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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1332Z Aug 12, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
932 AM EDT TUE AUG 12 2014

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

MODEL DISCUSSION (VALID FROM AUGUST 12 AT 00UTC): THE 200 HPA
ANALYSIS SHOWS A NARROW CELL OF THE SUBTROPICAL RIDGE WITH AXIS
WEST ACROSS NORTHERN SOUTH AMERICA INTO THE EASTERN TROPICAL
PACIFIC. A CLOSED HIGH OVER NORTHERN AMAZONAS IN BRASIL ANCHOR
THIS AXIS. SHORT WAVE PERTURBATIONS TO THE SOUTH ARE STREAMING
ACROSS BRASIL...WITH ONE ACROSS AMAZONAS AS ANOTHER MOVES ACROSS
PARA TO TOCANTINS/GOIAS. DEEP CONVECTIVE CELLS CONTINUE TO CLUSTER
ACROSS AMAZONAS TO COLOMBIA-NORTHERN PERU...WITH ACTIVITY ALIGNING
NORTH TO SOUTH ALONG A TROPICAL WAVE.

AT 250 HPA...THE SOUTHERN POLAR HAS ITS ENTRANCE AT 56S
122W...THEN ALONG A 138KT MAXIMUM AT 60S 96W...55S 84W...EXITING
AT 48S 75W. IT THEN REFORMS BETWEEN 43S 71W AND 41S 61W. THE
SOUTHERN POLAR HAS A BRANCH TO THE EAST WITH ENTRANCE AT 41S
50W...ALONG 43S 41W...44S 32W...A 143KT MAXIMUM AT 50S 21W...A
146KT MAXIMUM AT 55S 09W. THE NORTHERN POLAR HAS ITS ENTRANCE AT
41S 107W...ALONG 45S 104W...42S 90W...38S 79W.....33S 62W...
SOUTHERN URUGUAY...38S 44W...40S 32W...A 131KT MAXIMUM AT 43S
25W...EXITING AT 47S 03W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT
22S 106W...ALONG 31S 94W...32S 81W...29S 65W...A 139KT MAXIMUM AT
32S 49W...A 126KT MAXIMUM AT 35S 40W...EXITING AT 35S 24W.

AT 500 HPA...A HIGH NEAR 22S 89W EXTENDS A RIDGE TO THE
SOUTH-SOUTHWEST ALONG 40S 95W...45S 100W...TO 53S 115W. THIS IS
PRESSING AGAINST A TROUGH TO THE SOUTH...AS THE LATER CONFINES TO
SOUTH OF 60S WHILE CENTERING ON A LOW AT 73S 102W. A BROAD TROUGH
TO THE EAST ENVELOPS AREA BETWEEN 75W-20W AND TO THE SOUTH OF 25S.
SHORT WAVE PERTURBATIONS EMBED IN TIS FLOW...WITH ONE STREAMING
ACROSS PATAGONIA AS ANOTHER ENTERS CENTRAL CHILE. A THIRD IS
PULLING ACROSS RIO DE LA PLATA BASIN/URUGUAY. NORTH OVER THE
CONTINENT...AN EAST-TO-WEST RIDGE EXTENDS ACROSS THE TROPICAL
ATLANTIC ALONG 17S INTO BRASIL AND BOLIVIA...WHERE IT SUSTAINS A
TRADE WINDS CAP.

AT LOW LEVELS...A RIDGE OVER THE FAR EASTERN PACIFIC CENTERS ON A
1033 HPA HIGH AT 40S 89W. THIS IS PRESSING AGAINST A TROUGH TO THE
SOUTH...SUSTAINING A TIGHT BELT OF MID/UPPER LATITUDE WESTERLIES
INTO THE SOUTHERN CONE OF SOUTH AMERICA/DRAKE PASSAGE. EMBEDDED IN
THIS FLOW...A POLAR FRONT EXTENDS FROM AN OCCLUDED 984 HPA LOW AT
63S 81W...ALONG A 988 HPA LOW AT 56S 74W...53S 77W...52S 83W...57S
89W...A 988 HPA LOW AT 62S 93W...AND 60S 103W. THIS SUSTAINS
SCATTERED RAINS ACROSS EXTREME SOUTHERN CHILE/TIERRA DEL FUEGO.
ANOTHER FRONT TO THE EAST EXTENDS FROM AN OCCLUDED 982 HPA LOW AT
55S 62W...51S 57W...A 998 HPA LOW AT 48S 60W...40S 66W...TO 37S
81W. AN ELONGATED FRONT TO THE NORTH EXTENDS ALONG A 996 HPA LOW
AT 45S 22W...35S 29W...32S 42W...A 1014 HPA LOW AT 32S 48W...RIO
GRANDE DO SUL TO FORMOSA IN ARGENTINA. THIS SUSTAINS SCATTERED
CONVECTION ACROSS SOUTHERN BRASIL. A RIDGE TO THE SOUTH CENTERS ON
TWO 1021 HPA HIGHS...WITH ONE AT 34S 64W AND THE OTHER AT 30S 63W.
A RIDGE OVER THE SOUTH ATLANTIC CENTERS ON A 1029 HPA HIGH AT 27S
23W.

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