Prognostic Meteorological Discussion
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
845 AM EDT MON SEP 26 2016

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

SYNOPSIS (VALID FROM SEPTEMBER 26 AT 0000 UTC): AT 200 HPA...THE
UPPER LEVEL ANALYSIS SHOWS A LOW AMPLITUDE RIDGE OVER THE
CONTINENT ENVELOPING AREA TO THE NORTH OF 18S. THE RIDGE ALOFT IS
VENTING CONVECTION ACROSS NORTHERN BRASIL. A TROUGH TO THE WEST IS
PRESSING AGAINST THIS AXIS. AS IT NEARS THE COAST OF PERU THE
TROUGH ALOFT IS VENTING DIURNAL CONVECTION ALONG THE SIERRA AND
JUNGLE.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG
54S 120W...51S 110W...EXITING AT 44S 106W. IT REFORMS AT 53S
76W...THEN ALONG 60S 65W...EXITING AT 60S 47W. THE NORTHERN POLAR
HAS ITS ENTRANCE AT 38S 116W...THEN ALONG 31S 106W...32S 98W...A
132KT MAXIMUM AT 38S 89W...43S 79W...EXITING AT 44S 67W. IT HAS A
FINGER TO THE EAST THAT EXTENDS BETWEEN 42S 55W AND 31S 49W. THE
NORTHERN POLAR REFORMS AT 28S 40W...ALONG A 124KT MAXIMUM AT 34S
31W...37S 20W...33S 08W...AND 32S 01W. THE SUBTROPICAL JET HAS ITS
ENTRANCE AT 27S 109W...THEN ALONG 27S 99W...32S 87W...37S
73W...EXITING AT 35S 66W. THE JET REFORMS AT 20S 55W...CROSSING
22S 42W...26S 31W...29S 20W...EXITING AT 25S 10W.

AT 500 HPA...BUILDING RIDGE EXTENDS ALONG 120W/125W TO 55S.
THIS...IN-TURN...IS INDUCING THE NORTHWARD AMPLIFICATION OF A
TROUGH ALONG 60S 86W...50S 90W...30S 110W...TO 23S 115W. A RIDGE
TO THE EAST...MEANWHILE...LIES ACROSS ARGENTINA TO THE
MALVINAS/FALKLAND ISLANDS. DOWNSTREAM FROM THE RIDGE...BROAD
TROUGH EXTENDS OVER THE WESTERN ATLANTIC BETWEEN 50W-25W AND TO
THE SOUTH OF 20S...WHILE ANCHORING ON A DEEP LOW NEAR 40S 35W.

AT LOW LEVELS...A RIDGE OVER THE PACIFIC ANCHORS ON A 1033 HPA
HIGH AT 39S 116W. THIS FAVORS THE NORTHWARD AMPLIFICATION OF A
TROUGH ALONG THE COAST OF CHILE...WITH AN EMBEDDED POLAR FRONT
EXTENDING ALONG A 992 HPA LOW AT 58S 81W...54S 81W...A 1010 HPA
LOW AT 47S 85W...43S 86W...40S 92W...A 1014 HPA LOW AT 39S
97W...35S 96W...AND A 1016 HPA LOW AT 33S 100W. THIS IS PHASING
WITH ANOTHER FRONT TO THE EAST THAT EXTENDS ALONG A 992 HPA LOW AT
59S 74W...56S 71W...A 1002 HPA LOW AT 53S 71W...48S 72W...A 1006
HPA LOW AT 46S 78W...42S 77W...A 1014 HPA LOW AT 39S 83W...34S
84W...A 1018 HPA LOW AT 30S 91W...25S 96W...AND 22S 102W. OVER THE
ATLANTIC...BROAD TROUGH DOMINATES THE NORTHERN STREAM WHILE
ANCHORING ON AN OCCLUDED 996 HPA LOW AT 39S 35W. THIS EXTENDS A
FRONT ALONG A 1012 HPA LOW AT 44S 31W...41S 26W...35S 29W...A 1010
HPA LOW AT 28S 35W...23S 39W...RIO DE JANEIRO...A 1010 HPA LOW AT
20S 45W...TO MATO GROSSO. THIS SUSTAINS SCATTERED CONVECTION
ACROSS NORTHERN SAO PAULO-RIO DE JANEIRO AND MINAS GERAIS. A RIDGE
TO THE WEST AND SOUTH ANCHORS ON TWO HIGHS...A 1023 HPA HIGH AT
36S 55W AND A 1029 HPA HIGH AT 53S 44W.

OSORIO...DMC (CHILE)
ALVA...SENAMHI (PERU)
DAVISON/GALVEZ...WPC (USA)
$$




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