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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1442Z Dec 11, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
942 AM EST THU DEC 11 2014

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

SYNOPSIS (VALID FROM DECEMBER 11 AT 00UTC): THE 200 HPA ANALYSIS
SHOWS A RIDGE EXTENDING FROM A CLOSED HIGH OFF THE CENTRAL COAST
OF PERU...ACROSS SOUTHERN BOLIVIA/PARAGUAY-SOUTHERN STATES OF
BRASIL. EAST OF THIS AXIS...OVER BRASIL...AN ILL ORGANIZED TROUGH
EXTENDS BETWEEN 65W-48W. THIS IS ENHANCING CONVECTION ACROSS
PARA-AMAZONAS-RONDONIA IN BRASIL.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG
65S 119W...A 157KT MAXIMUM AT 63S 100W...54S 77W...EXITING AT 55S
53W. THE NORTHERN POLAR HAS ITS ENTRANCE AT 42S 54W...ALONG 43S
42W...49S 29W...A 136KT MAXIMUM AT 42S 08W...AND 41S 01W. THE
SUBTROPICAL JET HAS ITS ENTRANCE AT 27S 92W...ALONG 27S 80W...33S
71W...36S 57W...37S 46W...43S 32W...EXITING AT 40S 18W. THE JET
HAS A FINGER TO THE NORTH WITH ENTRANCE AT 20S 82W...ALONG 27S
70W...30S 60W...EXITING AT 31S 52W.

AT 500 HPA...MID LEVEL ANALYSIS SHOWS A TIGHT BELT OF MID LATITUDE
WESTERLIES ACROSS THE SOUTH PACIFIC INTO THE DRAKE
PASSAGE/SOUTHERN CONE. A BUILDING RIDGE TO THE WEST NOW EXTENDS
ALONG 120W/125W TO 60S. THIS IS STEERING SHORT WAVE VORTICES
NORTHWARD ACROSS THE BELLINGSHAUSEN SEA/DRAKE PASSAGE TO TIERRA
DEL FUEGO/SOUTHERN PATAGONIA. OTHER PERTURBATIONS POPULATE THE
NORTHERN STREAM FLOW...WITH ONE CENTERING ON A LOW NEAR 35S 95W AS
ANOTHER PULLS ACROSS 85W. A STRONGER PERTURBATION LIES TO THE
EAST...EXTENDING FROM A CLOSED LOW NORTH OF THE SOUTH GEORGIA
ISLANDS TO RIO GRANDE DO SUL IN BRASIL.

AT LOW LEVELS...A RIDGE OVER THE EASTERN PACIFIC CENTERS ON A 1029
HPA HIGH AT 42S 91W. A BROAD TROUGH LIES TO THE SOUTH...EXTENDING
NORTH FROM THE BELLINGSHAUSEN SEA/ANTARCTIC PENINSULA TO SOUTHERN
PATAGONIA IN ARGENTINA WHILE CENTERING ON AN OCCLUDED 962 HPA LOW
AT 65S 70W. A POLAR FRONT REVOLVES AROUND THIS AXIS AS IT EXTENDS
ALONG A 964 HPA LOW AT 65S 46W...63S 41W...60S 40W...A 984 HPA LOW
AT 59S 44W...57S 46W...55S 49W...52S 56W...A 1002 HPA LOW AT 51S
62W...50S 68W...50S 74W...A 1006 HPA LOW AT 52S 81W...50S
85W...51S 90W TO 53S 101W. THIS SUSTAINS SCATTERED RAINS ACROSS
TIERRA DEL FUEGO/EXTREME SOUTHERN CHILE. ANOTHER FRONT ON THE
NORTHERN STREAM EXTENDS FROM AN OCCLUDED 978 HPA LOW AT 49S
41W...ALONG A 980 HPA LOW AT 50S 36W...49S 33W...46S 32W...A 988
HPA LOW AT 46S 35W...41S 35W...39S 38W...A 1006 HPA LOW AT 37S
42W...RIO GRANDE DO SUL/NORTHERN URUGUAY TO MENDOZA IN ARGENTINA.
SCATTERED CONVECTION WAS BUILDING ALONG AND NORTH OF THIS
BOUNDARY. A POLAR RIDGE TO THE SOUTH CENTERS ON A 1021 HPA HIGH AT
38S 58W.

ARREAGA...INAMHI (ECUADOR)
DURAN...SENAMHI (PERU)
DAVISON...WPC (USA)