497  
FXSA20 KWBC 091540  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1040 AM EST FRI FEB 09 2018  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM FEB 09 AT 0000 UTC): AT 200 HPA...THE  
SUBTROPICAL RIDGE IS REFORMING. IT EXTENDS A RIDGE FROM WESTERN  
MATO GROSSO ACROSS NORTHERN BOLIVIA INTO CENTRAL PERU. THIS IS  
VENTILATING CONVECTION IN REGIONS TO THE SOUTH CROSS THE ALTIPLANO  
AND SOUTHERN PERUVIAN ANDES...AS WELL AS IN ITS NORTHERN PERIPHERY  
ACROSS SOUTHERN AMAZONAS AND RONDONIA IN BRASIL. AN UPPER LOW IS  
LOCATED TO THE NORTHEAST OF THE UPPER RIDGE EXTENDING ACROSS  
NORTHERN AMAZONAS AND NORTHERN PARA. TO THE EAST...A RIDGE IS  
STRENGTHENING ALONG 40-50W. THIS IS VENTILATING DEEP CONVECTION  
ALONG ITS PERIPHERY IN MARANHAO...TOCANTINS AND INTERIOR REGIONS  
OF THE BRAZILIAN NORDESTE.  
 
THE UPPER JET ANALYSIS SHOWS THE SOUTHERN POLAR JET EXTENDING  
ALONG 72S 80W...64S 78W...52S 79W...43S 75W...EXITING AT 40S 71W.  
IT REFORMS AT 41S 68W....A 147KT MAXIMA AT 56S 50W...A 149KT  
MAXIMA AT 58S 33W. THE NORTHERN POLAR JET FORMS AT 51S 97W ALONG  
40S 84W...37S 72...A 127KT MAXIMA AT 42S 64W...52S 48W...A 137KT  
MAXIMA AT 56S 19W. A FINGER FORMS AT 44S 52W EXITING AT 50S 35W. A  
FINGER OF THE SUBTROPICAL JET FORMS AT 34S 79W EXITING AT 34S 66W.  
ANOTHER BRANCH FORMS AT 26S 38W ALONG 37S 26W...31S 07W.  
 
AT 500 HPA...THE PATTERN IS BECOMING QUITE AMPLE. A LONG WAVE  
RIDGE EXTENDS ALONG 105W-90W FROM 30S TO 70W. THIS IS LEADING TO  
LONG-FETCH SOUTHERLY FLOW FROM THE BELLINGSHAUSEN SEA NORTH INTO  
AYSEN IN CHILE. A LARGE TROUGH LIES TO THE EAST OF THE  
RIDGE...EXTENDING FROM A LOW AT 62S 62W NORTH TO 32S 75W. IN THE  
NORTHERN STREAM...A WEAK TROUGH EXTENDS ALONG 58W FROM THE RIO DE  
LA PLATA INTO EXTREME SOUTHERN PARAGUAY. A BROADER TROUGH TO THE  
EAST CENTERS ON A LOW AT 34S 40W.  
 
THE SURFACE ANALYSIS SHOWS A 998 HPA LOW AT 49S 67W EXTENDING A  
FRONT ALONG 44S 67W...43S 73W...43S 76W. ANOTHER FRONT EXTENDS  
FROM A 998 HPA LOW AT 51S 52W ALONG 49S 53W...A 1002 HPA LOW AT  
47S 56W...A 1002 HPA LOW AT 45S 58W...42S 60W...41S 63W...A 1002  
HPA LOW AT 41S 66W...36S 70W. TO THE NORTHEAST...A FRONT EXTENDS  
FROM A 1002 HPA LOW AT 48S 49W ALONG 44S 48W...41S 51W...38S  
56W...34S 68W. SEVERE CONVECTION WAS OCCURRING TO THE NORTH OF  
THIS FRONT. A 1025 HPA AT 39S 91W.  
 
POMIER...SENAMHI (BOLIVIA)  
BALBINO...INMET (BRASIL)  
GALVEZ...WPC (USA)  

 
 
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