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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1316Z Apr 11, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
916 AM EDT FRI APR 11 2014

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

MODEL DISCUSSION (VALID FROM 11 APRIL 00UTC): ANALYSIS AT 200 HPA
SHOWS THE SUBTROPICAL RIDGE NOW CENTERING ON A CLOSED HIGH OVER
BRASIL NEAR 20S 50W...WITH AXIS NORTHWEST ACROSS MATO GROSSO/
RONDONIA TO CENTRAL PERU. THE SUBEQUATORIAL RIDGE TO THE
NORTH...MEANWHILE...EXTENDS WEST ACROSS THE TROPICAL ATLANTIC
ALONG A CLOSED HIGH NEAR 05N 30W...THE GUIANAS TO VENEZUELA. IN A
DIFFLUENT PATTERN ALOFT...THIS IS VENTING DEEP CONVECTION ACROSS
NORTHEAST BRASIL...WITH MOST ACTIVE ALONG THE NORTH COAST AS
ENHANCED BY THE ATLANTIC ITCZ.

AT 250 HPA...THE SOUTHERN POLAR LIES ALONG 56S 120W...58S
101W...52S 91W...47S 88W...45S 83W...46S 75W...EXITING AT 47S 77W.
IT REFORMS AT 55S 66W...ALONG 67S 60W...68S 39W...A 133KT MAXIMUM
AT 65S 29W...56S 17W...51S 18W...EXITING AT 44S 21W. THE NORTHERN
POLAR HAS ITS ENTRANCE AT 50S 111W...ALONG 50S 100W...A 156KT
MAXIMUM AT 45S 91W...43S 83W...42S 77W...EXITING AT 38S 68W. THE
JET REFORMS AT 37S 62W...ALONG A 143KT MAXIMUM AT 40S 54W...43S
48W...EXITING AT 49S 35W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT
30S 117W...THEN ALONG 34S 113W...40S 109W...44S 101W...42S
92W...37S 82W...EXITING AT 34S 79W. IT REFORMS AT 23S 75W...ALONG
24S 70W...27S 65W...RIO DE LA PLATA...36S 46W...EXITING AT 35S 37W.

THE 500 HPA ANALYSIS SHOWS MID LEVEL RIDGE WITH AXIS SOUTH ACROSS
THE EASTERN PACIFIC ALONG 100W TO 60S. EAST OF THIS AXIS A
BROAD/LOW AMPLITUDE TROUGH EXTENDS BETWEEN 980W-40W AND TO THE
SOUTH OF 37S. SHORT WAVE PERTURBATIONS REVOLVE AROUND THIS
AXIS...WITH ONE EXTENDING FROM THE BELLINGSHAUSEN SEA TO TIERRA
DEL FUEGO...WHILE ANOTHER IS LIFTING ACROSS 51S 87W. A THIRD
PERTURBATION TO THE EAST ORIGINATES ON A CLOSED LOW NEAR 51S 55W
TO THE BUENOS AIRES PROVINCE. TRAILING ON THE NORTHERN STREAM...A
SHORT WAVE TROUGH IS MOVING INTO NORTHERN CHILE...WHILE SHEARING
SHORT WAVE ENERGY ACROSS THE ANDES INTO THE NORTHWEST PROVINCES IN
ARGENTINA. THESE ARE THEN PRESSING AGAINST A LONG WAVE BLOCKING
RIDGE THAT EXTENDS SOUTH ALONG 35W/40W.

AT LOW LEVELS...THE ANALYSIS SHOWS A BROAD RIDGE ON THE NORTHERN
STREAM FLOW OVER THE FAR EASTERN PACIFIC...CENTERING ON A 1029 HPA
HIGH AT 32S 96W AND A 1029 HPA HIGH AT 33S 88W. A BROAD TROUGH
DOMINATES THE SOUTHERN CONE...WITH POLAR FRONTS THAT REVOLVE
AROUND THIS AXIS. ONE EXTENDS FROM AN OCCLUDED 970 HPA LOW AT 64S
72W...ALONG A 982 HPA LOW AT 66S 61W...54S 63W...A 996 HPA LOW AT
52S 67W...44S 65W...43S 70W...A 1008 HPA LOW AT 44S 77W...41S
76W...39S 81W...AND 40S 93W. ANOTHER FRONT EXTENDS FROM A 1000 HPA
LOW AT 49S 85W...ALONG A 998 HPA LOW AT 50S 83W...46S 78W...TO 43S
87W. THESE COMBINE IN SUPPORT OF MODERATE CONVECTION ACROSS
SOUTHERN REGIONS OF CHILE. OVER THE ATLANTIC...AN OCCLUDED 978 HPA
LOW AT 49S 55W EXTENDS A FRONT ALONG A 980 HPA LOW AT 52S
54W...44S 42W...A 1014 HPA LOW AT 38S 39W...35S 35W...29S
40W...27S 47W...A 1010 HPA LOW AT 27S 54W...TO JUJUY/SALTA IN
NORTHWEST ARGENTINA. THIS SUSTAINS ORGANIZED DEEP CONVECTION
ACROSS CENTRAL-SOUTHEAST PARAGUAY AND THE MESOPOTAMIA VALLEY.

ITA...SENAMHI (PERU)
FERNANDES...INMET (BRASIL)
DAVISON...WPC (USA)