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South American Forecast Discussion
 
(Latest Discussion - Issued 1846Z Oct 02, 2024)
 
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SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
246 PM EDT WED OCT 02 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 02 OCT 2024 AT 1845 UTC:

THE BOLIVIAN HIGH IS PRESENT OVER MOST OF THE NORTHERN AND CENTRAL
REGIONS OF SOUTH AMERICA. TO THE SOUTH...A BROAD UPPER LEVEL
TROUGH EXTENDS OVER MOST OF THE SOUTHERN CONE OF THE CONTINENT ON
WEDNESDAY. THE PRESENCE OF THE UPPER LEVEL CONDITIONS WILL FAVOR A
BLOCKING PATTERN OVER THE CENTRAL PORTIONS OF THE
CONTINENT...DECREASING THE EFFECTS OF THE UPPER TROUGH FURTHER
NORTH. IN THE LOWER LEVELS...A FRONTAL BOUNDARY IS PROGRESSING
NORTHWARD OVER CENTRAL BOLIVIA...THE BORDER OF
PARAGUAY/BRASIL...AND INTO SAO PAULO-BRASIL BY WEDNESDAY EVENING.
THE UPPER DIVERGENCE EXPECTED FROM THE PERIPHERY OF THE BOLIVIAN
HIGH WILL FAVOR MARGINAL RISK OF SEVERE WEATHER IN SOUTHERN BRASIL
ON WEDNESDAY. EXPECT MAXIMA OF 25-50MM IN SOUTHERN BRASIL. TO THE
NORTH...TROUGHS ALONG THE EASTERLY TRADES WILL PROPAGATE OVER THE
REGION...INCREASING THE AMOUNT OF AVAILABLE MOISTURE ON WEDNESDAY.
EXPECT MAXIMA OF 20-35MM FROM COLOMBIA TO ECUADOR...AND PERU. IN
THE SOUTHERN CONE OF THE CONTINENT...WEDNESDAY WILL SEE A MOIST
PLUME OF ABOUT 20-25MM OF PRECIPITABLE WATER ENTERING MAGALLANES
BY WEDNESDAY EVENING. THE WEAK SOUTH POLAR JET IS EXPECTED TO
PROVIDE DYNAMICS FOR SOME PRECIPITATION IN THE REGION OF RAIN AND
SNOW MIX. EXPECT MAXIMA OF 15-30MM.

ON THURSDAY...THE BOLIVIAN HIGH IS EXPECTED TO CONTINUE TO MEANDER
OVER BOLIVIA/SOUTH PERU AND EXTEND FURTHER SOUTH...AS THE UPPER
TROUGH CONTINUES PROPAGATING EASTWARD...INTO THE ATLANTIC OCEAN.
THIS SOUTHWARD EXTENSION WILL FAVOR DRIER CONDITIONS OVER
PARAGUAY...NORTH ARGENTINA...AND PORTIONS OF SOUTHERN BRASIL. THE
FRONTAL BOUNDARY CONTINUED TO MOVE NORTH AND EASTWARD AND EXPECTED
OVER RIO DE JANEIRO AND EXTENDING NORTHWARD INTO MINAS
GERAIS...AND WEAKENING OVER GOIASÂAND MATO GROSSO...AS THE
EFFECTS OF THE UPPER RIDGE WILL WEAKEN THE SYSTEM. TO THE
NORTH...THE CONTINUED ADVECTION OF MOISTURE OVER THE GUIANAS AND
VENEZUELA IS EXPECTED TO CONTINUE. ENHANCED MOISTURE CONVERGENCE
IS EXPECTED AS THE TROUGHS PROPAGATE OVER THE MOUNTAINOUSÂREGIONS
OF THE SHIELD OF THE GUIANAS. FROM SANTA CATARIAN TORIO DE JANEIRO
EXPECT MAXIMA OF 20-40MM ALONG THE COASTAL REGIONS.  FROM SOUTHERN
VENEZUELA...INTO EAST COLOMBIA...AND AMAZONAS-BRASIL EXPECT MAXIMA
OF 20-45MM. THE GUIANAS...INTO AMAPA AND PARA...AND RFOM SOUTH
COLOMBIAINTO PERU AND WEST AMAZONAS-BRASIL EXPECT MAXIMA OF
20-35MM. IN SOUTHERN CHILE...A DECREASE IN PRECIPITATIONÂIS
EXPECTED AS A RIDGE BEGINS TO ENTER THE REGION AND A DECREASE IN
AVAILABLE MOISTURE IS EXPECTED. MAXIMA COULD REMAIN BELOW 20MM IN
MAGALLANES.

BY FRIDAY...THE BOLIVIAN HIGH BECOMES A POTENT PATTERN OVER SOUTH
AMERICA. THE FRONTAL BOUNDARY OVER SOUTHERN BRASIL CONTINUES TO
WEAKEN...YET IT FAVORS ONSHORE FLOW ALONG THE COASTS OF RIO DE
JANEIRO AND ESPIRITOÂSANTO BY FRIDAY EVENING. A TROUGH FROM THE
REMNANTS OF THE FRONT EXTENDS INLAND INTO MINAS
GERAIS...GOIAS...AND MATO GROSSO...WHERE IT WILL TRIGGER
PRECIPITATION ON FRIDAY OF MAXIMA OF 15-30MM IN SAO PAULO AND RIO
DE JANEIRO. TO THE NORTH...THE TROUGHS MOVING ALONG THE TRADES
WILL BE CONVERGING ALONG VENEZUELA...PARA...THE GUIANAS...AND
PORTIONS OF EAST AMAZONAS...WHERE AN INCREASE IN AVAILABLE
MOISTURE IS EXPECTED. UPPER DIVERGENT CONDITIONS DUE TO THE
INTERACTION BETWEEN THE PERIPHERY OF THE BOLIVIAN HIGH AND AN
UPPER TROUGH EXTENDING INTO VENEZUELA FROM THE CENTRAL ATLANTIC
WILL FAVOR DEEP CONVECTION OVER THE REGION. EXPECT MAXIMA OF
25-50MM IN THE GUIANAS AND EAST VENEZUELA. NORTHWESTERN BRASIL CAN
EXPECT MAXIMA OF 20-35MM AS MOISTURE CONVERGENCE IS EXPECTED IN
THE REGION.

ACOSTA...(WPC)
LOPEZ...(DMH-PARAGUAY)