462  
FXSA20 KWBC 231418  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
918 AM EST TUE JAN 23 2018  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM JAN 23 AT 0000 UTC): AT 200 HPA...A HIGH NEAR  
20S 56W ANCHORS A RIDGE OVER MID SECTIONS OF SOUTH AMERICA...THAT  
ENVELOPS SOUTHERN PERU/BOLIVIA-SOUTHEAST STATES OF BRASIL. A  
TROUGH TO THE NORTHWEST EXTENDS FROM A CLOSED LOW AT 10S 96W TO  
NORTHERN PERU/SOUTHERN ECUADOR. THIS IS ENHANCING CONVECTION  
ACROSS NORTHERN JUNGLE OF PERU-AMAZONAS IN BRASIL. ANOTHER TROUGH  
EXTENDS OVER NORTHEAST BRASIL WHILE ANCHORING ON A CLOSED LOW AT  
10S 40W. THIS IS ENHANCING CONVECTION ALONG THE NORTHEAST COAST OF  
BRASIL.  
 
AT 250 HPA...THE SOUTHERN POLAR HAS A FINGER THAT EXTENDS ALONG  
54S 120W...56S 111W...EXITING AT 61S 101W. IT REFORMS BETWEEN 63S  
95W AND 54S 83W. A FINGER OF THE NORTHERN POLAR LIES BETWEEN 56S  
93W AND 49S 83W. IT REFORMS AT 46S 77W...THEN ALONG 51S 65W...A  
140KT MAXIMUM AT 54S 51W...A 128KT MAXIMUM AT 56S 40W...53S  
19W...AND 46S 02W. THE SUBTROPICAL JET HAS A FINGER BETWEEN 41S  
120W AND 43S 97W. ANOTHER FINGER TO THE NORTH EXTENDS BETWEEN 30S  
104W AND 29S 91W. IT REFORMS AT 26S 78W...THEN ALONG 31S  
62W...EXITING AT 35S 44W. THE SUBEQUATORIAL JET IS ANALYZED AT 175  
HPA WITH AXIS ALONG 03S 109W...00N 94W...EXITING AT 01N 77W. A  
FINGER TO THE SOUTH HAS ITS ENTRANCE AT 09S 84W...THEN ALONG 12S  
89W...EXITING AT 13S 96W. ANOTHER FINGER TO THE EAST EXTENDS AT  
150 HPA BETWEEN 20S 38W AND 10S 47W.  
 
AT 500 HPA...A RIDGE EXTENDS SOUTH ALONG 95W/100W TO THE POLAR  
ICECAP. THIS...IN-TURN...FAVORS THE NORTHWARD AMPLIFICATION OF A  
TROUGH ACROSS THE BELLINGSHAUSEN SEA TO THE SOUTHERN CONE OF SOUTH  
AMERICA. THE TROUGH IS FOCUSING SHORT WAVE ENERGY ACROSS SOUTHERN  
CHILE-TIERRA DEL FUEGO. OTHER SHORT WAVE PERTURBATIONS POPULATE  
THE NORTHERN STREAM FLOW...WITH ONE MOVING ACROSS 80W TO 24S AS  
ANOTHER PULLS ACROSS URUGUAY/SOUTHERN BRASIL TO THE WESTERN  
ATLANTIC. THE LATTER PROVIDES DYNAMICAL SUPPORT TO CONVECTION OVER  
SOUTHEAST BRASIL.  
 
AT LOW LEVELS...A RIDGE OVER THE EASTERN PACIFIC ANCHORS ON TWO  
1025 HPA HIGHS...WITH ONE AT 39S 105W AND THE OTHER AT 41S 96W.  
FARTHER EAST...AN ELONGATED FRONT ON THE SOUTHERN STREAM EXTENDS  
ALONG A 988 HPA LOW AT 60S 42W...57S 42W...54S 51W...50S 64W...A  
994 HPA LOW AT 48S 67W...45S 69W...TEMUCO CHILE...38S 90W...TO 39S  
98W. ANOTHER FRONT TO THE NORTH LIES ALONG A 1002 HPA LOW AT 52S  
33W...49S 35W...47S 41W...47S 47W...A 994 HPA LOW AT 49S 57W...43S  
56W...41S 60W...A 998 HPA LOW AT 41S 66W...TO SOUTHERN CUYO IN  
ARGENTINA. THIS SUSTAINS SCATTERED DEEP CONVECTION ACROSS CENTRAL  
ARGENTINA. A RIDGE OVER THE ATLANTIC CENTERS ON TWO HIGHS...A 1025  
HPA AT 42S 20W AND A 1027 HPA HIGH AT 36S 24W. AN ELONGATED FRONT  
TO THE NORTH LIES ALONG 30S 20W...30S 30W...32S 38W...31S 43W...A  
1002 HPA LOW AT 35S 52W...URUGUAY...ENTRE RIOS TO MENDOZA  
 
OVIEDO...SHN (ARGENTINA)  
POMIER...SENAMHI (BOLIVIA)  
DAVISON...WPC (USA)  

 
 
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