437  
FXSA20 KWBC 241432  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
932 AM EST WED JAN 24 2018  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM JAN 24 AT 0000 UTC): AT 200 HPA...BROAD CELL  
OF THE SUBTROPICAL RIDGE EXTENDS OVER THE CONTINENT BETWEEN  
35S-10S WHILE CENTERING ON A CLOSED HIGH AT 20S 57W. A TROUGH TO  
THE NORTHEAST EXTENDS ALONG 20S 32W...10S 40W...A CLOSED LOW AT  
08S 45W TO THE AMAZON RIVER DELTA REGION. THIS IS VENTING DEEP  
CONVECTION ALONG THE NORTHEAST COAST OF BRASIL. OTHER CONVECTION  
CLUSTERED ALONG THE NEAR EQUATORIAL TROUGH OVER NORTHERN  
PARA-AMAZONAS TO THE WEST. ANOTHER TROUGH EXTENDS ALONG 10S  
100W...A CLOSED LOW AT 09S 86W TO NORTHERN PERU. THIS IS ENHANCING  
CONVECTION ON THE CENTRAL-SOUTHERN SIERRA.  
 
THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG  
53S 120W...56S 105W...56S 94W...EXITING AT 60S 80W. IT REFORMS AT  
58S 44W...ALONG 60S 27W...EXITING AT 55S 06W. THE NORTHERN POLAR  
LIES ALONG 50S 120W...53S 104W...EXITING AT 55S 85W. IT REFORMS AT  
47S 60W...THEN ALONG A 137KT MAXIMUM AT 53S 49W...A 137KT MAXIMUM  
AT 55S 41W...56S 25W...EXITING AT 50S 02W. THE SUBTROPICAL JET HAS  
ITS ENTRANCE AT 30S 73W...ALONG 34S 55W...EXITING AT 34S 37W. THE  
SUBEQUATORIAL JET HAS A FINGER THAT EXTENDS FROM 11S 75W TO 17S  
81W. ANOTHER EXTENDS FROM 13S 87W TO 12S 96W. A FINGER OVER THE  
CONTINENT EXTENDS FROM 22S 36W TO 13S 45W.  
 
AT 500 HPA...IN A TIGHT BELT OF MID LATITUDE WESTERLIES...A  
PROGRESSIVE SHORT WAVE TROUGH IS STREAMING ACROSS 90W TO 50S. THIS  
IS PRESSING AGAINST AN INDUCED RIDGE TO THE EAST THAT EXTENDS  
ALONG 75W AND TO THE SOUTH OF 50S. A HIGHER AMPLITUDE TROUGH TO  
THE EAST EXTENDS FROM THE ANTARCTIC PENINSULA...ACROSS THE  
MALVINAS/FALKLAND ISLANDS...TO NORTHERN PATAGONIA IN ARGENTINA.  
SHORT WAVE PERTURBATIONS TO THE NORTH ARE STREAMING ACROSS MID  
SECTIONS OF CHILE AND ARGENTINA...WITH ONE OFF THE COAST EXTENDING  
ALONG 80W TO 23S...AS ANOTHER PULLS ACROSS 46W/47W TO 30S. THESE  
ARE PROVIDING THE DYNAMICAL SUPPORT TO ORGANIZED DEEP CONVECTION  
ACROSS NORTHERN ARGENTINA-RIO GRANDE DO SUL IN BRASIL.  
 
AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM OVER THE EASTERN  
PACIFIC ANCHORS ON TWO 1025 HPA HIGHS WITH ONE AT 35S 113W AND THE  
OTHER AT 42S 85W. A PROGRESSIVE FRONT TO THE SOUTH EXTENDS ALONG A  
984 HPA LOW AT 62S 78W...58S 76W...53S 84W...A 1006 HPA LOW AT 53S  
94W...51S 94W...48S 99W...AND 46S 108W. OVER THE ATLANTIC...AN  
ELONGATED FRONT LIES ALONG A 994 HPA LOW AT 53S 41W...50S  
39W...47S 46W...A 998 HPA LOW AT 45S 54W...42S 53W...A 1002 HPA  
LOW AT 37S 57W... SOUTHERN URUGUAY TO MENDOZA IN ARGENTINA. THIS  
IS INTERACTING WITH ANOTHER FRONT TO THE NORTH THAT EXTENDS FROM A  
998 HPA LOW AT 39S 49W...A 1004 HPA LOW AT 40S 42W...38S 39W...33S  
43W...RIO GRANDE DO SUL TO FORMOSA IN ARGENTINA. THIS TRIGGERED  
ORGANIZED DEEP CONVECTION ACROSS MID SECTIONS OF SOUTH AMERICA. A  
RIDGE TO THE EAST CENTERS ON A 1027 HPA HIGH AT 37S 16W.  
 
OVIEDO...SHN (ARGENTINA)  
POMIER...SENAMHI (BOLIVIA)  
DAVISON...WPC (USA)  

 
 
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