SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
834 AM EDT MON AUG 24 2009
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
 
SYNOPSIS (VALID FROM 00Z AUG 24). THE ANALYSIS AT 200 HPA SHOWS A
RIDGE OVER THE CONTINENT TO THE NORTH OF 15S...CENTERING ON A
CLOSED HIGH NEAR 02S 59W. SECONDARY HIGHS/RIDGES LIE TO THE WEST
AND EAST OF THIS AXIS...WITH ONE NEAR 05S 102W AND THE OTHER AT
05S 38W. OVER THE LAST FEW DAYS WE HAVE SEEN A SURGE IN TROPICAL
CONVECTION OVER THE CONTINENT TO THE NORTH OF 10S AND WEST OF
50W...WITH MOST INTENSE OVER PARA-AMAZONAS IN BRASIL...AS WELL AS
ACROSS COLOMBIA-SOUTHERN VENEZUELA. 

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH ENTRANCE
AT 44S 92W...ALONG 44S 75W...A 131KT MAXIMUM AT 41S 57W...39S
48W...41S 35W...40S 15W...AND A 136KT MAXIMUM AT 46S 02W. THE
NORTHERN POLAR LIES ALONG 34S 120W...A 134KT MAXIMUM AT 32S
116W...32S 107W...37S 98W...A 156KT MAXIMUM AT 39S 90W...EXITING
AT 34S 70W. IT REFORMS AT 34S 55W...ALONG 34S 44W...A 129KT
MAXIMUM AT 35S 33W...35S 14W...AND 37S 04W. THE SUBTROPICAL JET
HAS ITS ENTRANCE AT 19S 82W...ALONG 19S 66W...23S 51W...29S
39W...EXITING AT 29S 25W. IT HAS A FINGER BETWEEN 25S 20W AND 26S
10W.

AT 500 HPA...THE PATTERN HAS EVOLVED TO ONE WHERE SHORT WAVE
PERTURBATIONS DOMINATE. ON THE SOUTHERN STREAM...AN ELONGATED
TROUGH STRETCHES ALONG 70S 80W...55S 87W...TO 45S 90W. THERE IS
ALSO A CYCLONIC MAXIMA OVER THE DRAKE PASSAGE...WHILE FARTHER TO
THE EAST...A RIDGE EXTENDS BETWEEN 60W-20W AND TO THE SOUTH OF
55S. ON THE NORTHERN STREAM...IN A TIGHT BELT OF MID LATITUDE
WESTERLIES...PROGRESSIVE PERTURBATIONS ARE STREAMING TOWARDS THE
CONTINENT...WITH SHORT WAVE VORTICES STREAMING ACROSS CENTRAL
CHILE/ARGENTINA. A STRONGER PERTURBATION/TROUGH EXTENDS ALONG A
LOW NEAR 41S 107W TO 25S 115W. ANOTHER LIES OFF THE COAST OF
ARGENTINA ALONG 50S 50W TO RIO DE LA PLATA. FARTHER NORTH...A
SHORT WAVE TROUGH EXTENDS FROM CENTRAL MESOPOTAMIA...ACROSS
PARAGUAY TO SOUTHERN BOLIVIA. THE LATTER TRIGGERED ORGANIZED
CONVECTION ACROSS SOUTHEAST BRASIL.

AT LOW LEVELS...A LOW AMPLITUDE TROUGH ON THE SOUTHERN STREAM
EXTENDS ACROSS THE DRAKE PASSAGE TO THE STRAITS OF
MAGELLAN...WITH A 990 HPA LOW AT 59S 74W. A POLAR FRONT TO THE
NORTH ORIGINATES ON A 998 HPA LOW AT 55S 70W...ALONG 51S 68W...TO
CENTRAL PATAGONIA. ON THE NORTHERN STREAM...A 1008 HPA LOW NEAR
PUERTO MONTT CHILE EXTENDS A FRONT ALONG 41S 77W...A 994 HPA LOW
AT 46S 88W...40S 84W...37S 90W...A 1002 HPA LOW AT 36S 98W...33S
101W...A 998 HPA LOW AT 34S 107W...AND 27S 110W. THIS FAVORS
ORGANIZED CONVECTION OVER SOUTHERN CHILE. A RIDGE ON THE NORTHERN
STREAM CENTERS ON THREE 1021 HPA HIGHS...WITH ONE NEAR 26S
86W...THE SECOND AT 31S 77W...AND THE THIRD AT 35S 72W. THERE IS
ALSO A 1017 HPA HIGH AT 38S 63W ANCHORING A RIDGE OVER CENTRAL
ARGENTINA. THERE IS ALSO A RIDGE ON THE SOUTHERN STREAM OVER THE
SOUTH ATLANTIC CENTERING ON A 1023 HPA HIGH AT 60S 41W. NORTH OF
THIS CENTER...A TROUGH DOMINATES THE NORTHERN STREAM WHILE
CENTERING ON A 1004 HPA LOW AT 47S 48W...WITH A POLAR FRONT ALONG
A 1012 HPA LOW AT 45S 36W...41S 40W...A 1010 HPA LOW AT 41S
46W...35S 48W...RIO GRANDE DO SUL-CORRIENTES TO CHACO ARGENTINO.
A RIDGE ON THE NORTHERN STREAM CENTERS ON TWO 1029 HPA HIGHS AT
32S 32W AND 31S 23W RESPECTIVELY. AN ELONGATED FRONT TO THE NORTH
LIES ALONG 24S 30W...RIO GRANDE DO SUL-MATO GROSSO DO SUL...A
1014 HPA LOW AT 24S 57W...TO CENTRAL BOLIVIA. SCATTERED DEEP
CONVECTION WAS NOTED ACROSS SOUTHEAST BRASIL TO MATO GROSSO DO
SUL. 

GARCIA...SENAMHI (PERU)
MAZA...SMN (ARGENTINA)
DAVISON...HPC (USA)