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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1554Z Sep 25, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1154 AM EDT THU SEP 25 2014

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

COR DTG

SYNOPSIS (VALID FROM SEPTEMBER 25 AT 00UTC): AT 200 HPA...THE
SUBTROPICAL RIDGE DOMINATES FLOW ACROSS THE CONTINENT TO THE NORTH
OF 25S. THE RIDGE ANCHORS ON A CLOSED HIGH OVER RONDONIA IN
BRASIL. THIS IS FOCUSING THE SUBTROPICAL JET ACROSS NORTHERN
CHILE/ ARGENTINA-SOUTHERN BRASIL...WHERE IT IS ENHANCING UPPER
DIVERGENCE AND VENTING DEEP CONVECTION. ACTIVITY CLUSTERS ALONG A
LINE FROM SAO PAULO TO MATO GROSSO/RONDONIA. OTHER CONVECTION TO
THE NORTH WAS BUILDING ACROSS PARA AND AMAZONAS. WIDELY ISOLATED
CONVECTION DOTTED THE SIERRA OF PERU AND THE ALTIPLANO OF BOLIVIA.

THE 250 HPA JET ANALYSIS SHOWS A FINGER OF THE SOUTHERN POLAR WITH
AXIS BETWEEN 45S 93W AND 39S 84W. IT REFORMS BETWEEN 41S 69W AND
43S 51W. THE NORTHERN POLAR HAS ITS ENTRANCE AT 34S 86W...ALONG
34S 69W...36S 57W...38S 43W...EXITING AT 41S 32W. THE SUBTROPICAL
JET TO THE NORTH HAS ITS ENTRANCE AT 19S 103W...ALONG A 131KT
MAXIMUM AT 24S 90W...A 128KT MAXIMUM AT 26S 70W...28S
56W...EXITING AT 30S 38W.

AT 500 HPA...A RIDGE ON THE SOUTHERN STREAM EXTENDS ALONG 100W AND
TO THE SOUTH OF 45S...WHILE ANCHORING ON A HIGH NEAR 53S 101W.
EAST OF THIS AXIS...A BROAD AMPLITUDE TROUGH EXTENDS ACROSS THE
ANTARCTIC PENINSULA TO THE WEDDELL SEA. THIS IS IN PHASE WITH A
SHORT WAVE TROUGH TO THE NORTH...AS THE LATTER EXTENDS OVER THE
SOUTHERN CONE OF SOUTH AMERICA WHILE CENTERING ON A LOW NEAR 53S
73W. THIS IS FOCUSING SHORT WAVE ENERGY ACROSS CHILE AND ARGENTINA
TO THE SOUTH OF 30S.

AT LOW LEVELS...BROAD TROUGH ENVELOPS THE SOUTHERN CONE OF SOUTH
AMERICA. POLAR FRONTS EMBED IN THIS FLOW...WITH ONE THAT EXTENDS
FROM AN OCCLUDED 986 HPA LOW AT 55S 63W...ALONG 55S 65W...A 986
HPA LOW AT 58S 59W...56S 53W...52S 53W...A 992 HPA LOW AT 50S
55W...47S 50W...44S 51W...44S 58W...A 1000 HPA LOW AT 44S
66W...41S 65W...38S 67W...38S 71W...A 1014 HPA LOW AT 36S
74W...33S 79W...AND 31S 84W. THIS SUSTAINS SCATTERED RAINS ACROSS
CENTRAL CHILE AND EASTERN PATAGONIA. A SECONDARY FRONT
FOLLOW...EXTENDING FROM AN OCCLUDED 1002 HPA LOW AT 49S
75W...ALONG A 1000 HPA LOW AT 51S 71W...47S 69W...44S 75W...AND
43S 81W. EAST OVER THE ATLANTIC...AN OCCLUDED 990 HPA LOW AT 46S
40W EXTENDS A FRONT ALONG A 992 HPA LOW AT 47S 38W...45S 36W...A
1000 HPA LOW AT 42S 37W...36S 37W...30S 43W... PARANA
BRASIL-MISIONES ARGENTINA TO CHACO PARAGUAYO. ORGANIZED DEEP
CONVECTION IS BUILDING NORTH OF THIS BOUNDARY ACROSS SOUTHEAST TO
CENTRAL BRASIL. A POLAR RIDGE TO THE SOUTH CENTERS ON A 1017 HPA
HIGH AT 32S 50W...WHILE THE SUBTROPICAL RIDGE TO THE EAST CENTERS
ON A 1033 HPA HIGH AT 33S 21W.

JALFIN...SMN (ARGENTINA)
CAROCA...DMC (CHILE)
DAVISON...WPC (USA)