893  
FXSA20 KWBC 301441  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
940 AM EST TUE JAN 30 2018  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM JAN 30 AT 0000 UTC): BROAD UPPER LEVEL RIDGE  
REMAINS THE DOMINANT FEATURE OVER THE CONTINENT...WITH AXIS  
ENVELOPING AREA TO THE NORTH OF 40S WHILE ANCHORING ON A CLOSED  
HIGH OVER CHACO PARAGUAYO. THE RIDGE ALOFT VENTS DEEP CONVECTION  
OVER THE CONTINENT BETWEEN 23S AND 05S...WITH MOST ACTIVE  
CLUSTERING OVER SOUTHEAST BRASIL. TWO TROUGHS BOOKENDS THIS  
RIDGE...WITH ONE OVER THE PACIFIC EXTENDING ALONG 20S 90W TO  
NORTHERN PERU...WHILE THE OTHER OVER THE ATLANTIC EXTENDING ALONG  
20S 25W...10S 35W TO THE NORTHEAST STATES OF BRASIL.  
 
AT 250 HPA...THE SOUTHERN POLAR EXTENDS ALONG 57S 120W...A 148KT  
MAXIMUM AT 57S 110W...A A26KT MAXIMUM AT 54S 96W...EXITING AT 47S  
84W. IT REFORMS AT 47S 78W...ALONG A 130KT MAXIMUM AT 55S 62W...A  
128KT MAXIMUM AT 56S 50W...EXITING AT 46S 38W. THE NORTHERN POLAR  
LIES ALONG 52S 120W...49S 99W...43S 85W...43S 74W...EXITING AT 49S  
58W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT 14S 77W...THEN ALONG  
20S 80W...30S 78W...35S 69W...34S 56W...28S 49W...EXITING AT 26S  
42W. A FINGER OF THE SUBEQUATORIAL JET AT 200 HPA EXTENDS FROM 18S  
40W...ALONG 13S 41W...09S 44W...EXITING AT 05S 46W. ANOTHER FINGER  
AT 150 HPA LIES ALONG 05S 111W...01S 99W...01N 94W...EXITING AT  
02N 83W.  
 
AT 500 HPA...PROGRESSIVE MID LEVEL TROUGH ON THE SOUTHERN STREAM  
FLOW NOW EXTENDS ALONG 80W TO 40S...WITH AXIS FOCUSING ITS SHORT  
WAVE ENERGY ACROSS SOUTHERN CHILE TO PATAGONIA IN ARGENTINA. THE  
TROUGH IS PHASING WITH A PERTURBATION TO THE NORTH THAT MEANDERS  
OFF THE CENTRAL/NORTHERN COAST OF CHILE. A RIDGE ALONG 50W  
SEPARATES THIS TROUGH FROM ANOTHER TO THE EAST...AS THE LATTER  
EXTENDS FROM A CLOSED LOW AT 59S 34W...ALONG 45S 35W...TO 39S 39W.  
THIS IS INTERACTING WITH A SHORT WAVE TROUGH TO THE NORTH THAT  
MEANDERS OFF THE SOUTHERN/SOUTHEAST COAST OF BRASIL.  
 
AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM LIES OVER THE  
EASTERN PACIFIC...WITH AXIS CENTERING ON A 1025 HPA HIGH AT 33S  
112W AND A 1025 HPA HIGH AT 37S 101W. A FRONT TO THE SOUTHEAST  
EXTENDS FROM AN OCCLUDED 970 HPA LOW AT 60S 63W...ALONG A 982 HPA  
LOW AT 60S 55W...LAS MALVINAS...50S 62W...A 990 HPA LOW AT 49S  
68W... NORTHERN PATAGONIA IN ARGENTINA...TEMUCO CHILE...A 998 HPA  
LOW AT 46S 76W...43S 77W...38S 85W...A 1018 HPA LOW AT 37S  
90W...35S 94W...AND 37S 105W. THIS SUSTAINS SCATTERED CONVECTION  
ACROSS SOUTHERN CHILE...WHILE ALSO TRIGGERING PREFRONTAL  
CONVECTION OVER CENTRAL ARGENTINA. FARTHER EAST...OVER THE  
ATLANTIC...A RIDGE ANCHORS ON A 1013 HPA HIGH AT 37S 47W. AN  
ELONGATED FRONT TO THE NORTH IES ALONG A 1014 HPA LOW AT 35S  
16W...33S 19W...A 1014 HPA LOW AT 32S 20W...29S 21W...29S  
28W...32S 30W...A 1006 HPA LOW AT 32S 35W...30S 36W...29S 40W...A  
1006 HPA LOW AT 30S 44W...SAO PAULO TO CENTRAL PARAGUAY.  
CONVECTION IS CLUSTERING TO THE NORTH ACROSS SOUTHEAST STATES OF  
BRASIL.  
 
OVIEDO...SHN (ARGENTINA)  
POMIER...SENAMHI (BOLIVIA)  
DAVISON...WPC (USA)  

 
 
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