SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
940 AM EDT THU MAY 16 2013

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

SYNOPSIS (VALID FROM 00 UTC MAY 16): THE 200 HPA ANALYSIS SHOWS A
WEAK CELL OF THE SUBTROPICAL RIDGE ESTABLISHING ACROSS AMAZONAS IN
BRASIL. THIS WAS VENTING CONVECTION IN THE PERIPHERY ACROSS
AMAZONAS...NORTHERN PERU AND INTO THE SOUTHERN GUIANAS.

JET ANALYSIS AT 250 HPA SHOWS THE SOUTHERN POLAR JET FORMING AT
61S 82W ALONG 60S 67W...EXITING AT 50S 66W. THE NORTHERN POLAR JET
FORMED AT 32S 72W ALONG A 135KT MAXIMA AT 33S 60W...39S 43W...46S
21W. THE SUBTROPICAL JET FORMED AT 12S 99W ALONG 13S 85W...19S
73W...EXITING AT 22S 74W. IT REFORMED AT 26S 62W ALONG A 132KT
MAXIMA AT 31S 50W...A 139KT MAXIMA AT 36S 40W...A 127KT MAXIMA AT
37S 30W.

AT 500 HPA...A POTENT TROUGH EXTENDED FROM A LOW AT58S 28W INTO
THE RIO DE LA PLATA BASIN. THIS TROUGH WAS FOCUSING ITS ENERGY
ACROSS CENTRAL ARGENTINA AND...ESPECIALLY...THE BUENOS AIRES
PROVINCE. TO THE WEST...A RIDGE EXTENDED FROM 38S 90W INTO THE
DRAKE PASSAGE. TO THE NORTH...A TROUGH EXTENDED FROM CENTRAL CHILE
INTO 12S 100W.

SURFACE ANALYSIS SHOWS A 1008 HPA LOW AT 59S 62W EXTENDING A FRONT
ALONG 53S 65W...48S 68W. A 1006 HPA LOW AT 39S 55W EXTENDED INTO
THE SOUTHERN BUENOS AIRES PROVINCE PRODUCING NUMEROUS SHOWERS. A
998 HPA LOW AT 40S 42W EXTENDED A FRONT ALONG 32S
48W...CORRIENTES...PILCOMAYO RIVER. SHOWERS AND DRIZZLE WERE
OCCURRING BEHIND THE FRONT. A 996 HPA LOW AT 42S 37W EXTENDED A
FRONT ALONG 35S 40W...29S 49W...MISIONES...A 1014 HPA LOW IN
CENTRAL PARAGUAY...CHACO BOLIVIANO. THUNDERSTORMS WERE OCCURRING
NEAR AND AHEAD OF THIS BOUNDARY. A 1028 HPA POLAR HIGH CENTERED AT
28S 63W. A 1027 HPA HIGH CENTERED AT 34S 67W. A 1037 HPA HIGH
CENTERED AT38S 89W.

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