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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1311Z Apr 10, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
911 AM EDT FRI APR 10 2015

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

SYNOPSIS (VALID FROM APRIL 10 AT 00UTC): AT 200 HPA...A CROSS
EQUATORIAL TROUGH LIES OVER THE FAR EASTERN PACIFIC...WITH AXIS
SOUTH ALONG 10N 90W...GALAPAGOS ISLANDS TO 14S 95W. EAST OF THIS
AXIS...A SHORT WAVE TROUGH LIES OFF THE NORTHERN COAST OF CHILE TO
10S 80W. THIS IS FOCUSING A JET MAXIMA ACROSS SOUTHERN
PERU...WHERE IT FAVORS A DIVERGENT PATTERN ALOFT. IT ALSO FAVORS
ORGANIZED CONVECTION ACROSS THE CENTRAL-SOUTHERN SIERRA OF PERU TO
THE ALTIPLANO OF BOLIVIA. EAST OVER THE CONTINENT...A NARROW RIDGE
EXTENDS ALONG 10S 30W...13S 40W...TO RONDONIA IN BRASIL. THE RIDGE
ALOFT UNDERCUTS A TROUGH TO THE NORTH...AS THE LATTER CENTERS ON A
CLOSED LOW OVER AMAPA IN BRASIL. THE TROUGH IS ENHANCING
CONVECTION ALONG THE NORTH COAST OF BRASIL...AND WESTWARD INTO
PARA-AMAZONAS IN BRASIL.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET EXTENDING
ALONG A 123KT MAXIMA AT 51S 126W...46S 107W...51S 92W...EXITING AT
55S 81W. THE NORTHERN POLAR JET FORMS AT 42S 110W ALONG 45S
95W...EXITING AT 48S 84W. ANOTHER BRANCH FORMS AT 41S 92W ALONG
43S 71W...EXITING AT 42S 55W. THE SUBTROPICAL JET FORMS AT 30S
105W ALONG 37S 88W...EXITING AT 37S 69W. IT REFORMS AT 27S 56W
ALONG 27S 39W...28S 26W...32S 12W...EXITING AT 36S 01W.

AT 500 HPA...BROAD TROUGH DOMINATES FLOW OVER THE EASTERN
PACIFIC...WITH AXIS BETWEEN 120W-85W TO 20S. SHORT WAVE TROUGH IS
PULLING AHEAD OF THIS AXIS...STREAMING ACROSS SOUTHERN CHILE/DRAKE
PASSAGE AS ANOTHER MOVES ACROSS THE MALVINAS/FALKLAND ISLANDS.
THESE PERTURBATIONS ARE PRESSING AGAINST A RIDGE TO THE
EAST...WITH AXIS ALONG 40S 47W...ALONG 50S 48W...60S 50W...TO THE
ANTARCTIC PENINSULA. BROAD TROUGH TO THE EAST BOUNDS BETWEEN
40W-10W AND TO THE SOUTH OF 20S...MEANWHILE ANCHORING ON A CLOSED
LOW AT 48S 23W.

THE SURFACE ANALYSIS SHOWS A 970 HPA OCCLUDED LOW AT 58S 91W
EXTENDING A FRONT ALONG A 986 HPA LOW AT 56S 82W...53S 80W...A 994
HPA LOW AT 52S 84W...48S 89W. A 974 HPA LOW AT 63S 88W EXTENDS A
FRONT ALONG A 978 HPA LOW AT 62S 80W...60S 73W...53S 69W...A 1006
HPA LOW AT 51S 68W...44S 64W. A 1006 HPA LOW AT 49S 54W EXTENDS A
FRONT ALONG 43S 48W...39S 57W...37S 67W. A 1014 HPA LOW AT 25S 21W
EXTENDS A FRONT ALONG 19S 25W...17S 31W...15S 39W...18S 46W.
SCATTERED THUNDERSTORMS WERE OCCURRING NORTH OF THIS BOUNDARY.

CALLE...UNALM (PERU)
CHARPENTIER...DMC (CHILE)
SCHNEIDER...INMET (BRASIL)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)