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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1310Z Jul 21, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
910 AM EDT MON JUL 21 2014

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

SYNOPSIS (VALID FROM 21 JULY 00UTC): THE UPPER LEVEL ANALYSIS
SHOWS ILL ORGANIZED CYCLONIC CIRCULATION WITH AXIS WEST ACROSS
NORTHERN GUIANAS-VENEZUELA-COLOMBIA. THIS IS ENHANCING CONVECTIVE
DEVELOPMENT ACROSS EQUATORIAL SOUTH AMERICA...WITH MOST ACTIVE
NORTH OF THE EQUATOR. OTHERWISE...A NEAR ZONAL WESTERLY FLOW
DOMINATES FLOW ACROSS PERU-BRASIL.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH ENTRANCE AT
38S 99W...ALONG 35S 91W...EXITING AT 35S 83W. IT REFORMS AT 38S
79W...ALONG A 127KT MAXIMUM AT 48S 60W...50S 51W...43S
41W...EXITING AT 37S 34W. THE NORTHERN POLAR LIES ALONG 31S
120W...A 131KT MAXIMUM AT 37S 108W...A 145KT MAXIMUM AT 34S
98W...32S 92W...EXITING AT 31S 79W. IT REFORMS AT 32S 74W...ALONG
43S 65W...44S 55W...39S 45W...EXITING AT 33S 40W. THE SUBTROPICAL
JET HAS ITS ENTRANCE AT 19S 40W...ALONG 21S 30W...EXITING AT 28S
14W. IT HAS A BRANCH TO THE NORTH WITH ENTRANCE AT 14S 48W...ALONG
14S 38W...18S 26W...EXITING AT 21S 16W.

AT 500 HPA...A NORTH-TO-SOUTH RIDGE EXTENDS ALONG 105W TO 50S.
EAST OF THIS AXIS...A TROUGH EXTENDS BETWEEN 100W-65W TO THE SOUTH
OF 23S. THIS IS FOCUSING SHORT WAVE ENERGY ACROSS CENTRAL/SOUTHERN
CHILE TO ARGENTINA. A SKEWED RIDGE LIES TO THE EAST OF THIS
TROUGH...WITH AXIS SOUTH FROM PARAGUAY...ACROSS RIO DE LA PLATA
BASIN...50S 50W...TO THE SOUTH GEORGIA ISLANDS. IN A SINUSOIDAL
LONG WAVE PATTERN...ANOTHER TROUGH EXTENDS OVER THE SOUTH
ATLANTIC...WITH AXIS NORTH BETWEEN 45W-10W TO 20S.

AT LOW LEVELS...A BROAD RIDGE OVER THE EASTERN PACIFIC CENTERS ON
A 1029 HPA HIGH AT 34S 100W. A POLAR TROUGH TO THE SOUTH DOMINATES
FLOW ACROSS THE BELLINGSHAUSEN SEA-SOUTHERN CONE OF SOUTH AMERICA.
POLAR FRONTS REVOLVE AROUND THIS AXIS WITH ONE THAT EXTENDS ALONG
A 986 HPA LOW AT 67S 78W...62S 75W...58S 78W...A 998 HPA LOW AT
55S 81W...52S 79W...A 1002 HPA LOW AT 50S 81W...42S 82W...TO 37S
92W. AN OCCLUDED 994 HPA LOW NEAR 53S 63W...ALONG A 998 HPA LOW AT
50S 59W...44S 59W...NORTHERN  PATAGONIA...A 1014 HPA LOW AT 39S
74W... 31S 80W...AND 27S 89W. OVER THE SOUTH ATLANTIC...A RIDGE ON
THE SOUTHERN STREAM EXTENDS OVER THE WEDDELL SEA WHILE CENTERING
ON A 1021 HPA HIGH AT 61S 37W. BROAD POLAR TROUGH TO THE EAST
CENTERS ON AN OCCLUDED 978 HPA LOW AT 48S 21W. IT EXTENDS A POLAR
FRONT ALONG 1010 HPA LOW AT 35S 15W...28S 18W...23S 22W...TO
VITORIA IN EASTERN BRASIL. A RIDGE OVER SOUTHERN BRASIL CENTERS ON
A 1025 HPA HIGH AT 27S 49W.

FERNANDES...INMET (BRASIL)
JALFIN...SMN (ARGENTINA)
DAVISON...WPC (USA)