SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
919 AM EDT FRI MAY 10 2013

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

SYNOPSIS (VALID FROM 00 UTC MAY 10): AT 200 HPA...WESTERLY FLOW
WAS WELL ESTABLISHED TO THE SOUTH OF 12S. FURTHER NORTH...A WEAK
CELL OF THE SUBTROPICAL HIGH EXTENDED ALONG THE NORDESTE INGO
SOUTHERN PARA/NORTHERN MATO GROSSO. UPPER DIVERGENCE HAD WEAKENED
WITH RESPECT TO PREVIOUS DAYS. BEST VENTILATION WAS CONCENTRATING
OVER CEARA WESTWARD INTO THE AMAZON DELTA/EASTERN PARA. THIS WAS
VENTING WIDESPREAD DIURNAL CONVECTION OVER THESE REGIONS.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET EXTENDING
ALONG A 142KT MAXIMA AT 53S 112W...A 134KT MAXIMA AT 55S
101W...EXITING AT 50S 87W...REFORMING AT 48S 81W...A 138KT MAXIMA
AT 54S 60W...EXITING AT 54S 39W. THE NORTHERN POLAR EXTENDED ALONG
A 126KT MAXIMA AT 46S 118W...49S 106W...44S 92W...EXITING AT 39S
80W. IT REFORMED AT 45S 68W ALONG A 130KT MAXIMA AT 47S 49W...44S
41W...37S 34W...A 132KT MAXIMA AT 35S 25W. THE SUBTROPICAL JET
FORMED AT 25S 88W ALONG A 127KT MAXIMA AT 31S 77W...A 126KT MAXIMA
AT 36S 66W...38S 51W...33S 336W...31S 21W.

AT 500 HPA...A NORTHERN STREAM TROUGH EXTENDED ALONG 40S 78W INTO
18S 90W. THE TROUGH WAS FOCUSING ITS ENERGY ACROSS SOUTHERN CHILE.
A WEAK SHORT WAVE TROUGH HAD CROSSED THE ANDES WHILE EXTENDING
FROM NEUQUEN INTO THE CHACO. THIS SYSTEM WAS FOCUSING ITS ENERGY
ACROSS CENTRAL ARGENTINA. TO THE EAST...A BROAD RIDGE EXTENDED
OVER SOUTHERN BRASIL WHILE A BROAD TROUGH WAS EXITING THE AREA
EXTENDING ALONG 30W. IN THE SOUTHERN STREAM...A BROAD TROUGH
EXTENDED OVER ANTARCTICA/DRAKE PASSAGE WITH SHORT WAVE TROUGHS
REVOLVING AROUND MAIN AXIS. ONE EXTENDED OFF THE COAST OF CHILE
ALONG 85W.

THE SURFACE ANALYSIS SHOWS A 978 HPA LOW AT 52S 77W EXTENDING A
FRONT ALONG 45S 81W...41S 89W. A 100 HPA LOW AT 47S 53W EXTENDED A
FRONT ALONG 44S 57W...A 1002 HPA LOW AT 44S 65W...NORTHERN
PATAGONIA...NEUQUEN...A 1008 HPA LOW AT 39S 73W...32S 76W...25S
85W. RAINFALL WAS OCCURRING OVER COASTAL CHILE. A 1023 HPA HIGH
CENTERED AT 26S 49W...RIDGING TO A 1021 HPA HIGH AT 25S 39W. A
1002 HPA LOW AT 39S 12W EXTENDED A FRONT ALONG 28S 17W...19S
29W...SOUTHERN BAHIA IN BRASIL. RAINFALL WAS BEING REPORTED WITH
THIS SYSTEM.

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