SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
409 PM EDT THU AUG 22 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 22 AUG 2024 AT 20:10 UTC:

A SLOW-MOVING AND BROAD POLAR TROUGH IS CROSSING THE ANDES AND
SUSTAINING CYCLOGENESIS OFF THE COAST OF THE RIO DE LA PLATA
REGION. A REMARKABLE CHARACTERISTIC IS THE COLD AIR ASSOCIATED
WITH THIS TROUGH...WHICH REFLECTS ON LOW THICKNESS VALUES. MODELS
CONTINUE FORECASTING 1000-500 HPA THICKNESS REACHING 5340-5400 AS
FAR NORTH AS SANTA CATARINA ON SATURDAY. IN THE SURFACE EXPECT TWO
SURFACE FRONTS ASSOCIATED WITH THE CYCLOGENETIC PROCESS. THE
NORTHERN FRONT IS FORECAST TO MOVE FROM SANTA
CATARINA-PANTANAL-CENTRAL BOLIVIA ON THURSDAY INTO RIO DE
JANEIRO...CENTRAL MATO GROSSO...NORTHERN BOLIVIA...SOUTHERN PERU.
MOST PRECIPITATION WILL FOCUS WITH THE SOUTHERN FRONT...WHICH IS
FORECAST TO MOVE FROM RIO GRANDE DO SUL...MISIONES...CENTRAL
PARAGUAY ON THURSDAY...TO DISSIPATE ACCROSS
PARANA-BRASIL...PANTANAL BY SATURDAY.

IN TERMS OF PRECIPITATION...EXPECT STRONG THUNDERSTORMS TO DEVELOP
ON THURSDAY EXTENDING FROM THE CHACO PARAGUAYO INTO RIO GRANDE DO
SUL. THE LARGEST AMOUNTS ARE EXPECTED IN CENTRAL AND SOUTHERN
PARAGUAY AND MISIONES...WHERE EXPECT MAXIMA OF 50-100MM WITH A
MODERATE RISK FOR SEVERITY. DOWNSTREAM IN RIO GRANDE DO SUL/WEST
SANTA CATARINA EXPECT MAXIMA OF 25-50MM WITH A SLIGHT RISK OF
SEVERE CONVECTION. ONFRIDAY...EXPECT MAXIMA OF 20-40MM IN EASTERN
AND NORTHEAST PARAGUAY AND PARANA IN BRASIL...WITH A MARGINAL RISK
FOR SEVERE CONVECTION. ALONG THE SOUTHERN FRONT IN SANTA
CATARINA/RIO GRANDE DO SUL EXPECT MAXIMA OF 15-30MM. ON
SATURDAY...EXPECT THE LARGEST AMOUNTS IN EASTERN
PARANA-BRASIL...AS ONSHORE FLOW AND THE WEAKENING FRONT FAVOR
MAXIMA OF 20-45MM. IN EASTERN PARAGUAY/SOUTHERN MATO GROSSO DO SUL
EXPECT MAXIMA OF 20-35MM. ALSO ON SATURDAY...AS THE TAIL OF THE
FRONT INTERACTS WITH THE ANDES IN SOUTHERN PERU/NORTHERN
BOLIVIA...EXPECT AMOUNTS TO INCREASE TO MAXIMA OF 20-35MM. NOTE
THA INDIRECT IMPACTS OF THE FRONT WILL FAVOR LIGHT SNOWFALL IN THE
ANDES OF CENTRAL PERU.

ELSEWHERE IN SOUTHERN SOUTH AMERICA...A REMNANT OCCLUDED LOW
CONTINUES MEANDERING ONSHORE IN CENTRAL CHILE. ONSHORE FLOW WILL
FAVOR ADDITIONAL ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-30MM
ON THURSDAY...AS WELL AS MOUNTAIN SNOW...BETWEEN O'HIGGINS AND BIO
BIO PRIMARILY. ACCUMULATIONS DECREASE THEREAFTER.

QUIET CONDITIONS ARE EXPECTED IN TROPICAL REGIONS OF SOUTH AMERICA
GIVEN LIMITED AVAILABLE MOISTURE AND UPPER CONVERGENT MJO
CONDITIONS.

GALVEZ...(WPC)
PALAVECINO...(SMN ARGENTINA)
LOPEZ...(DMH PARAGUAY)