136  
FXSA20 KWBC 271346  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
845 AM EST MON NOV 27 2017  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM NOV 27 AT 0000 UTC): AT 200 HPA...A  
NEGATIVELY TILTED TROUGH EXTENDS TO THE NORTHWEST FROM 20S  
100W...ALONG 10S 89W TO ECUADOR/SOUTHWEST COLOMBIA. A RIDGE TO THE  
EAST DOMINATES THE FLOW OVER THE CONTINENT TO THE NORTH OF 25S AND  
WEST OF 45W...WHILE CENTERING ON A CLOSED HIGH AT 13S 67W. ANOTHER  
TROUGH LIES TO THE EAST-NORTHEAST OF THIS RIDGE...EXTENDING OVER  
NORTHEAST BRASIL WHILE CENTERING ON A CLOSED LOW AT 04S 38W. THE  
RIDGE ALOFT IS VENTING SCATTERED DEEP CONVECTION ACROSS SOUTHEAST  
BRASIL AND BOLIVIA/JUNGLE OF PERU. THE TROUGH OVER ECUADOR IS  
ENHANCING DIURNAL CONVECTION ALONG THE SIERRA/JUNGLE TO THE EAST.  
THE TROUGH OVER NORTHEAST...MEANWHILE...FAVORS A CONVERGENT  
PATTERN THAT IS INHIBITING ORGANIZED DEEP CONVECTION.  
 
THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG  
56S 120W...63S 100W...A 121KT MAXIMUM AT 65S 85W...A 128KT MAXIMUM  
AT 62S 69W...EXITING AT 55S 61W. IT REFORMS AT 54S 54W...ALONG 55S  
47W...58S 38W...A 158KT MAXIMUM AT 56S 26W...AND 51S 12W. THE  
NORTHERN POLAR LIES ALONG 47S 120W...51S 110W...A 137KT MAXIMUM AT  
55S 98W...54S 86W...EXITING AT 49S 79W. IT REFORMS AT 42S  
61W...ALONG 50S 48W...54S 35W...50S 20W...EXITING AT 45S 10W. THE  
SUBTROPICAL JET HAS ITS ENTRANCE AT 25S 86W...ALONG 25S 79W...26S  
67W...25S 52W...27S 45W...EXITING AT 32S 40W. THE SUBEQUATORIAL  
JET HAS A FINGER THAT EXTENDS ALONG 14S 120W...16S 112W...EXITING  
AT 18S 103W. ANOTHER FINGER TO THE NORTH LIES ALONG 08S 115W...09S  
107W...EXITING AT 08S 101W.  
 
AT 500 HPA...A LOW AMPLITUDE RIDGE ON THE SOUTHERN STREAM LIES  
OVER THE SOUTHEASTERN PACIFIC....WITH AXIS EXTENDING FROM 40S  
97W...ALONG 50S 85W...TO THE BELLINGSHAUSEN SEA. A LONG WAVE  
TROUGH TO THE EAST EXTENDS FROM THE WEDDELL SEA...ALONG 50S  
58W...TO NORTHERN PATAGONIA/LA PAMPA IN ARGENTINA. ON THE NORTHERN  
STREAM...A SHORT WAVE TROUGH TRAILS OFF THE CENTRAL COAST OF  
CHILE...WHILE ANOTHER TO THE EAST EXTENDS FROM A CLOSED LOW AT 35S  
46W TO THE SOUTHERN STATES OF BRASIL.  
 
AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM LIES OVER THE  
EASTERN PACIFIC...WITH AXIS CENTERING ON A 1033 HPA HIGH AT 36S  
98W AND A 1029 HPA HIGH AT 43S 84W. FARTHER EAST...BROAD TROUGH ON  
THE SOUTHERN STREAM EXTENDS OVER THE WESTERN ATLANTIC...WITH A  
POLAR FRONT EXTENDING FROM AN OCCLUDED 974 HPA LOW AT 56S 36W...A  
986 HPA LOW AT 54S 29W...51S 29W...50S 33W...A 986 HPA LOW AT 51S  
40W...48S 43W...47S 47W...A 1002 HPA LOW AT 44S 52W...39S 55W...A  
1002 HPA LOW OVER THE BUENOS AIRES PROVINCE...38S 67W...A 1018 HPA  
LOW AT 36S 73W...35S 79W...40S 88W...47S 90W...53S 91W...TO A 982  
HPA LOW AT 57S 96W. AN ELONGATED FRONT ON THE NORTHERN STREAM LIES  
ALONG A 1026 HPA LOW AT 35S 17W...33S 23W...34S 28W...37S 37W...A  
1006 HPA LOW AT 36S 43W...30S 39W...26S 43W...A 1006 HPA LOW AT  
25S 49W...TO PARAGUAY. ORGANIZED DEEP CONVECTION IS BUILDING TO  
THE NORTH ACROSS THE SOUTHEAST STATES OF BRASIL.  
 
OVIEDO...SHN (ARGENTINA)  
VANNUCCI...SMN (ARGENTINA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  

 
 
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