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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1246Z Sep 29, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
846 AM EDT MON SEP 29 2014

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

SYNOPSIS (VALID FROM SEPTEMBER 29 AT 00UTC): THE 200 HPA ANALYSIS
SHOWS A CELL OF THE SUBTROPICAL RIDGE OVER THE CONTINENT TO THE
NORTH OF 34S...WITH AXIS ANCHORING ON A CLOSED HIGH OVER BRASIL
NEAR 15S 50W. A TROUGH LIES TO THE NORTH-NORTHWEST...CENTERING ON
A LOW OVER RORAIMA. THE RIDGE ALOFT IS VENTING SCATTERED
CONVECTION ACROSS MATO GROSSO-SOUTHERN PARA IN BRASIL...WHILE THE
TROUGH ALOFT FAVORS AN UPPER CONVERGENT PATTERN THAT IS INHIBITING
DEEP CONVECTION ACROSS EQUATORIAL SOUTH AMERICA.

AT 250 HPA...THE SOUTHERN POLAR HAS ITS ENTRANCE AT 42S
89W...ALONG 41S 81W...45S 71W...44S 57W...A 137KT MAXIMUM AT 46S
41W...EXITING AT 46S 29W. THE NORTHERN POLAR LIES ALONG 34S
120W...A 137KT MAXIMUM AT 34S 114W...35S 101W...EXITING AT 32S
90W. IT REFORMS AT 38S 59W...ALONG A 132KT MAXIMUM AT 42S
45W...EXITING AT 39S 27W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT
21S 76W...ALONG A 27S 69W...A 137KT MAXIMUM AT 31S 60W...31S
39W...23S 31W...EXITING AT 22S 28W.

AT 500 HPA...IN A SPLIT FLOW PATTERN...THE FLOW DIVIDES BETWEEN A
RIDGE ON THE SOUTHERN STREAM AND A TROUGH TO THE NORTH. THE RIDGE
EXTENDS ALONG 90W AND TO THE SOUTH OF 50S...AS IT ANCHORS ON A
HIGH NEAR 63S 93W. THE TROUGH TO THE NORTH...MEANWHILE...EXTENDS
FROM A CLOSED LOW AT 44S 86W...ALONG 32S 81W...TO 23S 87W. THIS IS
FOCUSING SHORT WAVE ENERGY ACROSS CENTRAL/NORTHERN CHILE TO
ARGENTINA. A BROAD TROUGH DOMINATES FLOW ACROSS THE SOUTH
ATLANTIC...AS IT EXTENDS BETWEEN 70W-00W AND TO THE SOUTH OF 35S.
UNDER INFLUENCE OF THE RIDGE TO THE WEST...A PROGRESSIVE CLIPPER
LOW LIFTED ACROSS THE DRAKE PASSAGE...CENTERING JUST EAST OF
TIERRA DEL FUEGO. FARTHER NORTH...A MID LEVEL RIDGE EXTENDS WEST
ACROSS THE TROPICAL ATLANTIC TO CENTRAL BRASIL. THIS FAVORS A MID
LEVEL CAP INVERSION THAT IS INHIBITING DEVELOPMENT ACROSS
NORTHEAST BRASIL.

AT LOW LEVELS...IN A SPLIT FLOW...A RIDGE ON THE SOUTHERN STREAM
EXTENDS NORTH ACROSS THE BELLINGSHAUSEN SEA TO THE SOUTHEAST
PACIFIC WHILE CENTERING ON A 1013 HPA HIGH AT 61S 89W. NORTH OF
THIS AXIS...AN OCCLUDED 1000 HPA LOW AT 44S 85W EXTENDS A FRONT
ALONG A 1008 HPA LOW AT 47S 84W...A 1008 HPA LOW AT 44S 80W...38S
79W...TO 34S 86W. FARTHER EAST...OVER THE SOUTH ATLANTIC...A BROAD
TROUGH DOMINATES THE FLOW AS IT CENTERS ON AN OCCLUDED 952 HPA LOW
AT 68S 33W. POLAR FRONTS REVOLVE AROUND THIS AXIS...WITH ONE THAT
EXTEND ALONG A 1002 HPA LOW AT 49S 35W...45S 38W...43S 45W...A
1006 HPA LOW AT 43S 51W...TO URUGUAY. AN OLD FRONT TO THE EAST AND
NORTH LIES ALONG A 1022 HPA LOW AT 32S 27W...29S 33W...28S
40W...RIO GRANDE DO SUL...A 1006 HPA LOW OVER CORRIENTES ARGENTINA
TO FORMOZA. THIS SUSTAINS ORGANIZED DEEP CONVECTION ACROSS
SOUTHERN BRASIL TO MESOPOTAMIA VALLEY IN ARGENTINA/SOUTHEAST
PARAGUAY.

JALFIN...SMN (ARGENTINA)
CAROCA...DMC (CHILE)
DAVISON...WPC (USA)