580  
FXSA20 KWBC 081458  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
958 AM EST THU FEB 08 2018  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM FEB 07 AT 0000 UTC): AT 200 HPA...THE  
BOLIVIAN HIGH/SUBTROPICAL RIDGE CENTERS OVER EXTREME SOUTHERN  
PERU...AND EXTENDS AN AXIS EAST ACROSS BOLIVIA INTO MATO GROSSO. A  
REGION OF ENHANCED INSTABILITY AND MOISTURE CONTENT EXTENDS ALONG  
THE ALTIPLANO INTO THE CENTRAL ANDES OF PERU. THE UPPER HIGH IS  
HELPING TO VENTILATE DIURNAL CONVECTION...WHICH IS FLARING UP FROM  
CENTRAL PERU TO NORTHERN ARGENTINA PRODUCING LOCALLY HEAVY  
RAINFALL AMOUNTS FOR THE REGION. TO THE EAST...AN UPPER TROUGH  
LIES OVER SOUTHWESTERN PARA...AND CONNECTS WITH A TROUGH IN THE  
WESTERLIES THAT EXTENDS FROM 30S 43W ALONG SAO PAULO INTO EASTERN  
MATO GROSSO. VENTILATION IN THE PERIPHERY OF THE TROUGH IS  
INTERACTING WITH THE NET TO PRODUCE DEEP CONVECTION IN  
AMAZONAS-BRASIL...AND ALSO IN THE INTERIOR OF THE BRAZILIAN  
NORDESTE...WHERE INSTABILITY REMAINS HIGH. THE STRONGEST  
CONVECTION IN THE REGION IS OCCURRING OFF THE COASTS OF THE AMAZON  
DELTA OR NORTHEASTERN PARA/AMAPA/MARANHAO IN BRASIL...WHERE ITCZ  
CONVERGENCE IS INTERACTING WITH AN UPPER DIVERGENT PATTERN  
ASSOCIATED WITH A NORTHERN HEMISPHERE TROUGH.  
 
THE UPPER JET ANALYSIS SHOWS THE SOUTHERN POLAR FORMING 45S 109W  
ALONG 45S 98W...A 137KT MAXIMA AT 43S 87W...50S 70W...A 147KT  
MAXIMA AT 46S 59W...A 150KT MAXIMA AT 62S 35W...A 132KT MAXIMA AT  
58S 15W...48S 12W...EXITING AT 42S 07W. THE NORTHERN POLAR FORMS  
AT 35S 116W ALONG 43S 109W...41S 89W...A 140KT MAXIMA AT 46S  
71W...53S 55W...57S 28W...41S 11W. A BRANCH OF THE SUBTROPICAL JET  
HAS FORMED FROM 33S 95W ALONG 36S 86W...EXITING AT 36S 67W.  
ANOTHER FINGER FORMS AT 21S 43W EXITING AT 31S 34W. IT REFORMS AT  
33S 34W ALONG 36S 23W...A 134KT AT 34S 10W.  
 
AT 500 HPA...AN EXTENSIVE SOUTHERN STREAM TROUGH EXTENDS FROM THE  
ANTARCTIC PENINSULA NORTHWEST INTO THE SOUTHEASTERN PACIFIC TO 40S  
80W...WHILE CROSSING THE SOUTHERN CONE. A ROBUST RIDGE TRAILS  
BEHIND THE TROUGH WHILE EXTENDING ALONG 110-100W AND SOUTH INTO  
60S. IN THE NORTHERN STREAM A RIDGE CENTERS ON A HIGH AT 28S 82W  
AND EXTENDS ACROSS THE SUBTROPICAL EASTERN PACIFIC SOUTH TO 35S  
AND EAST INTO LA SERENA. TO THE EAST...A SHORT WAVE TROUGH IS  
CROSSING THE SANTA FE/WESTERN BUENOS AIRES PROVINCES IN ARGENTINA.  
A BROADER TROUGH EXTENDS TO THE EAST WHILE CENTERING ON A LOW AT  
31S 43W.  
 
THE SURFACE ANALYSIS SHOWS A 962 HPA OCCLUDED LOW AT 63S 73W  
EXTENDING AN OCCLUDED FRONT ALONG 64S 78W...67S 67W...61S  
61W...55S 72W. A FRONT EXTENDS FROM 49S 61W ALONG A 100 HPA LOW AT  
48S 66W...45S 67W...42S 72W...38S 83. A 1021 HPA HIGH CENTERS AT  
33S 83W. A 1009 HPA HIGH CENTERS AT 40S 60W. A 998 HPA OCCLUDED  
LOW AT 48S 48W EXTENDS A FRONT ALONG A 998 HPA LOW AT 50S  
48W...46S 45W...43S 50W...A 1006 HPA LOW AT 41S 54W...38S 56W...A  
1006 HPA LOW AT 35S 62W...31S 63W...29S 67W.  
 
POMIER...SENAMHI (BOLIVIA)  
BALBINO...INMET (BRASIL)  
GALVEZ...WPC (USA)  

 
 
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