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South American Synoptic Discussion
 
(Latest Discussion - Issued 1247Z Jun 27, 2017)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
847 AM EDT TUE JUN 27 2017

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

SYNOPSIS (VALID FROM JUNE 27 AT 0000 UTC): AT 200 HPA...THE
SUBTROPICAL RIDGE SPLITS IN TWO CELLS...WITH THE WESTERNMOST
ORIGINATING ON A CLOSED HIGH AT 07S 77W WHILE EXTENDING WEST ALONG
07S INTO THE EASTERN TROPICAL PACIFIC. THE EASTERNMOST...
MEANWHILE...EXTENDS FROM A CLOSED HIGH AT 13S 57W...ACROSS
SOUTHERN STATES OF BRASIL...40S 40W...TO 45S 30W. THIS IS INDUCING
THE AMPLIFICATION OF A TROUGH TO THE EAST...WITH AXIS ALONG 30S
20W...20S 35W...TO NORTHEAST BRASIL. IN THIS PATTERN...SCATTERED
CONVECTION IS CLUSTERING ACROSS BRASIL TO THE NORTH OF 02S...WITH
MOST ACTIVE ALONG THE NEAR EQUATORIAL TROUGH OVER THE
GUIANAS-VENEZUELA-COLOMBIA.

AT 250 HPA...THE SOUTHERN POLAR HAS A BRANCH THAT EXTENDS ALONG
68S 113W...65S 75W...61S 66W...EXITING AT 55S 43W. IT REFORMS AT
53S 37W...THEN ALONG 53S 23W...AND 47S 07W. ANOTHER BRANCH OF THE
SOUTHERN POLAR LIES TO THE NORTH...WITH AXIS ALONG A 135KT MAXIMUM
AT 38S 123W...43S 113W...A 126KT MAXIMUM AT 46S 101W...54S
77W...48S 60W...50S 35W...A 141KT MAXIMUM AT 46S 18W...39S
07W...AND 41S 02E. THE NORTHERN POLAR LIES ALONG 36S 120W...43S
104W...EXITING AT 44S 87W. A FINGER TO THE EAST LIES BETWEEN 37S
79W AND 31S 81W. IT REFORMS AT 27S 78W...THEN ALONG A 130KT
MAXIMUM AT 29S 69W...40S 64W...A 142KT MAXIMUM AT 45S 55W...A
159KT MAXIMUM AT 46S 40W...A 136KT MAXIMUM AT 44S 29W...35S
09W...AND 39S 03W. THE SUBTROPICAL JET TO THE NORTH HAS ITS
ENTRANCE AT 21S 91W...THEN ALONG 21S 80W...A 125KT MAXIMUM AT 25S
68W...35S 57W...EXITING AT 34S 29W. ANOTHER BRANCH TO THE NORTH
HAS ITS ENTRANCE AT 15S 86W...THEN ALONG 19S 70W...EXITING AT 27S
58W. IT REFORMS TO THE EAST NEAR 12S 39W...THEN ALONG 23S 19W...A
154KT MAXIMUM AT 27S 04W...AND 27S 07E.

AT 500 HPA...AN ELONGATED TROUGH DOMINATES THE SOUTHERN STREAM
FLOW...WITH AXIS EXTENDING ALONG A CLOSED LOW AT 55S 10W...47S
120W...TO 40S 140W. A RIDGE TO THE NORTH EXTENDS FROM A CLOSED
HIGH NEAR 19S 118W...ALONG 33S 100W...40S 90W...TO SOUTHERN CHILE.
THIS UNDERCUTS A TROUGH TO THE NORTH THAT EXTENDS BETWEEN 95W-60W
AND TO THE SOUTH OF 20S...WHILE CENTERING ON A CLOSED LOW AT 36S
77W. THE TROUGH IS FOCUSING SHORT WAVE ENERGY ACROSS
CENTRAL/NORTHERN CHILE INTO ARGENTINA.

AT LOW LEVELS...A PROGRESSIVE FRONT IS STREAMING ACROSS THE
SOUTHEAST PACIFIC...WITH SYSTEM ORIGINATING ON AN OCCLUDED 982 HPA
LOW AT 55S 101W...THEN ALONG A 986 HPA LOW AT 58S 93W...53S
88W...A 1002 HPA LOW AT 50S 89W...42S 92W...A 1020 HPA LOW AT 35S
108W...AND 31S 115W. A RIDGE TO THE NORTH ANCHORS ON A 1031 HPA
HIGH AT 33S 94W...A 1027 HPA HIGH AT 47S 78W AND A 1027 HPA HIGH
AT 45S 70W. NORTH OF THIS AXIS...WANING SUBTROPICAL CYCLONE
MEANDERS OFF THE CENTRAL COAST OF CHILE...CENTERING ON A REMNANT
1010 HPA LOW AT 34S 77W. AN ELONGATED POLAR FRONT TO THE EAST
EXTENDS ALONG A 1002 HPA LOW AT 44S 37W...A 1010 HPA LOW AT 44S
46W...38S 53W...A 1008 HPA LOW AT 34S 62W...31S 63W...TO 28S 67W.
THIS SUSTAINS ORGANIZED CONVECTION ACROSS THE BUENOS AIRES
PROVINCE/CENTRAL ARGENTINA. A RIDGE TO THE NORTH CENTERS ON TWO
1029 HPA HIGHS...WITH ONE AT 29S 34W AND THE OTHER 29S 27W.

ESPINOLA...DNM (PARAGUAY)
GONZALEZ...DMC (CHILE)
DAVISON...WPC (USA)