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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1428Z Dec 14, 2017)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
928 AM EST THU DEC 14 2017

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

SYNOPSIS (VALID FROM DEC 14 AT 0000 UTC): A 200 HPA HIGH NEAR 11S
60W ANCHORS A SHORT WAVE RIDGE OVER NORTHWEST SOUTH AMERICA. SOUTH
OF THIS AXIS...A SHORT WAVE TROUGH EXTENDS OVER THE SOUTHEAST
STATES OF BRASIL...WHILE FARTHER TO THE EAST A CLOSED LOW NEAR 06S
28W EXTENDS A TROUGH TO THE NORTH-NORTHWEST ACROSS THE EQUATOR.
THE RIDGE ALOFT IS VENTING DEEP CONVECTION ACROSS BRASIL TO THE
NORTH OF 13S...WITH MOST ACTIVE CLUSTERING ACROSS
PARA-TOCANTINS/GOIAS AND BAHIA.

AT 250 HPA...THE JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS
ALONG 55S 120W...51S 104W...A 151KT MAXIMUM AT 49S 90W...49S
78W...53S 64W...57S 50W...EXITING AT 48S 24W. THE NORTHERN POLAR
HAS ITS ENTRANCE AT 47S 104W...THEN ALONG A 139KT MAXIMUM AT 46S
90W...EXITING AT 44S 71W. IT REFORMS AT 45S 56W...THEN ALONG 46S
48W...41S 35W...41S 24W...42S 12W...AND 52S 04W. THE SUBTROPICAL
JET HAS ITS ENTRANCE AT 27S 125W...THEN ALONG 30S 113W...39S
107W...42S 90W...EXITING AT 38S 77W. A FINGER TO THE EAST HAS ITS
ENTRANCE AT 36S 67W...CROSSING 36S 59W...EXITING AT 39S 54W.
ANOTHER FINGER TO THE NORTH HAS ITS ENTRANCE AT 29S 76W...ALONG
31S 65W...EXITING AT 30S 56W. IT REFORMS BETWEEN 23S 42W AND 26S
30W. THE SUBEQUATORIAL JET HAS A FINGER THAT EXTENDS BETWEEN 10S
100W AND 10S 87W. ANOTHER BRANCH TO THE NORTH EXTENDS ALONG 03S
110W...03S 98W...EXITING AT 03S 89W.

AT 500 HPA...BROAD/LOW AMPLITUDE TROUGH ON THE SOUTHERN STREAM
ENVELOPS THE SOUTHEAST PACIFIC TO THE SOUTH OF 40S...WITH AXIS
CENTERING ON A CLOSED LOW NEAR 64S 81W. THIS IS FOCUSING SHORT
WAVE ENERGY ACROSS TIERRA DEL FUEGO TO EXTREME SOUTHERN REGIONS OF
CHILE. A SHORT WAVE TROUGH TO THE NORTH IS STREAMING ACROSS THE
BUENOS AIRES PROVINCE/ENTRE RIOS IN ARGENTINA. THESE THEN PRESS
AGAINST A LOW AMPLITUDE RIDGE TO THE EAST THAT EXTENDS SOUTH ALONG
50W. DOWNSTREAM FROM THIS AXIS...A TROUGH EXTENDS BETWEEN 35W-00W
AND TO THE SOUTH OF 30S.

AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM LIES OVER THE
EASTERN PACIFIC WHILE ANCHORING ON A 1025 HPA HIGH AT 34S 86W.
BROAD TROUGH LIES TO THE SOUTH...CENTERING ON AN OCCLUDED 962 HPA
LOW AT 63S 79W. POLAR FRONTS REVOLVE AROUND THIS AXIS...WITH ONE
EXTENDING ALONG A 974 HPA LOW AT 61S 61W...59S 59W...A 978 HPA LOW
AT 57S 67W...54S 65W...A 986HPA LOW AT 53S 70W...49S 69W...47S
71W...A 1002 HPA LOW AT 49S 77W...TO 49S 79W. ANOTHER FRONT TO THE
NORTH EXTENDS FROM A 992 HPA LOW AT 53S 58W...THEN ALONG 50S
58W...48S 62W...A 994 HPA LOW AT 48S 66W...42S 68W...41S 73W...A
1012 HPA LOW AT 44S 81W...41S 85W...41S 92W...AND 43S 102W. ALSO
OVER THE SOUTH ATLANTIC...A FRONT EXTENDS FROM A 990 HPA LOW AT
50S 22W...A 982 HPA LOW AT 53S 17W...42S 21W...38S 30W...39S
40W...42S 49W...A 1010 HPA LOW AT 41S 58W...URUGUAY TO CORDOBA IN
ARGENTINA. THIS FAVORS SCATTERED DEEP CONVECTION. A POLAR RIDGE TO
THE SOUTH CENTERS ON A 1013 HPA HIGH AT 34S 64W. A RIDGE OVER THE
ATLANTIC CENTERS ON A 1023 HPA HIGH AT 31S 35W. AN ELONGATED FRONT
LIES TO THE EAST AND NORTH...WITH AXIS ALONG A 1010 HPA LOW AT 40S
09W...30S 13W...24S 25W...TO ESPIRITO SANTO.

OVIEDO...SHN (ARGENTINA)
POMIER...SENAMHI (BOLIVIA)
RIVAS...SENAMHI (PERU)
GALVEZ...WPC (USA)