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South American Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1934Z Jul 01, 2024)
 
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SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
334 PM EDT MON JUL 01 2024

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

SOUTH AMERICAN DISCUSSION FOR 01 JUL 2024 AT 19 UTC: A MID-UPPER
RIDGE IS BUILDING OVER THE EASTERN PACIFIC...WHICH IS LIMITING
SYSTEMS IN THE WESTERLIES TO SOUTHERN AND SOUTH-CENTRAL CHILE OR
TO LATITUDES SOUTH OF 36-38S. EMBEDDED IN THE WESTERLIES...SEVERAL
SHORT WAVE PERTURBATIONS ARE PROPAGATING FROM WEST TO EAST. ON
MONDAY...A SHORT WAVE TROUGH WILL INTERACT WITH AN ATMOSPHERIC
RIVER OF 20-25MM TO FAVOR MODERATE PRECIPITATION BETWEEN SOUTHERN
BIO BIO AND LOS LAGOS IN CHILE. EXPECT AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 30-60MM...ACCOMPANIED BY A RISK OF SNOW IN ELEVATED
TERRAIN. EAST OF THE ANDES...A MIX OF RAIN AND SNOW IS EXPECTED IN
INTERIOR PORTIONS OF RIO NEGRO AND SOUTHERN NEUQUEN. ALTHOUGH PART
OF THIS SNOW MIGHT BE WET...EXPECT ACCUMULATION OF 01-05CM AND
MAXIMA OF 10CM. ON TUESDAY THIS DECREASES TO 05-10MM AND ISOLATED
MAXIMA OF 15-20MM IN LOS LAGOS...ALTHOUGH ISOLATED MOUNTAIN SNOW
IS POSSIBLE. THIS DECREASES THEREAFTER.

IN THE SOUTHERN STREAM...A LARGE MID-UPPER LOS EXTENDS OVER THE
BELLINGSHAUSEN SEA AND IS ACCOMPANIED BY AN UPPER JET ALONG ITS
REAR END. THIS IS FORECAST TO YIELD TO THE AMPLIFICATION OF THE
TROUGH AS IT MOVES EASTWARD DURING THE NEXT FEW DAYS. THE TROUGH
IS FORECAST TO CROSS THE SOUTHERN CONE ON TUESDAY/EARLY
WEDNESDAY...YIELDING TO AN EXTENSIVE PERIOD WITH SOUTHERLY FLOW
THROUGH THE WEST OF THE WORK WEEK. THIS WILL FAVOR ANOTHER ROUND
OF LOW TEMPERATURES AND PERIODS OF SNOWFALL IN AREAS SOUTH OF 40S.
ON MONDAY...A SURFACE FRONT IS FORECAST TO ARRIVE IN THE SOUTHERN
CONE IN THE EFENING ACCOMPANIED BY A TIGHT BELT OF WESTERLIES.
THIS WILL FAVOR SNOFALL AMOUNTS OF 01-05CM/DAY AND MAXIMA OF 15MM
IN WESTERN SLOPES AND ELEVATED TERRAIN OF NORTHERN MAGALLANES IN
CHILE. ON TUESDAY...A SECOND FRONT IS FORECAST TO ARRIVE FROM THE
SOUTHWEST ACCOMPANIED BY 35-50KT BOUNDARY LAYER WINDS. THIS WILL
LIKELY FAVOR SNOWFALL AMOUNTS OF 05-10CM/DAY AND ISOLATED MAXIMA
OF 15-25CM IN NORTHERN MAGALLANES/SOUTHERN AYSEN AND PORTIONS OF
FAR WESTERN SANTA CRUZ IN ARGENTINA. ON WEDNESDAY...COLD AIR IS
FORECAST TO EXTEND NORTH INTO LOS LAGOS...WHERE MODELS ARE
SUGGESTING THE 5280 1000-500 HPA THICKNESS CONTOUR REACHING PUERTO
MONTT AND BARILOCHE. THIS WILL FAVOR PERIODS WITH MIXED
PRECIPITATION IN THESE REGIONS WITH LIQUID ACCUMULATION OF
01-05MM/DAY AND MAXIMA OF 10MM. SOUTH-SOUTHWESTERLY FLOW IN AREAS
TO THE SOUTH WILL LIKELY FAVOR 05-10CM/DAY AND ISOLATED MAXIMA OF
15-25CM FROM WESTERN MAGALLANES INTO SOUTHERN AYSEN...WHILE
LIGHTER SNOW SHOWERS PERSTER THE REST OF TIERRA DEL FUEGO AND
SOUTHERN PATAGONIA.

A SURFACE FRONT IS WEAKENING IN THE COAST OF ESPIRITO
SANTO-BRASIL. GIVEN 35-40MM PRECIPITABLE WATER AMOUNTS AND ONSHORE
FLOW THROUGH EARLY TUESDAY...EXPECT AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-35MM ALTHOUGH VERY ISOLATED HIGHER AMOUNTS ARE
POSSIBLE. ACCUMULATIONS DECREASE THEREAFTER.

QUIET CONDITIONS ARE EXPECTED IN TROPICAL PORTIONS OF SOUTH
AMERICA. THE LARGEST ACCUMULATIONS ARE LIKELY TO CLUSTER IN AREAS
TO THE NORTH OF THE EQUATOR...PARTIALLY ASSOCIATED WITH TROPICAL
WAVES ASSOCAITED WITH THE PERTUBATIONS IN THE CARIBBEAN/TROPICAL
NORTH ATLANTIC. STILL...MAXIMA IN THUNDERSTORMS THAT FORM IN AREAS
SOUTH OF THE EQUATOR IS LIKELY TO LIMIT TO 15-25MM/DAY.

GALVEZ..(WPC)
PALAVECINO (SMN-ARGENTINA)
SARABIA (DMC-CHILE)