915
FXSA20 KWBC 041828
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 PM EDT FRI OCT 04 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 04 OCT 2024 AT 1830 UTC:
A FRONT IS PROPAGATING NORTHWARD ACROSS SOUTHEAST BRASIL AND IS
FORECAST FROM ESPIRITO SANTO ON FRIDAY...INTO CENTRAL BAHIA BY
SUNDAY. EXPECT A GRADUAL DECREASE OF PRECIPITATION WITH THIS
SYSTEM AS IT PROPAGATES NORTHWARD DUE TO A DECREASE IN AVAILABLE
MOISTURE AS WELL AS A DECREASE IN THE ONSHORE COMPONENT OF THE
LOW-LEVEL WINDS. ON FRIDAY...EXPECT MAXIMA OF 15-30MM IN RIO DE
JANEIRO AND ESPIRITO SANTO...DECREASING AFTERWARDS.
IN TROPICAL SOUTH AMERICA...THE SUBTROPICAL UPPER RIDGE OR
BOLIVIAN HIGH CONTINUES UNUSUALLY WELL ORGANIZED FOR THIS TIME OF
THE YEAR. IN NORTHERN SOUTH AMERICA...THIS IS AIDING WITH THE
VENTILATION OF CONVECTION...ALLOWING FOR MODERATE RAINFALL AMOUNTS
AS IT IS COMBINING WITH THE CLIMATOLOGICAL START OF THE RAINY
SEASON. FURTHER SOUTH...HOWEVER...A ROBUST MID-LEVEL RIDGE HAS
ESTABLISHED IN PARAGUAY/SOUTHWEST BRASIL. THIS WILL STIMULATE FAIR
WEATHER CONDITIONS AND WARM TEMPERATURES IN THE REGION. NOTE THAT
THE RIDGE IS EXPECTED TO HAVE GEOPOTENTIAL HEIGHTS OVER 5910 GPM
AT 500 HPA THROUGH SUNDAY...WHICH OFTEN MEANS STRONG IMPACTS IN
SUBSIDENCE IN THE REGION. THIS IS CONSISTENT WITH A SHARP
DECREASING TREND IN AMOUNTS IN SOUTHWEST BRASIL THROUGH THE CYCLE.
IN THE LOW-LEVELS...AN EASTERLY WAVE-LIKE FEATURE IS PROPAGATING
FROM 63-65W ON FRIDAY INTO THE ANDES OF PERU AND ECUADOR BY
SUNDAY. THIS SYSTEM WILL CONTINUE TO ENHANCE CONVECTION IN THE
REGION. ON FRIDAY...EXPECT MAXIMA OF 20-45MM IN RORAIMA...AND
MAXIMA OF 15-30MM IN AMAZONAS AND ACRE IN BRAZIL. ON SATURDAY
EXPECT MAXIMA OF 20-45MM IN RORAIMA AND MAXIMA OF 20-35MM IN FAR
NORTHWEST BRASIL AND IN CENTRAL AND NORTHERN PERU. ON
SUNDAY...EXPECT MAXIMA OF 20-35MM IN NORTHERN AND CENTRAL PERU AND
IN MOST OF THE COLOMBIAN AMAZON. ALSO...THE ACTIVATION OF THE
BOLIVIAN HIGH WILL CONTINUE TO FAVOR A FEW AFTERNOON THUNDERSTORMS
IN THE BOLIVIAN ALTIPLANO...TO PRODUCE CONSERVATIVE RAINFALL
AMOUNTS.
ANOTHER SYSTEM IF INTEREST IS A MID-UPPER TROUGH IN THE WESTERLIES
THAT IS PROPAGATING EASTWARD ALONG 94-96W ON FRIDAY. AS THIS
TROUGH APPROACHES THE ANDES OF CENTRAL CHILE...EXPECT AN
ACTIVATION OF ANDEAN SNOWFALL AS WELL AS A GRADUAL ACTIVATION OF
DEEP CONVECTION EAST OF THE ANDES. IN THE LOW-LEVELS...EXPECT AN
INTENSIFICATION OF THE CHACO LOW AND A GRADUAL DECREASE IN SURFACE
PRESSURES AS FAR AS INTERIOR PORTIONS OF CENTRAL ARGENTINA BY
SUNDAY. THIS WILL STIMULATE THE DEVELOPMENT OF LOW-LEVEL JETS...TO
AID WITH THE BUILDING OF A MOIST POOL IN THE REGION. EXPECT
ACTIVATION OF CONVECTION ON SATURDAY AS THE CHACO LOW AND
ASSOCIATED SURFACE TROUGHS INTERACT WITH SHORT WAVE MID-LEVEL
TROUGHS EXITING SOUTHERN BOLIVIA. ENHANCED VERTICAL WIND SHEAR AND
MID-LEVEL WARMING ASSOCIATED WITH THE MID-LEVEL RIDGE WILL LIMIT
MAXIMA OF 15-20MM IN NORTH-CENTRAL ARGENTINA AND SOUTHWEST
PARAGUAY. BY SUNDAY...EXPECT MAXIMA OF 20-45MM BETWEEN
TUCUMAN/SANTIAGO DEL ESTERO AND CORDOBA AND NORTHERN SAN
LUIS/MENDOZA IN CENTRAL ARGENTINA. LIGTHER ACCUMULATIONS ARE
EXPECTED IN NORTHEAST ARGENTINA AS WELL AS IN LA PAMPA/SOUTHERN
CORDOBA.
IN SOUTHERN SOUTH AMERICA...A PRONOUNCED WARMING TREND WILL LIMIT
AREAS OF SNOWFALL AS THE CYCLE PROGRESSES YIELDING TO MOSTLY
LIQUID PRECIPITATION IN LOW-LEVEL BY SATURDAY. EXPECT CONSERVATIVE
PRECIPITATION AMOUNTS...PRIMARILY CLUSTERING IN THE DARWIN
CORDILLERA.
GALVEZ...(WPC)
LOPEZ...(DMH-PARAGUAY)
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