SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
926 AM EDT FRI MAY 17 2013

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

SYNOPSIS (VALID FROM 00 UTC MAY 17): AT 200 HPA...UPPER LEVEL
ANALYSIS SHOWS CELL OF THE SUBTROPICAL RIDGE GRADUALLY BECOMING
BETTER ORGANIZED WHILE CENTERING ON A CLOSED HIGH OVER PARA IN
BRASIL. AS THE RIDGE STRENGTHENS...AN INDUCED TROUGH IS AMPLIFYING
ACROSS NORTHEAST STATES OF BRASIL ALONG 10S 40W TO THE AMAZON
RIVER DELTA REGION. ORGANIZED CONVECTION IS CLUSTERING TO THE
NORTH...ALONG THE NEAR EQUATORIAL TROUGH OVER THE
GUIANAS-VENEZUELA TO COLOMBIA. TO THE WEST...A POTENT TROUGH
EXTENDED OVER THE EASTERN PACIFIC AIDING RAIN/SNOW SHOWERS ACROSS
THE SOUTHERN PERUVIAN/BOLIVIAN ANDES...AND VENTILATING
THUNDERSTORMS ACROSS THE PERUVIAN JUNGLE/EXTREME WESTERN BRASIL.

THE SOUTHERN POLAR JET EXTENDS ALONG A 146KT MAXIMA AT 48S
122W...A 139KT MAXIMA AT 51S 112W...A 126KT MAXIMA AT 51S
101W...50S 84W...EXITING AT 50S 72W. THE NORTHERN POLAR JET FORMED
AT 20S 87W ALONG 26S 78W...31S 68W...A 134KT MAXIMA AT 32S
54W...33S 40W...A 157KT MAXIMA AT 39S 29W...A 200KT MAXIMA AT 44S
22W. THE SUBTROPICAL JET FORMED AT 15S 98W ALONG 14S 91W...A 128KT
MAXIMA AT 16S 84W...A 146KT MAXIMA AT 22S 76W...A 147KT MAXIMA AT
26S 67W...A 137KT MAXIMA AT 278S 57W...A 142KT MAXIMA AT 27S
42W...28S 37...EXITING AT 33S 24W.

AT 500 HPA...THE MID LEVEL ANALYSIS SHOWS A TIGHT BELT OF MID
LATITUDE WESTERLIES ACROSS THE EASTERN PACIFIC TO THE SOUTHERN
CONE...WITH PROGRESSIVE SHORT WAVE TROUGH EMBEDDING IN THIS FLOW
QUICKLY PULLING TOWARDS THE SOUTHERN CONE. IN THIS FLOW...SHORT
WAVE TROUGH IS INITIALIZED ALONG 80W AND SOUTH OF 50S...WHILE
ANOTHER IS PULLING ALONG 92W/94W. AS THEY APPROACH THE
CONTINENT...THE PERTURBATIONS ARE PRESSING AGAINST A SHORT WAVE
RIDGE THAT EXTENDS FROM TIERRA DEL FUEGO TO THE ANTARCTIC
PENINSULA. ON THE NORTHERN STREAM...MEANWHILE...A TROUGH EXTENDS
ALONG 30S 80W...A LOW AT 23S 85W...TO 15S 95W. FARTHER EAST...OVER
THE SOUTH ATLANTIC...A WANING TROUGH LIES BETWEEN 50W-20W AND TO
THE SOUTH OF 25S.

THE SURFACE ANALYSIS SHOWS A 996 HPA LOW AT 54S 60W EXTENDING A
FRONT ALONG 51S 65W...A 1008 HPA LOW AT 51S 71W...46S 73W...A 1014
HPA LOW AT 48S 78W...A 1014 HPA LOW AT 45S 86W. A 1025 HPA POLAR
HIGH CENTERED AT 31S 62W. TO THE EAST...A 1012 HPA HIGH AT 37S 25W
EXTENDED A FRONT ALONG 30S 33W...23S 45W...20S 53W...14S 60W.
RAINFALL WAS OCCURRING AHEAD OF THIS FRONT...WHILE STRONG
THUNDERSTORMS WERE OCCURRING OVER BOLIVIA AND PERU...ASSOCIATED
WITH A POTENT SOUTHERLY SURGE.

MAQUEDA...DINAC (PARAGUAY)
SILVA DE SOUZA...INMET (BRASIL)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)