343  
FXSA20 KWBC 171400  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
900 AM EST FRI NOV 17 2017  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM NOV 17 AT 0000 UTC): A 200 HPA HIGH OVER  
CENTRAL PERU EXTENDS A RIDGE EAST ACROSS NORTHERN BOLIVIA TO  
RONDONIA IN BRASIL...AND TO THE SOUTHEAST ACROSS MATO GROSSO DO  
SUL TO SAO PAULO. EAST OF THIS RIDGE A TROUGH EXTENDS OVER BRASIL  
BETWEEN 50W-30W TO 00N. UNDER INFLUENCE OF THE RIDGE TO THE WEST  
DEEP CONVECTION IS BUILDING ACROSS CENTRAL-WESTERN BRASIL INTO  
SOUTHERN COLOMBIA/NORTHERN PERU AND EASTERN ECUADOR. MOST INTENSE  
IS CLUSTERING OVER THE PERUVIAN JUNGLE-AMAZONAS IN BRASIL...WITH  
OTHER CONVECTION DOTTING THE SOUTHERN SIERRA OF PERU AND THE  
ALTIPLANO OF BOLIVIA.  
 
AT 250 HPA...THE SOUTHERN POLAR LIES ALONG 53S 120W...A 167KT  
MAXIMUM AT 55S 115W...58S 101W...EXITING AT 62S 90W. A FINGER TO  
THE NORTH EXTENDS BETWEEN 57S 81W AND 46S 75W. THE NORTHERN POLAR  
LIES ALONG A 157KT MAXIMUM AT 50S 119W...53S 107W...52S 90W...41S  
77W... 38S 69W...EXITING AT 38S 59W. IT REFORMS AT 36S 50W...ALONG  
A 135KT MAXIMUM AT 38S 45W...A 157KT MAXIMUM AT 41S 35W...A 120KT  
MAXIMUM AT 43S 23W...44S 14W...A 136KT MAXIMUM AT 42S 06W...AND  
39S 01E. A FINGER OF THE SUBTROPICAL JET LIES BETWEEN 33S 87W AND  
31S 69W. IT REFORMS AT 28S 54W...THEN ALONG 32S 49W...35S  
40W...EXITING AT 38S 29W.  
 
AT 500 HPA...BROAD RIDGE OVER THE EASTERN PACIFIC DOMINATES THE  
SOUTHERN AND NORTHERN STREAM FLOW. UNDER INFLUENCE OF THIS  
RIDGE...A LONG WAVE TROUGH EXTENDS NORTH FROM THE ANTARCTIC  
PENINSULA...ACROSS PATAGONIA IN ARGENTINA/SOUTHERN CHILE TO THE  
EASTERN PACIFIC NEAR 35S 80W. THIS IS FOCUSING SHORT WAVE ENERGY  
ACROSS PATAGONIA/LA PAMPA IN ARGENTINA...WHERE IT IS PROVIDING  
SUPPORT TO DEEP CONVECTION. UNDER THE INFLUENCE OF THE LONG WAVE  
TROUGH...A RIDGE EXTENDS FROM 43S 50W TO THE WEDDELL SEA. SHORT  
WAVE PERTURBATIONS ARE STREAMING TO THE NORTH AND EAST...WITH ONE  
PULLING ACROSS URUGUAY TO RIO GRANDE DO SUL IN BRASIL AS ANOTHER  
MEANDERS ACROSS 32W/34W WHILE CONFINING TO THE SOUTH OF 37S.  
 
AT LOW LEVELS...A POLAR FRONT ON THE SOUTHERN STREAM EXTENDS FROM  
AN OCCLUDED 990 HPA LOW AT 68S 63W...ALONG A 990 HPA LOW AT 65S  
57W...61S 52W...57S 55W...A 996 HPA LOW AT 51S 60W...TO 47S 55W.  
THIS IS INTERACTING WITH ANOTHER FRONT TO THE NORTH THAT EXTENDS  
FROM A 990 HPA LOW AT 48S 64W...ALONG A 992 HPA LOW AT 48S  
62W...45S 60W...43S 61W...A 996 HPA LOW AT 42S 64W...38S 66W...33S  
78W...32S 84W...WEAKENING AS IT EXTENDS ALONG 34S 90W AND 41S 95W.  
A RIDGE TO THE WEST ANCHORS ON A 1033 HPA HIGH AT 39S 99W. ANOTHER  
FRONT OVER THE ATLANTIC EXTENDS FROM AN OCCLUDED 982 HPA LOW AT  
44S 29W...A 992 HPA LOW AT 43S 24W...41S 25W...40S 27W...A 1000  
HPA LOW AT 39S 30W...36S 31W...33S 35W...31S 42W...RIO GRANDE DO  
SUL...A 1010 HPA LOW AT 30S 52W...26S 54W...CENTRAL PARAGUAY TO  
NORTHWEST ARGENTINA. ORGANIZED DEEP CONVECTION IS BUILDING ALONG  
AND NORTH OF THIS FRONT. A 1015 HPA HIGH AT 34S 53W ANCHORS A  
RIDGE TO THE SOUTH.  
 
OVIEDO...SHN (ARGENTINA)  
VANNUCCI...SMN (ARGENTINA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  

 
 
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