SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1014 AM EDT MON MAY 21 2018

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

SYNOPSIS (VALID FROM MAY 21 AT 0000 UTC): AT 200 HPA...LOW
AMPLITUDE RIDGE REMAINS OVER NORTHERN SOUTH AMERICA...WITH AXIS
ENVELOPING ARES TO THE NORTH OF 10S. THIS IS VENTING DIURNAL
CONVECTION ACROSS PARA-AMAZONAS-RORAIMA IN BRASIL...NORTHERN
PERU/SOUTHERN COLOMBIA-ECUADOR.

AT 250 HPA...THE SOUTHERN POLAR HAS A FINGER THAT EXTENDS BETWEEN
47S 116W AND 49S 97W. THE NORTHERN POLAR HAS ITS ENTRANCE AT 40S
104W...THEN ALONG 43S 98W...A 129KT MAXIMUM AT 43S 89W...41S
82W...A 128KT MAXIMUM AT 37S 76W...35S 69W...37S 60W...37S
53W...EXITING AT 34S 47W. THE SUBTROPICAL JET LIES ALONG 18S
120W...21S 108W...26S 102W...32S 96W...34S 90W...34S 82W...31S
73W...30S 66W...28S 59W...23S 52W...22S 48W...23S 44W...25S
40W...27S 37W...A 146KT MAXIMUM AT 30S 34W...36S 29W...39S 20W...A
127KT MAXIMUM AT 38S 10W...36S 03W...AND 32S 05W.

AT 500 HPA...A RIDGE EXTENDS OVER THE EASTERN SOUTH
PACIFIC...DOMINATING THE FLOW TO THE NORTH OF 40S AND WEST OF
95W...WHILE CENTERING ON A CLOSED HIGH AT 23S 86W. SHORT WAVE
PERTURBATIONS ARE STREAMING TO THE SOUTH OF THIS RIDGE...WITH ONE
ENTERING THE DRAKE PASSAGE/SOUTHERN CHILE...WHILE ANOTHER STREAMS
ACROSS CENTRAL CHILE TO CENTRAL ARGENTINA. THE LATTER IS ENHANCING
CONVECTION ACROSS THE RIO DE LA PLATA BASIN. FARTHER EAST...THE
FLOW DIVIDES BETWEEN A RIDGE ON THE SOUTHERN STREAM AND A TROUGH
TO THE NORTH. THE RIDGE EXTENDS SOUTH FROM A CLOSED HIGH AT 50S
43W TO THE WEDDELL SEA...WHILE THE TROUGH TO THE NORTH EXTENDS
FROM A CLOSED LOW AT 35S 39W TO SOUTHEAST BRASIL.

AT LOW LEVELS...RIDGE ON THE NORTHERN STREAM DOMINATES THE EASTERN
PACIFIC...WITH AXIS ANCHORING ON A 1025 HPA HIGH AT 39S 87W. BROAD
TROUGH TO THE SOUTH EXTENDS ACROSS THE SOUTHERN CONE OF SOUTH
AMERICA WHILE CENTERING ON AN OCCLUDED 982 HPA LOW AT 60S 75W. AN
ELONGATED FRONT BOUNDS THE NORTHERN FRINGES OF THIS
TROUGH...EXTENDING FROM A 986 HPA LOW AT 60S 67W...ALONG 58S
65W...56S 67W...A 994 HPA LOW AT 54S 70W... SOUTHERN PATAGONIA...A
1002 HPA LOW AT 51S 78W...48S 79W...47S 82W...A 1006 HPA LOW AT
47S 89W...47S 91W...AND 46S 94W. ANOTHER FRONT TO THE EAST AND
NORTH EXTENDS ALONG A 994 HPA LOW AT 71S 47W...69S 45W...64S
46W...A 998 HPA LOW AT 61S 51W...58S 52W...56S 53W...LAS MALVINAS/
FALKLAND ISLANDS...A 1010 HPA LOW AT 49S 61W...45S 59W...A 1010
HPA LOW AT 42S 60W...BUENOS AIRES PROVINCE TO CENTRAL CUYO IN
ARGENTINA. FARTHER EAST...IN A SPLIT FLOW PATTERN...A RIDGE OVER
THE SOUTH ATLANTIC CENTERS ON A 1033 HPA HIGH AT 50S 43W. NORTH OF
THIS AXIS...A 982 HPA OCCLUDED LOW AT 34S 38W ANCHORS A TROUGH ON
THE NORTHERN STREAM. THIS EXTENDS A FRONT ALONG A 994 HPA LOW AT
35S 31W...34S 28W...32S 28W...A 1002 HPA LOW AT 30S 30W...28S
31W...24S 33W...ESPIRITO SANTO TO RONDONIA IN BRASIL. THIS
SUSTAINS A PREFRONTAL SHEAR LINE THAT EXTENDS FROM BAHIA TO
CENTRAL AMAZONIA IN WESTERN BRASIL.

BALBINO...INMET (BRASIL)
DIAZ...INUMET (URUGUAY)
DAVISON...WPC (USA)