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South American Synoptic Discussion
 
(Latest Discussion - Issued 1255Z Nov 26, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
755 AM EST WED NOV 26 2014

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

SYNOPSIS (VALID FROM NOVEMBER 26 AT 00UTC): ORGANIZED DEEP
CONVECTION IS CLUSTERING ALONG A LINE FROM CENTRAL PERU/AMAZONAS
IN WESTERN BRASIL...ACROSS RONDONIA/NORTHERN BOLIVIA TO THE
SOUTHEAST STATES OF BRASIL. AT UPPER LEVELS THE SUBTROPICAL RIDGE
IS PROVIDING THE VENTILATION TO THE DEEP CONVECTION AS IT ANCHORS
ON A CLOSED HIGH NEAR 17S 57W. THE BROAD RIDGE PATTERN ENVELOPS
CONTINENTAL AREA TO THE NORTH OF 30S.

THE UPPER JET ANALYSIS...CENTERED AT 250 HPA...SHOWS THE SOUTHERN
POLAR JET FORMING AT 52S 110W ALONG 60S 93W...A 130KT MAXIMA AT
55S 74W...49S 55W...EXITING AT 48S 28W. THE NORTHERN POLAR  FORMS
AT 31S 126W ALONG A 145KT MAXIMA AT 35S 113W...37S 99W...EXITING
AT 42S 87W. THE SUBTROPICAL JET FORMED AT 31S 72W ALONG 33S
60W...A130KT MAXIMA AT 37S 46W...A 156KT MAXIMA AT 38S 37W...38S
27W...EXITING AT 40S 14W. ANOTHER BRANCH EXTENDED ALONG 21S 67W
ALONG 27S 58W...31S 46W...31S 34W.

AT 500 HPA...A NORTH-TO-SOUTH RIDGE NOW EXTENDS ALONG 85W TO 64S.
SOUTHERN AND NORTHERN STREAM PERTURBATIONS ARE PRESSING AGAINST
THIS AXIS...WITH ONE ALONG 110W TO 50S...WHILE ANOTHER TO THE
NORTH EXTENDS FROM A LOW AT 43S 100W TO 30S 120W. FARTHER EAST...A
BROAD/LOW AMPLITUDE TROUGH EXTENDS BETWEEN 73W-20W AND TO THE
SOUTH OF 34S. THIS IS FOCUSING SHORT WAVE VORTICES ACROSS CENTRAL
CHILE-ARGENTINA-RIO DE LA PLATA BASIN. OTHER VORTICES TO THE SOUTH
ARE STREAMING ACROSS THE DRAKE PASSAGE TO TIERRA DEL
FUEGO/SOUTHERN PATAGONIA IN ARGENTINA.

THE SURFACE ANALYSIS SHOWS A 978 HPA LOW AR 56S 64W EXTENDING A
FRONT ALONG A 980 HPA LOW AT 54S 62W...62S 64W...50S 71W...52S
80W. RAINFALL WAS OCCURRING OVER TIERRA DEL FUEGO. A 982 HPA
OCCLUDED LOW CENTERED AT 53S 40W EXTENDING A FRONT ALONG A 988 HPA
LOW AT 51S 39W...48S 41W...45S 49W...45S 55W...A 1004 HPA LOW AT
46S 66W...44S 66W...44S 71W. A 1000 HPA LOW AT 45S 22W EXTENDED A
FRONT ALONG 39S 25W...36S 30W...33S 41W...A 1010 HPA LOW AT 33S
46W...31S 48W...30S 51W...31S 54W...29S 60W. A 1013 HPA HIGH AT
38S 51W. A 1025 HPA HIGH CENTERED AT 34S 84W. A TROUGH EXTENDED
FROM NORTHERN PARAGUAY INTO CENTRAL BOLIVIA. STRONG THUNDERSTORMS
WERE OCCURRING TO THE NORTHEAST OF THE MAIN AXIS OF THIS TROUGH.

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