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South American Synoptic Discussion
 
(Latest Discussion - Issued 1327Z Sep 19, 2017)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
927 AM EDT TUE SEP 19 2017

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

SYNOPSIS (VALID FROM SEP 19 AT 0000 UTC): AT 200 HPA...A BUILDING
RIDGE DOMINATES THE FLOW OVER THE CONTINENT...WITH AXIS ANCHORING
ON TWO CLOSED HIGHS...WITH ONE OVER THE ALTIPLANO OF BOLIVIA AND
THE OTHER NEAR 12S 53W. THE RIDGE ALOFT IS VENTING DEEP DIURNAL
CONVECTION ACROSS PARA-AMAZONAS IN BRASIL.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET EXTENDING
ALONG 62S 120W...A 137KT MAXIMA AT 65S 93W...62S 70W...59S
59W...57S 44W...A 134KT MAXIMA AT 57S 34W...EXITING AT 53S 05W.
ANOTHER BRANCH FORMS AHEAD OF A LARGE TROUGH AT 43S 78W ALONG A
136KT MAXIMA AT 52S 56W...A 169KT MAXIMA AT 53S 37W...A 135KT
MAXIMA AT 52S 21W...EXITING AT 43S 01W. THE NORTHERN POLAR JET
FORMS AT 27S 89W ALONG 36S 80W...43S 70W...47S 55W...48S
35W...EXITING AT 42S 17W. THE SUBTROPICAL EXTENDS A BRANCH FROM
21S 100W ALONG A 135KT MAXIMA AT 22S 89W...A 157KT MAXIMA AT 30S
80W...A 141KT MAXIMA AT 37S 72W...EXITING AT 37S 59W. ANOTHER
BRANCH FORMS AT 16S 96W ALONG 20S 90W...26S 80W...33S 70W...29S
60W...23S 55W...EXITING AT 20S 48W. IT REFORMS AT 27S 37W ALONG
28S 25W...EXITING AT 23S 14W.

AT 500 HPA...A RIDGE EXTENDS SOUTH BETWEEN 115W-95W TO 50S.
THIS...IN-TURN...SUSTAINS THE NORTHWARD AMPLIFICATION OF A TROUGH
BETWEEN 95W-75W TO 18S. THE TROUGH IS FOCUSING SHORT WAVE ENERGY
ACROSS EXTREME SOUTHERN PORTIONS OF CHILE. THE LONG WAVE AXIS IS
INDUCING A RIDGE WITH AXIS SOUTH ACROSS ARGENTINA TO TIERRA DEL
FUEGO. BROAD/LOW AMPLITUDE TROUGH TO THE
SOUTH...MEANWHILE...EXTENDS OVER THE SOUTH ATLANTIC BETWEEN
60W-20W AND TO THE SOUTH OF 50S. A SHORT WAVE TROUGH ON THE
NORTHERN STREAM EXTENDS FROM 37S 43W TO SOUTHEAST BRASIL.

THE SURFACE ANALYSIS SHOWS A 1002 HPA LOW AT 50S 21W EXTENDING A
FRONT ALONG 50S 36W...51S 46W...A 1002 HPA LOW AT 52S 53W...50S
64W...A 1006 HPA LOW AT 50S 74W. A 1002 HPA OCCLUDED LOW AT 49S
79W EXTENDS A FRONT ALONG 44S 72W...39S 79W...A 1014 HPA LOW AT
37S 81W...31S 80W...A 1016 HPA LOW AT 27S 84W..19S 90W. A 1021 HPA
HIGH CENTERS AT 37S 53W. TO THE EAST...A 1018 HPA OCCLUDED LOW
CENTERS AT 34S 47W AND EXTENDS A FRONT INTO A 1020 HPA TRIPLE
POINT LOW AT 36S 44W...29S 44W...25S 48W...AND AN ILL-DEFINED
FRONT ALONG 21S 55W...21S 59W.

GONZALEZ...DMC (CHILE)
VANNUCCI...SMN (ARGENTINA)
DAVISON/GALVEZ...WPC (USA)