916  
FXSA20 KWBC 161432  
PMDSA  
 
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)  

 
 
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