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South American Synoptic Discussion
 
(Latest Discussion - Issued 1432Z Jan 16, 2018)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
932 AM EST TUE JAN 16 2018

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

SYNOPSIS (VALID FROM JAN 16 AT 0000 UTC): AT 200 HPA...THE
SUBTROPICAL RIDGE EXTENDS FROM PERU/EASTERN PACIFIC...ACROSS
BOLIVIA-SOUTHEAST BRASIL INTO THE ATLANTIC ALONG 23S 30W. THE
RIDGE ANCHORS ON TWO CLOSED HIGHS...WITH ONE OVER SANTA CRUZ IN
EASTERN BOLIVIA AND THE OTHER OVER MATO GROSSO DO SUL IN BRASIL.
THE RIDGE ALOFT IS VENTING DEEP CONVECTION ACROSS SOUTHEAST BRASIL
AND ACRE/AMAZONAS TO THE WEST. A TROUGH TO THE
NORTHEAST...MEANWHILE... CENTERS ON A CLOSED LOW AT 09S 37W. THIS
FAVORS AN UPPER CONVERGENT/ SUBSIDENT PATTERN OVER NORTHEAST
STATES OF BRASIL.

AT 250 HPA...THE SOUTHERN POLAR HAS ITS ENTRANCE AT 55S
120W...THEN ALONG 55S 105W...53S 89W...EXITING AT 55S 67W. IT
REFORMS AT 53S 33W...THEN ALONG 53S 24W...AND 52S 04W. THE
NORTHERN POLAR LIES ALONG 52S 120W...51S 108W...A 129KT MAXIMUM AT
50S 92W...50S 82W...EXITING AT 50S 71W. IT REFORMS AT 50S
53W...ALONG 48S 40W...A 171KT MAXIMUM AT 49S 32W...50S 19W...AND
48S 01W. A FINGER OF THE SUBTROPICAL JET HAS ITS ENTRANCE AT 49S
108W...THEN ALONG 48S 100W...EXITING AT 45S 92W. IT REFORMS AT 31S
89W...ALONG 31S 80W...32S 75W...37S 64W...38S 46W...44S 38W...A
181KT MAXIMUM AT 48S 25W...A 155KT MAXIMUM AT 46S 14W...AND 41S
01W.

AT 500 HPA...A PROGRESSIVE SHORT WAVE TROUGH IS STREAMING TOWARDS
THE SOUTHERN CONE AS IT EXTENDS ALONG 90W TO 45S. THIS IS FOCUSING
SHORT WAVE ENERGY INTO THE SOUTHERN REGIONS OF CHILE. ANOTHER
SHORT WAVE TROUGH TO THE NORTH...MEANWHILE...LIES OFF THE CENTRAL
COAST OF CHILE...WITH AXIS TO THE NORTHWEST FROM 35S 78W TO 28S
85W. THIS TROUGH IS PROVIDING DYNAMICAL SUPPORT TO SCATTERED
CONVECTION ACROSS CENTRAL REGIONS OF CHILE. FARTHER EAST...SHORT
WAVE TROUGH ON THE SOUTHERN STREAM EXTENDS FROM 60S 22W TO THE
SOUTH GEORGIA ISLANDS...WHILE A TRAILING SHORT WAVE TROUGH ON THE
NORTHERN STREAM EXTENDS FROM 43S 40W TO RIO GRANDE DO SUL IN
BRASIL.

AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM EXTENDS OVER THE
EASTERN PACIFIC WHILE CENTERING ON TWO 1029 HPA HIGHS AT 39S 99W
AND 38S 94W. A PROGRESSIVE POLAR FRONT TO THE SOUTH EXTENDS FROM
AN OCCLUDED 970 HPA LOW AT 65S 81W...ALONG A 974 HPA LOW AT 64S
73W... 58S 68W...51S 72W...A 1002 HPA LOW AT 52S 77W...49S 77W...A
998 HPA LOW AT 53S 84W...50S 89W...AND 48S 97W. THIS SUSTAINS
LIGHT RAINFALL ACROSS SOUTHERN REGIONS OF CHILE/TIERRA DEL FUEGO.
ANOTHER FRONT TO THE NORTH EXTENDS FROM A 1006 HPA LOW AT 48S
57W...ALONG 45S 58W...A 1006 HPA LOW AT 45S 67W... NORTHERN
PATAGONIA TO BARILOCHE. ORGANIZED DEEP CONVECTION WAS BUILDING TO
THE NORTH ACROSS CENTRAL ARGENTINA. FARTHER NORTH...AN OCCLUDED
1002 HPA LOW AT 38S 39W EXTENDS A FRONT ALONG A 1006 HPA LOW AT
39S 36W...38S 35W...35S 38W...A 1006 HPA LOW AT 34S 41W...31S
44W...29S 50W...SOUTHEAST PARAGUAY TO CHACO IN ARGENTINA. A RIDGE
TO THE SOUTH CENTERS ON TWO 1015 HPA HIGHS...WITH ONE AT 39S 56W
AND THE OTHER AT 45S 47W.

OVIEDO...SHN (ARGENTINA)
POMIER...SENAMHI (BOLIVIA)
DAVISON...WPC (USA)