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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1350Z Apr 19, 2018)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
950 AM EDT THU APR 19 2018

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

SYNOPSIS (VALID FROM APR 19 AT 0000 UTC): AT 200 HPA...A
NEGATIVELY TILTED TROUGH EXTENDS ACROSS THE EASTERN TROPICAL
PACIFIC...WITH AXIS NORTHEAST FROM 18S 90W TO ECUADOR. THIS IS
ENHANCING CONVECTION ACROSS NORTHERN JUNGLE OF PERU-SOUTHERN
AMAZONAS IN COLOMBIA AND EASTERN PORTIONS OF ECUADOR. A SHORT WAVE
RIDGE OVER ACRE/AMAZONAS IN BRASIL SEPARATES THIS TROUGH FROM
ANOTHER OVER BOLIVIA. THE LATTER SUSTAINS DEEP CONVECTION ACROSS
MATO GROSSO-MATO GROSSO DO SUL AND SOUTHERN PARA.

AT 250 HPA...THE SOUTHERN POLAR LIES ALONG A 149KT MAXIMUM AT 59S
122W...51S 114W...47S 102W...48S 89W...A 144KT MAXIMUM AT 54S
73W...57S 59W...EXITING AT 54S 44W. THE NORTHERN POLAR LIES ALONG
46S 120W...43S 109W...A 132KT MAXIMUM AT 43S 103W...43S 88W...45S
78W...49S 70W...EXITING AT 49S 61W. A BRANCH TO THE NORTH HAS ITS
ENTRANCE AT 30S 80W...THEN ALONG 34S 71W...37S 62W...38S
54W...EXITING AT 36S 43W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT
21S 41W...THEN ALONG 22S 30W...24S 20W...A 138KT MAXIMUM AT 31S
07W...AND 32S 00W. AT 200 HPA...THE SUBEQUATORIAL JET LIES ALONG
14S 121W...16S 110W...EXITING AT 15S 99W.

AT 500 HPA...BROAD TROUGH REMAINS THE DOMINANT FEATURE OVER THE
SOUTHEAST PACIFIC...WITH AXIS ENVELOPING AREA BETWEEN 130W-65W AND
TO THE SOUTH OF 36S. THIS IS FOCUSING SHORT WAVE ENERGY AND DEEP
SUBTROPICAL MOISTURE ACROSS EXTREME SOUTHERN PORTIONS OF
CHILE-TIERRA DEL FUEGO. THIS IS PHASING WITH A SHORT WAVE TROUGH
TO THE NORTH THAT EXTENDS FROM 38S 70W TO 24S 90W. THIS IS
SHEARING SHORT WAVE ENERGY ACROSS CENTRAL REGIONS OF CHILE TO
ARGENTINA...TRIGGERING DEEP CONVECTION ACROSS THE BUENOS AIRES
PROVINCE. THE DEEP TROUGH IS INDUCING A RIDGE TO THE EAST THAT
EXTENDS FROM 40S 60W...ACROSS 50S 55W...60S 45W...TO 70S 30W. ALSO
OVER THE ATLANTIC...ON THE NORTHERN STREAM...A TROUGH EXTENDS
ALONG 30S 20W TO RIO DE JANEIRO.

AT LOW LEVELS...ON THE NORTHERN STREAM FLOW...A RIDGE EXTENDS OVER
THE EASTERN SOUTH PACIFIC. THIS ANCHORS ON TWO 1025 HPA
HIGHS...WITH ONE AT 31S 87W AND THE OTHER AT 34S 119W. BROAD
TROUGH TO THE SOUTH DOMINATES THE SOUTHEAST PACIFIC WHILE
CENTERING ON AN OCCLUDED 942 HPA LOW AT 65S 82W. POLAR FRONTS
REVOLVE AROUND THIS AXIS...WITH ONE EXTENDING FROM A 962 HPA LOW
AT 63S 66W...A 974 HPA LOW AT 62S 61W...59S 60W...56S 66W...53S
71W...50S 76W...A 982 HPA LOW AT 50S 81W...47S 84W...TO 46S 88W.
ANOTHER FRONT TO THE NORTH EXTENDS ALONG A 986 HPA LOW AT 56S
59W...54S 60W...53S 62W...A 986 HPA LOW AT 54S 64W...52S 65W...51S
66W...A 990 HPA LOW AT 49S 69W...CENTRAL PATAGONIA-PUERTO MONTT
CHILE...A 990 HPA LOW AT 47S 78W...45S 80W...45S 82W...A 994 HPA
LOW AT 45S 86W...41S 88W...38S 97W...AND 36S 106W. THIS FAVORS
SCATTERED CONVECTION ACROSS SOUTHERN REGIONS OF CHILE. FARTHER
EAST...OVER THE SOUTH ATLANTIC...A 966 HPA LOW AT 54S 19W ANCHORS
A TROUGH ON THE SOUTHERN STREAM FLOW. THIS SUSTAINS A POLAR FRONT
THAT EXTENDS ALONG A 994 HPA LOW AT 46S 15W...44S 17W...43S
24W...A 1010 HPA LOW AT 43S 28W...40S 35W...39S 41W...A 1018 HPA
LOW AT 39S 46W...37S 48W...36S 52W...BUENOS AIRES PROVINCE TO
CENTRAL ARGENTINA. THIS FAVORS SCATTERED DEEP CONVECTION. A SHORT
WAVE RIDGE TO THE NORTH CENTERS ON A 1025 HPA HIGH AT 31S 36W. A
FRONT TO THE NORTH EXTENDS ALONG A 1014 HPA LOW AT 26S 16W...23S
17W...20S 23W... SOUTHERN BAHIA TO MINAS GERAIS. THIS IS ENHANCING
COASTAL CONVERGENCE.

BALBINO...INMET (BRASIL)
DIAZ...INUMET (URUGUAY)
DAVISON/GALVEZ...WPC (USA)