORTHERN PERU INTO WEST VENEZUELA CAN
EXPECT MAXIMA OF 20-35MM. AVAILABLE MOISTURE EXPECTED OVER THE
TROPICAL REGION HAS VALUES BELOW 55MM. ON SATURDAY A DECREASE IN
AVAILABLE MOISTURE IS EXPECTED IN NORTHERN BRASIL...AS AN UPPER
LEVEL RIDGE IS MEANDERING INTO THE REGION. MOISTURE CONVERGENCE
ALONG THE ANDEAN REGION OF SOUTHERN COLOMBIA AND EAST
ECUADOR...WILL FAVOR MAXIMA OF 20-40MM. ELSEWHERE AMOUNTS ARE
EXPECTED TO REMAIN BELOW 25MM. BY SUNDAY...THE DRYING TREND
CONTINUES AS THE RIDGE REMAINS OVER THE NORTHERN SOUTH AMERICA
REGION. THE PASSING OF THE TROUGHS WILL FAVOR MAXIMA BELOW 25MM IN
EAST ECUADOR...SOUTHERN VENEZUELA...AND THE GUIANAS.

ACOSTA...(WPC)