SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EST FRI NOV 29 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 29 NOV 2024 AT 1800 UTC: A
MID-UPPER TROUGH PROPAGATING ACROSS THE BELLINGSHAUSEN SEA IS
SUSTAINING A TRAIN OF FRONTS THAT IS FORECAST TO ENTER THE
SOUTHERN CONE EARLY ON SATURDAY MORNING. LONG-FETCH SOUTHWESTERLY
FLOW IN THE LOWER TROPOSPHERE WILL YIELD TO AN IMPORTANT DECREASE
IN TEMPERATURES AND AN INCREASE IN THE AREA WITH SNOW SHOWERS OR
MIXED PRECIPITATION ON SATURDAY. ON FRIDAY EXPECT MAXIMA OF
20-35MM IN WESTERN MAGALLANES AS MOIST AND ACCELERATED WESTERLIES
STIMULATE MOISTURE CONVERGENCE. ON SATURDAY...EXPECT MAXIMA OF
25-30MM IN NORTHWEST MAGALLANES AND SOUTHERN AYSEN. EXPECT A MIX
OF RAIN AND SNOW AND LIGHTER ACCUMULATIONS IN THE DARWIN
CORDILLERA AND PORTIONS OF SOUTHERN PATAGONIA. THE FRONT WILL
START WEAKENING ON SUNDAY. BY SUNDAY EVENING EXPECT THE BOUNDARY
ACROSS ARAUCANIA...WHERE EXPECT VERY LITTLE PRECIPITATION...AND
ACROSS THE CENTRAL BUENOS AIRES PROVINCE.

A MID-UPPER TROUGH IS FORECAST TO CROSS THE ANDES OF
CENTRAL/SOUTHERN CHILE ON SATURDAY. THIS WILL STIMULATE THE
POTENTIAL FOR DEEP CONVECTION IN INTERIOR PORTIONS OF CENTRAL
ARGENTINA ON SATURDAY...WHERE EXPECT 15-20MM/DAY AND ISOLATED
MAXIMA OF 30-60MM WITH A SLIGHT RISK FOR SEVERITY. IN NORTHERN
PATAGONIA EXPECT MAXIMA OF 15MM ALSO WITH A SLIGHT RISK FOR
SEVERITY. ON SUNDAY...EXPECT CYCLOGENESIS TO DEVELOP OFF THE EAST
COAST OF URUGUAY. THE RAPIDLY ORGANIZING FRONT IS FORECAST TO
PROPAGATE NORTHWARD RAPIDLY FROM CENTRAL ARGENTINA EARLY ON SUNDAY
TO SOUTHERN RIO GRANDE DO SUL...CORRIENTES...FAR SOUTH PARAGUAY
AND SALTA BY SUNDAY EVENING. STRONG LOW-LEVEL WINDS FROM THE SOUTH
WILL STIMULATE FAST PROPAGATION BUT ALSO ENHANCE MOISTURE
CONVERGENCE FAVORING HEAVY RAINFALL EXPECT THE LARGEST
ACCUMULATIONS FROM RIO GRANDE DO SUL AND CORRIENTES INTO SOUTHEAST
PARAGUAY...MISIONES-ARGENTINA AND WEST SANTA CATARINA WHERE THE
FORECASTS INDICATES 15-30MM/DAY AND MAXIMA OF 50-100MM WITH A RISK
OF NOCTURNAL MCS FORMATION. IN URUGUAY...SOUTHERN CORRIENTES/ENTRE
RIOS AND THE RIO DE LA PLATA REGION EXPECT 15-20MM/DAY AND
ISOLATED MAXIMA OF 25-50MM WITH A MARGINAL RISK FOR SEVERITY.

A REGION EXPECTED TO REMAIN SEASONALLY ACTIVE IN TERMS OF DIURNAL
CONVECTION AND PRECIPITATION ARE THE ANDES OF BOLIVIA AND PERU.
THE PERSISTENT VENTILATION OF THE BOLIVIAN HIGH AND TRANSPORT OF
MOISTURE FROM THE EAST WILL STIMULATE CONVECTION AND RAINFALL ON A
DAILY BASIS. ON FRIDAY AND SATURDAY EXPECT MAXIMA OF 15-25MM FROM
SOUTHERN PERU INTO THE CENTRAL BOLIVIAN ALTIPLANO. ON SUNDAY
EXPECT A DECREASE TO MAXIMA OF 15MM.

EAST OF THE ANDES...DIURNAL CONVECTION IS EXPECTED TO CLUSTER IN
CENTRAL AND SOUTHEAST BRASIL ON A DAILY BASIS TO FAVOR MAXIMA
GENERALLY IN THE 15-35MM/DAY RANGE WITH EXCEPT OF VERY ISOLATED
HIGHER AMOUNTS. MUCH DRIER CONDITIONS ARE EXPECTED IN NORTHERN AND
CENTRAL PORTIONS OF THE AMAZON...PARTICULARLY BETWEEN 02N AND
12S...ESPECIALLY ON SATURDAY AND SUNDAY.

GALVEZ...(WPC)