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South American Synoptic Discussion
 
(Latest Discussion - Issued 1323Z Nov 22, 2017)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
822 AM EST WED NOV 22 2017

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

SYNOPSIS (VALID FROM NOV 22 AT 0000 UTC): A 200 HPA HIGH CENTERS
OVER BOLIVIA NEAR 14S 62W...ANCHORING A BROAD RIDGE OVER THE
CONTINENT TO THE NORTH OF 30S. A TROUGH TO THE EAST EXTENDS OVER
THE NORTHEAST STATES OF BRASIL WHILE CENTERING ON A CLOSED LOW AT
06S 38W. THE RIDGE ALOFT IS VENTING CONVECTION BETWEEN MINAS
GERAIS AND AMAZONAS TO THE WEST. THE TROUGH...MEANWHILE...FAVORS
AN UPPER CONVERGENT PATTERN THAT IS INHIBITING DEEP CONVECTION ON
THE NORTHEAST STATES OF BRASIL.

AT 250 HPA...THE SOUTHERN POLAR LIES ALONG 60S 120W...58S
109W...54S 99W...60S 81W...EXITING AT 59S 75W. IT REFORMS AT 57S
64W...THEN ALONG 51S 60W...EXITING AT 47S 53W. THE NORTHERN POLAR
LIES ALONG 53S 120W...51S 107W...EXITING AT 51S 97W. A FINGER TO
THE EAST EXTENDS BETWEEN 50S 67W AND 43S 61W. THE NORTHERN POLAR
REFORMS AT 35S 53W....THEN ALONG 38S 44W...A 159KT MAXIMUM AT 43S
34W...46S 22...AND 45S 09W. ANOTHER FINGER OF THE NORTHERN POLAR
JET HAS ITS ENTRANCE AT 34S 102W...CROSSING 29S 98W...EXITING AT
31S 92W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT 12S 91W...THEN
ALONG 21S 90W...28S 81W...28S 70W...A 124KT MAXIMUM AT 28S
62W...29S 53W...A 133KT MAXIMUM AT 33S 45W...33S 31W...34S
19W...EXITING AT 32S 07W. THE SUBEQUATORIAL JET LIES ALONG 15S
120W...10S 110W...EXITING AT 01S 100W.

AT 500 HPA...PROGRESSIVE TROUGH ON THE SOUTHERN STREAM NOW EXTENDS
ALONG 100W TO THE SOUTH OF 47S. THIS IS PRESSING AGAINST A RIDGE
TO THE EAST...WITH AXIS EXTENDING FROM 50S 87W...ALONG 65S 75W TO
THE ANTARCTIC PENINSULA. A SHORT WAVE TROUGH IS LIFTING ACROSS
SOUTHERN CHILE TO PATAGONIA IN ARGENTINA...WHILE FARTHER EAST A
BROAD/HIGH AMPLITUDE TROUGH OVER THE SOUTH ATLANTIC EXTENDS NORTH
BETWEEN 60W-30W TO 25S.

AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM OVER THE EASTERN
PACIFIC CENTERS ON A 1033 HPA HIGH AT 40S 106W. SOUTH OF THIS
RIDGE...A PROGRESSIVE FRONT EXTENDS ALONG A 982 HPA LOW AT 68S
83W...62S 77W...58S 82W...A 1006 HPA LOW AT 57S 92W...53S
92W...48S 103W...AND 47S 114W. ANOTHER FRONT TO THE NORTH EXTENDS
FROM AN OCCLUDED 1010 HPA LOW AT 53S 77W...ALONG A 1006 HPA LOW AT
50S 69W...46S 72W...45S 80W...45S 90W...A 1026 HPA LOW AT 47S
96W...44S 97W...AND 43S 109W. FARTHER EAST...OVER THE SOUTH
ATLANTIC...BROAD TROUGH DOMINATES THE FLOW WHILE CENTERING ON AN
OCCLUDED 954 HPA LOW AT 63S 28W. POLAR FRONTS REVOLVE AROUND THIS
AXIS...WITH ONE EXTENDING ALONG A 982 HPA LOW AT 50S 43W...44S
51W...43S 60W...TO NORTHERN PATAGONIA. ANOTHER FRONT TO THE NORTH
EXTENDS ALONG A 1000 HPA LOW AT 44S 29W...38S 33W...32S 41W...A
1010 HPA LOW AT 30S 47W...PARANA TO PARAGUAY. A POLAR RIDGE TO THE
SOUTH CENTERS ON A 1017 HPA HIGH AT 34S 57W. AN OLD ELONGATED
FRONT TO THE NORTH LIES ALONG A 1014 HPA LOW AT 35S 30W...30S
31W...28S 36W...NORTHERN SAO PAULO TO MATO GROSSO. THIS SUSTAINS
ORGANIZED DEEP CONVECTION ON THE SOUTHEAST STATES OF BRASIL.

OVIEDO...SHN (ARGENTINA)
VANNUCCI...SMN (ARGENTINA)
RIVAS...SENAMHI (PERU)
DAVISON...WPC (USA)