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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1415Z Apr 30, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1015 AM EDT THU APR 30 2015

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

SYNOPSIS (VALID FROM APRIL 30 AT 00UTC): AT 200 HPA...IN A
TRANSITION PATTERN...WEAK/ILL ORGANIZED CELL OF THE SUBTROPICAL
RIDGE EXTENDS ACROSS THE CONTINENT TO THE NORTH OF 13S. THIS IS
VENTING SCATTERED CONVECTION ACROSS AMAPA/ILHA DE MARAJO INTO
PARA-AMAZONAS IN BRASIL. OTHER CONVECTION WAS CLUSTERING ALONG A
LINE TO THE SOUTH THAT EXTENDS BETWEEN MATO GROSSO/RONDONIA AND
MINAS GERAIS. WEST OVER THE PACIFIC...A CROSS EQUATORIAL
LOW/TROUGH EXTENDS BETWEEN 110W-80W AND TO THE NORTH OF
23S...ANCHORING ON A CLOSED LOW NEAR 10S 89W.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG
63S 110W...A 124KT MAXIMUM AT 53S 102W...46S 96W...47S 82W...57S
67W...A 137KT MAXIMUM AT 65S 48W...65S 35W...EXITING AT 60S 19W.
THE NORTHERN POLAR LIES ALONG 55S 120W...52S 108W...45S
104W...EXITING AT 41S 104W. IT REFORMS AT 40S 98W...ALONG A 122KT
MAXIMUM AT 41S 76W...40S 66W...EXITING AT 38S 60W. IT REFORMS AT
37S 48W...ALONG 33S 40W...33S 31W...41S 17W...AND 44S 01W. THE
SUBTROPICAL JET HAS ITS ENTRANCE AT 32S 120W...THEN ALONG 25S
113W...22S 103W...07S 95W...34S 85W...35S 72W...EXITING AT 30S
60W. THE JET REFORMS AT 18S 52W...ALONG 20S 40W...EXITING AT 23S
26W.

AT 500 HPA...A NORTH-TO-SOUTH RIDGE EXTENDS OVER THE PACIFIC ALONG
120W TO 70S. EAST OF THIS AXIS...A TROUGH ON THE SOUTHERN STREAM
LIES BETWEEN 110W-60W AND TO THE SOUTH OF 40S. TWO LOWS EMBED IN
THIS AXIS...WITH ONE NEAR 70S 88W AND THE OTHER AT 56S 88W. SHORT
WAVE TROUGH ON THE NORTHERN STREAM TRAILS THIS AXIS...ORIGINATING
ON A CLOSED LOW NEAR 29S 104W TO 18S 110W. A SKEWED RIDGE LIES TO
THE EAST...EXTENDING FROM NORTHERN/CENTRAL PROVINCES IN
ARGENTINA...ALONG 50S 50W/THE SOUTH GEORGIA ISLANDS TO 70S 20W. A
TROUGH TO THE EAST EXTENDS ALONG 60S 10W...50S 20W...A CLOSED LOW
AT 43S 28W...TO SOUTHEAST BRASIL.

AT LOW LEVELS...AN OCCLUDED 960 HPA LOW AT 55S 87W EXTENDS A FRONT
ALONG A 978 HPA LOW AT 59S 86W...48S 80W...44S 87W...AND 44S 96W.
AN ELONGATED FRONT TO THE EAST EXTENDS ALONG A 984 HPA LOW AT 69S
29W...65S 35W...63S 55W...A 998 HPA LOW AT 60S 61W...55S 65W...A
1006 HPA LOW AT 49S 70W...PATAGONIA-PUERTO MONTT CHILE...40S
81W...AND 36S 93W. A BROAD RIDGE DOMINATES THE WESTERN ATLANTIC AS
IT CENTERS ON A 1037 HPA HIGH AT 49S 45W. AN ELONGATED TROUGH LIES
TO THE EAST...WITH A POLAR FRONT EXTENDING ALONG 1008 HPA LOW AT
38S 17W...32S 22W...A 1010 HPA LOW AT 31S 28W...26S 35W...24S
43W...TO SOUTHERN SAO PAULO. AN OLD FRONT TO THE EAST AND NORTH
LIES ALONG A 1010 HPA LOW AT 31S 21W...24S 25W...21S 31W...TO 22S
40W.

CALLE...UNALM (PERU)
CHARPENTIER...DMC (CHILE)
SCHNEIDER...INMET (BRASIL)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)