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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1323Z Oct 20, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
923 AM EDT MON OCT 20 2014

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

SYNOPSIS (VALID FROM OCTOBER 20 AT 00UTC): AT 200 HPA...OPEN CELL
OF THE SUBTROPICAL RIDGE EXTENDS ACROSS AMAZONAS-RONDONIA IN
BRASIL. THIS IS PHASING WITH A SHORT WAVE RIDGE TO THE EAST...AS
THE LATTER EXTENDS FROM A CLOSED HIGH AT 17S 50W TO 30S 30W. THE
LATTER UNDERCUTS A TROUGH TO THE NORTH...WITH TROUGH EXTENDING
ALONG 17S 25W...13S 40W...TO 10S 50W.RIDGE ALOFT IS VENTING DEEP
CONVECTION ACROSS MATO GROSSO-MATO GROSSO DO SUL TO SAO PAULO IN
BRASIL. THE TROUGH...MEANWHILE...IS INHIBITING ORGANIZED
CONVECTION ACROSS NORTHEAST BRASIL.

AT 250 HPA...THE SOUTHERN POLAR HAS A FINGER WITH ENTRANCE AT 59S
95W...ALONG 66S 84W...TO 73S 78W. IT REFORMS BETWEEN 63S 45W AND
52S 44W. THE NORTHERN POLAR LIES ALONG 34S 120W...A 136KT MAXIMUM
AT 33S 113W...35S 102W...A 135KT MAXIMUM AT 39S 90W...44S
73W...37S 57W...A 139KT MAXIMUM AT 39S 39W...A 152KT MAXIMUM AT
42S 24W...41S 13W... EXITING AT 35S 08W. THE SUBTROPICAL JET HAS
ITS ENTRANCE AT 20S 73W...ALONG 27S 62W...A 129KT MAXIMUM AT 32S
49W...35S 39W...EXITING AT 35S 25W.

AT 500 HPA...A HIGH AMPLITUDE TROUGH EXTENDS ALONG 70S 95W...60S
95W...54S 100W...TO 44S 110W. THIS TROUGH IS INTERACTING WITH A
SHORT WAVE TROUGH TO THE NORTH...WITH THE LATTER EXTENDING FROM A
CLOSED LOW AT 42S 109W TO 30S 115W. EAST OF THIS AXIS...ANORTHER
SHORT WAVE TROUGH EXTENDS FROM A LOW NEAR 53S 85W TO SOUTHERN
ARGENTINA. THIS IS PRESSING AGAINST A RIDGE TO THE EAST THAT
EXTENDS FROM CENTRAL CHILE...ACROSS NORTHERN PATAGONIA-LAS
MALVINAS/FALKLAND ISLANDS TO THE WEDDELL SEA/ANTARCTIC PENINSULA.
BROAD TROUGH OVER THE SOUTH ATLANTIC ENVELOPS AREA BETWEEN 50W-10W
AND TO THE SOUTH OF 40S.

AT LOW LEVELS...BROAD TROUGH EXTENDS ACROSS THE SOUTHEAST
PACIFIC... ENVELOPING THE BELLINGSHAUSEN SEA AND SOUTHERN CONE OF
SOUTH AMERICA. POLAR FRONTS REVOLVE AROUND THIS AXIS...WITH ONE
THAT EXTENDS FROM AN OCCLUDED 990 HPA LOW AT 53S 82W...A 998 HPA
LOW AT 53S 73W...53S 70W...50S 69W...A 1006 HPA LOW AT 46S
70W...44S 68W... 41S 69W...39S 72W...A 998 HPA LOW AT 43S
81W...41S 78W...37S 80W...A 1014 HPA LOW AT 31S 102W...AND 28S
104W. THIS SUSTAINS SCATTERED RAINS ACROSS CHILE SOUTH OF TEMUCO.
ANOTHER TROUGH LIES TO THE EAST...WITH AXIS OVER SOUTH ATLANTIC
CENTERING ON AN OCCLUDED 974 HPA LOW AT 54S 18W. THIS EXTENDS A
FRONT ALONG A 980 HPA LOW AT 53S 13W...49S 12W...46S 16W...44S
23W...42S 31W...40S 36W...38S 42W...A 1010 HPA LOW AT 38S
48W...35S 50W...TO SOUTHERN URUGUAY. A RIDGE TO THE SOUTH CENTERS
ON A 1021 HPA HIGH AT 44S 59W. AN OLD FRONT TO THE NORTH LIES
ALONG A 1002 HPA LO AT 38S 30W...36S 31W...35S 35W...A 1006 HPA
LOW AT 34S 39W..30S 40W...PARANA-SOUTHEAST PARAGUAY TO NORTHWEST
ARGENTINA. THIS SUSTAINS SCATTERED DEEP CONVECTION ACROSS MID
SECTIONS OF SOUTH AMERICA.

CAROCA...DMC (CHILE)
DURAN...SENAMHI (PERU)
DAVISON...WPC (USA)