487  
FXSA20 KWBC 111409  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
909 AM EST THU JAN 11 2018  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM JAN 11 AT 0000 UTC): AT 200 HPA...BROAD CELL  
OF THE SUBTROPICAL RIDGE DOMINATES AREA TO THE NORTH OF 30S...WITH  
AXIS CENTERING ON A CLOSED HIGH NEAR 18S 63W. A TROUGH TO THE EAST  
EXTENDS OVER THE NORTHEAST STATES OF BRASIL WHILE CENTERING ON A  
LOW AT 09S 45W. THE TROUGH ALOFT IS ENHANCING CONVECTION ACROSS  
NORTHEAST BRASIL...WHILE THE RIDGE IS VENTING ACTIVITY BUILDING  
BETWEEN SOUTHEAST BRASIL AND BOLIVIA. THE RIDGE ALOFT WAVE ALSO  
VENTING CONVECTION ACROSS WESTERN BRASIL...THE PERUVIAN JUNGLE AND  
ECUADOR.  
 
AT 250 HPA...THE SOUTHERN POLAR HAS ITS ENTRANCE AT 45S  
103W...THEN ALONG 49S 96W...A 138KT MAXIMUM AT 53S 89W...A 130KT  
MAXIMUM AT 59S 76W...62S 58W...59S 43W...A 137KT MAXIMUM AT 55S  
36W...49S 24W...EXITING AT 44S 09W. THE NORTHERN POLAR HAS ITS  
ENTRANCE AT 41S 111W...THEN ALONG 43S 101W...50S 88W...56S  
71W...56S 55W...52S 42W...EXITING AT 45S 29W. THE SUBTROPICAL JET  
LIES ALONG 31S 120W...35S 110W...A 140KT MAXIMUM AT 41S 97W...44S  
90W...EXITING AT 45S 81W. IT REFORMS AT 44S 64W...CROSSING 48S  
56W...EXITING AT 40S 35W. FARTHER NORTH...A FINGER OF THE  
SUBTROPICAL JET EXTENDS BETWEEN 28S 82W AND 21S 84W. ANOTHER  
FINGER LIES BETWEEN 21S 80W AND 30S 71W.  
 
AT 500 HPA...A HIGH AMPLITUDE TROUGH EXTENDS NORTH BETWEEN  
115W-85W TO 30S. THIS IS FOCUSING SHORT WAVE ENERGY ACROSS THE  
DRAKE PASSAGE INTO EXTREME SOUTHERN PORTIONS OF CHILE. A BROAD/LOW  
AMPLITUDE RIDGE TO THE EAST EXTENDS BETWEEN 65W-40W TO 64S.  
FARTHER EAST...A TROUGH EXTENDS BETWEEN 35W-10E AND TO THE SOUTH  
OF 30S.  
 
AT LOW LEVELS...BROAD TROUGH ON THE SOUTHERN STREAM ANCHORS ON AN  
OCCLUDED 966 HPA LOW AT 68S 86W. POLAR FRONTS REVOLVE AROUND THIS  
TROUGH...WITH ONE EXTENDING ALONG A 988 HPA LOW AT 61S 58W...58S  
59W...57S 66W...A 982 HPA LOW AT 59S 72W...54S 74W...49S 82W...A  
994 HPA LOW AT 49S 89W...46S 90W...A 1002 HPA LOW AT 42S 97W...AND  
37S 97W. A RIDGE TO THE NORTH ANCHORS ON TWO 1021 HPA HIGHS...WITH  
ONE AT 25S 101W AND THE OTHER AT 35S 83W. FARTHER EAST...OVER THE  
ATLANTIC...AN ELONGATED FRONT EXTENDS FROM AN OCCLUDED 998 HPA LOW  
AT 46S 22W...A 998 HPA LOW AT 45S 18W...43S 16W...A 1002 HPA LOW  
AT 42S 22W...37S 24W...34S 32W...42S 46W...A 1014 HPA LOW AT 46S  
57W...43S 59W...A 1006 HPA LOW AT 45S 68W...TO SOUTHERN PATAGONIA.  
THIS SUSTAINS SCATTERED CONVECTION ACROSS PATAGONIA IN ARGENTINA.  
A RIDGE TO THE NORTH CENTERS ON A 1025 HPA HIGH AT 32S 38W. AN OLD  
FRONT TO THE NORTH LIES ALONG 31S 07W...26S 19W...25S 35W...TO RIO  
GRANDE DO SUL/URUGUAY.  
 
OVIEDO...SHN (ARGENTINA)  
POMIER...SENAMHI (BOLIVIA)  
DAVISON...WPC (USA)  

 
 
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