246  
FXSA20 KWBC 041440  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
939 AM EST MON DEC 04 2017  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM DEC 04 AT 0000 UTC): AT 200 HPA...A HIGH NEAR  
05S 59W EXTENDS A RIDGE OVER THE CONTINENT THAT ENVELOPS AREA TO  
THE NORTH OF 33S. THE RIDGE ALOFT IS VENTING DEEP CONVECTION  
ACROSS BRASIL TO THE SOUTH OF 05S...AND ACROSS  
ECUADOR-PERU-BOLIVIA.  
 
THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG  
54S 120W...A 160KT MAXIMUM AT 55S 109W...56S 93W...EXITING AT 59S  
80W. IT REFORMS AT 70S 65W...THEN ALONG 67S 54W...A 124KT MAXIMUM  
AT 51S 45W...EXITING AT 44S 42W. ANOTHER BRANCH OF THE SOUTHERN  
POLAR TO THE EAST HAS ITS ENTRANCE AT 44S 39W...THEN ALONG 51S  
27W...AND 56S 09W. THE NORTHERN POLAR LIES ALONG 49S 120W...52S  
101W...EXITING AT 52S 77W. IT REFORMS AT 40S 45W...CROSSING 41S  
36W...EXITING AT 43S 26W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT  
22S 77W...ALONG 31S 61W...A 121KT MAXIMUM AT 32S 48W...EXITING AT  
29S 36W. THE SUBEQUATORIAL JET HAS A BRANCH THAT EXTENDS ALONG 07S  
114W...10S 100W...EXITING AT 11S 89W. ANOTHER FINGER TO THE NORTH  
LIES ALONG 01S 108W...01S 98W...EXITING AT 00N 89W.  
 
AT 500 HPA...TIGHT BELT OF MID LATITUDE WESTERLIES DOMINATE THE  
FLOW BETWEEN 140W-70W AND TO THE SOUTH OF 47S. A SHORT WAVE RIDGE  
TO THE EAST...MEANWHILE...EXTENDS SOUTH OF 45S AND ALONG 60W TO  
THE ANTARCTIC PENINSULA. THIS...IN-TURN...FAVORS THE NORTHWARD  
AMPLIFICATION OF A TROUGH BETWEEN 50W-30W TO 30S. SHORT WAVE  
TROUGH ON THE NORTHERN STREAM TRAILS TO THE WEST...WITH AXIS  
EXTENDING FROM 34S 77W TO 20S 85W.  
 
AT LOW LEVELS...BROAD RIDGE ON THE NORTHERN STREAM LIES OVER THE  
EASTERN PACIFIC WHILE CENTERING ON TWO 1029 HPA HIGHS...WITH ONE  
AT 35S 98W AND THE OTHER AT 39S 99W. BROAD/LOW AMPLITUDE TROUGH TO  
THE SOUTH CENTERS ON A AN OCCLUDED 950 HPA LOW AT 64S 115W. POLAR  
FRONTS REVOLVE AROUND THIS TROUGH...WITH ONE EXTENDING FROM AN  
OCCLUDED 966 HPA LOW AT 60S 97W...A 982 HPA LOW AT 59S 89W...55S  
87W...51S 94W...TO 52S 102W. ANOTHER TO THE EAST EXTENDS FROM AN  
OCCLUDED 982 HPA LOW AT 63S 78W...A 986 HPA LOW AT 62S 72W...57S  
65W...A 1006 HPA LOW AT 51S 70W.... SOUTHERN PATAGONIA...48S  
71W...46S 76W...A 1014 HPA LOW AT 46S 83W...42S 84W...AND 38S 93W.  
OVER THE SOUTH ATLANTIC...A FRONT EXTENDS FROM A 990 HPA LOW AT  
49S 30W...A 993 HPA LOW AT 49S 28W...45S 28W...44S 31W...A 1002  
HPA LOW AT 44S 36W...39S 39W...34S 45W...A 1008 HPA LOW AT 31S  
50W...30S 54W...TO 30S 66W. A POLAR RIDGE TO THE SOUTH CENTERS ON  
A 1027 HPA HIGH AT 44S 59W. AN ELONGATED FRONT TO THE NORTH  
EXTENDS FROM AN OCCLUDED 1002 HPA LOW AT 40S 20W...A 1004 HPA LOW  
AT 42S 18W...37S 15W...33S 18W...A 1010 HPA LOW AT 31S 23W...26S  
24W...23S 29W...RIO DE JANEIRO TO MATO GROSSO DO SUL.  
 
OVIEDO...SHN (ARGENTINA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  

 
 
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