802  
FXSA20 KWBC 201350  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
849 AM EST MON NOV 20 2017  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM NOV 20 AT 0000 UTC): THE 200 HPA ANALYSIS  
SHOWS A RIDGE OVER NORTHERN SOUTH AMERICA CENTERING ON A CLOSED  
HIGH OVER BRASIL NEAR 10S 64W. A TROUGH TO THE EAST OF THIS RIDGE  
CENTERS ON A CLOSED LOW AT 04S 30W. THE RIDGE ALOFT IS VENTING  
CONVECTION ALONG A LINE BETWEEN MINAS GERAIS/RIO DE JANEIRO AND  
SOUTHERN AMAZONAS/ACRE IN WESTERN BRASIL. RIDGE ALOFT WAS ALSO  
ENHANCING CONVECTION ACROSS THE PERUVIAN JUNGLE/EASTERN ECUADOR  
AND NORTHERN BOLIVIA.  
 
AT 250 HPA...THE SOUTHERN POLAR HAS A BRANCH THAT EXTENDS ALONG  
63S 120W...65S 84W...51S 73W...EXITING AT 47S 66W. THE NORTHERN  
POLAR HAS ITS ENTRANCE AT 47S 118W...THEN ALONG 57S 100W...EXITING  
AT 49S 87W. IT REFORMS AT 42S 71W...ALONG 40S 58W...A 121KT  
MAXIMUM AT 40S 44W...44S 36W...52S 28W...A 172KT MAXIMUM AT 41S  
09W...AND 34S 00W. THE SUBTROPICAL JET HAS A FINGER THAT EXTENDS  
ALONG 34S 120W...33S 112W...EXITING AT 29S 104W. IT REFORMS AT 23S  
81W...ALONG 26S 66W...A 121KT MAXIMUM AT 27S 55W...30S 42W...A  
128KT MAXIMUM AT 38S 32W...43S 23W...33S 07W...EXITING AT 27S 01E.  
THE SUBEQUATORIAL RIDGE LIES ALONG 20S 120W...19S 115W...13S  
108W...EXITING AT 01S 99W.  
 
AT 500 HPA...LONG WAVE RIDGE NOW EXTENDS TO THE SOUTHEAST FROM 40S  
100W TO THE BELLINGSHAUSEN SEA/ANTARCTIC PENINSULA. BROAD TROUGH  
TO THE EAST EXTENDS BETWEEN 85W-30W AND TO THE SOUTH OF 25S. THE  
DEEP TROUGH CENTERS ON TWO CLOSED LOWS...WITH ONE AT 57S 60W AND  
THE OTHER AT 53S 52W. LONG WAVE RIDGE TO THE  
EAST...MEANWHILE...EXTENDS ALONG 20W TO 70S.  
 
AT LOW LEVELS...THE SURFACE ANALYSIS SHOWS A BROAD RIDGE OVER THE  
EASTERN PACIFIC THAT ANCHORS ON TWO 1033 HPA HIGHS...WITH ONE AT  
41S 102W AND THE OTHER AT 49S 93W. BROAD TROUGH LIES TO THE  
EAST... DOMINATING THE WESTERN ATLANTIC/WEDDELL SEA...WHILE  
ANCHORING ON A 970 HPA LOW AT 61S 50W. POLAR FRONTS REVOLVE AROUND  
THIS AXIS...WITH ONE EXTENDING FROM AN OCCLUDED 974 HPA LOW AT 51S  
51W...A 976 HPA LOW AT 53S 53W...52S 48W...49S 47W...A 978 HPA LOW  
AT 46S 45W...40S 42W...35S 47W...CENTRAL URUGUAY-ENTRE RIOS...A  
1006 HPA LOW AT 40S 66W...37S 69W...39S 73W...A 1022 HPA LOW AT  
42S 80W...39S 84W AND 39S 90W. POLAR HIGH TO THE SOUTH CENTERS ON  
A 1013 HPA HIGH AT 37S 58W. ANOTHER FRONT TO THE EAST AND NORTH  
EXTENDS ALONG A 986 HPA LOW AT 46S 32W...40S 29W...35S 29W...A  
1010 HPA LOW AT 32S 34W...30S 35W...29S 37W...A 1012 HPA LOW AT  
27S 40W...24S 42W...RIO DE JANEIRO...A 1008 HPA LOW AT 23S  
52W...TO CHACO PARAGUAYO/SOUTHERN BOLIVIA. THIS FAVORS SCATTERED  
CONVECTION ACROSS SOUTHEAST BRASIL.  
 
OVIEDO...SHN (ARGENTINA)  
VANNUCCI...SMN (ARGENTINA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  

 
 
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