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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1443Z Feb 26, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
943 AM EST THU FEB 26 2015

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

SYNOPSIS (VALID FROM FEBRUARY 26 AT 00UTC): AT 200 HPA...NARROW
TROUGH OVER BRASIL SEPARATES THE SUBTROPICAL RIDGE FROM THE
SUBEQUATORIAL RIDGE. THE TROUGH EXTENDS ACROSS SAO PAULO...20S
50W...A LOW AT 10S 60W...TO AMAZONIA IN COLOMBIA. THE SUBTROPICAL
RIDGE TO THE SOUTH ANCHORS ON A HIGH OVER THE ALTIPLANO OF
BOLIVIA. THE HIGH RIDGES TO THE SOUTHEAST ACROSS PARAGUAY/NORTHERN
ARGENTINA-SOUTHERN BRASIL...AND TO THE NORTHWEST ACROSS SOUTHERN
PERU INTO THE TROPICAL PACIFIC. THE SUBEQUATORIAL RIDGE TO THE
NORTH ENVELOPS THE NORTHEAST STATES OF BRASIL WHILE ANCHORING ON A
HIGH NEAR 07S 37W. IN THIS PATTERN...MOST ACTIVE CONVECTION IS
BUILDING TO THE NORTH OF 10S ACROSS BRASIL TO
PERU-COLOMBIA/EASTERN ECUADOR.

AT 250 HPA...THE SOUTHERN POLAR LIES ALONG 43S 120W...A 146KT
MAXIMUM AT 48S 115W...A 155KT MAXIMUM AT 54S 109W...61S 100W...59S
73W...56S 56W...EXITING AT 51S 48W. THE NORTHERN POLAR LIES ALONG
39S 120W...42S 114W...A 137KT MAXIMUM AT 48S 109W...56S 99W...A
140KT MAXIMUM AT 55S 84W...51S 67W...EXITING AT 45S 55W. IT
REFORMS AT 42S 52W...ALONG 42S 39W...A 132KT MAXIMUM AT 44S
31W...46S 19W...AND 45S 00W. THE SUBTROPICAL JET LIES ALONG 34S
120W...40S 111W...51S 97W...EXITING AT 48S 74W. IT HAS A FINGER
BETWEEN 39S 74W AND 35S 82W. THE SUBTROPICAL JET REFORMS AT 28S
75W...ALONG 35S 60W...EXITING AT 37S 42W.

AT 500 HPA...A BUILDING RIDGE ON THE SOUTHERN STREAM ORIGINATES ON
A CLOSED HIGH NEAR 41S 89W...WITH AXIS ALONG 53S 95W TO 63S 110W.
UNDER INFLUENCE OF THIS RIDGE...SHORT WAVE PERTURBATIONS ON THE
SOUTHERN STREAM ARE LIFTING ACROSS THE DRAKE PASSAGE/TIERRA DEL
FUEGO. THESE THEN FEED INTO A BROAD TROUGH TO THE EAST. THE TROUGH
BOUNDS BETWEEN 55W-15W AND TO THE SOUTH OF 30S...WITH TROUGH
ANCHORING ON A CLOSED LOW NEAR 66S 36W. FARTHER NORTH...A SHORT
WAVE TROUGH MEANDERS OFF THE CENTRAL/NORTHERN COAST OF
CHILE...WHILE CENTERING ON A CLOSED LOW NEAR 35S 76W. THIS IS
FOCUSING SHORT WAVE ENERGY ACROSS CENTRAL CHILE-ARGENTINA-RIO DE
LA PLATA BASIN. THE INFLOW OF SHORT WAVE ENERGY FAVORS ORGANIZED
DEEP CONVECTION ACROSS THE MESOPOTAMIA VALLEY IN NORTHERN
ARGENTINA-PORTIONS OF URUGUAY.

AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM ANCHORS ON A 1029
HPA HIGH AT 41S 89W. POLAR FRONT TO THE SOUTH EXTENDS FROM AN
OCCLUDED 1008 HPA LOW AT 53S 76W...ALONG A 1000 HPA LOW AT 54S
70W...48S 73W...48S 83W...49S 91W...A 1012 HPA LOW AT 51S
101W...46S 103W...TO A 1006 HPA LOW AT 43S 109W. A POLAR FRONT
OVER THE ATLANTIC EXTENDS ALONG A 998 HPA LOW AT 45S 22W...36S
42W...RIO DE LA PLATA TO 35S 68W. A POLAR RIDGE TO THE SOUTH
CENTERS ON A 1025 HPA HIGH AT 40S 62W. THE FRONT SUSTAINS
ORGANIZED DEEP CONVECTION ACROSS URUGUAY TO THE NORTHERN PROVINCES
IN ARGENTINA.

ARREAGA...INAMHI (ECUADOR)
SCHNEIDER...INMET (BRASIL)
DAVISON...WPC (USA)