546  
FXSA20 KWBC 131255  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
855 AM EDT FRI OCT 13 2017  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM OCT 13 AT 0000 UTC): AT 200 HPA...AN OPEN  
RIDGE EXTENDS AN AXIS FROM RORAIMA-BRASIL SOUTH INTO  
RONDONIA...MATO GROSSO AND MATO GROSSO DO SUL. TO THE EAST...A LOW  
CENTERS OVER CENTRAL BAHIA. SCATTERED DIURNAL CONVECTION IS  
OCCURRING ACROSS MOST OF THE AMAZON BASIN. ALSO...UNDER THE  
INFLUENCE OF A SURFACE FRONT IN SOUTHERN BOLIVIA...AND VENTILATION  
DOWNSTREAM FROM A WEAK TROUGH IN SOUTHERN PERU...STRONG CONVECTION  
WAS DEVELOPING IN EASTERN BOLIVIA.  
 
THE UPPER JET ANALYSIS SHOWS THE SOUTHERN POLAR JET FORMING AT 60S  
105W ALONG A 150KT MAXIMA AT 59S 76W...EXITING AT 54S 58W. IT  
REFORMS AT 48S 51W ALONG 47S 39W...EXITING AT 44S 29W. ANOTHER  
BRANCH EXTENDS ALONG 41S 120W...49S 109W...A 165KT MAXIMA AT 57S  
91W...54S 755W...EXITING AT 45S 68W. IT REFORMS AT 41S 55W ALONG  
42S 39W...39S 23W. THE NORTHERN POLAR JET EXTENDS ALONG 26S  
82W...30S 69W...38S 51W...A 163KT MAXIMA AT 37S 29W...36S 19W. THE  
SUBTROPICAL JET FORMS AT 21S 83W ALONG 25S 70W...31S 58W...36S  
42W...32S 23W...25S 15W.  
 
AT 500 HPA...IN THE SOUTHERN STREAM...A LOW CENTERS IN THE  
BELLINGSHAUSEN SEA AT 72S 90W. AS IT INTERACTS WITH A RIDGE THAT  
CENTERS ON A HIGH AT 38S 99W TO ITS NORTH...A TIGHT BELT OF  
WESTERLIES EXTENDS FROM 100W INTO TIERRA DEL FUEGO. TO THE  
EAST...A TROUGH EXTENDS ALONG 52S 48W...INTO THE SOUTHERN BUENOS  
AIRES PROVINCE...INTO NORTHERN MENDOZA AND 28S 75W. A RIDGE  
EXTENDS TO THE NORTH AT 22S 34W.  
 
AT LOW LEVELS...A 960 HPA LOW CENTERS AT 68S 85W AND EXTENDS A  
FRONT INTO A 960 HPA TRIPLE POINT LOW AT 70S 79W...62S 71W...58S  
87W...56S 100W. A 988 HPA OCCLUDED LOW AT 53S 45W EXTENDS A FRONT  
ALONG A 996 HPA LOW AT 51S 40W...46S 51W...44S 64W...A 1016 HPA  
LOW AT 46S 68W...46S 75W...53S 80W...A 992 HPA LOW AT 56S 90W. A  
1039 HPA HIGH CENTERS AT 37S 94W AND EXTENDS A RIDGE EAST INTO LOS  
LAGOS-CHILE...TO A 1025 HPA HIGH AT 34S 68W IN CUYO...A 1023 HPA  
HIGH AT 40S 55W...A 1023 HPA HIGH AT 39S 47W...AND A 1021 HPA HIGH  
AT 25S 29W. A FRONT EXTENDS ALONG 29S 35W...30S 47W...A 1012 HPA  
LOW AT 29S 55W...24S 58W...20S 65W.  
 
VANNUCCI...SMN (ARGENTINA)  
RIVAS...SENAMHI (PERU)  
GALVEZ...WPC (USA)  

 
 
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