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South American Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1557Z Oct 14, 2014)
 
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SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1157 AM EDT TUE OCT 14 2014

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

MODEL DISCUSSION (VALID FROM OCTOBER 14 AT 00UTC): CONFIDENCE IN
THE FORECAST IS HIGH...WITH GLOBAL MODELS CONVERGING ON A SIMILAR
SOLUTION THROUGH DAY 06. THE DETERMINISTIC MODELS ARE WELL
SUPPORTED BY LARGE MAJORITY OF GLOBAL ENSEMBLE MEMBERS.

PROGRESSIVE MID LEVEL TROUGH ON THE NORTHERN STREAM IS TO ENTER
CENTRAL CHILE EARLY IN THE CYCLE. THROUGH 42/48 HRS IT IS TO
RAPIDLY PULL ACROSS ARGENTINA TO THE WESTERN ATLANTIC...THEN
MEANDER TO THE EAST-SOUTHEAST AS THE CYCLE PROGRESSES. AS THE
TROUGH ENTERS THE CONTINENT IT IS TO FOCUS A SUBTROPICAL JET
ACROSS CENTRAL/NORTHERN CHILE INTO ARGENTINA.
THIS...IN-TURN...FAVORS A DIVERGENT PATTERN ALOFT ACROSS NORTHERN
ARGENTINA-SOUTHERN BRASIL/URUGUAY BY 42-96 HRS. AT LOW
LEVELS...THIS IS TO SUSTAIN A BROAD OCCLUDED TROUGH OVER THE FAR
EASTERN PACIFIC EARLY IN THE CYCLE. THIS MOVES ACROSS SOUTHERN
CHILE TO PATAGONIA IN ARGENTINA BY 36/42 HRS...INTO THE WESTERN
ATLANTIC BY 48 HRS. ASSOCIATED FRONT RACES ACROSS PATAGONIA TO LA
PAMPA/MENDOZA IN ARGENTINA BY 42-48 HRS...AND ACROSS RIO DE LA
PLATA-CORDOBA IN ARGENTINA BY 72 HRS. FRONT IS TO THEN STALL OVER
URUGUAY/NORTHERN ARGENTINA THROUGH 96-108 HRS. AS THE FRONT ENTERS
SOUTHERN CHILE IT IS TO TRIGGER SCATTERED CONVECTION WITH RAINFALL
AMOUNTS OF 05-10MM. MOST ACTIVE IS EXPECTED ACROSS ENTRE RIOS IN
ARGENTINA/URUGUAY-RIO GRANDE DO SUL IN BRASIL ON DAYS 02-04. IN
THIS AREA...A NORTHERLY LOW LEVEL JET ACROSS PARAGUAY IS TO
SUSTAIN A WARM/MOIST ADVECTIVE PATTERN...WITH PRECIPITABLE WATER
CONTENT FORECAST TO INCREASE TO 50MM. IN THIS AREA EXPECTING
MAXIMA OF 30-60MM/DAY...WITH LOCALLY HIGHER AMOUNTS HIGHLY LIKELY
DUE TO STRONG MESO-SYNOPTIC FORCING.

THE NEXT MID LEVEL PERTURBATION ENTERS CENTRAL CHILE BY 84-96
HRS...RAPIDLY MOVING ACROSS THE ANDES INTO ARGENTINA BY 108
HRS...AND OFF THE COAST TO THE WESTERN ATLANTIC BY 120 HRS.
ASSOCIATED FRONT ENTERS SOUTHERN/CENTRAL CHILE BY 84 HRS...AND
THROUGH 96 HRS IT IS TO SPILL ACROSS THE ANDES INTO
PATAGONIA/CENTRAL PROVINCES IN ARGENTINA. AS IT ENTERS CHILE THE
FRONT/TROUGH IS TO SUSTAIN A SUBTROPICAL CONNECTION. THIS WILL
HELP SUSTAIN ORGANIZED CONVECTION AND RAINFALL AMOUNTS OF 15-20MM.

NORTH OVER THE CONTINENT...AT 200 HPA...A RIDGE EXTENDS SOUTH
ALONG 70W TO PATAGONIA IN ARGENTINA. A HIGH OVER SOUTHERN
ECUADOR/NORTHERN PERU IS TO ANCHOR THIS AXIS EARLY IN THE CYCLE.
THROUGH 72-96 HRS THE HIGH IS TO MEANDER WEST TO THE EASTERN
TROPICAL PACIFIC...TO CENTER NEAR 10S 90W LATER IN THE CYCLE. A
TROUGH LIES TO THE WEST...WITH AXIS ACROSS SAO PAULO IN BRASIL TO
ACRE/SOUTHERN AMAZONAS. THROUGH 72-84 HRS THE TROUGH IS TO MEANDER
NORTH INTO ESPIRITO SANTO/MINAS GERAIS IN BRASIL TO MATO
GROSSO/RONDONIA. RIDGE/TROUGH PAIR ALOFT IS TO VENT CONVECTION
OVER THE CONTINENT TO THE NORTH OF 10S...WITH MOST ACTIVE ACROSS
PARA-AMAZONAS IN BRASIL TO THE NORTHERN JUNGLE OF PERU/SOUTHERN
COLOMBIA. IN THIS AREA THE DAILY MAXIMA IS FORECAST TO PEAK AT
15-30MM.

CAROCA...DMC (CHILE)
DURAN...SENAHMI (PERU)
GALVEZ...WPC (USA)