736  
FXSA20 KWBC 291338  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
837 AM EST WED NOV 29 2017  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM NOV 29 AT 0000 UTC): THE 200 HPA ANALYSIS  
SHOWS BROAD CELL OF THE SUBTROPICAL RIDGE ENVELOPING CONTINENTAL  
AREA TO THE NORTH OF 34S...WITH AXIS ANCHORING ON A CLOSED HIGH  
THAT MEANDERS BETWEEN NORTHERN BOLIVIA AND RONDONIA IN BRASIL. A  
TROUGH TO THE EAST...MEANWHILE...EXTENDS TO THE NORTHWEST ALONG  
20S 26W...10S 30W...TO 00N 47W. THE RIDGE ALOFT IS VENTING  
ORGANIZED DEEP CONVECTION ACROSS AMAZONAS-ACRE IN BRASIL-NORTHERN  
BOLIVIA AND THE PERUVIAN JUNGLE TO EASTERN ECUADOR.  
 
AT 250 HPA...THE SOUTHERN POLAR EXTENDS ALONG 52S 120W...47S  
110W...48S 101W...EXITING AT 49S 95W. IT REFORMS AT 51S  
84W...ALONG 54S 77W...65S 62W...A 127KT MAXIMUM AT 63S  
42W...EXITING AT 57S 32W. THE NORTHERN POLAR LIES ALONG 43S  
120W...42S 110W...41S 90W...A 166KT MAXIMUM AT 53S 74W...56S  
59W...52S 51W...EXITING AT 44S 51W. THE SUBTROPICAL JET EXTENDS  
ALONG 39S 120W...37S 103W...36S 93W...EXITING AT 37S 86W. IT  
REFORMS AT 28S 81W...ALONG A 123KT MAXIMUM AT 31S 70W...31S  
59W...27S 48W...EXITING AT 27S 39W. IT REFORMS AT 29S 35W...ALONG  
A 120KT MAXIMUM AT 36S 28W...EXITING AT 42S 19W. THE SUBEQUATORIAL  
JET HAS A FINGER THAT EXTENDS ALONG 09S 116W...10S 106W...EXITING  
AT 10S 98W. ANOTHER FINGER TO THE NORTH LIES ALONG 00N  
108W...EXITING AT 01S 102W.  
 
AT 500 HPA...BROAD TROUGH DOMINATES THE FLOW OVER THE SOUTHEAST  
PACIFIC...AS IT EXTENDS BETWEEN 115W-70W AND TO THE SOUTH OF 30S.  
THIS IS FOCUSING ITS SHORT WAVE ENERGY ACROSS THE DRAKE PASSAGE TO  
TIERRA DEL FUEGO IN SOUTHERN CHILE. THE TROUGH IS PRESSING AGAINST  
A LONG WAVE RIDGE TO THE EAST...AS THE LATTER EXTENDS NORTH TO  
SOUTH FROM ENTRE RIOS/BUENOS AIRES PROVINCE IN ARGENTINA...ACROSS  
THE MALVINAS/FALKLAND ISLANDS...TO THE ANTARCTIC PENINSULA/WEDDELL  
SEA. A SHORT WAVE TROUGH ON THE NORTHERN STREAM...MEANWHILE...LIES  
OFF THE CENTRAL COAST OF CHILE...WITH AXIS TO THE NORTH-NORTHWEST  
FROM 34S 77W...ALONG 25S 80W...TO 23S 85W. FARTHER EAST...OVER THE  
WESTERN SOUTH ATLANTIC...A TROUGH EXTENDS BETWEEN 50W-25W AND TO  
THE SOUTH OF 20S. THIS CENTERS ON A CLOSED LOW AT 44S 33W.  
 
AT LOW LEVELS...BROAD TROUGH DOMINATES THE FLOW OVER THE SOUTHEAST  
PACIFIC WHILE CENTERING ON AN OCCLUDED 950 HPA LOW AT 67S 91W.  
POLAR FRONTS REVOLVE AROUND THIS AXIS...WITH A PROGRESSIVE FRONT  
EXTENDING FROM AN OCCLUDED 962 HPA LOW AT 59S 103W...A 972 HPA LOW  
AT 57S 94W...51S 93W...47S 104W...AND 47S 113W. ANOTHER FRONT TO  
THE EAST EXTENDS ALONG A 978 HPA LOW AT 60S 66W...54S 67W...49S  
72W...A 1008 HPA LOW AT 49S 79W...43S 81W...38S 90W...AND 34S  
100W. A RIDGE TO THE NORTH CENTERS ON A 1025 HPA HIGH AT 31S 93W.  
OVER THE ATLANTIC...AN OCCLUDED 998 HPA LOW AT 44S 31W EXTENDS A  
FRONT ALONG A 1006 HPA LOW AT 45S 29W...38S 27W...29S 37W...28S  
44W...SANTA CATARINA...CORRIENTES TO A 1004 HPA LOW AT 34S 67W.  
THIS FAVORS SCATTERED CONVECTION ACROSS CUYO IN ARGENTINA. A RIDGE  
TO THE SOUTH CENTERS ON A 1023 HPA HIGH AT 37S 52W. AN OLD FRONT  
TO THE NORTH...MEANWHILE...EXTENDS ALONG A 1018 HPA LOW AT 42S  
23W...37S 23W...33S 26W...A 1014 HPA LOW AT 32S 30W...27S  
32W...23S 36W...A 1014 HPA LOW AT 22S 39W...ESPIRITO SANTO-MINAS  
GERAIS TO MATO GROSSO/NORTHERN BOLIVIA. THIS FAVORS SCATTERED DEEP  
CONVECTION ACROSS SOUTHEAST BRASIL.  
 
OVIEDO...SHN (ARGENTINA)  
VANNUCCI...SMN (ARGENTINA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  

 
 
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