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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1332Z Mar 13, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
932 AM EDT FRI MAR 13 2015

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

SYNOPSIS (VALID FROM MARCH 13 AT 00UTC): AT 200 HPA...THE
SUBTROPICAL RIDGE/BOLIVIAN HIGH CONTINUES CENTERING OFF THE COAST
OF EXTREME NORTHERN CHILE. THIS IS LEADING TO VENTILATION IN ITS
PERIPHERY...FAVORING DIURNAL CONVECTION ACROSS THE ANDES
CENTRAL/SOUTHERN PERU AND TO A LESSER EXTENT NORTHERN CHILE AND
BOLIVIA. TO THE EAST...A ROBUST UPPER TROUGH EXTENDS FROM SANTA
CATARINA INTO MATO GROSSO DO SUL AND THEN EASTERN
BOLIVIA-RONDONIA. ALTHOUGH THIS TROUGH IS WEAKENING...IS STILL
VENTILATING DEEP CONVECTION IN PARTS OF SOUTHEASTERN BRASIL BUT
ESPECIALLY ACROSS SOUTHERN AND CENTRAL PARA/NORTHERN MATO
GROSSO...WHERE AN UPPER DIFFLUENT AND DIVERGENT PATTERN DOMINATES.
DEEP CONVECTION IS ALSO OCCURRING IN A MORE ISOLATED TO SCATTERED
MANNER ACROSS THE AMAZON DELTA...FAVORED BY A DIFFLUENT/DIVERGENT
SOUTHERLY FLOW IN THE WESTERN PERIPHERY OF THE CAVADO DO NORDESTE
THAT CURRENTLY CENTERS OFF THE COAST OF PERNAMBUCO AT 10S 32W.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET EXTENDING
ALONG A 123KT MAXIMA AT 54S 108W...51S 97W...EXITING AT 47S 90W.
IT REFORMS AT 46S 81W ALONG 52S 69W...61S 62W...68S 38W...A 127KT
MAXIMA AT 64S 21W...EXITING AT 62S 20W. THE NORTHERN POLAR JET
FORMS AT 44S 106W EXITING AT 39S 91W. IT REFORMS AT 37S 89W ALONG
40S 73W...EXITING AT 45S 58W. IT REFORMS AT 45S 50W ALONG 43S
36W...AND A 148KT MAXIMA AT 45S 20W. THE SUBTROPICAL JET FORMS AT
31S 84W ALONG 36S 71W...39S 57W.

AT 500 HPA...LARGE TROUGH IN THE WESTERLIES IS APPROACHING THE
SOUTHERN CONE. THE TROUGH EXTENDS FROM A LOW OVER THE
BELLINGSHAUSEN SEA AT 70S 90W AND EXTENDS TO THE NORTH ALONG
80W-85W INTO 30S...OFF THE COAST OF CENTRAL AND SOUTHERN CHILE.
THIS TROUGH IS FOCUSING CYCLONIC VORTICITY OVER PATAGONIA AND
SOUTHERN CHILE. TO THE EAST...A RIDGE EXTENDS FROM URUGUAY TO THE
SOUTHEAST INTO 48S 52W AND THEN 70S 35W. TO THE EAST...A TROUGH
EXITING INTO THE SOUTHEASTERN ATLANTIC STILL EXTENDS ITS TAIL INTO
SOUTHERN BRASIL ALONG 40S 30W...30S 54W INTO A LOW OVER MATO
GROSSO DO SUL. THIS TROUGH IS FOCUSING ITS ENERGY OVER SOUTHERN
AND SOUTHEASTERN BRASIL...AS WELL AS GOIAS AND MATO GROSSO.

THE SURFACE ANALYSIS SHOWS A 980 HPA LOW AT 69S 49W EXTENDING A
FRONT ALONG A 982 HPA LOW AT 65S 54W...59S 58W...A 990 HPA LOW AT
53S 64W...44S 67W...40S 73W...36S 80W. THIS SYSTEM IS GENERATING
SCATTERED POST-FRONTAL COLD CUMULUS THAT ARE GENERATING SCATTERED
SHOWERS IN SOUTHERN CHILE. RAINFALL IS ALSO BEING REPORTED IN
PARTS OF PATAGONIA. A 1010 HPA LOW AT 41S 44W EXTENDS A FRONT
ALONG 40S 51W...A 1006 HPA LOW AT 40S 59W...A 1006 HPA LOW AT 38S
63W. SCATTERED THUNDERSTORMS WERE OCCURRING ALONG THIS BOUNDARY IN
PARTS OF CENTRAL ARGENTINA. A 1013 HPA HIGH CENTERS AT 35S 51W. TO
THE NORTHEAST...A 1002 HPA LOW AT 33S 41W. THIS IS EXTENDING A
TROUGH INTO NORTHERN RIO GRANDE DO SUL.

ARREAGA...INAMHI (ECUADOR)
SCHNEIDER...INMET (BRASIL)
GALVEZ...WPC (USA)