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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1347Z Oct 21, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
947 AM EDT TUE OCT 21 2014

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

SYNOPSIS (VALID FROM OCTOBER 21 AT 00UTC): AT 200 HPA...TWO SHORT
WAVE PERTURBATIONS ARE STREAMING TOWARDS MID SECTIONS OF SOUTH
AMERICA...WITH ONE ALONG 90W AND THE OTHER OFF THE NORTHERN COAST
OF CHILE/SOUTHERN PERU. THE LATTER SUSTAINS AN UPPER DIVERGENT
PATTERN ACROSS SOUTHERN PERU AND PORTIONS OF BOLIVIA...VENTING
SCATTERED DEEP CONVECTION. AS THEY NEAR THE CONTINENT...THE
TROUGHS ARE PRESSING AGAINST A RIDGE TO THE EAST...AS IT EXTENDS
FROM AMAZONAS IN BRASIL TO NORTHERN SAO PAULO. THIS RIDGE IS
VENTING DEEP CONVECTION ACROSS CENTRAL-NORTHWEST BRASIL. IT ALSO
UNDERCUTS A TROUGH TO THE EAST THAT EXTENDS FROM A CLOSED LOW AT
13S 37W TO THE AMAZON RIVER DELTA. THIS IS ENHANCING CONVECTION
ACROSS NORTHEAST BRASIL.

AT 250 HPA...THE SOUTHERN POLAR LIES ALONG 61S 120W...A 160KT
MAXIMUM AT 61S 110W...55S 103W...EXITING AT 44S 108W. THE NORTHERN
POLAR LIES ALONG A 134KT MAXIMUM AT 35S 123W...32S 113W...30S
107W...33S 98W...A 139KT MAXIMUM AT 38S 90W...A 143KT MAXIMUM AT
46S 74W...43S 59W...A 150KT MAXIMUM AT 32S 39W...36S 29W...A 157KT
MAXIMUM AT 40S 19W...AND 47S 02W. THE SUBTROPICAL JET LIES ALONG
29S 120W...26S 109W...EXITING AT 26S 97W. IT REFORMS AT 26S
60W...ALONG 28S 47W...32S 28W...EXITING AT 36S 13W.

AT MID LEVELS...THE 500 HPA ANALYSIS SHOWS A PROGRESSIVE TROUGH ON
THE SOUTHERN STREAM...WITH AXIS ALONG 70S 88W...60S 90W...TO 50S
100W. THIS IS IN PHASE WITH A TROUGH TO THE NORTH...AS IT EXTENDS
BETWEEN 120W-85W AND TO THE SOUTH OF 23S...WHILE CENTERING ON A
CLOSED LOW AT 45S 105W. THIS TROUGH IS FOCUSING SHORT WAVE ENERGY
AND SUBTROPICAL MOISTURE INTO SOUTHERN PORTIONS OF CHILE. A RIDGE
TO THE EAST EXTENDS FROM NORTHERN ARGENTINA...ACROSS THE BUENOS
AIRES PROVINCE...50S 55W...TO THE WEDDELL SEA. A BROAD TROUGH TO
THE EAST EXTENDS BETWEEN 45W-00W AND TO THE SOUTH OF 25S.

AT LOW LEVELS...THE SURFACE ANALYSIS SHOWS A BROAD TROUGH OVER THE
FAR EASTERN PACIFIC TO THE SOUTHERN CONE OF SOUTH AMERICA. POLAR
FRONTS REVOLVE AROUND THIS AXIS WITH ONE THAT EXTENDS ALONG A 984
HPA LOW AT 62S 69W...59S 63W...55S 64W...A 994 HPA LOW AT 51S
67W...49S 62W...46S 61W...A 1002 HPA LOW AT 43S 63W... NORTHERN
PATAGONIA-LA PAMPA...PUERTO MONTT...A 1002 HPA LOW AT 42S
82W...37S 83W...32S 88W...26S 99W...AND 22S 110W. ANOTHER TROUGH
DOMINATES FLOW OVER THE CENTRAL ATLANTIC AS IT CENTERS ON AN
OCCLUDED 966 HPA LOW AT 57S 06W. A POLAR FRONT TO THE NORTH LIES
ALONG A 1002 HPA LOW AT 36S 19W...33S 21W...30S 26W...A 1010 HPA
LOW AT 28S 32W...25S 34W...23S 39W...RIO DE JANEIRO... NORTHERN
SAO PAULO...MATO GROSSO DO SUL TO SOUTHEAST PARAGUAY. SCATTERED
DEEP CONVECTION WAS BUILDING TO THE NORTH OVER BRASIL. A RIDGE TO
THE SOUTH CENTERS ON A 1021 HPA HIGH AT 37S 50W.

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